Obestetric analgesia and anesthesia, by Daniel A..pptx

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1. Seminar topic – Obstetric Analgesia and Anesthesia Moderator: Dr. Bekalu Mola ( Ass’t prof., Obstetrician & Gynecologist ) Presenter : Daniel Angamo (C-I )

2. Outlines Objectives Introduction Anatomic and physiologic changes during pregnancy and implications for anesthesia Principles of pain relief in labour Labour analgesia Anesthesia for obstetrics surgery Building shared responsibility with anesthesia personnel to get the work done References

3. Objectives To discuss common analgesics & anesthetic used in management of labour pain, To discuss different methods of analgesia and anesthesia in obstetric surgery; To highlight common complications associated with obstetric analgesia, and anesthesia;

4. Various physiologic changes takes place to adapt the enlarging uterus and support the growing fetus. These changes must be considered when designing a plan for the analgesia anesthesia. Anestheisia carries increased risk of aspiration and respiratory arrest among pregnant women, Introduction

5. The usual physiological adaptations of pregnancy require special consideration, especially with disorders such as : Preeclampsia, Placental abruption, or Sepsis . Although uncommon, failed intubation is a major cause of anesthesia-related maternal mortality . Introduction

6. Obstetric anesthesia involves caring for both the parturient and the fetus . But it accompanies challenges unique to pregnancy; Labor begins without warning, and anesthesia may be required within minutes of a full meal. Vomiting with aspiration of gastric contents is a constant threat. Introduction …

7. Labor and delivery result in severe pain for most women. Labour pain has been identified as an important reason for women to prefer caesarean section (CS). The pain of childbirth is rated 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 . Introduction …

8. Many women desire pain management during labor and delivery, and there are many medical indications for analgesia and anesthesia during labor and delivery. In the absence of contraindications, maternal request is a sufficient medical indication for pain relief during labor. A woman who requests epidural analgesia during labor should not be deprived of this service based on the status of her health insurance.  Introduction …

9. Cardiovascular system: Due to the effects of increased levels of oestrogen and progesterone, peripheral vasodilatation and resultant decrease in systemic vascular resistance (SVR) begin to occur by 8 th  week of gestation. Since there is no autoregulation  in utero  placental circulation, cardiac output (CO) has to increase in order to maintain blood pressure (CO × SVR). Changes during pregnancy and implications for anesthesia

10. Cardiovascular system: In early pregnancy, this increase in CO is achieved by an increase in heart rate (HR) by 15–25% followed by an increase in stroke volume (SV) by 20–30 %. Most of the increase in CO goes to the uterus, kidneys and skin to provide nutrients to the foetus , excrete maternal and foetal waste products and assist in maternal temperature control, respectively . Changes during pregnancy and implications for anesthesia

11. Cardiovascular system … Increased blood volume provides some reserve for the normal blood loss during delivery (about 300–500 ml for vaginal delivery and 600–1000 ml for caesarean delivery) and peripartum haemorrhage . But due to this increase in blood volume, pregnant patients may not manifest the signs and symptoms of hypovolemia (tachycardia, hypotension, oliguria) till about 1500 ml of blood loss has occurred. Changes during pregnancy and implications for anesthesia

12. Cardiovascular system … By 20 weeks of gestation, the gravid uterus begins to cause mechanical compression of inferior vena cava (IVC) and descending aorta in supine position. This leads to a decrease in venous return and CO resulting in maternal hypotension and foetal compromise ( acidaemia ). To compensate for aortocaval compression, sympathetic tone and HR increase and blood from lower limb is shunted to the right side of heart through vertebral plexus and azygos veins . Changes during pregnancy and implications for anesthesia

13. Cardiovascular system … In many parturient, the above compensatory mechanisms may be inadequate to maintain blood pressure in supine position and result in supine hypotensive syndrome ( aortocaval compression syndrome ). It is characterised by pallor, transient tachycardia followed by bradycardia, sweating, nausea, hypotension and dizziness in supine position which get relieved by turning lateral. In its severe form, it can lead to unconsciousness or sudden maternal death . Changes during pregnancy and implications for anesthesia

14. Cardiovascular system … Engorgement of epidural venous plexus can result in increased risk of bloody tap and intravascular catheter placement during epidural anaesthesia and analgesia. Due to down-regulation of adrenergic receptors, higher doses of vasopressors like phenylephrine are required in the event of hypotension . Changes during pregnancy and implications for anesthesia …

15. Cardiovascular system … Reduction in SV and CO during general anaesthesia (GA) and sympathetic blockade during neuraxial anaesthesia can aggravate supine hypotensive syndrome. So , supine position should be avoided or the uterus should be displaced laterally with wedge under hip. The adverse effects of aortocaval compression are reduced once the foetal head is engaged. Changes during pregnancy and implications for anesthesia …

16. Cardiovascular system … For neuraxial anaesthesia , the Oxford position has been found to have better haemodynamic stability, more reproducible block height and prevents adverse effects of aortocaval compression. It is a modified lateral position with an upward slope in the thoracic region with avoidance of supine position till surgery begins . Changes during pregnancy and implications for anesthesia …

17. Respiratory system Upper airway changes, enlarged breasts and obesity can make intubation difficult during pregnancy. Laryngoscopes with short handles, smaller diameter endotracheal tubes and ramp position at the head end might be needed in difficult scenarios. Changes during pregnancy and implications for anesthesia …

18. Respiratory system … Venous engorgement of airway mucosa, and Edema of airway mucosa Mallampati score worsens during pregnancy and more so during labour . Changes during pregnancy and implications for anesthesia …

19. Respiratory system … Nasotracheal intubation should be avoided as there is increased risk of nasal bleed during pregnancy. A decreased FRC & increased oxygen consumption can lead to rapid desaturation during apnoea despite adequate pre-oxygenation. An increased MV and low FRC result in faster de- nitrogenation (pre-oxygenation) and rapid uptake of inhalational agents. Changes during pregnancy and implications for anesthesia …

20. Respiratory system … Hyperventilation should be avoided as it may cause respiratory alkalosis, leftward shift in oxygen dissociation curve and decreased oxygen delivery to the foetus . Uncontrolled maternal pain during labour can further increase the metabolic demands with resultant increase in maternal lactate levels indicating that oxygen requirements are increased more than supply. Changes during pregnancy and implications for anesthesia …

21. Respiratory system … Decrease in MAC by 25 to 40% – MAC is defined as the concentration of inhaled anesthetic within the alveoli at which 50% of people do not move in response to a surgical stimulus ). Despite enhanced response to hypoxic ventilatory drive, it is not possible to meet increased oxygen demand without supplemental oxygen in susceptible parturient. Changes during pregnancy and implications for anesthesia …

22. Haematologic and immune system: The leukocyte count gradually increases to around 15,000/mm. Major contribution to this increase is by polymorphonuclear cells, which have impaired function. This explains the increased severity of infections but this apparently impaired immunity does not make parturient prone to infections. Changes during pregnancy and implications for anesthesia …

23. Haematologic and immune system: The autoantibody production and levels of immunoglobulins A, G and M are unaltered . There is an increased production of platelets but due to enhanced destruction and haemodilution , rise in count does not occur. In a minority, platelet count decreases (90,000–100,000) which is physiological (gestational thrombocytopaenia ) and resolves in the postpartum period . Changes during pregnancy and implications for anesthesia …

24. Haematologic and immune system: The coagulation and fibrinolytic pathways are altered with an increased risk of thromboembolism during pregnancy (10 X ) and postpartum (25 X ). The net result of the physiologic changes is a hypercoagulable state of pregnancy. The concentration of all clotting factors increases except factor II, V, XI and XIII . Changes during pregnancy and implications for anesthesia …

25. Haematologic and immune system: There is an increased risk of epidural haematoma in patients with severe preeclampsia due to exponential fall in platelets. Platelet count should be obtained within 6 h before placing an epidural or catheter removal. But, it is advisable to test for both platelet count and function ( aggregability ). Changes during pregnancy and implications for anesthesia …

26. Gastrointestinal system: The secretory and absorptive functions of the gastrointestinal (GI) system are not much affected but the motility is affected. Owing to the inhibition of GI contractile activity by progesterone, oesophageal peristalsis & intestinal transit slow down resulting in constipation. The changes in GI system return to baseline within 1–2 days postpartum . Changes during pregnancy and implications for anesthesia …

27. Gastrointestinal system … Mendelson syndrome (results from the effect of pregnancy on the stomach). Delay gastric emptying Relaxation of gastro-esophageal sphincter Raised intragastric pressure Mendelson syndrome a chemical pneumonitis characterized by fever, cyanosis, hypoxia, pulmonary edema, and potential death caused by aspiration of gastric contents. Changes during pregnancy and implications for anesthesia …

28. Gastrointestinal system … No alteration is required in the fasting guidelines. In uncomplicated labour , moderate amount of clear fluids is recommended . Delayed gastric emptying in pregnant & peripartum females receiving systemic or neuraxial opioids. There is an increased risk of aspiration of gastric contents due to increased intra-abdominal pressure and a low LOS tone. Changes during pregnancy and implications for anesthesia …

29. Gastrointestinal system … The risk of aspiration of gastric contents is increased during GA and intubation. Important steps in prevention include preference to neuraxial techniques & use of aspiration prophylaxis. If GA is indicated, rapid sequence induction is recommended. Changes during pregnancy and implications for anesthesia …

30. Gastrointestinal system … Spider nevi and palmar erythema, indicators of liver disease, can be physiologically seen during pregnancy due to raised oestrogen levels. Despite an increase in CO, proportionate increase in hepatic blood flow is not observed. Due to an increase in splanchnic, portal and oesophageal venous pressure, more than 50% of the pregnant females develop oesophageal varices which rapidly resolve postpartum. Changes during pregnancy and implications for anesthesia …

31. Gastrointestinal system … Dilution due to an increased plasma volume causes a decline in serum albumin by up to 60 %. Plasma cholinesterase begins to fall (by 25%) in first trimester & this level maintained till the term . Despite a decrease in plasma cholinesterase, clinically significant prolongation of effect of a single dose of succinylcholine does not occur. This is probably due to increased volume of distribution and decreased sensitivity. Changes during pregnancy and implications for anesthesia …

32. Nervous system Cerebral blood flow is increased due to a decrease in cerebrovascular resistance. Permeability of the blood–brain barrier increases. There is an increase in threshold to pain at full term and in labour probably due to increased levels of plasma endorphins and progesterone. Due to the compression of the IVC by the gravid uterus, dilatation of the epidural venous plexus occurs. Changes during pregnancy and implications for anesthesia …

33. Nervous system … There is an increase in epidural fat and decrease in epidural free space and spinal cerebrospinal fluid (CSF) volume. CSF pressure remains unchanged during pregnancy but is increased during uterine contractions and bearing down. There is more dependence on sympathetic nervous system for maintenance of haemodynamics . Changes during pregnancy and implications for anesthesia …

34. Nervous system … There is up to 30% decrease in minimum alveolar concentration of volatile anaesthetic agents. Pregnant females are physiologically more sensitive to intravenous induction and sedative agents. There is a 25–40% decrease in spinal dose of local anaesthetics (LA) since the end of first trimester implying that changes in epidural space anatomy is not the sole reason. Changes during pregnancy and implications for anesthesia …

35. Nervous system … It has been found that progesterone increases the sensitivity of neuronal membranes to LA . Pregnant females are more prone to hypotension and haemodynamic instability following sympathetic blockade caused by neuraxial anaesthesia . Changes during pregnancy and implications for anesthesia …

36. Nervous system … Decreased inhalational anesthetic requirements Decreased dose of Local Anesthetic requirement for regional techniques. Decreased dose of local anesthetic for same effect More rapid onset of neural blockade Increased risk of local anesthetic toxicity Changes during pregnancy and implications for anesthesia …

37. Renal system: Renal blood flow and glomerular filtration rate (GFR) are increased but no change is observed in histology or number of nephrons. Due to progesterone and mechanical compression of ureters, renal pelvis and calyces are dilated. Increase in GFR causes decrease in serum creatinine (normal range: 0.4–0.8 mg/dl) and blood urea nitrogen (normal range: 8–10 mg/dl). Changes during pregnancy and implications for anesthesia …

38. Renal system … Reduced vascular responsiveness to vasopressors (angiotensin II, norepinephrine and antidiuretic hormone) is observed due to an altered vascular receptor expression. Nitric oxide synthesis is increased during pregnancy resulting in systemic and renal vasodilation . Changes during pregnancy and implications for anesthesia …

39. Renal system … Since pregnant females have a lower normal range of serum creatinine, a small rise in values reflects a larger reduction in renal function. Low albumin level due to renal albumin loss leads to increased free levels of highly protein-bound drugs such as digoxin, midazolam, thiopentone sodium and phenytoin . Changes during pregnancy and implications for anesthesia …

40. Endocrine system: TSH receptors can be activated by beta-human chorionic gonadotropin. Thyroid gland is enlarged due to both follicular hyperplasia and increased vascularity. Due to the increase in thyroid-binding globulin caused by oestrogen , total T3 and T4 levels are increased by 50% but free T3 and T4 levels do not change. Changes during pregnancy and implications for anesthesia …

41. Endocrine system … Thyroid stimulating hormone levels fall during first trimester but recover during rest of the pregnancy. Pathological states arising due to iodine-deficient hypothyroidism or hyperthyroidism have much relevance to the practice of anaesthesia and should be managed keeping in mind the physiological changes of pregnancy. Changes during pregnancy and implications for anesthesia …

42. Endocrine system … Both subclinical hypo- and hyperthyroidism occur and are not associated with adverse outcomes. Human placental lactogen causes reduced tissue sensitivity to insulin and thus higher blood glucose levels after carbohydrate-rich meals during pregnancy when compared to pre-pregnancy state . In contrary, the  rising estrogen levels stimulate insulin production by the pancreas beta cells, causing changes in glucose metabolism. Changes during pregnancy and implications for anesthesia …

43. Endocrine system … Pregnant females rapidly develop hypoglycaemia and ketoacidosis, particularly during periods of fasting as the fetus draws on maternal fat stores. GA can mask the signs and symptoms of hypoglycaemia while neuraxial anaesthesia can lead to exaggerated haemodynamic instability in patients with autonomic dysfunction related to diabetes mellitus or diabetic ketoacidosis. Changes during pregnancy and implications for anesthesia …

44. Musculoskeletal system: Due to relaxin , progesterone and mechanical effects of pregnancy, joint laxity is increased to prepare for childbirth . Hormonal changes and weight gain result in a series of musculoskeletal effects. To compensate for the change in centre of gravity, the lumbar lordosis is exaggerated with anterior flexion of neck & downward movement of shoulders. Changes during pregnancy and implications for anesthesia …

45. Musculoskeletal system … Lordosis can decrease the distance between the spinous processes and can make lumbar flexion and neuraxial techniques difficult. Widening of the pelvis causes a head down position in lateral decubitus and may lead to cephalad spread of LA during spinal anaesthesia in lateral position . A pillow placed beneath the dependent shoulder can negate this effect. Changes during pregnancy and implications for anesthesia …

46. Transplacental transfer of drugs and safety: None of the anaesthetic drugs and other commonly used drugs during anaesthesia are teratogenic. However , FDA has issued a warning that repeated or prolonged use (>3 h) of general anaesthetic and sedative drugs during procedures in full-term pregnant women may affect the developing brain. Thus , the benefits of a certain anaesthetic techniques in this population should be balanced against potential risks . Changes during pregnancy and implications for anesthesia …

47. Transplacental transfer of drugs and safety … Highly lipid soluble drugs may easily enter the placenta but get trapped within placental tissue. Transplacental transfer of highly protein bound drugs depends on the concentration of maternal and foetal plasma proteins which may vary with gestational age and disease. During foetal acidosis, maternal– foetal transfer of basic drugs like opioids and LA is enhanced and results in “ion trapping.” Changes during pregnancy and implications for anesthesia …

48. Summary Knowledge of various physiological changes which occur during pregnancy is crucial in the anaesthetic management of both healthy females and those with coexisting diseases. Proper preparation of equipment, drugs, availability of qualified anaesthesiologists and adaptation of anaesthetic technique to suit the changes in pregnancy contribute to reduce in maternal– foetal morbidity and mortality. Changes during pregnancy and implications for anesthesia …

49. 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. 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. Causes and neural pathways of labor pain

50. 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, 1 st stage pain generally occurs only during uterine contraction. Causes and neural pathways of labor pain …

51. 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. 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. Causes and neural pathways of labor pain …

52. 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. The location of this pain is explained by the concept of referred pain as described below. Causes and neural pathways of labor pain …

53. 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. Causes and neural pathways of labor pain …

54. Second-stage pain occurs as the fetus descends through the birth canal. This results in stretching and tearing of fascia, skin, and subcutaneous tissue causing pain. 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. Causes and neural pathways of labor pain …

55. 1 st stage of labor – mostly visceral Early labor – T11 - T12 Progressing cervical dilatation – T10 - L1 Slow conducting visceral fibers enter spinal cord at T10 to L1 Dilation of the cervix and distention of the lower uterine segment Dull, aching and poorly localized Summary of 1 st stage pain

56. 2 nd stage of labor – mostly somatic Distention of the pelvic floor, vagina vault and perineum Sharp, severe and well localized Rapidly conducting fibers enter spinal cord at S2 to S4 Is somatic pain transmitted primarily through the pudendal nerve , which is derived from the anterior primary divisions of sacral nerves S2- S4 . Summary of 2 nd stage pain

57. Labor Pain at different Stages of Labor

58. Blockade of Sensory Pathways 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.

59. 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. Pudendal block is a relatively safe and simple method of providing analgesia for spontaneous delivery. The pudendal nerve passes beneath the posterior surface of the sacrospinous ligament just as the ligament attaches to the ischial spine. Blockade of Sensory Pathways …

60. Blockade of Sensory Pathways … Paravertebral block is a technique used in order to ease chest pain. Paravertebral block, especially thoracic paravertebral block, is  an effective regional anesthetic technique that can provide significant analgesia for numerous surgical procedures, including breast surgery, pulmonary surgery, and herniorrhaphy . An analgetic agent, usually Bupivacaine or morphine, is injected into a narrow space that lies next to the spine. A fine tube is left in place in order to readminister the local anesthetic whenever necessary.

61. Possible Sites for Pain Pathways Blockade of Labour Pain Management (S2 to S4)

62. Pathways of labor pain . Pain stimuli from the cervix and uterus travel through the paracervical region and the pelvic and hypogastric plexus to enter the lumbar sympathetic chain .

63. Fear and pain The experience of labor pain is a highly individual reflection of variable stimuli that are uniquely perceived and interpreted by each woman. These stimuli are modified by emotional, motivational, cognitive, social, and cultural circumstances. A woman who is free from fear, and who has confidence in the obstetrical staff that cares for her, usually requires smaller amounts of analgesia. Principles of pain relief …

64. Fear and pain … The intensity of pain during labor is related largely to emotional tension . So that the women should be well informed about the physiology of parturition and the various hospital procedures they may experience during labor and delivery. When motivated and women have been prepared for childbirth, pain and anxiety during labor have been found to be diminished significantly, labors become shorter and even the cesarean delivery rate will significantly lowered . Principles of pain relief …

65. The complexity and individuality of the experience suggest that a woman and her caregivers may have a limited ability to anticipate her pain experience prior to labor. Thus , the choice among a variety of methods and individualization of pain relief is necessary. When uterine contractions and cervical dilatation cause discomfort, pain relief with: Non-pharmacological methods for pain relief, and Pharmacological pain relief. Principles of pain relief …

66. Potential effects of pain on O 2 delivery to the fetus Principles of pain relief

67. Goals: Should allow parturient to participate in birthing experience Dramatically reduce pain of labor Minimal motor block to allow ambulation Minimal effects on fetus Minimal effects on progress of labor Labor analgesia

68. Non-pharmacological approach: Non-pharmacological pain management is  the management of pain without medications . This method utilizes ways to alter thoughts and focus concentration to better manage and reduce pain and includes: Physical Modalities – Massage, water immersion, hot showering, breathing techniques (deep, slow, and patterned breathing), positioning, and movement. Psychological techniques (cognitive behavioral therapy) – Relaxation techniques; Music; Distraction technique; Virtual reality (VR). Labor analgesia …

69. P harmacological approach: Systemic analgesia – Nitrous oxide ( N2O), Opioids(IM/IV), NSAIDs, IV acetaminophen, Regional analgesia – Epidural, spinal, or combined spinal-epidural (CES), Pudendal block , Epidural analgesia he most effective technique to alleviate labor pain  and is used in 70% of birthing women in the US ), Intravenous opioids can be given as intermittent doses or patient-controlled analgesia ( PCIA). Epidural analgesia can also be given as patient controlled analgesia (PCEA ). Labor analgesia …

70. Nitrous oxide (N 2 O) Inhalation of nitrous oxide is  used frequently to relieve pain associated with childbirth, trauma, oral surgery and acute coronary syndrome (including heart attacks) . Its use during labour has been shown to be a safe and effective aid for birthing women. N 2 O can be used for analgesia during the first, second, or third stage of labor; during postpartum procedures (laceration repair, manual extraction of placenta); and to facilitate epidural placement. Labor analgesia …

71. Opioid analgesics: Meperidine( 25 to 50 mg every 1 to 2 hours ) is the most common opioid used worldwide for pain relief in during the first stage of labor – data regarding comparisons with other types of analgesics are scarce. Neonates who are born <1 hour or >4 hours after meperidine administration have a low chance of developing respiratory depression, whereas neonates who are born 2 to 3 hours following meperidine injection are frequently affected. Labor analgesia …

72. Opioid analgesics: Morphine is less commonly used for pain relief during labor because the dose needed to achieve a sedative effect carries a higher risk for maternal and neonatal side effects . Fentanyl and remifentanil are also used for pain relief during labor, but due to their short duration of action they are more suitable for patient-controlled analgesia use. Fentanyl is a fast-onset & short-acting synthetic opioid, especially with intravenous administration. Labor analgesia …

73. Opioid analgesics … A recent meta-analysis of RCTs comparing remifentanil patient–controlled analgesia and epidural analgesia (10 trials, 3086 women) reported that pain relief during labor was similar between the 2 groups. Use of remifentanil patient–controlled analgesia ( PCIA) significantly reduced the incidence of maternal fever; however, it was associated with a higher rate of respiratory depression.  Remifentanil is given  directly into a vein   using a client controlled pump by pressing a button, so that it starts to work quickly. Labor analgesia …

74. Opioid analgesics … The use of remifentanil for patient–controlled analgesia is limited because of safety concerns, despite its efficacy in reducing labor pain. The potential adverse effects of remifentanil include pruritus, nausea and vomiting, maternal hypoxia , respiratory arrest, and cardiac arrest . Labor analgesia …

75. Opioid analgesics … Fentanyl can also be administrated nasally and carries less risk of maternal adverse effects, including sedation, nausea, vomiting, and pruritus, than meperidine. One of the major advantages of fentanyl is that unlike meperidine or morphine, it hardly crosses the placenta, although, there are reports on neonatal respiratory depression following its administration. Labor analgesia …

76. Opioid analgesics … Tramadol a synthetic analog of codeine, inhibits norepinephrine  and serotonin reuptake and binds to μ-opioid receptors, resulting in inhibitory effect on pain transmission in the spinal cord. Several studies showed that tramadol provides effective analgesia without maternal and neonatal respiratory depression that are related to opioid use. But it is a less efficient pain reliever compared with intramuscular meperidine . Labor analgesia …

77. Opioid analgesics … Nalbuphine and butorphanol are mixed opioid agonist-antagonists (MOAA)– Alhough respiratory depression is a significant consideration in opioid agonists, the risk is reduced (although not eliminated) with MOAA. Labor analgesia …

78. All opioids significantly cross the placenta associated with: 2- to 3-fold increased risk of Apgar scores lower than 7 at 5 min and 4-fold increased need for neonatal naloxone . Fentanyl has relatively short half-life, less nausea, vomiting and sedation than Demerol (trade mark for pethidine). Normeperidine (active metabolite of demerol ) has prolonged duration of neonatal sedation. All drugs have decreased heart rate variability on fetus. Maternal respiratory and neurobehavioral depression may occur by using opioid and in case naloxone is given intravenously. Labor analgesia …

79. Naloxone is a narcotic antagonist capable of reversing respiratory depression induced by opioid narcotics, drug of choice for this effect. Acts by displacing the narcotics 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 C/I in a newborn of a narcotic-addicted mother. Given after establishing adequate ventilation to reverse respiratory depression . Opioid a ntagonists

80. The usual dose is 200-400mcg intravenously, titrated to effect. It is imperative the naloxone be administered slowly to avoid reactive pulmonary hypertension with the development of acute pulmonary oedema probably from antagonism of endogenous opioid effects. Smaller doses (0.5-1.0mcg/kg) may be titrated to reverse undesirable effects of opioids , for example itching associated with the intrathecal or epidural administration of opioids , without significantly affecting the level of analgesia. Opioid a ntagonists …

81. The duration of effective antagonism is limited to around 30 minutes and therefore longer acting agonists will outlast this effect and further bolus doses or an infusion (5-10mcg/kg/h) will be required to maintain reversal. Caution must be used in opioid addicts as giving naloxone may cause an acute withdrawal state with hypertension, pulmonary oedema and cardiac arrhythmias. Antanalgesic effects may be observed in opioid naïve subjects who are given naloxone . Opioid antagonists …

82. Epidural analgesia(EDA) … Currently , epidural analgesia(EA) is regarded as the leading and most effective treatment for labor and delivery pain – considered to be gold standard. However, EDA has an 8.5% failure rate, and its downsides include costs, prolonged labor, reduction in women’s sense of control and their participation in the labor process, and can involve adverse effects such as intrapartum fever, dural puncture, and postpartum headache. Labor analgesia …

83. Epidural analgesia(EDA): A catheter (small infusion tube) inserted into the epidural space, and medications can be given as continuous epidural infusion using the catheter. Combination of a low dose local anesthetic, such as bupivacaine, with an opioid are preferred because they decrease motor blockade, however there is controversial issue. The use of local anesthetics as sole agents for PCEA results in significant motor effects . Can be used for C/S, or postpartum tubal ligation . Labor analgesia …

84. Labor analgesia …

85. Layers injection needles should pass through to reach epidural space, and subarchnoid space; Skin, subcutaneous fat Supraspinous ligament Interspinous ligament Ligamentum flavum (last layer before epidural space) Dura + arachnoid for spinal anesthesia Labor analgesia …

86. Labor analgesia …

87. Epidural analgesia and the labour outcome: Epidural prolongs labor by 40-90 minutes and approximately twofold increased need for oxytocin augmentation to keep up the labor duration. The American College of Obstetricians and Gynecologists previously recommended that practitioners delay initiating epidural analgesia in nulliparous women until the cervical dilatation reached 4-5 cm. However , more recent studies have shown that epidural analgesia does not increase the risks of cesarean delivery . Labor analgesia …

88. Epidural analgesia and the labour outcome: Total spinal b lockade Ineffective analgesia Hypotension Epidural hematoma Maternal pyrexia Back pain Labor analgesia …

89. Spinal analgesia: Single-shot spinal analgesia provides excellent pain relief for procedures of limited duration, such as C/S, the second stage of labor, rapidly progressing labor and postpartum tubal ligation . Low-dose intrathecal bupivacaine and intrathecal opioids can provide sufficient pain relief without reducing ambulation of the labouring parturients . Limited use for the management of labor due to its inability to extend the duration of action . Labor analgesia …

90. Spinal analgesia … Drugs can be used in combination to gain rapid onset, sufficient duration and additive or synergistic analgesic effects. Long-acting local anesthetic often is used with or without an opioid . The use of local anesthetics as sole agents for PCEA results in significant motor effects . Drugs such as epinephrine can be used as adjuvant. Labor analgesia …

91. Pudendal block: This is a relatively safe and simple method of providing analgesia for spontaneous delivery . A tubular introducer that allows 1.0 to 1.5 cm of a 15-cm 22-gauge needle to protrude beyond its tip is used to guide the needle into position over the pudendal nerve. The end of the introducer is placed against the vaginal mucosa just beneath the tip of ischial spine. Labor analgesia …

92. Pudendal block … 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. The needle is advanced farther through the ligament, and as it pierces the loose areolar tissue behind the ligament, where the resistance of the needle decreases . This is the region where 3 mL of solution is injected. Next , the needle is withdrawn into the introducer. The procedure is then repeated on the other side. Labor analgesia …

93. Pudendal nerve block

94. Regional anaesthesia : Spinal anaesthesia is probably the most commonly administered regional anesthetic for emergency cesarean section because of its speed of onset and reliability. Spinal anaesthesia is a lso called spinal block, or subarachnoid, intradural or intrathecal block , is a form of neuraxial regional anaesthesia involving injection of a local anaesthetic or opioid into the subarachnoid space . Anesthesia for obstetrics surgery

95. Advantages of regional anesthesia compared to the GA include : Avoids hazards of general anesthesia The increased safety of regional analgesia has increased the relative risk of maternal mortality related to GA (32/1000000 v.s . 1.9/1000000 ). When compared with GA, the SA is the preferred method of regional anesthesia for cesarean delivery unless contraindications exist . Anesthesia for obstetrics surgery …

96. Advantages of regional anesthesia compared to the GA include … The mother remains awake, early FM bonding Quicker return to the diet after surgery Low blood loss Lower incidence of Nausea/Vomiting Better Pain Control/Less Narcotics Less risk of a chest infection after surgery Anesthesia for obstetrics surgery …

97. Baricity of anesthetic solution Position of the patient During injection Immediately after injection Drug dosage (mg) Concentration and volume Addition of o pioids Site of injection Important factors affecting SAB height

98. Patient Age Elderly patients >80 yrs Patient height Intra-abdominal pressure Pregnancy & obesity Drug volume Another factors to consider with SAB height

99. Spinal anesthesia … Sympathetic Block 2-6 dermatomes higher than the sensory block Motor Block 2 dermatomes lower than sensory block Sensory Motor Sympathetic T5 Differential SAB

100. Rapid onset, prolonged duration. The spinal component may be an intrathecal narcotic plus a small dose of local anesthetic. Emergency C/S for fetal bradycardia is increased compared with epidural only. Combined Epidural -Spinal anesthesia

101. Better pain relief – r apid onset of intense analgesia. Ideal in late or rapidly progressing labor Very low failure rate Less need for supplemental boluses Minimal motor block (“walking epidural”) Eg : Bupivicaine 0.0625% plus 2 µ g/ml fentanyl (+/- epinephrine) @ 10-12 ml/hr. Advantages of CES for Labor Analgesia

102. Hypotension Postdural puncture headache Pruritus Failed regional block (need for general endotracheal anesthesia) High spinal block Chemical meningitis or epidural abscess or hematoma obese women have significantly impaired ventilation. Complications Of R egional A nesthesia

103. ABSOLUTE Patients refusal Inability to cooperate Increased intracranial pressure Severe coagulopathy Refractory maternal hypotension LMWH Skin infection over site of needle placement RELATIVE Systemic maternal infection Preexisting neurological deficiency Mild or isolated coagulation abnormalities Correctable hypovolemia Contra indications t o Regional A nesthesia

104. General anesthesia: General anaesthesia was once the primary anaesthetic technique used in obstetrics, both for vaginal deliveries and Caesarean section (CS) . As the field of obstetric anaesthesia has advanced, the use of GA has been largely replaced by neuraxial techniques. Anesthesia for obstetrics surgery …

105. General anesthesia: Increased relative risk of general anesthesia Vs increased safety of regional anesthesia. Failed tracheal intubation and risk of aspiration & resulting aspiration pneumonitis have historically been the most dreaded complications of GA. Detailed guidelines for the management of difficult intubation in obstetrics have been developed . Anesthesia for obstetrics surgery …

106. General anesthesia: Failed intubation occurs in approximately 1 of every 250 GA administered to pregnant women, a 10-fold higher rate than the nonpregnant population. The case-fatality rate of GA for cesarean delivery is estimated to be approximately 32 per million live births compared with 1.9 per million for regional anesthesia. Anesthesia for obstetrics surgery …

107. General anesthesia … Relative increased morbidity and mortality suggest that regional anesthesia is preferred to GA . The latest decennial survey on obstetric anaesthesia practices in USA reported a reduction of GA for CS from 35% in 1981 to < 25 % in 2011, with the majority of cases corresponding to emergency procedures . It is currently estimated that about 6 % of CS still require GA and tracheal intubation (Delgado et al., 2020). Anesthesia for obstetrics surgery …

108. General anesthesia … Anesthesia remains responsible for approximately 3% to 12% of all maternal deaths. The majority of these deaths occur during general anesthesia: failed intubation, failed ventilation oxygenation, pulmonary aspiration of gastric contents. Anesthesia for obstetrics surgery …

109. General anesthesia … A systematic review and meta-analysis analyzed anaesthesia -related maternal mortality in low-income and middle-income countries in 2016 In the analysis, maternal mortality associated with neuraxial anaesthesia and general anesthesia were found to be 1.2 per 1000, and 5.9 per 1000, respectively. Anesthesia for obstetrics surgery …

110. General anesthesia … Complications are associated with: obesity, hypertensive disorders of pregnancy, and Emergently performed procedures. Anesthesia for obstetrics surgery …

111. General anesthesia … Despite the increased relative risk the general anesthesia carries compared to regional block, anasthesia , it may be the technique of choice for emergency CS in the folloeing conditions : when regional anaesthesia is refused, or when regional anesthesia is contraindicated , or when large blood loss is expected . w hen the mother is hypotensive w hen there is increased ICP when there is sepsis Anesthesia for obstetric surgery …

112. General anesthesia … If general anaesthesia is chosen, Rapid sequence induction with cricoid pressure, Position the patient with a lateral tilt to avoid aortocaval compression. Insert an orogastric tube before completion of surgery. Extubate when the patient is awake, the anesthesia is adequately reversed, and the patient is following commands . Anesthesia for obstetrics surgery …

113. General anesthesia … Advantage : Simple, Rapid Disadvantage Patient not awake for birth. Unprotected airway. Possible “can’t intubate, can’t ventilate” scenario. Nausea, post-op pain, sore throat . Anesthesia for obstetrics surgery …

114. General anesthesia … Sodium thiopental 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. Anesthesia for obstetrics surgery …

115. General anesthesia … Sodium thiopental … The anesthetic effect persists for 5-10 minutes so it is most commonly used in the induction phase of GA. Liver and renal disease may associated with low albumin levels, so result in an increase in free thiopental which increase the anesthetic toxicity and potency. Metabolism occurs primarily in the liver with approximately 10-15% of drug level metabolized per hour. Anesthesia for obstetrics surgery …

116. General anesthesia … Ketamine Sole anesthetic for diagnostic procedures Used for induction of anesthesia Used to supplement spinal anesthesia Appropriate for patients with asthma – a potent bronchodilator, and in contrary causes increased secretions but can be limited by anticholinergic drugs . Not appropriate in hypertensive cases. Anesthesia for obstetrics surgery …

117. General anesthesia … Ketamine contra indication air way obstruction history of sychosis c erebral vascular disease Anesthesia for obstetrics surgery …

118. General anesthesia … Isoflurane and halothane Volatile anestheticsIsoflurane the most commonly used volatile anesthetic in the United States. 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. Anesthesia for obstetrics surgery …

119. Cesarean delivery under local anesthesia: Cesarean delivery with infiltrative anesthesia may be seen as an antiquated method, but it is an important clinical option as it may still have some useful applications. Performing CS with infiltrative anesthesia (local anesthetic) should be viewed as an alternative in specific situations & not simply a procedure of historic interest ( Rezai et al., 2018) Anesthesia for obstetrics surgery …

120. Anesthesia for obstetrics surgery …

121. Anesthesia for obstetrics surgery …

122. Cesarean delivery under local anesthesia … The use of general anesthesia is more common in invasive procedures, mainly for patient comfort and compliance. However, many procedures are still performed using local anesthetic( Rezai et al., 2018 ) The use of local anesthetic in cesarean delivery involves the anesthetic agent being applied to the subdermal layer, penetrating the various layers of fascia, muscle, and peritoneum, excluding the fatty tissue. Anesthesia for obstetrics surgery …

123. Cesarean delivery under local anesthesia … Each subsequent layer must be infiltrated once the previous layer has been dissected. As previously known, the use of local anesthetic onset is much slower than that compared to general or spinal anesthesia. Lidocaine has shown to have the quickest infiltrative onset of 10 to 20minutes, compared to other local agents. Compared to general and spinal anesthesia, 10 to 20minutes is a very long time. Anesthesia for obstetrics surgery …

124. Cesarean delivery under local anesthesiac … However , when evaluating its use for cesarean section with limited resources; it serves as a very useful option, even though onset is longer. Various small incisions can be made to introduce infiltration to ensure adequate block prior to minimize onset time. In relation to the overall procedure, infiltration should be established as quickly as possible to proceed with the cesarean section; especially in emergent cases. Anesthesia for obstetrics surgery …

125. Potential effects of anesthetics and analgesia used in obstetrics … Without exception, all GA 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 should be prepared to provide respiratory support immediately following delivery with a general anesthetic. Ideally, induction-to-delivery time should be minimized when general anesthesia is used.

126. Potential effects of anesthetics and analgesia used in obstetrics … PCEA minimize the dosage of opioid and maternal sedation compared with IV opioid. Addition of local anesthesia in PCEA results in increased motor weakness, which may inhibit patient mobilization. All intrathecal and epidural opioid is accompanied with a dose-dependent incidence(35-56%) of maternal pruritus which can be treated by prophylactic naloxone. NSAIDs through their respective effect routes are useful in minimizing the cumulative maternal opioid consumption by 30-39%.

127. Potential effects of anesthetics and analgesia used in obstetrics … Intrapartum opioid use may decrease neonatal rooting reflexes and delay initiation of breastfeeding, but no evidence showed these delays affect the ultimate success of breastfeeding. Continuous epidural bupivacaine infusion for postoperative pain results in significantly increased milk production and greater infant weight gain compared with diclofenac IM .

128. Building shared responsibility with anesthesia personnel to get the work done Do not neglect that the anesthetists have also their own, valid point of view and concerns. Just like you, they also want the best outcome for mother and child. Tell them what has happened with the patient and what you need to do – don’t tell them what anesthetic to give.

129. Building shared responsibility with anesthesia personnel to get the work done … For example, Say “The patient has a retained placenta and the uterus appears to have contracted down around it, so we need to relax the uterine muscle and manually take out the placenta.” This could be achieved with GA or IV analgesia plus nitroglycerin. Don’t say, “This patient needs a spinal so I can get the placenta out.” Spinal will not relax uterine muscle. Let them design the anesthetic plan – that’s their job !

130. END!

131. References Gabbe obstetrics, 8th Edition Williams obstetrics 26 rd ed. ACOG Practice Bulletin: Obstetrics & Gynecology, Vol 100, NO.1, JULY 2002 e-SAFE resources: Developed and funded by RCoA and AAGBI. Clinical anesthesia 5 th ed. Millers anesthesia 7 th ed . Options for pain relief during labor: https :// www.sciencedirect.com/science/article/pii/S000293782300145X Ambulatory labor analgesia: https :// obgyn.onlinelibrary.wiley.com/doi/full/10.1111/j.0001-6349.2004.00344.x

132. References Physiological and anatomical changes of pregnancy and implications for anaesthesia : https ://www.ncbi.nlm.nih.gov/pmc/articles/PMC6144551 / Sympathetic nervous system in healthy and hypertensive pregnancies: https :// physoc.onlinelibrary.wiley.com/doi/10.1113/EP089665 Non-Pharmacological Pain Management in Labor (Systematic Review): https :// www.mdpi.com/2077-0383/12/23/7203 Epidural analgesia during labor vs no analgesia (A comparative study): https :// www.ncbi.nlm.nih.gov/pmc/articles/PMC3299112/ Isobaric and Hyperbaric Bupivacaine: https://www.hindawi.com/journals/jan/2014/141324/ Anaesthesia-related maternal mortality in low-income and middle-income countries: a systematic review and meta-analysis: https :// www.thelancet.com/journals/langlo/article/PIIS2214-109X(16)30003-1