Spinal and Epidural Anaesthesia.pptx

Anesthesia types

1. SPINAL & EPIDURAL ANAESTHESIA Dr . Chandrika Bhut Assistant Professor Dept. Of Anaesthesiology GMC, Bhavnagar

2. SUBARACHNOID BLOCK DEFINITION Spinal anaesthesia is the regional anaesthesia obtained by blocking the spinal nerves in the subarachnoid space .

3. HISTORY Corning, in 1885, accidentally administered cocaine intrathecally Quincke, in 1891, - made use of spinal puncture in diagnosis August Bier, of Greifswald, Germany, in 1898, introduced the technique of spinal anaesthesia. Pitkin popularized the method of introducing agents intrathecally. QUINCKE AUGUST BIER

4. Spinal Column Anatomy Vertebra Vertebral Body Pedicles Anterior (2) & Laminae Posterior (2) Transverse Process – Junction of the Pedicles and Laminae Spinous Processes – Joining of the Laminae Intervertebral Disks

5. The spine is composed of the vertebral bones and fibrocartilaginous intervertebral disks . There are 7 cervical, 12 thoracic, 5 lumbar,5 sacral and 4-5 coccygeal vertebra -Vertebral column has: 2 primary curves which are concave anteriorly -thoracic and pelvic. 2 secondary curves which are convex anteriorly -cervical and lumbar. All the cervical vertebrae are horizontal except for the last which is slightly inclined downwards with progressive increase in angle of inclination of the vertebra as we move down the spine

6. Anatomy of ligaments Supraspinous ligament The supraspionous ligament is a strong, thick, fibrous band connecting the apices of the spines from the seventh cervical to the sacrum. Above C-7 it blends with ligamentum nuchae in neck & attaches to external occipital protuberance of skull Interspinous ligament The interspinous ligament is thin, fibrous structure connecting adjacent spines. The fibers are almost membranous and extend from the apex and upper surface of a lower spine towards the root and inferior surface of the lower vertebrae.

7. 3) Ligamentum flavum : - most important ligament -consists of yellow elastic tissue - fibres are perpendicular in direction - extends between lamina from the anterior inferior surface of the upper lamina downwards to the anterior superior surface of the lower lamina. - extends from foramen magnum to sacral hiatus. - although portrayed as a single ligament, it is composed of two ligaments right and left,which join in the middle forming acute angle with a ventral opening.

8. Ligament thickness,distance to dura and skin to dura distance vary with area of vertebral canal as follows

9. Meninges of spinal cord: 1) Duramatter . 2) Arachnoidmatter 3) Piamatter —firmly attached to spinal cord. Duramatter : forms sac around cord - Continuation of cranial dura matter -extends from foramen magnum to S2 vertebrae. -potential space between duramatter and arachnoid matter is called subdural space which contains small amount of serous fluid. Arachnoidmatter : delicate non-vascular structure , closely attached to dura. Piamatter : highly vascular thin membrane covering cord, terminates at phylum terminalae

10. Sub arachnoid space : potential space lined externally by arachnoid matter and internally by pia matter close to spinal cord. Although spinal cord ends at L1 in adults, the space continues to S2. CONTENTS : CSF Spinal nerves Trabecular network Blood vessels that supply the spinal cord Lateral extensions of pia mater and dentate ligaments, which supply lateral support from spinal cord to dura Shape : annular (3mm) – Cervical , thoracic region. circular – lumbar

11. PHYSIOLOGY OF CSF CSF is an ultrafiltrate of the blood plasma. VOLUME OF CSF Total Volume- 120-150ml. 20-25ml- in ventricles 30-90ml – Cisterna reservoir at the base of brain. 25-30ml- Spinal subarachnoid space. FORMATION OF CSF 50 to 70% is formed by ultrafiltration through the choroid plexus Formed around blood vessels and along ventricular walls. Total production 550 ml/day Absorption of csf : Cranial region-through arachnoid villi Spinal region -venous plexus . CONTROL OF CSF PRODUCTION Under sympathetic control Stimulation of superior cervical ganglia increases production and fluid pressure.

12. CHARACTERISTICS OF CSF CSF pressure -70-180mm of H2O in recumbent position, 375 -550 mm of H2O in vertical position. PH -7.4-7.6 Specific gravity- 1.003-1.009 Density- 1.0003 (at37 o c)

13. PREOPERATIVE EVALUATION AND PREPARATION FOR SAB Informed written consent Physical Examination of spine for any anatomical abnormality like kyphosis or scoliosis Laboratory Tests:Hb,TLC,DLC,PLT,PT,INR,BT,CT,RBS,RFT,LFT AND S.electrolytes INDICATIONS OF SPINAL ANAESTHESIA Surgeries for lower extremities, hip, perineum, lower abdomen. Upper abdominal procedures- cholecystectomy Urologic endoscopic surgery -TURP Rectal Surgeries-Sacral anaesthesia Obsetrics-LSCS.  .

14. Relative contraindications Cardiac disease-severe ischaemic heart disease Neurological disease Major spinal abnormalities Patient refusal Shock, hypovolaemia Skin infection at injection site Systemic infection Increased ICT Coagulopathy Therapeutic anticoagulation CONTRAINDICATION OF SAB Absolute Contraindications

15. SPINAL ANAESTHESIA-TECHNIQUE NEEDLES The standard spinal needle- Three parts .Hub with lever lock connection, cannula, stylet - Points of cannula are bevelled and have sharp edges. Cannulae made of stainless steel should be stiff, flexible and resistant to breakage. Sizes- 16 G to 30 G Length- 3.5 to 4 inches  NEEDLES CLASSIFIED 1. Standard bevelled with cutting edges- Quincke, Babcock 2. Pencil point needle with conical point with no cutting edges- Sprotte or whitacre .

16. Structures pierced by spinal needle Skin Subcutaneous tissue Supraspinous ligament Interspinous ligament Ligamentum flavum Dura Arachnoid Membrane

17. POSITIONS L.P. is most easily performed when there is maximum flexion of lumbar spine .By this ligaments get stretched and space is open. Positions for SAB are: 1)Sitting position 2)Lateral position 3)Prone jackknife position

18. SITTING POSITION The patient is placed with the buttocks near the edge of the table, and the legs over the opposite edge with the feet supported on a stool. The patient rests his elbow on his thighs, or folds his arms forwards over pillows, and flexes the neck. An assistant should support the patient from the front; every effort should be made to see that the back remains vertical & open up the lumbar vertebral space .

19. Preferred for obese patients and saddle block anaesthesia Advantage- Proper curvature of back is obtained

20. LATERAL POSITION . Ideal positioning consists of having the back of the patient parallel to the edge of the bed closest to the anaesthetist, knees flexed to the abdomen, and neck flexed

21. Prone Jackknife appropriate for rectal, perineal, or lumbar procedures Patient can position himself Hypobaric solution of LA is used Paramedian approach should be used CSF has to be aspirated

22. LANDMARKS FOR SPINAL ANAESTHESIA Vertebral Spinous processes and the iliac crests Spinous processes clearly define the midline. First prominent spinous process – spine of C7 Most prominent spinous process – spine of T1 T7 lies opposite to the inferior angle of scapula. Line drawn between the iliac crests- intercristine or Tuffier’s line crosses the 4 th lumbar vertebrae.

23. RECOMMENDATIONS FOR SAFE. SPINAL TECHNIQUE Scrub hands according to aseptic surgical technique Use sterile gloves 3. Use aseptic technique when opening tray. 4. Cleanse the skin prior to needle puncture. Touch only sterile articles once gloved. Needle directed just under and parallel to spinous process 7. Avoid repeated traumatic punctures. 8 Use approved local anaesthetic agents in std conc  

24. MIDLINE APPROACH Palpate space Local infiltration. Needle directed just under and parallel to spinous process Bevel parallel to dural fibers Two resistance- First Ligamentum flavum and then duramater Verify free flow of CSF Inject the drug.  APPROACHES-MIDLINE,PARAMEDIAN AND TAYLOR

25. PARAMEDIAN OR LATERAL APPROACH Useful for-Arthritic or deformed spine Space is chosen and needle inserted 1.5 cm lateral to the midline at an angle of 25 o with the needle directed towards the center . TAYLOR’S APPROACH Useful for- Arthritic spine, fused spine. The needle should be inserted at a point 1 cm medial and inferior to the posterior superior iliac spine, then angled cephalad 45-55 degrees. This should be medial enough to reach the midline at the L5 spinous process. After needle insertion, the first significant resistance felt is the ligamentum flavum , and then the dura mater is punctured to allow free flow of CSF as the subarachnoid space is entered

26. Practical Problems The spinal needle feels as if it is in the right position but no CSF appears . Wait at least 30 seconds, then try rotating the needle 90 degrees and wait again. If there is still no CSF, attach an empty 2ml syringe and inject 0.5-1ml of air to ensure the needle is not blocked then use the syringe to aspirate whilst slowly withdrawing the spinal needle. Stop as soon as CSF appears in the syringe. Blood flows from the spinal needle . Wait a short time. If the blood becomes pinkish and finally clear, all is well. If blood continues to drip, then space should be changed The patient complains of sharp, stabbing leg pain. The needle has hit a nerve root because it has deviated laterally. Withdraw the needle and redirect it more medially away from the affected side . Wherever the needle is directed, it seems to strike bone . Make sure the patient is still properly positioned with as much lumbar flexion as possible and that the needle is still in the mid-line. It might be better to attempt a paramedian approach to the dura.

27. FACTORS POSTULATED TO BE RELATED TO SPINAL ANAESTHETIC BLOCK HEIGHT AGE Spinal and epidural spaces become smaller with  age – higher distribution of drug and higher level of block OBESITY Increase in intra-abdominal pressure results in increase in pressure in epidural space and decreased subarachnoid space and hence higher level of block PREGNANCY Increase in intra-abdominal pressure Increase in volume of epidural venous plexus - Small subarachnoid spaces hence higher level of block

28. INTRAABDOMINAL PRESSURE Changes resulting from increased intra-abdominal pressure include collateral flow through epidural venous plexus and higher distribution of the drug SPINAL CURVATURE Abnormal curvature has an effect on technical aspects Changes the contour of Subarachnoid space. POSITION Hyperbaric solutions in the sitting position cause the solution to gravitate into the caudal areas. RATE OF INJECTION Slow injections - low level of anaesthesia Rapid injections - high level of anaesthesia

29. Volume/Dose/Concentration Difficult to change one factor alone Most studies show no effect of volume or concentration Dose may have a significant effect on block height: Two studies showed significantly lower blocks with 10mg vs. 15 or 20 mg isobaric bupivicaine .

30. Effect of speed of injection and volume on LA spread

31. Baricity Ratio of the density (mass/volume) of the LA solution divided by the density of CSF (1.0003) Hypobaric = LA + distilled water, <0.9990 Isobaric = LA + saline Hyperbaric = LA + dextrose, > 1.0010 Affected by gravity and positioning

32. Head down position- hyperbaric solution will move cephalad; hypobaric solution will move caudally. Head up position- hyperbaric solution will move in a caudal direction; hypobaric solution will move in cephalad direction. Lateral position- hyperbaric solution will move toward the dependent area; hypobaric solution will move towards the non-dependent area. Isobaric solutions- will stay in the general area of injection regardless of the position.

33. Site of injection : the level that you place the local anesthetic will influence the spread of local anesthetic. If you place your medication at L2 it will cover higher levels than if you inject it at L5.

34. Barbotage The technique first was described by Bier and consists of the injection of the anesthetic solution into the subarachnoid space, immediate withdrawal of a portion of the solution and reinjection. This may be repeated. The to-and-fro movement agitates the injectate in the spinal fluid, and the currents mix the agent more completely and carry the agent more extensively and to higher levels. Caution must be observed and each operator must learn the results of his barbotage

35. LEVEL OF ANAESTHESIA SEGMENTAL LEVELS Perineum S1-S4 Inguinal region L1 Umbilicus T10 Subcostal arch T6-T8 Nipple line T4 Second intercostals space T2 Clavicle C3 –C4 SEGMENTAL LEVELS OF SPINAL REFLEXES Epigastric T7 and T8 Abdominal T9-T12 Cremasteric L1- L2 Plantar S1-S2 Knee jerk L2-L4 Ankle jerk S1-S2

36. ORDER OF BLOCK Autonomic fibers (mediated by C fibers) are most sensitive as they are smallest and non-myelinated, are blocked earliest followed by sensory and the motor fibers. Autonomic level is tested by temperature, sensory by pin prick and motor by lower limb movements.

37. Differential Block with SAB Sympathetic Block 2-6 dermatomes higher than the sensory block Motor Block 2 dermatomes lower than sensory block Sensory Motor Sympathetic T5

38. SEQUENCE OF NERVE MODALITY BLOCK Vasomotor Block- dilatation of skin vessels. Block of cold temperature fibers. Modified Bromage Scale Sensation of Warmth by patient Temperature discrimination is lost Slow pain Fast pain Tactile sense lost Motor paralysis Pressure sense abolished Proprioception During recovery, anaesthesia recedes from head and feet areas towards the middle i.e a point near site of anaesthetic agent

39. INDIRECT EFFECTS Sympathetic blockade is the major determinant of physiological responses. I. HYPOTENSION:CAUSES Paralysis of vasoconstrictor nerve fibers- arteriolar paralysis Venous dilatation Vasodilatation cause decreased venous return with decreased cardiac output Direct action on medullary centers Loss of skeletal muscle tone. Paralysis of nerve supply to adrenal glands with decreased catecholamine release

40. II. CARDIAC EFFECTS Heart rate slows down because of: Paralysis of cardioaccelator nerves Decreased Venous return which leads to Decreased right heart pressure and hence decrease heart rate. ( bainbridge reflex) The baroraceptors normally respond to fall in blood pressure by tachycardia( Marey’s Law).But In spinal anaesthesia bainbridge reflex predominates. III.RESPIRATORY EFFECTS Vital Capacity decreases from 4 to 3.73 L Decrease in expiratory reserve volume related to paralysis of abdominal muscles necessary for forced exhalation. Respiratory arrest occurs due to hypoperfusion of respiratory centre caused by high or total spinal’ Peripheral pooling of blood results in decreased alveolar blood supply which leads to decreased oxygen supply and hence reflex bronchodilation .

41. IV. GASTROINTESTINAL EFFECT Sympathetic block and parasympathetic over activity Contracted gut – intestines active- segmental movements Increase peristaltic activity Increase in gastric emptying, relaxed sphincters. Therefore post operative period of fasting is enhanced to avoid paralytic ileus and patient is kept NBM till effect of spinal weans off’

42. ENDOCRINE EFFECTS Spinal Anaesthesia is able to block the sympathetic stimulations caused by surgical stress. Blockade of Sympathetic afferents will prevent increase in plasma prolactin , growth hormone ACTH and ADH. GENITAL SYSTEM Flaccid paralysis of nervi erigentes and engorged penis THERMO REGULATION Vasodilatation causes heat loss at site of block causing shivering which is compensated by vasoconstriction RENAL FUNCTION- Neuraxial blockade has little effect on the blood flow to the renal system. Autoregulation maintains adequate blood flow to the kidneys as long as perfusion pressure is maintained. Neuraxial blockade effectively blocks sympathetic and parasympathetic control of the bladder at the lumbar and sacral levels. Urinary retention can occur due to the loss of autonomic bladder control. Detrusor function of the bladder is blocked by local anesthetics. Normal function does not return until sensory function returns to S3

43. SUBARACHNOID BLOCK IN NEONATES, INFANTS AND CHILDREN SAB in children does not produce haemodynamic instability because: 1.Small venous capacitance of the lower extremities less prone to venodilation . 2.Immature sympathetic autonomic system INDICATION---- Lower abdominal, pelvic and lower limb surgeries DOSAGE – Hyperbaric 0.5% bupivacaine for T4 level 1mg/kg bupivacaine-Premature infant 0.8mg/kg – full term 0.5mg/kg – small children Complication Technically difficult High failure rate Duration of block is short

44. SPINAL ANAESTHESIA CAN BE SAID TO HAVE THE FOLLOWING ADVANTAGES OVER EPIDURAL It is easier. It is quicker It provides slightly better relaxation of the abdomen The danger of toxicity due to the drugs is negligible because of smaller doses of the drugs used.

45. ADVANTAGES OF SPINAL ANAESTHESIA OVER GENERAL ANAESTHESIA Cheap 2. Obviates the need for general anaesthesia, which may be problematic in some patients. 3. Spontaneous respiration, with good abdominal relaxation (useful in patients with respiratory disease like COPD) 4. Avoids need for intubation where this is likely to be difficult. Reduction of surgical hemorrhage, e.g. at prostatectomy. 6. Decreased incidence of thromboembolism due to early ambulation

46. DISADVANTAGES OF SPINAL OVER GENERAL ANAESTHESIA Discomfort, especially for long operations. Discomfort eliciting paraesthesia . Contraindicated in confused patient. Profound cardiovascular effects. Leg weakness and urinary retention. Toxicity with high serum levels of anaesthetic drugs or accidental i.v . injection. Poor communication of intentions if deaf patient

47. EPIDURAL ANESTHESIA

48. Epidural Anesthesia A N euraxial technique that offers a wide range of applications. An Epidural block can be performed at the Lumbar, Thoracic, Cervical and Caudal level Wide use of applications; Operative anesthesia, Obstetric Anesthesia & Analgesia, Postop pain control and Chronic Pain Management It can be used as a “Single Shot” or with a catheter that allows intermittent boluses or a Continuous Infusion

49. Anatomy The Epidural space surrounds the Dura Mater posteriorly, laterally and anteriorly Nerve roots travel in this space as they exit the spinal cord laterally They then exit the foramen and travel peripherally to become peripheral nerves carrying both afferent and efferent pathways

50. 54 Boundaries Contents Cranially by foramen magnum. Caudally by sacrococcygeal ligament. (sacral hiatus) Anteriorly by posterior longitudinal ligament Laterally by vertebral pedicles & intervertebral foramina. Posteriorly by ligamentum flavum & vertebral lamina. Nerve roots Blood vessels-Batson’s venous plexus Lymphatic Fat Areolar tissue

51. Physiology Local anesthetics or other solutions injected into the epidural space (steroids, narcotics) spread anatomically Horizontal spread to the region of the Dural cuffs with diffusion into the CSF and leakage through the intervertebral foramen into paravertebral spaces Longitudinal spread is preferentially cephalad in direction.

52. Physiology Possible sites of anesthetic action include: 1 Intradural spinal roots 2 Dorsal and Ventral spinal roots 3 Dorsal root ganglia 4 The Spinal Cord 5 The Brain itself (by diffusion) 6 Paravertebral nerve roots

53. Physiology Initial blockade is PROBABLY a result of anesthetic blockade at the spinal roots within the Dural sleeves The Dural Cuffs or Sleeves have a proliferation of arachnoid villi and granulation tissue that effectively reduce the THICKNESS of the dura mater facilitating rapid diffusion of the LA from the Epidural space, through the Dura and into the CSF surrounding the nerve roots Then the local anesthetic diffuses into the nerve root itself, producing anesthesia to that particular dermatome

54. 58 Difference between spinal and epidural anesthesia Spinal anesthesia Epidural Anesthesia Level: below L1/L2, where the spinal cord ends Level: at any level of the vertebral column. Injection: subarachnoid space i.e. puncture of the Dura mater Injection: epidural space (between Ligamentum flavum and dura mater) i.e without puncture of the dura mater Identification of the subarachnoid space: When CSF appears Identification of the Epidural space: Using the Loss of Resistance technique. Dose: 2.5- 3.5 ml bupivacaine 0.5% heavy Dose: 15- 20 ml bupivacaine 0.5% Onset of action: rapid (2-5 min) Onset of action: slow (15-20 min) Density of block: more dense Density of block: less dense Hypotension: rapid Hypotension: slow Headache: is a probably complication Headache: is not a probable.

55. 59 Advantage Minimise effect of surgery on Cardiopulmonary reserve. patient with compromised Respiratory system Morbid obesity COPD Elderly Earlier mobilization Decreased chances of DVTE

56. 60 Effective analgesia without taking systemic opioids .( analgesics are given through catheter) Reduce the incidence of Myocardial infarction Surgery induced Stress response is decreased Blood loss is less and Everything can be regulated and changed by: Choice of drug Concentration of LA Dosage Level of Injection

57. 61 D isadvantage Risk of block failure Onset is slower Risk of infection Epidural hematoma Continous epidural catheter should not be used in the ward if monitoring is not proper.

58. 62 Indications Epidural anesthesia with or without sedation has been used as the sole anaesthetic or as an adjunct to general anesthesia (reduces patient’s requirement for opioid analgesics) Orthopaedic surgery : Major hip/knee surgery, pelvic fractures Obstetrics : Caesarean section, labour analgesia Gynaecologic surgery : Procedures involving female pelvic organs Urologic surgery : Prostate, bladder procedures General surgery : Upper and lower abdominal procedures Paediatric surgery : Penile procedures, inguinal hernia repair, anal surgery, orthopaedic procedures on the feet; supplement to GA, postoperative pain relief.

59. 63 Vascular surgery : Vascular reconstruction of the lower limb vessels, amputations involving the lower extremities. Thoracic surgery : Postoperative analgesia, combination with GA to reduce GA requirements. Diagnosis and management of chronic pain : Chronic benign pain - Cervical & lumbar radiculopathy, vertebral compression fracture , degenerative disc disease, peripheral neuropathy, low back pain, pelvic pain syndrome. Cancer related pain- pain secondary to face, neck, shoulder, genital, pelvic, perineal etc .malignancy. & chemotherapy related peripheral neuropathy .

60. 64 Contraindications Patient refusal Infection at site Raised ICP Severe AS, severe MS Allergy to LA drugs Severe hypovolaemia /shock Coagulation disorder Pre-existing neurological disease Demyelinating disease(Multiple sclerosis) Abnormalities of spine Uncooperative patient

61. 65 Physiologic Effects of Epidural Block Most physiologic effects of epidural block stem from Autonomic Blockade due to action of LA on autonomic nerve fibres of the spinal cord. The actions mostly pertain to either Blockage of Sympathetic outflow or Unopposed dominance of Parasympathetic outflow.

62. Epidural needle Epidural needles have larger diameter than Spinal needle. Typically sized of 16-19 gauge. 1 Tuohy & Hustead needle –with gently curve of 15-30° degree. 2 Crawford needle- with straight tip. 66

63. 67 Epidural needle Epidural needles have larger diameter than Spinal needle. Typically sized of 16-19 gauge. 1 Tuohy & Hustead needle –with curved tip 2 Crawford needle- with straight tip

64. Common LA Used for Epidural Anesthesia Bupivacaine: 0.125-0.25% for analgesia 0.5% for anesthesia Ropivacaine : 0.1 - 0.2% for analgesia 0.5-1% for anesthesia Lidocaine : 2% for anesthesia levobupivacaine : 0.5 -0.75% for anesthesia 0.125-0.25% for analgesia 68

65. 69 Pharmacology related to Epidural Anesthesia Anaesthetic administered epidurally 20-30 ml volume. Drug Conc Onset(min) Duration Plain Duration with Epinephrine Lidocaine 2% 15 80-120 120-180 Bupivacaine 0.5-0.75% 20 165-225 180-240 Levobupivacaine 0.5-0.75% 15-20 150-225 150-240 Ropivacaine 0.75%-1% 15-20 140-180 150-200 Mepivacaine 2% 15 90-140 140-200

66. 70 Some Common Procedural Preferences Labour analgesia LSCS Hip/Knee surgery Laparotomy under GA Thoracotomy/ fractured ribs Level of insertion L2-L4 L2-L4 L2-L4 T8-T10 At relevant interspace usally Height of block T8-T9 T6-T7 T10 Upper abdo.T7-T8,Lower abdo.T10 Relevant area Density of block Sensory & Minimal motor Motor & Sensory Motor & Sensory Sensory & Minimal Motor Sensory & minimal motor

67. 71 Labour Analgesia LSCS Hip/Knee surgery Laparotomy under GA Thoracotomy/ Fractured ribs Choice of local anaesthetic 0.1%-0.25% Bupivacaine Lignocaine2% + Bupivacaine0.5% Bupivacaine 0.5% 0.25%-0.5% Bupivacain 0.25%-0.5% Bupivacaine in theatre or establish block Infusion Bupivacaine.1%+ Fentanyl 2mcg/ml Post op Bupivacaine 0.166%+Diamorphine .1mg/ml Not usually necessary Post op Bupivacain0.166%+Diamorphine 0.1mg/ml Post op Bupivacaine 0.166%+Diamorphine .1mg/ml Rate of infusion 0-12 ml/hr 0-8mls/hr -- 0-12mls/hr 0-8mls/hr

68. 72 Performing the procedure Position of patient- Careful attention to the patient’s position is essential to successful placement of the epidural needle and catheter. Depending on the patient’s medical status, weight, and ability to cooperate, the sitting or lateral decubitus position can be used. Easier in sitting position. Approach - Four common approaches to the epidural space are possible: Midline, Paramedian, Taylor (modified paramedian), Caudal

69. Technique The most commonly performed Epidural is a Lumbar Epidural, followed by a Caudal, then Thoracic and finally Cervical. Today most high thoracic and cervical epidurals are performed under flouroscopic guidance by pain specialists as it takes a greater level of skill to successfully perform those procedures.

70. Technique  

71. 76 Needle angulation required to accomplish epidural blockade in the high thoracic/low thoracic/lumbar regions. A: High thoracic region. B: Low thoracic region. C: Lumbar region.  

72. 77 Locating the Epidural space All aseptic precaution is taken. Skin is infiltrated with local anesthetic in to desired space(identified). Needle is advanced slowly, feel of increase resistance. 3 methods are used to identify Epidural space- Loss of resistance (to with air or saline):- As needle reaches Epidural space Loss of Resistance is felt less 2 yr old air LORS Vs LORA : LORA is associated with nerve root compression, pneumocephalus and greater incidence of incomplete analgesia, paresthesia and venous air embolism. LORS is associate with reduces incidence of dural puncture in adult, while in pediatric patients, dural puncture incidence are more. LORA is safer than LORS in children less than 2 yrs old.

73. Hanging drop method:- As needle reaches Epidural space Hanging drop is sucked in d/t negative pressure. In cervical region, negative pressure poorly reliable and only useful in sitting position. The negative intra-thoracic pressure may influence the pressure in epidural spaces in thoracic region and should be maximal during inspiration. Ultrasonography / Fluoroscopy

74. 80 Hanging Drop Technique

75. Single –end hole catheter Spring wire-reinforced catheter Closed tip, multiple-side hole catheter Types of epidural catheter

76. 82 Catheter placement The catheter is made of a flexible, calibrated, durable, radiopaque plastic . Typically, 19-or 20- gauge catheter is introduced through 17-or 18- gauge epidural needle. Catheter is threaded through needle after placing in space. Needle is withdrawn over the catheter. 4-6 cms catheter remain in epidural space. Threading more catheter may increase the likelihood of catheter malposition. Catheter is firmly secured to skin with surgical tape.

77. 83 Epidural catheter placement

78. 84 Continuous infusion

79. CAUTION NEVER pull the catheter back through the needle once it has been inserted It is possible to catch the catheter on the needle tip and shear or cut the tip off Then it becomes a permanent new addition to the epidural space and will be there for the rest of the patient’s life!!!!

80. 86 Epidural Dosing As a general guideline, 1–2 mL per segment in a lumbar epidural, 0.7 mL per segment in a thoracic epidural, and 3 mL per segment for a sacral/caudal epidural is used as an initial loading dose. Test Dose Incremental Dosing Aspiration to check for blood or CSF before each dose. After the initial loading dose, one quarter to one third of the amount can be administered 10–15 min later to intensify the sensory block. The overall level of the block will not be significantly increased with this method.

81. 87 Test Dose The purpose of the “test dose” is to make sure that the catheter is not in the subarachnoid, intravascular, or subdural space. The classic test dose combines 3 mL of 1.5% lidocaine with 15 mcg of epinephrine. The intrathecal injection of 45 mg of lidocaine will produce a significant motor block consistent with spinal anesthesia . A change in heart rate of 20% or greater is an indication of intravascular injection warranting the removal and replacement of the catheter. If the heart rate does not increase by 20% or greater, or if a significant motor block does not develop within 5 min of administering the test dose, it is considered negative. False- ve if pt is on β blocker, false + ve in pregnancy if coincides with labour pain.

82. 88 Factors affecting Epidural Anesthesia Site of injection- Lumbar- spread cranially more than caudally Thoracic- spread evenly from site of injection Upper thoracic & lower cervical fibers are comparatively resistant d/t larger size of nerve roots-requires larger dose of LA. Thoracic epidural space is smaller, require lower volume of drug. Dose- 1-2 ml /segment. Depends on volume & concentration of drug. Higher conc. produces a profound motor and sensory block, whereas low conc. a selective sensory block.

83. 89 Age - as patient age increases reduced size of intervertebral foramina decreased epidural space size and compliance. Decreased epidural fat necessitates decrease of dose in elderly. Weight - There is little correlation between the spread of analgesia and the weight of the patient. In morbidly obese patients, there may be compression of the epidural space secondarily to increased intra-abdominal pressure, creating a higher block for a given dose of local anesthetic .

84. 90 Height - The correlation with height is usually not clinically significant. Ht. <5 ft 2 inch, reduce the dose to 1 ml / segment to be blocked. Bromage dosing regime - Increasing the dose of local anaesthetic by 0.1 mL per segment for each 2 inch over 5 ft of height. Addition of Vasoconstrictors - Epinephrine 5 mcg/ml (1:200000) is most commonly added. Prolongs duration of action by reducing the vascular absorption of drug.

85. 91 Posture- Block Ht. - Whether the patient is sitting or in the lateral position, there is no significant difference in block height. This is explained by the fact that gravity and soln. baricity are not intimately related to block spread. Onset, Duration & Density - slightly faster on the dependent side when the epidural in placed with the patient in the lateral position Pregnancy- Increased sensitivity to regional anesthetics leads to faster onset time. Engorgement of Epidural veins from caval compression leads to increased incidence of blood vessel puncture during procedure.

86. Complications Drug Related Complications- CNS toxicity CVS toxicity Procedure Related Complications- Minor Back Pain Postdural Puncture Headache Subarachnoid Injection/High or Total Spinal Major Subdural Injection Sheering of catheter Neurologic Complications- Spinal nerve neuropathy Transient neurological symptoms Anterior spinal artery syndrome Adhesive arachnoiditis Epidural hematoma Epidural abscess

87. 93 Postdural Puncture Headache : Due to inadvertent dural puncture. TOC – Epidural blood patch . Cosyntropin , ( ACTH analogue) .  Postulated mechanisms include increased CSF production via sodium channels; aldosterone mediated salt and water retention, and possibly increased β endorphin output. One of the trials used 1 mg of cosyntropin for the prophylaxis of PDPH. It showed more than 50% reduction in the incidence of PDPH Mannitol - It acts “ acute increases in blood osmolality  decreases brain water content (mainly in healthy brain tissue with intact blood brain barrier)decrease brain bulk, intracranial pressure, increased intracranial compliances.” decrease brain bulk, causes brain re-float in contracted CSF volume. It believe that re-floatation of brain is an important factor to alleviate PDPH with other factors.

88. 94 Neuraxial block in setting of anticoagulant and antiplatelet drugs (recommended by American Society of Regional Anesthesia) Neuraxial block and indwelling catheters are safe in patients on aspirin , NSAID’s & cox-2 inhibitors. Discontinue clopidogrel for 7 days , ticlopidine for 14 days , abciximab for 24-48 hrs , tirofiban & eptifibatide for 4-8 hrs before technique. Wait at least 12 hrs before last thromboprophylaxis dose of LMWH and 24 hrs after last full dose When LMWH is begun post-op first dose should be withheld for at least 24 hrs if using a twice daily dosing regimen and 6-8 hrs if using once daily dosing regimen

89. 95 An indwelling epidural catheter should not be removed until 12 hrs after the last prophylaxis dose of LMWH, and the next dose should be administered no sooner than 2 hrs after catheter removal If a single daily thromboprophylaxis dose of LMWH is administered, then indwelling catheters may be maintained postoperatively. But the concurrent use of twice daily or therapeutic LMWH and an indwelling epidural catheter is not recommended. The LMWH dose is delayed for 24 hr if the patient experienced excessive trauma during attempted epidural or spinal anesthesia . Neuraxial blocks should not be performed in patients chronically taking warfarin unless the warfarin is stopped and the INR is <1.5 Neuraxial catheters should be removed only when the INR is <1.5

90. 96 Combined spinal-epidural anesthesia Introduced in 1939 when Soresi et al presented a paper on usage of CSE in 200 patients. Technique combining both spinal and epidural. Spinal component gives rapid onset and dense predictable block. Epidural catheter is used to supplement insufficient subarachnoid block (to increase height or duration of block) and also to provide long-lasting analgesia. reduces the incidence of several potential problems associated with the conventional epidural technique, including incomplete (patchy) blockade, motor block, and poor sacral spread.

91. 97 The sequential CSE technique may be particularly advantageous in high-risk patients, such as in those with cardiac disease, when slower onset of sympathetic blockade is desirable. Two approaches are mostly used: Needle Through Needle Needle Below Needle.

92. THANK YOU