anesthesia of obestetric for 3rd year students .pptx

Anesthesia for 3rd TMP

1. OBSTETRICAL ANESTHESIA By Kurabachew Mengistu

2. Dr. John Snow 2 born 15 March 1813 in England . Queen Victoria was given chloroform by John Snow for the birth of her eighth child and this did much to popularize the use of pain relief in labor.

3. Does Labor Pain Need Analgesia? 3

4. Chapter 3 16 Unto the woman he said, I will greatly multiply thy sorrow and thy conception; in sorrow thou shalt bring forth children; and thy desire shall be to thy husband, and he shall rule over thee 16 ለሴቲቱም አለ፦ በፀነስሽ ጊዜ ጭንቅሽን እጅግ አበዛለሁ፤ በጭንቅ ትወልጃለሽ፤ ፈቃድሽም ወደ ባልሽ ይሆናል፥ እርሱም ገዥሽ ይሆናል The name “cesarean” is probably derived, not from Julius Caesar, but from the Latin caedere , to cut. 4

5. Analgesia for Labor and Delivery Always controversial! “Birth is a natural process” Women should suffer!! Concerns for mother’s safety Concerns for baby Concerns for effects on labor 5

6. Why have a Caregiver dedicated to pain management during labor and delivery? Labor and delivery result in severe pain for most women. In an attempt to quantify this pain, parturients were asked to rate their pain during labor. These results were then compared to values obtained from patients in a general pain clinic and emergency department. The pain of childbirth was greater than a fractured arm and cancer pain . Only causalgia and amputation of a digit exceeded the pain of labor and delivery. Parturients described the pain as sharp, cramping, aching, throbbing, stabbing, hot, shooting, and tight. 6

7. What is the cause of labor pain in stage 1? What type of pain is it? The pain resulting from the first stage of labor is primarily due to dilatation of the cervix with consequent distention and stretching. As the uterus contracts, the fetal head pushes against the cervix and causes dilatation. Therefore, stage 1 pain generally occurs only during uterine contraction. 7

8. While the majority of pain during this stage occurs from the fetal head pushing against the cervix, there is also pain from pressure and stretching of the uterine muscles, which activate the high-threshold mechanoreceptors In the first stage of labor, the pain is visceral It is strong and dull, and occurs over the lower abdomen between the umbilicus and the symphysis pubis, laterally over the iliac crest, and posteriorly in the skin and soft tissue over the lower lumbar spines 8

9. The location of labor pain in stage 1?? The location of this pain is explained by the concept of referred pain. The sensory nerves of the uterus and cervix leave the cervix and join the sympathetic nerves as they pass through the hypogastric plexus to the sympathetic chain, synapsing within the dorsal horn of the spinal cord at T10, T11, T12, and L1 . 9

10. This area of the spinal cord receives not only these visceral high-threshold afferents, but also the low-threshold cutaneous afferents of the skin from T10, T11, T12, and L1. With the convergence of both somatic and visceral fibers within the same area of the spinal cord, the parturient interprets the uterine pain as originating from the cutaneous afferents of these spinal segments. The pain is referred to this area. 10

11. What is the cause of labor pain in stage 2? What type of pain is it ? Second-stage pain occurs as the fetus descends through the birth canal. This results in stretching and tearing of fascia, skin, and subcutaneous tissue. This somatic pain is transmitted primarily through the pudendal nerve. The pudendal nerve is derived from the anterior primary divisions of sacral nerves, S2, S3 and S4. Of note, the fetus often begins to descend during the first stage of labor. During the transitional stage of the first stage, it is not uncommon for the mother to experience both visceral and somatic pain 11

12. Labor Pain at different Stages of Labor 12 Eltzschig , Leiberman , Camann , NEJM 348; 319:2003

13. The Physiology of Pain in Labor 1 st stage of labor – mostly visceral Dilation of the cervix and distention of the lower uterine segment Dull, aching and poorly localized Slow conducting, visceral C fibers, enter spinal cord at T10 to L1 2 nd stage of labor – mostly somatic Distention of the pelvic floor, vagina and perineum Sharp, severe and well localized Rapidly conducting A-delta fibers, enter spinal cord at S2 to S4 13

14. Pain Pathways of Labor 14

15. 15 Labor Cardiovascular Urinary Neuro -endocrine post-traumatic stress syndrome Respiratory Gastro-intestinal

16. Potential effects of maternal hyperventilation and subsequent hypocarbia on oxygen delivery to the fetus 16

17. 17 The adverse effects of pain in labour on mother and fetus

18. 18 Pathways of labor pain

19. How do psychological factors influence labor pain? While labor is a physiologic process, psychological factors also affect the pain. Anxiety is a particularly powerful factor in reducing pain tolerance. HOW?? Attention, the selective orientation of the receptor system to one source or pattern of stimulation to the exclusion of other sources, either enhances or diminishes the painful experience. Motivation is another psychodynamic mechanism that can have a marked influence on the physiologic, behavioral, and affective aspects of pain. Breathing exercises divert the mother's attention from the pain of contractions. 19

20. Introduction Pain relief in labor presents unique problems. Labor begins without warning, and obstetrical anesthesia may be required within minutes of a full meal. Vomiting with aspiration of gastric contents is a constant threat that poses serious maternal morbidity and mortality. Moreover, a host of disorders unique to pregnancy, such as preeclampsia, placental abruption, and chorioamnionitis, all superimposed on unique physiological adaptations of pregnancy, are directly affected by the choice of analgesia and anesthesia selected. 20

21. Introduction Anesthesia complications caused 1.6 percent of pregnancy-related maternal deaths Several factors likely have contributed to improved safety of obstetrical anesthesia; The recent trend toward increased use of regional analgesia, rather than general anesthesia, may be the most significant factor 21

22. GENERAL PRINCIPLES A woman’s request for labor pain relief is sufficient medical indication for its provision. It is the responsibility of the obstetrician or certified nurse-midwife, in consultation with an anesthetist, if appropriate, to formulate a suitable plan for pain relief. Identification of any of the risk factors, should prompt consultation with anesthesia personnel to permit a joint management plan. This plan should include strategies to minimize the need for emergency anesthesia in women for whom such anesthesia would be especially hazardous. 22

23. Maternal Risk Factors That Should Prompt Anesthesia Consultation Marked obesity Severe edema or anatomical abnormalities of face, neck, or spine, including trauma or surgery Abnormal dentition, small mandible, or difficulty opening mouth Extremely short stature, short neck, or arthritis of the neck Goiter Serious maternal medical problems, such as cardiac, pulmonary, or neurological disease Bleeding disorders Severe preeclampsia Previous history of anesthetic complications Obstetrical complications likely to lead to operative delivery—e.g., placenta previa or higher-order multiple gestation 23

24. Goals of Labour Analgesia Dramatically reduce pain of labor Should allow parturient to participate in birthing experience Minimal motor block to allow ambulation Minimal effects on fetus Minimal effects on progress of labor 24

25. Types of Labor Analgesia Non-pharmacological analgesia Pharmacological Regional Anesthesia/Analgesia General Anesthesia 25

26. NONPHARMACOLOGICAL METHODS OF PAIN CONTROL Fear potentiates pain. Make a woman who is free from fear, and develop confidence in the obstetrical staff that cares for her Avoid emotional tension Teaching pregnant women relaxed breathing and their labor partners psychological support techniques. Motivation The presence of a supportive spouse The Lamaze technique , one of the most popular, coaches the parturient to take a deep breath at the beginning of each contraction followed by rapid, shallow breathing for the duration of the contraction 26

27. ANALGESIA AND SEDATION DURING LABOR When uterine contractions and cervical dilatation cause discomfort, pain relief with a narcotic such as meperidine , plus one of the tranquilizer drugs such as promethazine , is usually appropriate. With a successful program of analgesia and sedation, the mother should rest quietly between contractions. In this circumstance, discomfort usually is felt at the acme of an effective uterine contraction, but the pain is generally not unbearable . 27

28. Neuraxial Opioids The following opioids have been used: Morphine,fentanyl,sufentanil,meperidine, diamorphine. Spinal opioid dosages for labor and delivery. 28

29. Parenteral Agents for Labor Pain Agent Usual Dose Frequency Onset Neonatal Half-Life Meperidine 25–50 mg (IV) 1–2 hr 5 min 13–22.4 hr   50–100 mg (IM) 2–4 hr 30–45 min 63 hr for active metabolites Fentanyl 50–100 ug (IV) 1 hr 1 min 5.3 hr Nalbuphine 10 mg (IV or IM) 3 hr 2–3 min (IV) 4.1 hr       15 min (IM)   Butorphanol 1–2 mg (IV or IM) 4 hr 1–2 min (IV) Not known       10–30 min (IM) Similar to nalbuphine in adults Morphine 2–5 mg (IV) 4 hr 5 min 7.1 hr   10 mg (IM)   30–40 min   29

30. Butorphanol ( Stadol ): This synthetic narcotic, given in 1- to 2-mg doses, compares favorably with 40 to 60 mg of meperidine. The major side effects are somnolence, dizziness, and dysphoria. Neonatal respiratory depression is reported to be less than with meperidine, but care must be taken that the two drugs are not given contiguously because butorphanol antagonizes the narcotic effects of meperidine Fentanyl: This short-acting and potent synthetic opioid may be given in doses of 50 to 100mcg intravenously every hour. Its main disadvantage is a short duration of action, which requires frequent dosing or the use of a patient-controlled intravenous pump. 30

31. Efficacy and Safety of Parenteral Agents Meperidine is the most common opioid used worldwide for pain relief in labor. There is no convincing evidence demonstrating that alternative opioids are better. There is no evidence that parenteral opioids influence the length of labor or need for obstetrical intervention. Epidural analgesia provides superior pain relief. Intravenous and intramuscular sedation are not without risks. Maternal anesthetic-related deaths were from such sedation-aspiration, inadequate ventilation, and over dosage. Moreover, meperidine or other narcotics used during labor may cause newborn respiratory depression Meperidine is usually administered early in labor when delivery is not expected for at least 4 h 31

32. Narcotic Antagonists Naloxone is a narcotic antagonist capable of reversing respiratory depression induced by opioid narcotics. It acts by displacing the narcotic from specific receptors in the central nervous system. Withdrawal symptoms may be precipitated in recipients who are physically dependent on narcotics. For this reason, naloxone is contraindicated in a newborn of a narcotic-addicted mother. Naloxone, along with proper ventilation, may be given to reverse respiratory depression in a newborn infant whose mother received narcotics. 32

33. Nitrous Oxide A self-administered mixture of 50-percent nitrous oxide (N 2 O) and oxygen provides satisfactory analgesia during labor for many women. Some preparations are premixed in a single cylinder ( Entonox ), and in others, a blender mixes the two gases from separate tanks ( Nitronox ). The gases are connected to a breathing circuit through a valve that opens only when the patient inspires. 33

34. Nitrous Oxide The use of intermittent nitrous oxide for labor pain ,the following technique suggested: Instruct the woman to take slow deep breaths and to begin inhaling 30 seconds before the next anticipated contraction and to cease when the contraction starts to recede. Remove the mask between contractions and encourage her to breathe normally. No one but the patient or knowledgeable personnel should hold the mask. Instruct a caregiver to remain in verbal contact with the patient. Provide the expectation that the pain will likely not be eliminated, but that the gas should provide some relief. Ensure intravenous access, pulse oximetry , and adequate scavenging of exhaled gases. Use with additional caution after previous opioid administration because the combination can more easily render a woman unconscious and unable to protect her airway. 34

35. Regional anesthetic techniques, were introduced to obstetrics in 1900, when Oskar Kreis described the use of spinal anesthesia. Unfortunately he was an obstetrtian 35

36. Regional Anesthesia/Analgesia Various nerve blocks have been developed over the years to provide pain relief during labor and delivery. They are correctly referred to as regional analgesics. Epidural Spinal Combined Spinal Epidural (CSE) Continuous spinal analgesia Paracervical block Lumbar sympathetic block Pudendal block Perineal infiltration 36

37. 37 Pathways of labor pain

38. Uterine Innervation The motor pathways to the uterus leave the spinal cord at the level of the T7 and T8 vertebrae. Theoretically, any method of sensory block that does not also block the motor pathways to the uterus can be used for analgesia during labor. 38

39. Lower Genital Tract Innervation Pain with vaginal delivery arises from stimuli from the lower genital tract. These are transmitted primarily through the pudendal nerve, the peripheral branches of which provide sensory innervation to the perineum, anus, and the more medial and inferior parts of the vulva and clitoris. The pudendal nerve passes beneath the posterior surface of the sacrospinous ligament just as the ligament attaches to the ischial spine. The sensory nerve fibers of the pudendal nerve are derived from the ventral branches of the S2 through S4 nerves . 39

40. Anesthetic Agents Some preparations that contain dilute epinephrine to prolong the action of the anesthetic will also cause symptoms when a test dose is inadvertently given intravenously. The dose of each agent varies widely and is dependent on the particular nerve block and physical status of the woman. The onset, duration, and quality of analgesia can be enhanced by increasing the dose. This can be done safely by only incrementally administering small-volume boluses of the agent and by carefully monitoring for early warning signs of toxicity. Administration of these agents must be followed by appropriate monitoring for adverse reactions, and equipment and personnel to manage these reactions must be immediately available. 40

41. Most often, serious toxicity follows inadvertent intravenous injection. For this reason, when epidural analgesia is initiated, dilute epinephrine is sometimes added and given as a test dose. A sudden significant rise in the maternal heart rate or blood pressure immediately after administration suggests intravenous catheter placement. Personnel using these agents must be cognizant that these agents are manufactured in more than one concentration and ampule size, which increases the potential for dosing errors. 41

42. Some Local Anesthetic Agents Used in Obstetrics Plain Solutions

43. Anesthetic Agent Usual Concentration (%)   Usual Volume ( mL )   Usual Dose (mg)   Onset Average Duration (min)   Clinical Use Amino-esters     2-Chloroprocaine 1–2 20–30 400–600 Rapid 15–30 Local or pudendal block 2–3 15–25 300–750   30–60 Epidural (not subarachnoid) for cesarean delivery   Tetracaine 0.2 — 4 Slow 75–150 Low spinal block/6%glucose 0.5 — 7–10   75–150 Spinal for cesarean delivery/5%glucose 43

44. Anesthetic Agent Usual Concentration (%) Usual Volume (mL)  Usual Dose (mg) Onset Average Duration (min) Clinical Use Amino-amides    Lidocaine 1 20–30 200–300 Rapid 30–60 Local or pudendal block 2 15–30 300–450   60–90 Epidural for cesarean delivery 5 1–1.5 50–75   45–60 Spinal for cesarean delivery or puerperal tubal ligation/7.5%glucose 5 0.5–1 25–50   30–60 Spinal for vaginal delivery/7.5%glucose 44

45. Bupivacaine 0.5 15–20 50–100 Slow 90–150 Epidural for cesarean delivery 0.25 8–10 20–25   60–90 Epidural for labor 0.75 1–1.5 7.5–11   60–120 Spinal for cesarean delivery/8.25%glucose   Ropivacaine 0.5 15–20 75–100 Slow 90–150 Epidural for cesarean delivery 0.25 8–10 20–25   60–90 Epidural for labor 45

46. Addition of glucose to local anesthetics creates a hyperbaric solution, which is heavier and denser than cerebrospinal fluid. Toxicity: Systemic toxicity from local anesthetics typically manifests in the central nervous and cardiovascular systems. 46

47. Central Nervous System Toxicity Early symptoms are those of stimulation but, as serum levels increase, depression follows. Symptoms may include light-headedness, dizziness, tinnitus, metallic taste, and numbness of the tongue and mouth. Patients may show bizarre behavior, slurred speech, muscle fasciculation and excitation, and ultimately, generalized convulsions, followed by loss of consciousness. The convulsions should be controlled, an airway established, and oxygen delivered. Succinylcholine abolishes the peripheral manifestations of the convulsions and allows tracheal intubation. Thiopental or diazepam act centrally to inhibit convulsions. Magnesium sulfate, administered according to the regimen for eclampsia, also controls convulsions 47

48. Central Nervous System Toxicity Abnormal fetal heart rate patterns, such as late decelerations or persistent bradycardia, may develop from maternal hypoxia and lactic acidosis induced by convulsions. With arrest of the convulsions, administration of oxygen, and application of other supportive measures, the fetus usually recovers more quickly in utero than following immediate cesarean delivery. Moreover, maternal well-being is usually better served by waiting until the intensity of the hypoxia and the metabolic acidosis have diminished . 48

49. Cardiovascular Toxicity These manifestations generally develop later than those from cerebral toxicity. They do not always follow central nervous system involvement, because they are induced by higher drug levels. The notable exception is bupivacaine, which is associated with the development of neurotoxicity and cardiotoxicity at virtually identical serum drug levels. Because of this risk of systemic toxicity, use of 0.75-percent solution of bupivacaine for epidural injection was proscribed . 49

50. Cardiovascular Toxicity Similar to neurotoxicity, cardiovascular toxicity is characterized first by stimulation and then by depression. Accordingly, there is hypertension and tachycardia, which soon is followed by hypotension and cardiac arrhythmias. The latter contribute appreciably to impaired uteroplacental perfusion and fetal distress. Hypotension is managed initially by turning the woman onto either side to avoid aortocaval compression. A crystalloid solution is infused rapidly along with intravenously administered ephedrine. Emergency cesarean delivery should be considered if maternal vital signs have not been restored within 5 minutes of cardiac arrest. As with convulsions, however, the fetus is likely to recover more quickly in utero once maternal cardiac output is reestablished. 50

51. Pudendal Block This block is a relatively safe and simple method of providing analgesia for spontaneous delivery. The end of the introducer is placed against the vaginal mucosa just beneath the tip of the ischial spine. The needle is pushed beyond the tip of the director into the mucosa and a mucosal wheal is made with 1 mL of 1-percent lidocaine solution or an equivalent dose of another local anesthetic. To guard against intravascular infusion, aspiration is attempted before this and all subsequent injections. 51

52. Pudendal Block The needle is then advanced until it touches the sacrospinous ligament , which is infiltrated with 3 mL of lidocaine. The needle is advanced farther through the ligament, and as it pierces the loose areolar tissue behind the ligament, the resistance of the plunger decreases. Another 3 mL of the anesthetic solution is injected into this region. Next, the needle is withdrawn into the introducer, which is moved to just above the ischial spine. The needle is inserted through the mucosa and the rest of 10 mL of solution is deposited. The procedure is then repeated on the other side. 52

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54. Pudendal Block Within 3 to 4 minutes of the time of injection, the successful pudendal block will allow pinching of the lower vagina and posterior vulva bilaterally without pain. It is often of benefit before pudendal block to infiltrate the fourchette, perineum, and adjacent vagina with 5 to 10 mL of 1-percent lidocaine solution directly at the site where the episiotomy is to be made. Then, if delivery occurs before pudendal block becomes effective, an episiotomy can be made without pain. By the time of the repair, the pudendal block usually has become effective. Pudendal block usually does not provide adequate analgesia when delivery requires extensive obstetrical manipulation. Moreover, such analgesia is usually inadequate for women in whom complete visualization of the cervix and upper vagina, or manual exploration of the uterine cavity, are indicated. 54

55. Complications of Pudendal Block Central Nervous System Toxicity , intravascular injection of a local anesthetic agent may cause serious systemic toxicity. Hematoma formation Rarely, severe infection may originate at the injection site. The infection may spread posterior to the hip joint, into the gluteal musculature, or into the retropsoas space. 55

56. Paracervical Block This block usually provides satisfactory pain relief during the first stage of labor. Because the pudendal nerves are not blocked, however, additional analgesia is required for delivery. Usually lidocaine or chloroprocaine, 5 to 10 mL of a 1-percent solution, is injected into the cervix laterally at 3 and 9 o'clock. Bupivacaine is contraindicated because of an increased risk of cardiotoxicity. Because these anesthetics are relatively short acting, paracervical block may have to be repeated during labor . 56

57. Complications Of Paracervical Block Fetal bradycardia(15%) Bradycardia usually develops within 10 minutes and may last up to 30 minutes. The effect may be the consequence of transplacental transfer of the anesthetic agent or its metabolites and in turn, a depressant effect on the fetal heart. For these reasons, paracervical block should not be used in situations of potential fetal compromise. 57

58. Spinal Anesthesia /Analgesia Used mainly for very late in labor because it has limited duration of action Faster onset than Epidural Amount of local anesthetic used is much smaller 58

59. Spinal (Subarachnoid) Block Introduction of a local anesthetic into the subarachnoid space to effect analgesia has long been used for delivery. Advantages include a short procedure time, rapid onset of the block, and high success rate. Because of the smaller subarachnoid space during pregnancy, likely the consequence of engorgement of the internal vertebral venous plexus, the same amount of anesthetic agent in the same volume of solution produces a much higher blockade in parturients than in nonpregnant women. 59

60. Vaginal Delivery Low spinal block is a popular form of analgesia for forceps or vacuum delivery. The level of analgesia should extend to the T10 dermatome, which corresponds to the level of the umbilicus. Blockade to this level provides excellent relief from the pain of uterine contractions. Several local anesthetic agents have been used for spinal analgesia. Addition of glucose to any of these agents creates a hyperbaric solution, which is heavier and denser than cerebrospinal fluid. A sitting position causes a hyperbaric solution to settle caudally, whereas a lateral position will have a greater effect on the dependent side. Lidocaine given in a hyperbaric solution produces excellent analgesia and has the advantage of a rapid onset and relatively short duration 60

61. Vaginal Delivery Bupivacaine in an 8.25-percent dextrose solution provides satisfactory anesthesia to the lower vagina and the perineum for more than 1 hour. Neither is administered until the cervix is fully dilated and all other criteria for safe forceps delivery have been fulfilled. Preanalgesic intravenous hydration with 1 L of crystalloid solution will prevent or minimize hypotension in many cases. Cesarean Delivery: A level of sensory blockade extending to the T4 dermatome is desired for cesarean delivery. Depending on maternal size, 10 to 12 mg of hyperbaric bupivacaine or 50 to 75 mg of hyperbaric lidocaine are administered. The addition of 20 to 25 ug of fentanyl increases the rapidity of the onset of the block and reduces shivering. The addition of 0.2 mg of morphine improves pain control during delivery and postoperatively 61

62. Complications Hypotension Postdural puncture headache Pruritus Failed regional block (need for general endotracheal anesthesia) High spinal block Chemical meningitis or epidural abscess or hematoma O bese women have significantly impaired ventilation 62

63. Hypotension May develop soon after injection of the local anesthetic agent and is the consequence of vasodilatation from sympathetic blockade compounded by obstructed venous return from uterine compression of the vena cava and adjacent large veins. In the supine position, even in the absence of maternal hypotension measured in the brachial artery, placental blood flow may still be significantly reduced. Treatment of spinal block hypotension includes uterine displacement, intravenous hydration, and intravenous bolus injections of ephedrine or phenylephrine The predominant action of ephedrine is to raise blood pressure by increasing cardiac output rather than vasoconstriction. Phenylephrine is a pure –alpha agonist which, at least until recently, we have generally avoided because of concerns about potential adverse effects on uterine blood flow 63

64. High Spinal Blockade Most often, complete spinal blockade is the consequence of administration of an excessive dose of local anesthetic agent. This is certainly not always the case, because accidental total spinal block has even occurred following an epidural test dose. In complete spinal block, hypotension and apnea promptly develop and must be immediately treated to prevent cardiac arrest. In the undelivered woman, (1) the uterus is immediately displaced laterally to minimize aortocaval compression; (2) effective ventilation is established, preferably with tracheal intubation; and (3) intravenous fluids and ephedrine are given to correct hypotension. 64

65. Spinal ( Postdural Puncture) Headache Leakage of cerebrospinal fluid from the site of puncture of the meninges is thought to be the major factor in the genesis of spinal headache. Presumably, when the woman sits or stands, the diminished volume of cerebrospinal fluid allows traction on pain-sensitive central nervous system structures. With severe headache, an epidural blood patch is effective. A few milliliters of autologous blood are obtained aseptically by venipuncture without anticoagulant. This is injected into the epidural space at the site of the dural puncture. Relief is immediate and complications uncommon. 65

66. Convulsions In rare instances, postdural puncture cephalgia is associated with blindness and convulsions. Bladder Dysfunction: With spinal analgesia, bladder sensation is likely to be obtunded and bladder emptying impaired for the first few hours after delivery. As a consequence, bladder distention is a frequent postpartum complication, especially if appreciable volumes of intravenous fluid are given . 66

67. Oxytocics and Hypertension Paradoxically, hypertension from ergonovine or methylergonovine injected following delivery is more common in women who have received a spinal or epidural block. 67

68. Arachnoiditis and Meningitis Local anesthetics are no longer preserved in alcohol, formalin, or other toxic solutes, and disposable equipment is used by most. These practices, coupled with aseptic technique, have made meningitis and arachnoiditis rarities Still, these complications are occasionally occur. Contraindications to Spinal Analgesia Obstetrical complications that are associated with maternal hypovolemia and hypotension—such as severe hemorrhage—are contraindications to the use of spinal block 68

69. Absolute Contraindications to Regional Analgesia Refractory maternal hypotension Maternal coagulopathy Treatment with once-daily dose of low-molecular-weight heparin within 12 hr Untreated bacteremia Skin infection over site of needle placement Increased intracranial pressure caused by mass lesion 69

70. In addition to refractory maternal hypotension, disorders of coagulation and defective hemostasis also preclude the use of spinal analgesia. Similarly, subarachnoid puncture is contraindicated when the skin or underlying tissue at the site of needle entry is infected. Neurological disorders are considered by many to be a contraindication, if for no other reason than that exacerbation of the neurological disease might be attributed without cause to the anesthetic agent. Other maternal conditions, such as significant aortic stenosis or pulmonary hypertension, are also relative contraindications to the use of spinal analgesia Preeclampsia: As with significant hemorrhage, severe preeclampsia is another complication in which markedly decreased blood pressure can be predicted when subarachnoid analgesia is used. It has inherent risks of difficult intubation due to airway edema and cerebrovascular accidents due to increased blood pressure. It to be quite controversial, they concluded that with severe preeclampsia, epidural analgesia is preferable to a subarachnoid block and especially preferable to a general anesthetic . 70

71. Epidural Analgesia Provides excellent pain relief reducing maternal catecholamines Ability to extend the duration of block to match the duration of labor Blunts hemodynamic effects of uterine contractions: beneficial for patients with preeclampsia. 71

72. Indications for LEA PAIN EXPERIENCED BY A WOMAN IN LABOR When medically beneficial to reduce the stress of labor ACOG and ASA stated(The American College of Obstetricians and Gynecologists ) “ in the absence of a medical contraindication, maternal request is a sufficient medical indication for pain relief…” 72

73. Obstetric conditions where epidural analgesia is more likely to be indicated: Pre eclampsia/hypertensive disease Prolonged labour Two or more babies in utero Anticipated instrumental delivery Diabetes Mellitus Breech presentation for vaginal delivery Significant respiratory disease 73

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76. Contraindications for LEA(lumbar EA) ABSOLUTE Patients refusal Inability to cooperate Increased intracranial pressure Infection Severe coagulopathy Severe hypovolemia Inadequate training RELATIVE Systemic maternal infection Preexisting neurological deficiency Mild or isolated coagulation abnormalities Relative (and correctable) hypovolemia 76

77. We are All Ready…Now What? - Last Check Obstetrician is consulted and confirmed LEA Preanesthetic evaluationis performed/verified Pt’s (and only patient’s) desire to have LEA is reconfirmed Pt’s understanding of risks of LEA is reconfirmed 77

78. We are All Ready…Now What? - Last Check Fetal well-being is assessed and reassured 78

79. We are All Ready…Now What? - Last Check Supporting personal is available and present 79

80. We are All Ready…Now What? - Last Check Resuscitation equipment and drugs are immediately available in the area where LEA placed 80

81. Epidural Analgesia Relief from the pain of labor and childbirth, including cesarean delivery, can be accomplished by injection of a local anesthetic agent into the epidural or peridural space. This potential space contains areolar tissue, fat, lymphatics, and the internal venous plexus . These latter vessels become engorged during pregnancy such that the volume of the epidural space is appreciably reduced. Entry for obstetrical analgesia is usually through a lumbar intervertebral space, and less often through the sacral hiatus and sacral canal for caudal epidural analgesia . Although one injection may be used, these usually are repeated through an indwelling catheter, or they are given by continuous infusion using a volumetric pump. 81

82. Standard Technique of LEA Pre epidural check list is completed Aspiration prophylaxis Intravenous hydration (what? When? How?) Monitoring BP every 1 to 2 min for 20 min after injection of drugs Continuous maternal HR during induction ( e.g., pulse oximetry) Continuous FHR monitoring Continual verbal communication 82

83. Standard Technique of LEA 4. Maternal position ( sitting or lateral?) 83

84. Comparison of Sitting and Lateral Positions for Performing Spinal or Epidural Procedures Sitting Lying (left lateral) Advantages Midline easier to identify in obese women  Obese patients may find this position more comfortable Can be left unattended without risk of fainting. No orthostatic hypotension Uteroplacental blood flow not reduced (particularly important in the stressed fetus) Disadvantages Uteroplacental blood flow decreased Orthostatic hypotension may occur Increased risk of orthostatic hypotension if Entonox and pethidine have been administered Assistant (or partner) needed to support patient May he more difficult to find the midline in obese patient 84

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87. Influence of epidural analgesia on maternal plasma concentrations of catecholamines during labor. Modified from Shnider SM et al. Maternal catecholamines decrease during labor after lumbar epidural analgesia. Am J Obstet Gynecol 1983;147:13-5 .

88. Continuous Lumbar Epidural Block Complete analgesia for the pain of labor and vaginal delivery necessitates a block from the T10 to the S5 dermatomes. For cesarean delivery, a block extending from the T4 to the S1 dermatomes is desired. The spread of the anesthetic depends upon the location of the catheter tip; the dose, concentration, and volume of anesthetic agent used; and whether the mother is head-down, horizontal, or head-up. Individual variations in the epidural space anatomy also will affect the block, and in some cases, synechiae may preclude a completely satisfactory block. It also should be recognized that the catheter tip might move from its original location during the course of labor. Appropriate resuscitation equipment and drugs must be available during administration of epidural analgesia 88

89. Technique for Labor Epidural Analgesia Informed consent is obtained, and the obstetrician consulted. Monitoring includes the following: Blood pressure every 1–2 min for 15 min after giving a bolus of local anesthetic. Continuous maternal heart rate monitoring during analgesia induction. Continuous fetal heart rate monitoring. Continual verbal communication. Hydration with 500 to 1000 mL of lactated Ringer solution. The woman assumes a lateral decubitus or sitting position. The epidural space is identified with a loss-of-resistance technique. 6 .The epidural catheter is threaded 3–5 cm into the epidural space 89

90. 7. A test dose of 3 mL of 1.5%lidocaine with 1:200,000 epinephrine or 3 mL of 0.25%bupivacaine with 1:200,000 epinephrine is injected after careful aspiration and after a uterine contraction—this minimizes the chance of confusing tachycardia that results from labor pain with tachycardia from intravenous injection of the test dose. 8. If the test dose is negative, one or two 5-mL doses of 0.25%bupivacaine are injected to achieve a cephalad sensory T10 level. 9. After 15–20 min, the block is assessed using loss of sensation to cold or pinprick. If no block is evident, the catheter is replaced. If the block is asymmetrical, the epidural catheter is withdrawn 0.5–1.0 cm and an additional 3–5 mL of 0.25%bupivacaine is injected. If the block remains inadequate, the catheter is replaced. 10. The woman is positioned in the lateral or semilateral position to avoid aortocaval compression. 11. Subsequently, maternal blood pressure is recorded every 5–15 min. The fetal heart rate is monitored continuously. 12. The level of analgesia and intensity of motor block are assessed at least hourly 90

91. Complications of epidural analgesia Total Spinal Blockade Ineffective Analgesia Hypotension Central Nervous Stimulation Maternal Pyrexia Back Pain 91

92. Effect on Labor R eport that epidural analgesia prolongs labor and increases the need for oxytocin stimulation. I ncrease the need for instrumental delivery due to prolonged second-stage labor Fetal Heart Rate Compared with intravenous meperidine, no deleterious effects were identified. In fact, reduced beat-to-beat variability and fewer accelerations were more common in fetuses whose mothers received Based on their systematic review of eight studies, Reynolds and co-workers (2002) found that epidural analgesia was associated with improved neonatal acid–base status compared with that with meperidine 92

93. Cesarean Delivery These results are consistent with the belief of many investigators that the epidural administration of dilute solutions of local anesthetic is less likely to increase cesarean delivery rates than concentrated solutions. 93

94. Contraindications A ctual or anticipated serious maternal hemorrhage, infection at or near the sites for puncture, and suspicion of neurological disease Rolbin and colleagues (1988) advise against epidural analgesia if the platelet count is below 100,000/L. Conversely, Rasmus and associates (1989) found no cases in which bleeding was caused by regional analgesia in thrombocytopenic women. They recommended consideration of this method if the patient might be difficult to intubate or ventilate. The American College of Obstetricians and Gynecologists (2002b) has concluded that women with platelet counts of 50,000 to 100,000/L may be considered potential candidates for regional analgesia. 94

95. Anticoagulation Women receiving anticoagulation therapy who are given regional analgesia are at increased risk for spinal cord hematoma and compression. The American College of Obstetricians and Gynecologists (2002b) has recommended the following for women taking anticoagulants: Women receiving unfractionated heparin therapy should be able to receive regional analgesia if they have a normal activated partial thromboplastin time ( aPTT ). 95

96. Cont… Women receiving prophylactic doses of unfractionated heparin or low-dose aspirin are not at increased risk and can be offered regional analgesia. For women receiving once-daily low-dose low-molecular-weight heparin, regional analgesia should not be placed until 12 hours after the last injection . Low-molecular-weight heparin should be withheld for at least 2 hours after the removal of an epidural catheter. The safety of regional analgesia in women receiving twice-daily low-molecular-weight heparin has not been studied sufficiently. 96

97. Severe Preeclampsia– Eclampsia As previously discussed, ideal labor analgesia for women with severe preeclampsia is controversial. Obstetrical concerns include hypotension induced by sympathetic blockade, dangers from pressor agents given to correct hypotension, and potential for pulmonary edema following infusion of large volumes of crystalloid. Conversely, general anesthesia with tracheal intubation may result in severe, sudden hypertension further complicated by pulmonary or cerebral edema or intracranial hemorrhage. 97

98. Over the past two to three decades, most obstetrical anesthesiologists have come to favor epidural blockade for labor and delivery in women with severe preeclampsia. There seems to be no argument that epidural analgesia for women with severe preeclampsia–eclampsia can be safely used when specially trained anesthesiologists and obstetricians are responsible for the woman and her fetus (ACOG) Epidural analgesia provided superior pain relief without a significant increase in maternal or neonatal complications. Intravenous Fluid Preload: Women with severe preeclampsia have remarkably diminished intravascular volume compared with normal pregnancy. And also aggressive volume replacement increases the risk for pulmonary edema, especially in the first 72 hours postpartum Importantly, this risk can be reduced or obviated with judicious prehydration —usually with 500 to 1000 mL of crystalloid solution . 98

99. Contd . Moreover, vasodilation produced by epidural blockade is less abrupt if the analgesia level is achieved slowly with dilute solutions of local anesthetic agents. This allows maintenance of blood pressure while simultaneously avoiding infusion of large volumes of crystalloid. With vigorous intravenous crystalloid therapy, there is also concern about development of cerebral edema. The majority of cases of pharyngolaryngeal edema were related to aggressive volume therapy. 99

100. Epidural Opiate Analgesia Their mechanism of action derives from interaction with specific receptors in the dorsal horn and dorsal roots. Apparently both cerebral and spinal opioid receptors are stimulated by these narcotics. Opiates alone usually will not provide adequate analgesia, and they most often are given with a local anesthetic agent such as bupivacaine. The major advantages of using such a combination are the rapid onset of pain relief, a decrease in shivering, and less dense motor blockade . 100

101. Continuous Infusion of Dilute Local Anesthetic Plus Opioid Better pain relief while producing less motor block. Maternal and neonatal drug concentrations safe. 101 Regimen 0.0625% - 0.08% bupivacaine with 2-3 mcg /ml fentanyl , with or without epinephrine, infusing at 10-12 ml/hour

102. Searching For Balanced Labor Analgesia Ambulatory Labor Analgesia (CSE) 102

103. Combined Spinal–epidural Techniques May provide rapid and effective analgesia for labor as well as for cesarean delivery. An introducer needle is first placed in the epidural space. A small-gauge spinal needle is then introduced through the epidural needle into the subarachnoid space—this is called the needle-through-needle technique . A single bolus of an opioid, sometimes in combination with a local anesthetic, is injected into the subarachnoid space, the spinal needle is withdrawn, and an epidural catheter is then placed. The use of a subarachnoid opioid bolus results in the rapid onset of profound pain relief with virtually no motor blockade. The epidural catheter permits repeated dosing of analgesia . 103

104. Combined spinal epidural (CSE) I nitial reports: two interspace technique-epidural followed by spinal Later evolution of CSE in the direction of needle through needle technique Postdural puncture headache: 1% or less incidence for CSE with small bore atraumatic needles. Combined method produced excellent immediate pain relief. ate pain relief 104

105. Advantages of CSE for Labor Analgesia Rapid onset of intense analgesia (the patient loves you immediately! ) Ideal in late or rapidly progressing labor Very low failure rate Less need for supplemental boluses Minimal motor block (“walking epidural”) 105

106. 106

107. Combined Spinal epidural 107

108. Espocan CSE Needle (B. Braun) 108

109. Espocan CSE Needle (B. Braun) 109

110. Eldor needle Combined Spinal Epidural for Obstetric Anesthesia 110

111. Intermittent bolus injections: Bupivacaine: 0.125%-0.375%, 5-10 ml, duration:1-2 hr Ropivacaine : 0.125%-0.25%, 5-10 ml, duration: 1-2 hr Lidocaine : 0.75%-1.5%, 5-10 ml, duration: 1-1.5 hr Maintenance of epidural analgesia can be achieved by: R egular top-ups A n epidural infusion P atient-controlled epidural analgesia (PCEA). 111

112. Neuraxial Labor Techniques 112

113. Local Infiltration for Cesarean Delivery Local block is occasionally useful to augment an inadequate or "patchy" regional block that was given in an emergency. On more rare occasions, local infiltration may be used to perform an emergency cesarean to save the life of the fetus in the absence of any anesthesia support. 113

114. 114

115. 115 Local anesthetic block for cesarean delivery.

116. General Anesthesia The increased safety of regional analgesia has increased the relative risk of general anesthesia. The case-fatality rate of general anesthesia for cesarean delivery is estimated to be approximately 32 per million live births compared with 1.9 per million for regional anesthesia Failed intubation occurs in approximately 1 of every 250 general anesthetics administered to pregnant women, a 10-fold higher rate than the nonpregnant population. The American College of Obstetricians and Gynecologists (2002b) has concluded that this relative increased morbidity and mortality suggest that regional analgesia is the preferred method of pain control and should be used unless contraindicated 116

117. Patient Preparation Prior to anesthesia induction, several steps should be taken to help minimize the risk of complications for the mother and fetus. These include the Use of antacids, Lateral uterine displacement, and Preoxygenation . 117

118. Induction of Anesthesia Thiopental Ketamine Propofo l Etomidate 118

119. Thiopental This thiobarbiturate given intravenously is widely used and offers the advantages of ease and extreme rapidity of induction as well as prompt recovery with minimal risk of vomiting. Thiopental and similar compounds are poor analgesic agents, and the administration of sufficient drug given alone to maintain anesthesia may cause appreciable newborn depression. Thus, thiopental is not used as the sole anesthetic agent, but rather is administered in a dose that induces sleep. 119

120. Ketamine This agent also may be used to render the patient unconscious. Given intravenously in low doses of 0.2 to 0.3 mg/kg , ketamine may be used to produce analgesia and sedation just prior to vaginal delivery. Doses of 1 mg/kg induce general anesthesia. Ketamine may prove useful in women with acute hemorrhage because, unlike thiopental, it is not associated with hypotension. Conversely, it usually causes a rise in blood pressure, and thus it generally should be avoided in women who are already hypertensive. Unpleasant delirium and hallucinations are commonly induced by this agent. 120

121. Etomidate Etomidate causes less myocardial depression than thiopental or propofol and less histamine release, making it a good choice in patients with asthma or who are hemodynamically unstable Propofol Propofol allows a rapid smooth induction of anesthesia. Propofol attenuates the hypertensive response to laryngoscopy and intubation more effectively than other induction agents, making it a good choice for the induction of general anesthesia in hypertensive patients 121

122. Intubation Immediately after the patient is rendered unconscious, a muscle relaxant is given to facilitate intubation. Succinylcholine, a rapid-onset and short-acting agent, commonly is used. Cricoid pressure—the Sellick maneuver —is used to occlude the esophagus from induction until intubation is completed by a trained assistant. Before the operation begins, proper placement of the endotracheal tube must be confirmed. Such confirmation includes auscultation of bilateral breath sounds and end-tidal carbon dioxide analysis. 122

123. Neuromuscular Blockers Succinylcholine Succinylcholine, a depolarizing neuromuscular blocker,in a dose of 1 to 1.5 mg/kg, is the muscle relaxant of choice for most patients It is the only agent that combines rapid onset, allowing intubation within 90 seconds , with rapid offset, allowing spontaneous respiration to return 1 to 5 minutes after administration Rocuronium Rocuronium , a nondepolarizing neuromuscular blocker , at a dose of 0.6 mg/kg, can achieve intubating conditions at about 80 seconds Intubating conditions were significantly better after a dose of 1 mg/kg, comparing more favorably with succiny choline The disadvantage of rocuronium is that at these doses neuromuscular blockade lasts 50 to 60 minutes 123

124. Vecuronium and Atracurium These nondepolarizing muscle relaxants are not well suited to a rapid sequence induction Vecuronium 0.05 mg/kg or atracurium 0.25 mg/kg can be used to provide 20 to 30 minutes of muscle relaxation after succinylcholine has worn Interactions with Magnesium Sulphate Patients receiving magnesium sulphate may not fasciculate after the intubating dose of succinylcholine, even though the action of succinylcholine is unaffected Magnesium sulphate also prolongs the neuromuscular blockade produced by nondepolarizing neuromuscular blockers 124

125. TERATOGENICITY It is well accepted that anesthetic agents may slow cell growth and division, and their cytotoxic and teratogenic effects have been demonstrated in many in vitro and animal model First , a drug may be a teratogen in one species but not in others Adverse Fetal Outcomes Congenital anomalies Spontaneous abortion Intrauterine fetal death Premature labor 125

126. Failed Intubation Although uncommon, failed intubation is a major cause of anesthesia-related maternal mortality. A history of previous difficulties with intubation as well as a careful assessment of anatomical features of the neck, maxillofacial, pharyngeal, and laryngeal structures may help predict a difficult intubation. Even in cases where the initial assessment of the airway was uneventful, edema may develop intrapartum and present considerable difficulties. Morbid obesity is also a major risk factor for failed or difficult intubation. 126

127. Management of failed intubation Start the operative procedure only after it has been ascertained that tracheal intubation has been successful and that adequate ventilation can be accomplished. Even with an abnormal fetal heart rate pattern, initiation of cesarean delivery will only serve to complicate matters if there is difficult or failed intubation. Frequently, the woman must be allowed to awaken and a different technique used, such as an awake intubation or regional analgesia. 127

128. Following failed intubation, the woman is ventilated by mask and cricoid pressure is applied to reduce the chance of aspiration. Surgery may proceed with mask ventilation or the woman may be allowed to awaken. In those cases where the woman has been paralyzed, and where ventilation cannot be reestablished by insertion of an oral airway, laryngeal mask airway , or use of a fiberoptic laryngoscope to intubate the trachea, a life-threatening emergency exists. To restore ventilation, percutaneous or even open cricothyrotomy is performed, and jet ventilation begun. Gas Anesthetics: Once the endotracheal tube is secured, a 50:50 mixture of nitrous oxide and oxygen is administered to provide analgesia. Usually, a volatile halogenated agent is added to provide amnesia and additional analgesia. 128

129. Volatile Anesthetics The most commonly used volatile anesthetic in the United States is isoflurane . Both isoflurane and halothane are potent, nonexplosive agents that produce remarkable uterine relaxation when given in high, inhaled concentrations. Their use in high concentrations is restricted to those uncommon situations in which uterine relaxation is a requisite rather than a hazard. They are used for internal podalic version of the second twin, breech decomposition and replacement of the acutely inverted uterus. As soon as the maneuver has been completed, anesthetic administration should be stopped and immediate efforts begun to promote myometrial contraction to minimize hemorrhage. Because of cardiodepressant and hypotensive effects, these agents may intensify the adverse effects of maternal hypovolemia . Halothane and isoflurane occasionally have been associated with hepatitis and massive hepatic necrosis. 129

130. Anesthesia Gas Exposure and Pregnancy Outcome Without exception, all anesthetic agents that depress the maternal central nervous system cross the placenta and depress the fetal central nervous system. As a result, personnel responsible for the care of the newborn immediately following delivery with a general anesthetic should be prepared to provide respiratory support. Ideally, induction-to-delivery time should be minimized when general anesthesia is used. In one study, Datta and colleagues (1981) concluded that fetal exposure of more than 8 minutes was associated with increased neonatal depression. Kavak and co-workers (2001) randomly assigned 84 women scheduled for elective cesarean delivery to either spinal analgesia or general anesthesia. There were no significant differences in short-term measures of neonatal outcome, including Apgar scores, umbilical artery blood gas determinations, or length of stay. 130

131. Extubation The tracheal tube may be safely removed only if the woman is conscious to a degree that enables her to follow commands and is capable of maintaining oxygen saturation with spontaneous respiration. Typically, the stomach is emptied via a nasogastric tube prior to extubation. 131

132. Aspiration Massive gastric acidic inhalation causing pulmonary insufficiency from aspiration pneumonitis. Such pneumonitis has in the past been the most common cause of anesthetic deaths in obstetrics and therefore deserves special attention. Procedures mentioned previously that are important to effective prophylaxis include use of antacids, skillful intubation accompanied by cricoid pressure, emptying of the stomach with a nasogastric tube, and use of regional analgesia when possible. 132

133. Fasting Clear liquids such as water, clear tea, black coffee, carbonated beverages, and fruit juices without pulp may be allowed in uncomplicated laboring women. Obvious solid foods should be avoided. "A fasting period of 8 hours or more is preferable for uncomplicated parturients undergoing elective cesarean delivery." Despite these precautions, it should be assumed that any woman in labor has both gastric particulate matter as well as acidic contents. Pathophysiology I f the pH of aspirated fluid was below 2.5, severe chemical pneumonitis developed. The right mainstem bronchus usually offers the simplest pathway for aspirated material to reach the lung parenchyma, and therefore the right lower lobe is most often involved. In severe cases, there is bilateral widespread involvement 133

134. The woman who aspirates may develop evidence of respiratory distress immediately or as long as several hours after aspiration, depending in part on the material aspirated and the severity of the process. Aspiration of a large amount of solid material causes obvious signs of airway obstruction. Smaller particles without acidic liquid may lead to patchy atelectasis and later to bronchopneumonia. When highly acidic liquid is inspired, decreased oxygen saturation along with tachypnea, bronchospasm, rhonchi, rales, atelectasis, cyanosis, tachycardia, and hypotension are likely to develop. At the sites of injury, pulmonary capillary leakage results in protein-rich fluid containing numerous erythrocytes exuding from capillaries into the lung interstitium and alveoli to cause decreased pulmonary compliance, shunting of blood, and severe hypoxemia. Radiographic changes may not appear immediately and they may be quite variable, although the right lobe most often is affected. Therefore, chest radiographs alone should not be used to exclude aspiration. 134

135. Treatment Respiratory rate and oxygen saturation as measured by pulse oximetry are the most sensitive and earliest indicators of injury. As much of the inhaled fluid as possible should be immediately wiped out of the mouth and removed from the pharynx and trachea by suction. If large particulate matter is inspired, bronchoscopy may be indicated to relieve airway obstruction. If clinical evidence of infection develops, however, then vigorous treatment is given. When acute respiratory distress syndrome develops, mechanical ventilation with positive end-expiratory pressure may prove lifesaving. 135

136. What anesthetic options are available for cesarean delivery? What options are available for pain control following cesarean delivery? What anesthetic risks accompany preeclampsia? Is fetal outcome any different between regional and general anesthesia? 136

137. 137 Anesthesia for Cesarean Section

138. Anesthesia for Cesarean Section The choice of anesthesia depend on: The indication for the CS The urgency of the procedure The medical condition of the mother and the fetus The desire of the mother 138

139. Anesthesia for Cesarean Section GA associated with higher risk of airway problems . Incidence of failed tracheal intubation in pregnant women is 1 in 200 to 1 in 300 cases Anesthesia2000;55:690-4 Maternal death due to anesthesia is the sixth leading cause of pregnancy related death in USA Obstet Gynecol 1996;88:161-7 139

140. Anesthesia for Cesarean Section The risk of maternal death from complications of GA is 17 times as high as that associated with Regional anesthesia In USA the shift from GA to RA for CS resulted in decrease in anesthesia related maternal mortality from 4.3 to 1.7 per 1 million live birth Anesthsiology 1997;86:277-84 140

141. Epidural anesthesia Advantage Titration (volume dependent, not gravity dependent), decreased likelihood of hypotension Incremental dose (for longer operation) Disadvantage Dural puncture :1/200-1/500 in experienced hands, higher in training institution If unintentional dural puncture, PDPH incidence is 50-85% Slower onset 141

142. Spinal anaesthesia Hyperbaric bupivacaine 0.5% is the drug most commonly used for spinal anaesthesia for Caesarean section. Pregnant patients require a smaller dose than the nonpregnant population (why?) The dose used via a standard lumbar approach is typically 2.0–2.75 ml. no significant correlation between age, height, weight, body mass index and length of vertebral column and the final block height achieved Anesthesiology1990; 72: 478–482. 142

143. Combined spinal epidural(CSE ) Combines the rapid onset and efficacy of the spinal technique with the ability to: Extend anaesthesia if surgery is prolonged Provide excellent postoperative epidural analgesia. Combined Spinal Epidural for Obstetric Anesthesia.flv BITEW(IESO) 143

144. Optimal Neuraxial Medication Combinations for Cesarean Delivery Medication Spinal Epidural Local anesthetic Bupivacaine 12 mg (range 9–15) Lidocaine 2%; Fentanyl 15–35 ug 50–100 ug Morphine 0.1 mg 3.75 mg 144

145. Complications of Regional Anesthesia 145

146. Complications of regional anesthesia Post Dural Puncture Headache (PDPH) severe, disabling fronto -occipital headache with radiation to the neck and shoulders. present 12 hours or more after the dural puncture worsens on sitting and standing relieved by lying down and abdominal compression. 146

147. Complications of regional anesthesia PDPH syndrome 1. Photophobia 2. Nausea 3. Vomiting 4. Neck stiffness 5. Tinnitus 6. Diplopia 7. Dizziness 147

148. Complications of regional anesthesia Differential diagnosis of post- dural puncture headache in the obstetric patient: 1 . Non-specific headache 2. Caffeine-withdrawal headache 3. Migraine 4. Meningitis 5. Sinus headache 6. Pre- eclampsia 7. Drugs (amphetamine, cocaine) 8. Pneumocephalus -related headache 9. Intracranial pathology ( hemorrhage , venous thrombosis) 148

149. Complications of regional anesthesia Management of PDPH Conservative: Bed rest Encourage oral fluids and/or intravenous hydration Caffeine - either i.v . (e.g. 500mg caffeine in 1litre of saline) or orally Regular Analgesia Reassurance 149

150. Complications of regional anesthesia Management of PDPH Others 1. Theophylline 3. Sumatriptan(treatment of migraine) 4. Epidural saline 5. Epidural dextran 6. Subarachnoid catheter 7. Epidural blood patch 150

151. Complications of regional anesthesia The new method of prevention of post- dura puncture headache (maintaining CSF volume): 1. Injecting the CSF in the glass syringe back into the subarachnoid space through the epidural needle 2. Passing the epidural catheter through the dural hole into the subarachnoid space 3. Injecting of 3-5 ml of preservative free saline into the subarachnoid space through the intrathecal catheter 4. Administering bolus and then continuous intrathecal labor analgesia through the intrathecal catheter 5. Leaving the subarachnoid catheter in-situ for a total of 12-20 h 151

152. Complications of regional anesthesia Cardiovascular complications Hypotension (can lead to cord ischaemia ) Bradycardia Effects on the course of labour and on the fetus 152

153. Effect of epidural analgesia on the progress and outcome of labour The recently published guidelines on intrapartum care by the UK national institute of health and clinical excellence indicate that epidural analgesia is: Not associated with a longer first stage of labour or an increased chance of a caesarean birth Associated with a longer second stage of labour and an increased chance of an instrumental birth. 153

154. Effect of epidural analgesia on the progress and outcome of labour The most important factors determining labour outcome are: Low concentrations of local anaesthetics Oxytocin Maternal pushing in the second stage of labour should, if possible be delayed! 154

155. Complications of regional anesthesia Neurological complications Needle damage to spinal cord, cauda equina or nerve roots. Spinal haematoma Spinal abscess Meningitis and Arachnoiditis Neurotoxicity 155

156. Complications of regional anesthesia Miscellaneous Venous puncture e.g. of dural veins Catheter breakage Extensive block (including unplanned blocks) Shivering Backache - Long-term backache is not a complication of neuraxial techniques although there will always be some local bruising. 156

157. Complications of regional anesthesia Drug side effects Nausea and vomiting (opiates) Respiratory depression (opiates) Anaphylaxis Toxicity (including intravascular injection of local anaesthetics) 157

158. Toxicity of local anaesthetics : Causes: An overdose of local anaesthetic is given, Large dose of local anaesthetic is inadvertently given intravenously. The recommended protocol is • Take a 500 ml bag of intralipid 20% and immediately give a 100 ml bolus over 1 minute 158

159. Toxicity of local anaesthetics • Infuse at a rate of 400 ml over 20 minutes • Give two further boluses of 100 ml at 5-minute intervals if Circulation is not restored • Continue infusion at a rate of 400 ml over 10 minutes until stable circulation is restored. 159 Airway, ventilatory and cardiovascular support should be maintained via standard protocols. It may be >1 hour before recovery

160. Conclusion “ The delivery of the infant into the arms of a conscious and pain-free mother is one of the most exciting and rewarding moments in medicine.” Moir DD. Extradural analgesia for caesarean section. Br J Anaesth 1979; 51: 1093. 160

161. Fetal and Neonatal Resuscitation Objectives On successfully completing this topic, you will be able to: U nderstand the important physiological differences in the newly born baby Understand the equipment used for resuscitation at birth Understand how to assess the baby at birth Understand how to resuscitate the baby at birth Understand additional measures for special situations 161

162. NEONATAL RESUSCITATION Neonatal resuscitation The condition of the infant at birth may be assessed by: Apgar score - a clinical scale based on colour , heart rate , respiratory rate , capillary perfusion and tone of the limbs It is obtained at 1 and 10 min after delivery, with maximum score being 10 Umbilical cord vein pH, which is normally 7.25-7.35 162

163. Introduction The resuscitation of babies at birth is different from the resuscitation of all other age groups, Knowledge of the relevant physiology and pathophysiology is essential. However , the majority of newly born babies will establish normal respiration and circulation without help 163

164. Normal physiology At birth the baby must change from an organism with fluid-filled lungs whose respiratory function is carried out by the placenta to a separate being whose air-filled lungs can successfully take over this function Preparation for this begins during labour , when the fluid-producing cells within the lung cease secretion and begin reabsorption of that fluid Delivery by caesarean section before the onset of labour may slow the clearance of pulmonary fluid from the lungs During vaginal delivery some lung fluid, perhaps 35 ml in a term baby, is expelled by passage through the birth canal 164

165. Normal physiology In a healthy baby the first spontaneous breaths may generate a negative pressure of between – 30 cm H2O and –90 cm H2O which aerates the lungs for the first time After delivery, a healthy term baby usually takes its first breath within 60–90 seconds of clamping or obstructing the umbilical cord Physical stimuli such as cold air or physical discomfort may also provoke respiratory efforts. In a 3-kg baby up to 100 ml of fluid is cleared from the airways following the initial breaths, a process aided by full inflation and prolonged high pressure on expiration, i.e. crying Neonatal circulatory adaptation commences with the detachment of the placenta 165

166. Pathophysiology When the placental oxygen supply is interrupted, the fetus attempts to breathe Should these attempts fail to provide an alternative oxygen supply – as they will inevitably fail to do so in utero – the baby will lose consciousness If hypoxia continues, the respiratory centre becomes unable, through lack of sufficient oxygen, to continue initiating breathing and the breathing stops, usually within 2–3 minutes (primary apnoea ) Fetal bradycardia ensues but blood pressure is maintained, primarily by peripheral vasoconstriction and diversion of blood away from non-vital organs, and also by an increased stroke volume The circulation is almost always maintained until all respiratory activity ceases Once the lungs are inflated, oxygen will be carried to the heart and then to the brain provided the circulation is still functional Once gasping ceases, however, the circulation starts to fail and these infants are likely to need more extensive resuscitation 166

167. Equipment for newborn resuscitation A flat surface Radiant heat source and dry towels (or suitable plastic bags for preterm infants ) Suction with catheters at least 12 Fr Face masks Bag-valve-mask or T piece w pressure limiting device Source of air and/or oxygen Oropharyngeal ( Guedel ) airways Laryngoscopes with straight blades, 0 and 1 Nasogastric tubes Cord clamp Scissors Tracheal tubes sizes 2.5 to 4.0 mm Umbilical catheterization equipment Adhesive tape Disposable gloves Plastic bag for preterm babies Saturation monitor/stethoscope 167

168. Strategy for assessing and resuscitating a baby at birth Resuscitation is likely to be rapidly successful if begun before the baby has become so anoxic that all potential for respiratory activity has vanished Always start by drying and covering the baby to prevent it from getting cold Airway Breathing Chest Compressions (Drugs) 168

169. At birth There is no need to rush to clamp the cord, particularly if the baby appears well Dry the baby quickly and effectively Remove the wet towel and wrap in a fresh dry warm towel Then clamp and cut the cord Keep the baby warm A cold baby has increased oxygen consumption and cold babies are more likely to become hypoglycaemic and acidotic Ideally, delivery should take place in a warm room, and an overhead heater should be switched on Babies also have a large surface area to weight ratio; thus heat can be lost very quickly. 169

170. Assessment of the newborn baby Whilst keeping the baby warm make an initial assessment by assessing: Apgar score Respiration (rate and quality) Airway and Breathing Heart rate (fast, slow, absent Colour (pink, blue, pale) ) Circulation Tone (unconscious, apneic babies are floppy) 170

171. APGAR Score Sign 1 2 Heart Rate Absent < 100 bpm > 100 bpm Respiratory Effort Absent Slow, irregular Crying Muscle Tone Flaccid Some flexion of extremities Active motion Reflex Irritability No response Grimace Vigorous cry Color Blue, pale Blue extremities Completely pink 171

172. Recommendations of the National Institute of Child Health and Human Development Research Planning Workshop for Standardizing FHR Tracing Definitions (1997) Baseline FHR: Mean FHR rounded to increments of 5 bpm during a 10-minute segment (excluding periodic changes, episodes of marked FHR variability) Bradycardia : FHR < 110 bpm Tachycardia : FHR > 160 bpm 172

173. Assessment of the newborn baby Respiration Most babies will establish spontaneous regular breathing sufficient to maintain the heart rate above 100 beats/min and to improve the skin colour within 3 minutes of birth Heart rate Auscultating at the cardiac apex is the best method to assess the heart rate Palpation of the umbilical pulse can only be relied upon if it is > 100 beats/min A rate less than this should be checked by auscultation if possible An initial assessment of heart rate is vital because an increase in the heart rate will be the first sign of success during resuscitation 173

174. Assessment of the newborn baby Colour Very pale babies who remain pale after resuscitation may be hypovolaemic as well as acidotic Using a saturation monitor will allow a rapid assessment of heart rate and saturation within 90 seconds of application After assessment, resuscitation follows: Airway Breathing Circulation With the use of drugs in a few selected cases 174

175. Assessment of the newborn baby Airway The baby should be positioned with the head in the neutral position The newborn baby’s head has a large, often moulded occiput, which tends to cause the neck to flex when the baby is supine on a flat surface Overextension may also collapse the newborn baby’s pharyngeal airway, leading to obstruction A 2cm folded towel and placed under the neck and shoulders may help to maintain the airway in a neutral position and a jaw thrust may be needed to bring the tongue forward and open the airway especially if the baby is floppy Continued 175

176. Meconium aspiration Meconium-stained liquor (light green tinge) is relatively common and occurs in up to 10% of births Meconium aspiration usually happens in term infants in utero before delivery If the baby has absent or inadequate respirations, a heart rate <100 beats/min or hypotonia , inspect the oropharynx with a laryngoscope and aspirate any particulate meconium seen using a wide-bore catheter If, while attempting to clear the airway, the heart rate falls to less than 60 beats/min then stop airway clearance, give aeration breaths and start ventilating the baby 176

177. 177 Chin lift in infants

178. 178 Jaw thrust

179. Breathing (aeration breaths and ventilation ) The first five breaths in term babies should be “inflation ‟ breaths in order to replace lung fluid in the alveoli with air These should be 2-3 second sustained breaths using a continuous gas supply , a pressure limiting device and a mask Use a transparent, circular soft mask big enough to cover the nose and mouth of the baby 179

180. 180 Bag and mask ventilation

181. Breathing (aeration breaths and ventilation) The chest may not move during the first 1–3 breaths as fluid is displaced Adequate ventilation is usually indicated by either a rapidly increasing heart rate or a heart rate that is maintained at more than 100 beats per minute Where possible, start resuscitation of the baby at birth with air There is now good evidence for this in term babies and oxygen toxicity is a real concern with premature babies 181

182. 182 Circulation If the heart rate remains slow or absent, despite adequate ventilation for 30 seconds as shown by chest movement, then chest compressions should be started Chest compressions will help to move oxygenated blood from the lungs to the heart and coronary arteries The most efficient way of delivering chest compressions in the neonate is to encircle the chest with both hands The fingers lie behind the baby and the thumbs are apposed on the sternum just below the inter-nipple line Continued

183. Circulation Compress the chest briskly, by one third of its depth In newborn babies, current advice is to perform three compressions for each ventilation breath (3:1 ratio) The purpose of chest compression is to move oxygenated blood or drugs to the coronary arteries in order to initiate cardiac recover Simultaneous delivery of compressions and breaths should be avoided, as the former will reduce the effectiveness of the breaths Once the heart is above 60 beats/min and rising, chest compression can be discontinued 183

184. 184 Infant chest compression: hand- encircling technique

185. Drugs The most common reason for failure of the heart rate to respond is failure to achieve lung inflation, and there is no point in giving drugs unless the airway is open and the lungs have been inflated Venous access will be required via an umbilical venous line , because ideally drugs should be given centrally Adrenaline : The alpha-adrenergic effect of adrenaline increases coronary artery perfusion during resuscitation, enhancing oxygen delivery to the heart 185

186. Adrenaline The alpha-adrenergic effect of adrenaline increases coronary artery perfusion during resuscitation, enhancing oxygen delivery to the heart In the presence of profound unresponsive bradycardia or circulatory standstill, 10 micrograms/kg (0·1 ml/kg 1:10000) adrenaline may be given intravenously Further doses of 10–30 micrograms/kg (0·1–0·3 ml 1:10000) may be tried at 3–5-minute intervals if there is no response The tracheal route cannot be recommended, as there is insufficient data 186

187. Bicarbonate Any baby who is in terminal apnoea will have a significant metabolic acidosis. Acidosis depresses cardiac function Bicarbonate 1-2 mmol /kg (2-4 ml/kg of 4·2% solution) may be used to raise the pH and enhance the effects of oxygen and epinephrine Glucose Hypoglycaemia is a potential problem for all stressed or asphyxiated babies It is treated using a slow bolus of 2.5 ml/kg of 10% glucose intravenously, and then providing a secure intravenous glucose infusion at a rate of 100 ml/kg/day of 10% glucose 187

188. Fluid Very occasionally hypovolaemia may be present because of known or suspected blood loss (antepartum haemorrhage , placenta or vasa praevia , unclamped cord ) I t may be secondary to loss of vascular tone following asphyxia Volume expansion, initially with 10 ml/kg, may be appropriate Normal saline can be used Non-cross-matched O-negative blood should be given immediately 188

189. Naloxone If respiratory depressant effects are suspected the baby should be given naloxone intramuscularly (200 micrograms in a full term baby ) Response to resuscitation The first indication of success will be an increase in heart rate Tracheal intubation Most babies can be resuscitated using a mask system Tracheal intubation should be considered if mask ventilation has failed A normal full-term newborn usually needs a 3·5 mm tracheal tube, but 4·0- 3·0- and 2·5 mm tubes should also be available 189

190. Special cases Pre-term babies Premature babies are more likely to get cold (higher surface area to mass ratio), and more likely to become hypoglycaemic (fewer glycogen stores) Use of plastic bags placed over babies of <29 weeks gestation or <1000g before drying in order to keep warm 190

191. Guidelines for use of plastic bags for pre-term babies (< 29weeks ) at birth Pre-term babies born below 29 completed weeks‟ gestation may be placed in plastic bags or wrap for temperature stability during resuscitation At birth the baby should not be dried, but should be slipped straight into the prepared plastic bag or wrapping Suitable plastic bags are food-grade bags designed for microwaving and roasting The bag should cover the baby from the shoulders to the feet, with the head protruding through the V-cut The head will stick out of the V-cut and will be dried as usual and resuscitation commenced The bag should not be removed unless deemed necessary by the registrar or consultant The bag is only removed when the incubator humidity is satisfactory, 191

192. The more premature a baby the less likely it is to establish adequate respirations Preterm babies (less than 32 weeks gestation) are likely to be deficient in surfactant especially after unexpected or precipitate delivery The surfactant, secreted by pneumocytes in the alveolar epithelium, reduces alveolar surface tension and prevents alveolar collapse on expiration Small amounts of surfactant can be demonstrated from about 20 weeks‟ gestation, but a surge in production occurs at 30–34 weeks Surfactant is released at birth due to aeration and distension of the alveoli. The half-life of the surfactant is approximately 12 hours Production is reduced by hypothermia (<35 C), hypoxia and acidosis (pH <7.25) The lungs of pre-term babies are more fragile than those of term babies and thus are much more susceptible to damage from over-distension Therefore, it is appropriate to start with a lower inflation pressure of 2·0–2·5 kPa (20–25 cmH2O ) 192

193. Premature babies are more susceptible to the toxic effects of hyperoxia . Using a pulse oximeter to monitor both heart rate and oxygen saturation in these babies from birth makes stabilisation much easier Saturation monitoring Pulse oximetry gives a quick and relatively accurate display of both heart rate and oxygen saturation 193

194. 194 Newborn Resuscitation Algorithm Reproduced with the kind permission of the Resuscitation Council (UK)

195. Cardiac disease in pregnancy Cardiac disease is a leading cause of maternal mortality in the UK Maternal death due to ischaemic heart disease is increasing in the developed world Rheumatic heart disease is the leading cause of maternal heart disease in the developing world Some conditions still have such a high maternal mortality rate that foetal termination is advised Low dose epidural infusion for labour with assisted second stage is suitable management in many cases Oxytocin can cause haemodynamic instability and should be used with care in mothers with cardiac disease 195

196. Background The incidence of cardiac disease in pregnancy is increasing in the developed world The leading cause of death was myocardial infarction, mainly secondary to ischaemic heart disease, followed by cardiomyopathy, sudden adult death syndrome Deaths related to pulmonary hypertension and congenital heart disease have fallen but deaths due to rheumatic heart disease have increased due to immigration of women from areas of high prevalence 196

197. Introduction More women with congenital heart disease now survive to adulthood due to improved surgical techniques and drug therapy New York Heart Association (NYHA) functional class NYHA 1: Known cardiac disease with no limitation of physical activity and no objective evidence of cardiovascular disease NYHA 2: Slight limitation of normal physical activity and objective evidence of minimal disease NYHA 3: Marked limitation of physical activity and objective evidence of moderate disease NYHA 4: Severe limitation of activity including symptoms at rest and objective evidence of severe disease 197

198. Rheumatic fever is still prevalent in the developing world so severe uncorrected valvular heart disease is more common in women reaching childbearing age Rheumatic heart disease most commonly affects the mitral valve causing stenosis or regurgitation but can also affect the aortic valve and less commonly the pulmonary valve Mothers with known cardiac disease need to be seen early in pregnancy or preferably preconception so they can be counselled on potential complications and mortality to themselves and their foetus Pregnant women with cardiac disease should ideally be managed in specialist centres by a multi-professional team of cardiologists, obstetricians and anaesthetists who will make a plan for delivery and monitor cardiac function throughout pregnancy by regular clinical examination and investigations including ECG, echocardiogram and in some cases cardiopulmonary exercise testing 198

199. Mothers who develop incipient cardiac disease in late pregnancy are difficult to diagnose as symptoms are similar to the later stages of pregnancy i.e. shortness of breath, swollen ankles, fatigue, reduction in exercise capacity, murmurs , third heart sound and arrhythmias Physiological Changes in Pregnancy By the 20th week of gestation, cardiac output increases by 40% due to increased stroke volume and heart rate Blood volume increases by up to 50 % while systemic vascular resistance (SVR) falls This will place additional strain on a failing heart and in those with a significant shunt As SVR falls there will be increased right to left shunting which may reduce pulmonary perfusion Coupled with the increased oxygen demand of pregnancy this can lead to increasing hypoxia 199

200. Labour and delivery Labour and delivery can further compromise cardiac function Pain may lead to a tachycardia which reduces diastolic coronary filling as well as increasing circulatory catecholamines which increase SVR Cardiac output increases during each contraction due to autotransfusion of up to 500ml of blood into the circulating volume In some cases, pushing during the 2nd stage may cause haemodynamic compromise due to the effects of the Valsalva manoeuvre 200

201. Potential problems at delivery include: Blood loss may be poorly tolerated since many women are unable to compensate by the usual response of increasing heart rate and stroke volume and may rely on venous return to maintain cardiac output • Bleeding may be increased due to concurrent anticoagulation. • Pulmonary oedema is more likely to occur peripartum due to fluid shifts and as a consequence of additional IV fluids to replace losses Careful fluid balance is essential and this may be aided by running drug infusion in smaller volumes of increased concentration Arrhythmias and tachycardia are poorly tolerated 201

202. Potential problems at delivery include: Drugs causing tachycardia should be avoided or limited (e.g. oxytocin, ephedrine) Alpha-adrenergic agonists (e.g. phenylephrine and metaraminol ) are the vasopressors of choice Reduction in SVR by regional techniques or other drugs may cause problems if cardiac output is fixed (e.g. severe aortic stenosis) or in the presence of a shunt Increased right to left shunting reduces pulmonary blood flow and increases hypoxia 202

203. Congenital and Acquired Valvular Heart Disease Women may often have asymptomatic valvular disease until compromised by the physiological changes of pregnancy Pregnancy is better tolerated in regurgitant lesions than in stenotic lesions as reduced SVR promotes forward blood flow Labour can be managed with a carefully titrated epidural 203

204. Aortic stenosis (AS) If asymptomatic before conception then pregnancy is usually well tolerate • In severe stenosis (valve area < 0.5cm2 (best guide) or gradient > 60 mmHg ) mortality is up to 5%. • Fall in SVR poorly tolerated in severe aortic stenosis due to fixed cardiac output. • Tachycardia, bradycardia, hypovolaemia and venocaval compression poorly tolerated. Coronary artery perfusion dependent on aortic diastolic pressure so hypotension can lead to acute left ventricular failure secondary to ischaemia Blood pressure should be closely monitored and carefully managed with alpha-adrenergic agonists and appropriate fluid to replace losses 204

205. Aortic stenosis (AS) Avoid ephedrine due to the risk of tachycardia as a result of beta 1 receptor stimulation. Invasive arterial blood pressure monitoring should be used in cases of severe AS • General anaesthesia may be indicated in severe aortic stenosis ; however there are many reports of carefully titrated regional anaesthesia with a vasopressor infusion and close observation of blood pressure Gradual epidural top-up, combined spinal epidural with low dose spinal block and careful epidural top-up and cautious spinal block with a spinal catheter have all been successfully used to manage women with moderate and severe AS Acute aortic valve replacement may be required in cases of severe symptomatic stenosis Women at risk must be managed in a hospital with cardiac surgery facilities 205

206. Mitral stenosis Defined as severe if valve area on echocardiography is <1cm2 Problems due to large gradient between left ventricle and left atrium which may cause pulmonary oedema , pulmonary hypertension and right ventricular failure. Dyspnoea at rest is an important marker of severity. If pulmonary hypertension is already present then risk to the mother is significant and termination of pregnancy maybe the best option. Tachycardia and arrhythmias will reduce cardiac output by reducing diastolic filling 206

207. Mitral stenosis Rate control is most important and tachyarrhythmias should be controlled with β-blockers or digoxin If the valve stenosis is severe a balloon valvotomy may be considered during pregnancy. Vaginal delivery with carefully titrated epidural analgesia and invasive arterial blood pressure monitoring is preferable in those who are symptomatic or with severe stenosis 207

208. Pulmonary stenosis Pulmonary stenosis in isolation constitutes 10% of congenital heart disease Also part of the Tetralogy of Fallots and may be present following its repair Isolated pulmonary stenosis is often asymptomatic but may lead to increased right ventricular work and right ventricular failure. Balloon valvuloplasty may be considered in women developing right heart failure Goals during labour and delivery are to maintain right ventricular preload , left ventricular afterload and right ventricular contraction. Vaginal delivery with epidural analgesia is probably the most optimal management 208

209. Oxytocin and single shot spinal both cause large decreases in SVR which is very poorly tolerated in those with severe aortic stenosis Cautious regional anaesthesia may be appropriate for delivery with close monitoring of BP and therapeutic measures to maintain SVR 209

210. NON-VALVULAR CONGENITAL HEART DISEASE : Conditions with a left to right shunt Left to right shunt may be due to a ventricular septal defect (VSD), atrial septal defect (ASD) or patent ductus arteriosus. Small shunts do not usually cause problems. Moderate shunts may increase if SVR increases due to pain and catecholamine release If there is a large drop in SVR (e.g. following spinal block) then the shunt may reverse in direction and may result in hypoxia. Large shunts (most likely from a VSD) can result in pulmonary hypertension 210

211. Tetralogy of Fallot ( ToF ) Most common cyanotic congenital heart lesion. Large VSD , right ventricular outflow tract obstruction , right ventricular hypertrophy and overriding aorta Risks dependant on the status of the repair Pregnancy often well tolerated in those with repaired ToF but women should have their right ventricle fully assessed; deaths have occurred in recent years from arrhythmias secondary to unrecognised right heart failure 211

212. Coarctation of the Aorta Narrowing of the aorta around the site of the ductus arteriosus Most women presenting with coarctation will have had a previous repair Problems during labour and delivery are unlikely if successfully repaired, however late hypertension, re- coarctation and aneurysm formation at the site of previous repair may occur All women with previous repairs should be closely monitored throughout pregnancy by serial echocardiography and regular BP measurement (measure BP in both arms since left subclavian may have been used as part of previous repair). 212

213. Coarctation of the Aorta If present with un-repaired coarctation (native coarctation ), risks to both mother and fetus are high due to hypertension refractory to medical treatment. Regional anaesthesia or analgesia must be carefully titrated with close monitoring of BP and drugs to maintain SVR (phenylephrine, metaraminol ). In severe cases women are at risk of aortic rupture, dissection and left ventricular failure. 213

214. Pulmonary Hypertension (PH) and Eisenmenger Syndrome There is a very high risk of maternal mortality with PH and termination of pregnancy is often recommended . There is increased pulmonary vascular resistance resulting in an increased workload placed on the right heart PH may be primary or secondary The causes of secondary PH include: C ardiac , respiratory (chronic obstructive or parenchymal conditions, cystic fibrosis, obstructive sleep apnoea , thoracic cage abnormalities) venous thromboembolism, vasculitis , hyperviscosity syndrome, infection, portal hypertension, cirrhosis and drugs(oral contraceptive, crotalaria teas, appetite suppressants ) 214

215. Pulmonary Hypertension (PH) and Eisenmenger Syndrome PH is poorly tolerated due to insufficient adaptation of the right heart to the increased cardiac output and poor compliance of the pulmonary vasculature. Symptoms of right ventricular decompensation are: shortness of breath, fatigue, chronic cough, haemoptysis and syncope. Signs include; tachycardia, cyanosis, right ventricular heave, elevated JVP and hepatomegaly. Death occurs from irreversible right ventricular failure and arrhythmias. Therapies targeted at pulmonary arterial vasodilatation may be useful during pregnancy ( e.g. prostaglandin analogues including Iloprost ) 215

216. Pulmonary Hypertension (PH) and Eisenmenger Syndrome Timing of delivery is dependant on the impact of PH on the mother as pregnancy progresses If possible , aim to deliver at 32-34 weeks. Increases in pulmonary vascular resistance (PVR) must be prevented by avoiding rises in PaCO2, falls in PaO2 and pH, hypothermia, high ventilatory pressures and sympathetic agents. Right ventricular preload, left ventricular afterload and right ventricular contractility must be maintained . Vaginal delivery is probably the safest mode of delivery with a low dose epidural to reduce pain, stress and haemodynamic fluctuations while maximising oxygen consumption Avoid pushing in second stage due to the reduction in venous return and right heart preload that results 216

217. Pulmonary Hypertension (PH) and Eisenmenger Syndrome Pulmonary arterial pressure may rise significantly during intubation if general anaesthesia is provided Measures to obtund the pressor response to laryngoscopy should be used. Oxytocin should be used cautiously after delivery Eisenmenger’s syndrome is pulmonary hypertension at systemic values with reversal of bidirectional shunt either due to a large left to right communication or pulmonary artery occlusion. • The shunt flow depends on the PVR: SVR ratio. • Hypovolaemia will lead to shunt reversal, reduced cardiac output and increased cyanosis. • Mortality in pregnancy and delivery is very high due to right ventricular failure 217

218. Ischaemic heart disease and myocardial infarction This is now the leading cause of cardiac maternal mortality in the UK. All women who died from ischaemic heart disease had identifiable risk factors including: • Obesity • Advanced maternal age Higher parity • Pre existing hypertension • Smoking • Family history of cardiac disease • Type 2 diabetes mellitus 218

219. Previously undiagnosed ischaemic heart disease (IHD) usually manifests itself in the 3rd trimester, labour or post delivery at a time when maternal stress and cardiac demand are at their greatest I t presents with chest pain, ischaemic changes on the ECG and elevated troponin but may sometimes present atypically with abdominal or epigastric pain Beware the use of uterotonics . Ergometrine causes coronary artery vasospasm and should be avoided if there is a history or IHD 219

220. GENERAL APPROACHES TO MANAGEMENT OF PREGNANT WOMEN WITH CARDIAC DISEASE Monitoring • Basic monitoring for mothers with heart disease during labour , delivery and in the immediate post partum period includes; blood pressure, pulse oximetry and continuous 3-lead ECG. • Invasive blood pressure monitoring is very useful in higher risk cases and can be easily managed on labour ward with appropriate anaesthetic input. • There is debate over the use of central venous pressure (CVP) and pulmonary artery catheter(PAC ) monitoring These interventions are not without risk and benefits may sometimes be limited. • Long lines placed in the antecubital fossa can be used to measure CVP and infuse vasoactive drugs and may be a safer approach to central venous cannulation. 220

221. Delivery • Stress on the mother and her cardiovascular system must be minimised while maintaining placental and foetal circulation. Effective pain relief results in less tachycardia and catecholamine release. It also reduces the haemodymanic effects of pushing . • Low-dose epidural anaesthesia sited early in labour for effective pain control and reduced catecholamine release is highly beneficial in most cases. • If caesarean section is required due to obstetric indications or decompensation of the underlying disease , then this can be done with either general or regional anaesthesia . • If general anaesthesia is planned, measures to suppress the pressor response to laryngoscopy must be provided e.g. alfentanil 10-20 mcg/Kg. If regional anaesthesia is planned, single-shot spinals are best avoided. Alternative options include: careful titration of an epidural, combined spinal-epidural or incremental spinal anaesthesia (via spinal 221

222. Anticoagulation Warfarin is teratogenic and not recommended during the first trimester of pregnancy It is avoided in the third trimester since it crosses the placenta and can cause foetal haemorrhage It also precludes regional anaesthesia and its effects may be difficult to rapidly reverse in an emergency Low molecular weight heparin (LMWH) can be used instead of warfarin throughout the whole of pregnancy Regional anaesthesia can be performed provided adequate time has elapsed since the last dose of LMWH For women receiving prophylactic LMWH, regional anaesthesia or removal of epidural catheter can be performed 12 hours after last dose of LMWH After insertion of epidural or spinal a dose can be given 4 hours later 222

223. Uterine atony Many oxytocics have severe consequences for those with cardiac disease but withholding them can lead to haemorrhage • Oxytocin can cause profound tachycardia, vasodilatation and hypotension when administered as an IV bolus so administer the bolus as an infusion (e.g. 5 units in 20mls over 5-10 mins) If at particular risk of cardiovascular effects (e.g. severe aortic stenosis) then it may be best omitted A low dose infusion with 10 units per hour can be used post-delivery with careful monitoring Ergometrine causes pulmonary vasoconstriction and hypertension so avoid in most cardiac cases especially pulmonary hypertension Prostaglandin F2∝ ( Carboprost ) can cause severe bronchospasm, hypertension , cardiovascular collapse and pulmonary oedema making it unsuitable in most cases Uterine massage can be used to provide temporary relief but may require adequate analgesia 223

224. Pharmacological management of PPH The most common cause of PPH is uterine atony In addition to uterine massage, the following drugs stimulate uterine contraction Syntocinon Syntocinon is a synthetic analogue of oxytocin and 5IU is given by slow intravenous injection. Rapid injection may result in vasodilatation and subsequent hypotension and tachycardia. The dose may be repeated once (maximum of 10IU). Thereafter, an infusion of 30 to 40IU in 500mls 0.9% Saline may be commenced at a rate of 125ml.hr- 224

225. Pharmacological management of PPH Ergometrine The dose is 500mcg by slow intravenous or intramuscular injection Adverse effects include nausea, vomiting and vasoconstriction leading to a marked rise in BP It is therefore best avoided in patients with cardiovascular disease and pre-eclampsia Carboprost • Carboprost is a prostaglandin F2 receptor agonist which stimulates uterine contraction • 250mcg is given by intramuscular injection This may be repeated at 15 minute intervals to a maximum of eight doses • Adverse effects include bronchospasm, hypoxia, flushing, nausea and vomiting It should be avoided in patients with asthma 225

226. Pharmacological management of PPH Misoprostol • Misoprostol is a prostaglandin E1 analogue which also stimulates uterine contraction It rarely causes any serious side effects . The dose is 1mg rectally 226

227. Perioperative Management of the Diabetic Patient DEFINITION Diabetes mellitus is defined as a syndrome characterized by sustained hyperglycemia due to insulin deficiency, impaired insulin action or a combination of both 227

228. Diagnostic criteria for diabetes according to ADA/WHO guidelines 228

229. 229

230. Type 1 DM : absolute insulin deficiency, unopposed catabolic action leads to hyperglycemia and diabetic ketoacidosis. Type 2 DM: peripheral resistance to insulin, less susceptible to developing ketoacidosis 230

231. Mortality / morbidity rates in diabetics have been estimated to be up to 5 times greater than in nondiabetics Related to the end-organ damage . 231

232. DM is an independent predictor of postop myocardial ischemia and infectious complications in patients undergoing surgery . The ultimate goal in the management of diabetic patients is to achieve equivalent outcomes as those patients without DM A strong grasp of the complexities of glucose insulin interrelationship and of the effects of anesthesia and surgery is essential to optimal management and outcomes. 232

233. PHYSIOLOGY OF GLUCOSE METABOLISM Glucose metabolism is largely a function of the liver, the pancreas, and, to a lesser degree, peripheral tissue. Role of liver in glucose regulation: Extracts glucose Stores it in the form of glycogen Performs gluconeogenesis Glycogenolysis Pancreas secretes counterregulatory hormones : Insulin from islet beta cells, which lowers blood glucose concentrations. Glucagon from islet alpha cells, which raises blood glucose concentrations 233

234. Additional contributors to glucose metabolism include the catabolic hormones: epinephrine, glucocorticoids, and growth hormone, which all raise blood glucose concentrations. Peripheral tissues participate in glucose metabolism by extracting glucose for energy needs, thus lowering blood glucose levels. 234

235. PREOPERATIVE ASSESSMENT Suggestive symptoms - polyuria/polydipsia, blurred vision Current Rx of diabetes, including medication regimen, diet, and glucose monitoring results Frequency, severity, and etiology of acute complications (ketoacidosis / hypoglycemia) Prior or current infections ( eg , skin, foot, dental, genitourinary) Symptoms and treatment of chronic eye; kidney; nerve; genitourinary, bladder, and GI function; heart; peripheral vascular; foot; and cerebrovascular complications Nondiabetic medications that may affect blood glucose levels ( eg , corticosteroids ) 235

236. Preanaesthetic evaluation Severity and type of the diabetic state Anti-diabetic Medications Control of blood sugar Treatment regimens used Associated complications of DM Airway assessment Comorbid conditions 236

237. Physical examination Orthostatic hypotension - sign of autonomic neuropathy 237

238. Autonomic neuropathy Most commonly a distal symmetrical sensory polyneuropathy with a variable degree of autonomic involvement . Autonomic dysfunction, which is of particular importance to the anaesthetist , is detectable in up to 40% of type 1 and 17% of type 2 diabetic patients 238

239. Diabetic gastroparesis is characterized by a delay in gastric emptying without any gastric outlet obstruction . The increased amount of gastric contents enhances the risk of acid aspiration during the induction of anaesthesia Stiff joint” syndrome Significant risk during airway management . Affects temporomandibular, atlantooccipital , and other cervical spine joints . Short stature and waxy skin . Related to chronic hyperglycemia and nonenzymatic glycosylation of collagen and its deposition in joints. 239

240. “PRAYER SIGN” A positive “prayer sign” can be elicited on examination with the patient unable to approximate the palmar surfaces of the phalangeal joints while pressing their hands together; Represents cervical spine immobility and the potential for a difficult endotracheal intubation . 240

241. Further airway evaluation should include assessment of thyroid gland size, as patients with type 1 DM have a 15% association of other autoimmune diseases, such as Hashimoto thyroiditis (hypothyroidism) and Graves disease(hyperthyroidism) 241

242. The degree of preoperative neurological dysfunction is important to document, especially prior to regional anesthesia or peripheral nerve blocks, to assess the degree of subsequent nerve injury. Lab evaluation Fasting serum glucose concentration HbA1c Serum electrolytes Blood urea nitrogen Creatinine . Urinalysis - assess for proteinuria and microalbuminuria 242

243. GENERAL PREOP MANAGEMENT On the day of surgery, patients on oral regimens should be advised to discontinue these medications. Sulfonylureas , meglitinides have the potential to cause hypoglycemia. Sulfonylureas have been associated with interfering with ischemic myocardial preconditioning and may theoretically increase risk of perioperative myocardial ischemia and infarction. For these patients, short-acting insulin may be administered subcutaneously as a sliding scale or as a continuous infusion , to maintain optimal glucose control, depending on the extent of surgery 243

244. Problems faced by a diabetic for surgery Surgical stress response with catabolic hormone secretion Altered consciousness - masks the symptoms of hypoglycaemia Circulatory disturbances - which may alter the absorption of s/c insulin. A nondiabetic patient is able to maintain glucose homeostasis by secreting a corresponding amount of insulin to balance the glucose generated by the stress response 244

245. This compensatory mechanism in diabetic patients is impaired through a relative insulin deficiency (type 2) or absolute insulin deficiency (type 1) necessitating supplementation of insulin in the perioperative period Anesthetic agents can affect glucose metabolism through the modulation of sympathetic tone; in vitro evidence suggests that inhalational agents suppress insulin secretion. The resulting relative insulin deficiency often leads to glucose dysregulation and hyperglycemia. 245

246. The use of regional anesthesia or peripheral nerve blocks may mitigate(ease) these concerns, but no data suggest that these forms of anesthesia will improve postoperative survival in patients with DM 246

247. GOALS OF PERIOPERATIVE GLYCEMIC CONTROL The goals for glycemic control are tailored to each patient based on : Nature of surgery, Severity of underlying illness, Modality used to achieve glycemic control Patient age, Sensitivity to insulin 247

248. Prior to elective surgery, it is ideal for patients to have their HbA1c < 6 %. Less intensive glycemic control may be indicated in patients with severe or frequent episodes of hypoglycemia. Catecholamines are also counter-regulatory hormones that oppose insulin activity 248

249. Methods of Achieving Glycemic Control Intravenous insulin is the most flexible and readily titratable agent, with few, if any, contraindications, making it an ideal agent for perioperative use The length, type of surgery, and degree of glycemic dysregulation will dictate the degree of supplemental intravenous insulin therapy. Patients with type 1 diabetes should have elective surgeries scheduled as the first case of the day to minimally disrupt their DM regimen. Administer half of their daily dose of long-acting insulin. Arrive at the preop admitting area early enough to have an I.v infusion of dextrose instituted and their serum glucose monitored until the time of surgery 249

250. Establish separate iv access for a “piggyback” infusion of regular insulin . The infusion rate can be determined by using the formula: insulin (U/h) = serum glucose (mg/ dL )/150. Intravenous glucose solution should be administered concomitantly to avoid hypoglycemia. Typically, a 5% D solution is started when serum glucose levels are less than 150 mg/ dL . Patients suspected of gastroparesis should receive a prokinetic drug prior to general anesthesia to decrease the incidence of gastric acid aspiration Aseptic technique is critical for all procedures in patients with DM to decrease the incidence of postoperative infection. Temperature control is also essential in patients with DM, as hypothermia can lead to peripheral insulin resistance, hyperglycemia, deceased wound healing, and infection 250

251. Intraop management of intravascular volume may require the use of a central venous pressure catheter, a pulmonary artery catheter, or TEE( transechocardiography ) to best guide therapy and to protect against end-organ hypoperfusion Arterial blood gas analysis should not only include assessment of blood glucose levels but also levels of sodium, potassium, and assessment of pH Type 1 diabetic patients are predisposed to developing ketoacidosis during periods of major stress; therefore, they should be monitored by arterial blood gas analysis during and after major surgery. 251

252. Day of surgery Check fasting sugar No subcutaneous insulin Start 10% Dextrose (500ml) with 10 U human insulin and KCI 1Ommol for 4-6 h Adjust insulin according to the blood sugar values <4 ( mmol /L) No insulin 4-6( mmol /L) Insulin 5 U / 500 mL 10%glucose 6-10 ( mmol /L) Same as above 10-20 ( mmol /L) 15 U/ 500 Ml 10% glucose >20 20 ( mmol /L) 15U/500 mL 10%glucose K+ is adjusted according to serum K+ K +<3 mmol /L add 20 mmol K+/500 ml K+>5 mmol /L no KCI 252

253. Postop major surgery Check blood sugar every 2-6 h Check urea, electrolytes every 4-6h Continue infusion till oral feeding is established If feeding is delayed, change to 20% glucose with less volume When oral diet is established, q8h soluble insulin prior to each feed When insulin requirements are stable,restart the preoperative regimen 253

254. Emergency surgery and DKA DKA( Diabetic ketoacidosis ) results from inadequate insulin dosage or increased insulin requirement often precipitated by trauma, infection or surgical stress. Administer insulin at the rate of 4-8U/ hr , depending on factors such as blood sugar levels, ketosis and acidosis . Correct dehydration, sodium depletion and subsequent potassium depletion Replace fluids with isotonic solution of NaCI 1 L in 30 min,1 L in the next hour and further 1 L over the next 2 hours . Monitor blood glucose levels, arterial pH and blood gases K + may be normal or elevated due to presence of acidosis 254

255. Magnesium 5-10 mmol is also required along with K+ depletion. 5% Dextrose can be started when blood glucose decreases to 15 mmol /L Surgery is ideally carried out after reversal of acidosis and hyperglycemia. However, if the indication for surgery is emergent, surgery can be started when volume resuscitation is underway, with the diabetic management being continued in the intraop and postop periods. 255

256. Tight control of blood glucose Tight control of blood sugar between 80 – 120 mgs/ dL Prevents ischemia Improves wound healing Improves weaning from CPB REGIMEN – 1 Preprandial sugar levels on the evening before surgery. Start infusion of 5% D at the rate of 50 ml/ hr To this infusion, piggyback regular insulin 50 U in 250 ml 0.9 Nacl . Set the infusion rate U/ hr = Plasma glucose 150 256

257. REGIMEN - 1 Repeat glucose values q4h, and adjust insulin infusion to achieve plasma glucose of 100-200 mg/dl. Intraop - use non dextrose containing fluids. Determine plasma glucose q2h and adjust insulin accordingly. Serum K+ should be checked and adjusted accordingly with particular care for poor renal function 257

258. 258

259. Anaesthetic technique and the diabetic patient Regional blockade, may modulate the secretion of the catabolic hormones and any residual insulin secretion. The perioperative increase in circulating glucose, epinephrine and cortisol concentrations found in non-diabetics exposed to surgical stress under GA is blocked by epidural anesthesia The perioperative infusion of phentolamine, a competitive -adrenergic receptor blocking drug , decreases the glycaemic response to surgery by partially reversing the suppression of insulin secretion 259

260. Regional anaesthesia may carry greater risks in the diabetic patient with autonomic neuropathy. Profound hypotension may occur with deleterious consequences in a patient with co-existing coronary artery, cerebrovascular or renovascular disease Medical / Legal Pitfalls Overtreatment or undertreatment of hypoglycemia, eg , premature discharge of a patient who develops hypoglycemia due to a sulfonylurea agent, is a pitfall(dangerous). Failure to record the blood glucose levels of patients with wounds or active infections when they are <250 mg/ dL is a pitfall and may lead to poor healing 260

261. Medical / Legal Pitfalls Failure to provide adequate hydration to patients with mild diabetic nephropathy before contrast material is given may precipitate acute renal failure. Failure to examine the patient's feet and failure to detect small ulcers or underestimation of their seriousness are also pitfalls. Failure to consider myocardial ischemia in patients with nonspecific symptoms is a pitfall 261

262. Conclusions There have been major advances in the last few years in understanding and treating complications of diabetes. The main focus has been on good glycemic control. The incidence of diabetes is on the rise in most populations, with Indians being more prone to develop diabetes. Diabetes mellitus is likely to be the most common comorbid factor encountered in Surgical practice. A clear understanding of the metabolic process, well controlled glycemic regimens and excellent periop care will go a long way towards decreasing the mortality and morbidity in diabetes patients 262