EPIDURAL ANESTHESIA AND ANALGESIA with its consideration

Epidural analgesia with anesthesic consideration

1. EPIDURAL ANESTHESIA AND ANALGESIA PRESENTER: Dr. R.L.PAVANI MODERATOR: Dr .PRAVEEN KUMAR

2. HISTORY J. Leonard Corning proposed injecting an anesthetic solution into the epidural space in the 1880 s. Jean Sicard , Fernand Cathelin are credited with the first intentional administration of epidural anesthesia . Fidel Pages, Mirave described a single-shot thoraco lumbar epidural anesthesia. Achille Dogliotti popularized a reproducible loss-of-resistance (LOR ) technique. Alberto Gutierrez described the “sign of the drop” technique. Manual Martinez Curbelo continuous technique in 1947.

3. A Neuraxial technique that offers a wide range of applications. An Epidural block can be performed at the Lumbar, Thoracic, Cervical and Caudal level. Onset: slower than spinal. Block height: depends on injection site, LA volume -  1-2ml / segment . ↓ pulmonary and cardiac morbidity.

4. 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.

5. Boundaries Cranially: foramen magnum. Caudally: sacrococcygeal ligament. (sacral hiatus) Anteriorly: posterior longitudinal ligament Laterally: vertebral pedicles & intervertebral foramina. Posteriorly: ligamentum flavum & vertebral lamina.

6. Contents Nerve roots Blood vessels-Batson’s venous plexus ( This area is probably a common site of epidural catheter blood vessel puncture .) Lymphatic Fat Areolar tissue

7. The ligamentum flavum varies in thickness at different spinal levels and is thickest in the lumbar region. Its thickness also varies within each interspace . The variable thickness of the ligamentum flavum and the presence of midline gaps may contribute to failure to identify the epidural space.

8. Thickness of the ligamentum flavum at different vertebral levels. Vertebral Level Thickness (mm) Cervical 1.5–3.0 Thoracic 3.0–5.0 Lumbar 5.0–6.0 Caudal 2.0–6.0

9. SURFACE ANATOMY

10. DERMATOME LEVELS

11. Cervical Thoracic Lumbar Sacral Thoracic surgery - Thoracotomy - Pectus repair - Thoracic aortic aneurysm repair Upper abdominal surgery - Esophagectomy - Gastrectomy - Pancreatectomy - Hepatic resection Lower abdominal surgery - Abdominal aortic aneurysm repair - Colectomy - Abdominal perineal resection

12. Distance From Skin to Epidural Space S kin to space of 2 to 9 cm , ( 3.5–7.5 cm). The distance between the ligamentum flavum and the dura is typically estimated as 7 mm, broad range from 2 mm to 2.5 cm . The anterior-posterior distance is largest in the lumbar region (L3–L4) Decreases in the thoracic region , and is absent in the cervical region.

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

14. ADVANTAGE Minimise effect of surgery on Cardiopulmonary reserve. Morbid obesity. Elderly. Earlier mobilization. Decreased chances of DVTE.

15. DISADVANTAGE 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.

16. Everything can be regulated and changed by: Choice of drug Concentration of LA Dosage Level of Injection

17. MECHANISM OF ACTION Disruption of nerve transmission with spinal cord, spinal nerve roots and dorsal nerve root ganglion. Blocks spinal nerves in the epidural space –the nerve emerges from dura and passes through the intervertebral foramina . Speed of neural blockade depends on the size, surface area, degree of myelination of the nerve fibers. BLOCK ONSET BLOCK REVERSAL B - fibers.(1-3µm)  sympathetic C - fibers (0.3-1µm)  cold temperature A δ - fibers (1-4µm)  pin prick A β - fibers (5-12µm)  touch A α - fibers (12-20µm)  motor

18. INDICATIONS

19. CONTRAINDICATIONS

20. Hip arthroplasty , arthrodesis, synovectomy T10 Open reduction internal fixation of acetabular fracture T10 Open reduction internal fixation of femur, tibia, ankle, or foot T12 Closed reduction and external fixation of femur and tibia T12 Above- and below-knee amputation T12 Knee arthrotomy , Arthroscopy of knee, Distal tibia, ankle, and foot procedures T12 Orthopedic surgeries suitable for epidural

21. Procedure Sensory Level Required Cystectomy T4 Extracorporeal shock wave lithotripsy T6 Open prostatectomy T8 Ureteral stone extraction T8 Cystoscopy T9 Transurethral resection of prostate T9 Surgery involving testes T10 Surgery involving penis L1 Urethral procedures Sacral block

22. 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.

23. 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.

24. Differential Blockade Differential blockade occurs when sensory, motor, and sympathetic nerve functions are obtunded at different rates and to different degrees. In general, sympathetic blockade >2-6 dermatomes sensory blockade, which > than the motor blockade . Although the mechanism has not been fully elucidated, it may be attributed to anatomic features of blocked nerves - eg , diameter and presence or absence of myelin - the length of blocked nervous tissue. - lipid membrane and ion channel composition, - LA type and concentration.

25. Cardiovascular system Block below T5 Sympathetic blockade venodilation in blocked segments venous return CO hypotension The compensatory mechanism for the decrease in mean arterial pressure causes 1)reflex vasoconstriction above the level of the block 2)release in catecholamines from the adrenal medulla. Block above T4 (cardiac sym fibres T1-T4) so profound hypotension and bradycardia ,d/t high level of sympathetic blockade.

26. Respiratory system Minimal impact on Pulmonary function in normal & healthy patient, until if it reaches cervical region - phrenic nerve involvement. In patients with severe chronic lung disease dependent on accessory muscle function to maintain adequate ventilation, because accessory muscles in expiration is blocked. Inspiratory muscle function is unaffected.

27. Gastrointestinal system V agal dominance leads to increased secretions, peristalsis and and contracted gut. intramucosal PH. sympathetic activity, relaxed sphincters.

28. Renal system RBF is maintained through autoregulation , has little effect on renal function . Block both Sympathetic & Parasympathetic fibres (S2-S4) Impair control of bladder function. Loss of control of bladder function Urinary retention

29. Endocrine system Abolishes stress response to surgery. Decreased release of catecholamines , GH, cortisol, TSH, ADH, vasopressin, renin, angiotensin, norepinephrine

30. Emergency equipment and drugs for initiation of neuraxial block. Airway equipment Ambu bag with mask Oxygen source Oral and nasal airways Laryngoscope handles and blades Endotracheal tubes Eschmann stylet / bougie Syringes and needles Emergency drugs Ephedrine Phenylephrine Epinephrine Atropine Sedative/hypnotic 20% lipid emulsion Succinylcholine

31. Equipment Commercially prepared, sterile, disposable epidural trays are available from several manufacturers. A standard kit typically includes the following : - sterile drape/ prep swabs /gauze sponges. paper towel/ povidone -iodine solution. 0.9 % NaCl . 5-mL of 1.5% lidocaine with Epi 1:200,000.

32. 5-mL of 1% lidocaine for skin infiltration . B acterial filter/ styletted epidural needle. 5-or 10-mL glass or plastic LOR syringe. catheter connector securing device Epidural catheter with a connector/adapter.

33. 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.

34. TUOHY NEEDLE 17 or 18 gauge. 9 cm or 3.5 inch in length, with surface markings at 1-cm intervals. longer needle upto 15cm (6 inch) – obese patients. blunt bevel with a curved tip. wings at the junction of needle shaft, for better control.

35. NEEDLE THROUGH NEEDLE

36. EPIDURAL CATHETER 19/20 G needles are available. Material with nylon blend catheters. Has varying degrees of stiffness to facilitate threading . 10cm -- 12cm __ 15cm --- 20cm ----

37. Wire-reinforced catheters embedded in either a polyurethane or nylon-blend catheter are more recent technological advance and becoming popular. The use of these catheters reduces the incidence of complications including epidural vein cannulation , paresthesias , and inadequate analgesia.

38. Single end-hole wire-reinforced catheter

39. Multi-orifice wire-reinforced catheter

40. Single –end hole catheter Closed tip, multiple-side hole catheter Spring wire-reinforced catheter

41. 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 : 0.125-0.25 % for analgesia 0.5 -0.75% for anesthesia

42. Drug Concentration (%) Onset Time (min) Duration (min) Lidocaine 2 10–20 60–120 Bupivacaine 0.0625–0.5 15–20 160–220 Ropivacaine 0.1–0.75 15–20 140–220 Levobupivacaine 0.0625–0.5 15–20 150–225 Commonly used local anesthetics for epidural anesthesia and analgesia

43. Adjuvants to Local Anesthetics   Fentanyl Sufentanil Morphine Clonidine Neostigmine.

44. Potential benefits of the administration of clonidine in the epidural space: Prolongation and enhancement of the effects of epidural LAs without an additional risk of hypotension. Reduction in LA dose requirements for labor epidural analgesia. Effective analgesia without motor impairment. Synergistic effect with opioids and opioid agonist-antagonists. Modulation of the stress response to thoracic surgery. Preservation of lung function after thoracotomy. Possible reduction in cytokine response, further reducing pain sensitivity.

45. SIDE EFFECTS D ose-independent hypotension. Bradycardia . Sedation . Dry mouth.

46. FACTORS AFFECTING EPIDURAL BLOCK S ame dermatome level - surgical incision . L owers the dose of the drug - reducing the side effects. DOSE: it is function of volume and concentration of LA’s. CONCENTRATION: of the drug effects the density of the block. HIGHER CONC : more profound motor and sensory blockade. LOWER CONC : selective sensory block. VOLUME: Larger volume with same concentration of LA -blocks greater number of segments . Eg : To achieve a T10 sensory level from an L3–L4 injection, approximately 8 mL of LA should be administered.

47. WHEN TO REPEAT THE DOSE? Doses should be administered before the nerve block regresses to the point the patient experiences pain. “Time to two-segment regression”: the time it takes for the sensory nerve block to regress by two dermatome levels . When two-segment regression has occurred, 1/3 rd – 1/2 of the initial loading dose can safely be administered to maintain the nerve block.

48. REDOSING LOCAL ANESTHETICS Drug Concentration (%) Time to Two-Segment Regression (min) Recommended Time for “Top-Up” Dose From Initial Dose (min) Lidocaine 2 60–140 60 Bupivacaine 0.10 180–260 120 Ropivacaine 0.10 180–260 120

49. OTHER FACTORS AGE : reduced size of the intervertebral foramina  decreased epidural fat  which allows more of the drug to bathe the nerves . WEIGHT: Morbidly obese patient  compression of the epidural space  increased intra-abdominal pressure  chance of higher nerve block. HEIGHT: </= 5ft reduce the dose to 1 mL per segment to be blocked. >5ft ↑0.1ml per segment for every 2inch height.

50. TECHNIQUE 4-P ’ s: P reparation, P osition, P rojection, P uncture. PREPARATION: informed consent, IV resuscitation equipment keep ready. POSITION: Lateral decubitus / sitting. PROJECTION: Median, Paramedian, Taylor (modified paramedian ), Caudal approach. PUNCTURE: LOR technique or hanging drop technique. Other new modalities in identifying epidural space.

51. SITTING POSITION Technically easier to identify the midline – obese, scoliotic . Difficult in –elderly, parturients in advance stage of labor, hip fractures, sedated and uncooperative patients.

52. LATERAL DECUBITUS POSITION Sedation can be used more liberally Reduced patient movement Improved patient satisfaction Hemodynamic changes better tolerated Bedside assistance may not be required

53. TECHNIQUES 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 fluoroscopic guidance by pain specialists as it takes a greater level of skill to successfully perform those procedures . The angles of approach for the various levels are markedly different.

54. ANGLE OF NEEDLE Cervical Epidural Space: Single-shot or continuous cervical epidural techniques are used. C7-T1 is the widest and easiest to access. M idline and paramedian approaches are used. Can be initiated in the prone, lateral, or sitting position. Fluoroscopic guidance is becoming increasingly common –PRONE POSITION. F lexion of the neck serves  increase the distance from the ligamentum flavum to the dura mater  to expand the interlaminar space.

55. Thoracic Epidural S pace : The Thoracic is at 40 degree angle due to the anatomical arrangement of the Thoracic Spinous Processes. M id-thoracic (T4 -T7) -tip of the spine overlies to the next lower vertebrae. Mid line approach, para median approach.   BENEFITS Improved perioperative analgesia compared with other modalities Decreased postoperative pulmonary complications Decreased duration of postoperative ileus Decreased duration of mechanical ventilation Decreased mortality in patients with rib fractures

56. Lumbar Epidural Space: -Midline approach, Sitting position Maximum flexion –open ups MORE intervertebral space.

57. Locating the Epidural space Loss of resistance: LOR to air LOR to saline with or W/O air bubble springe loaded syringe Macintosh balloon method Epi -detection Epimatic

58. LOSS OF RESISTANCE TO AIR A dvance the needle slowly, exerting either continuous or intermittent pressure on the LOR syringe . As the needle enters the ligamentum flavum , there is usually a distinct sensation of increased resistance. F ollowed by a subtle “give” when light pressure is exerted on the plunger.

59. LOR TO SALINE WITH OR W/O AIR BUBBLE Syringe filled with 2–3 mL of saline or saline with a clearly visible air bubble. B ubble provides a gauge of the appropriate pressure to be applied on the LOR syringe C ompress and provide some resistance if the epidural needle tip is engaged in ligament. E ffortlessly with only light pressure once the needle enters the epidural space, saline can be injected directly for fluid predistension .

60. LORS Vs LORA 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. LORA is associated with nerve root compression, pneumocephalus and greater incidence of incomplete analgesia, paresthesia and venous air embolism.

61. Pneumocephalus Increased risk of accidental dural puncture Faster onset of signs and symptoms of PDPH Higher incidence of PDPH Incomplete/patchy block Spinal cord or nerve root compression by air Venous air embolism Subcutaneous emphysema Increased incidence of epidural vein cannulation Difficult catheter insertion

62. The Hanging Drop Technique W hich is more pronounced and reliable in the cervical and thoracic regions than in the lumbar segments. T he pressure that appears to “suck in” the drop of fluid . A drop of saline is placed at the hub of the needle once the needle is engaged in ligament . The needle is advanced continuously with the thumb and index fingers firmly grasping the wings and the third through fifth fingers of both hands positioned against the patient’s back .  Entry into the epidural space is signaled by entry of the drop into the hub of the needle.

63. ULTRASOUND GUIDED Suggest that the use of USG to identify the anticipated depth to space, particularly in obese parturients . T o identify the midline prior to placement.

64. Technique of Epidural block Midline Approach: most commonly used for epidural placement in the sitting position and for epidural procedures in the lumbar, low thoracic, and cervical spine region . Identify the desired interspace by surface anatomic landmarks and palpation Infiltrate the skin and subcutaneous tissue with LA (most commonly 1% lidocaine ) Insert the stylettedepidural needle along the same track with the bevel oriented cephalad .

65. To engage the epidural needle properly, advance through the skin, subcutaneous tissue, fatty tissue, supraspinous ligament, interspinous ligament, and, possibly, into the ligamentum flavum ; at that point, the needle should sit firmly in the midline. If the needle shaft wobbles or deviates sideways, it is not properly anchored in ligament. The epidural needle can be engaged in the interspinous ligament or the ligamentum flavum .

66. Remove the stylet from the epidural needle and attach the LOR syringe with air or saline (with or without an air bubble) firmly to the hub of the needle. Pressure is exerted on the LOR plunger either continuously or intermittently After it enters the epidural space –LOR achieves For continuous epidurals, a small volume of saline can be injected into the epidural space to dilate the space, thereby reducing the risk of epidural vein cannulation and facilitating catheter insertion.

67. Note the depth of the needle at the skin. For eg , if 4 markings remain visible between the skin and the needle hub, subtract 4 from 9 -depth to epidural space is 5 cm .

68. Insert the catheter with the assistance of the insertion device that fits into the epidural needle hub. U ntil the 15-cm mark is visualized entering the needle hub. R emove the needle without dislodging the catheter .

69. PARAMEDIAN APPROACH P aramedian approach offers a larger opening into the epidural space than the midline approach, for who cannot flex the spine during epidural placement. - calcified ligaments or spinal deformities. - kyphoscoliosis , prior lumbar  surgery. - in the low-to midthoracic area (as spinous processes from T4–T9 are sharply angled)

70. Identify the intended interspace with surface landmarks, palpation, or ultrasound guidance. Raise a skin wheal roughly 1 cm laterally & caudally to the inferior aspect of the superior spinous process. Epidural needle is inserted 15°off the sagittal plane, angled toward midline with a cephalad tilt. If bone is encountered, the needle is redirected - cephalad and medial direction. If the lateral aspect of the spinous process is encountered, redirected -laterally and cephalad .

71. TAYLOR APPROACH Is a modified paramedian approach - large L5–S1 interspace. The epidural needle is inserted into this site in a medial and cephalad direction at a 45° to 55° angle. If the needle contacts bone (usually the sacrum ), the needle should  direct more medial and cephalad directions.

72. INITIATION AND MANAGEMENT Test Dose : Before administering medications through the epidural catheter . Subarachnoid, intravascular, and subdural placement should be ruled out . Dose of 3 mL of 1.5% lidocaine with 15 μgof epinephrine . The intrathecal injection of 45 mg of lidocaine -produce a significant motor nerve block if catheter is in the subarachnoid space , but it is not always reliable.

73. An increase in systolic blood pressure greater than 20 mm Hg has been used as an indicator of intravascular injection. I ncrease in heart rate of 10 to 25 beats per minute. within 1 minute suggests that the catheter has been placed in a vessel and should be replaced. If the heart rate does not increase by 20% or greater or if a significant motor nerve block does not develop within 5 minutes, it is considered as negative. False- ve if pt is on β blocker, false + ve in pregnancy if coincides with labour pain.

74. Incremental Dosing   Incremental dosing of LA ( ie , 3- to 5-mL), at 3-5 min interval with simultaneous aspiration for blood and CSF and careful observation, is required when dosing an epidural . Its purpose is to avoid excessively high anaesthetic levels. Appropriate loading doses for postoperative analgesia include 10 mL of 0.2%–0.25% bupivacaine, levobupivacaine , or ropivacaine with or without adjuvants.

75. Top-Up Dosing Repeat doses, commonly referred to as “top-ups,” should be administered before the level of the nerve block has receded more than two dermatomes.

76. Administration Techniques Intermittent bolus - additional therapeutic bolus doses of local anaesthetic when analgesia begins to wane - disadvantage : pain relief constantly interrupted by periods of regression of analgesia Continuous infusion - maintainence of stable level of analgesia, less frequent need for bolus doses, maternal haemodyanamic stability - decreased workload for anaesthesiologist - disadvantage : administration of larger dose of local anaesthetic .

77. Patient controlled epidural analgesia(PCEA) and Computer controlled PCEA pumps Advantages over bolus/continuous infusion: - better patient satisfaction, less breakthrough pain - reduced consumption of local anaesthetics - optimal analgesia with minimal side effects - less incidence of motor blockade - stable haemodyanamics - less need for anesthesia provider intervention

78. PCEA Bupivacaine 0.05 - 0.125 % + Fentanyl 2 µg / ml - 5 ml bolus - Background infusion 5-10 ml / hr - Hourly limit 30 ml - lockout interval 5 - 15 mins

79. Problem Possible Explanation Action Needle floppy; needle angles laterally Entry off midline; missed supraspinous ligament Reassess midline; redirect needle Bone contact at < 2 cm Contacted spinous process; spinal flexion inadequate Reidentify interspace; place needle in caudal region of interspace Bone contact at ≥ 4 cm Needle entry too lateral; contacted lamina Redirect needle toward midline Bony resistance throughout Ossified ligaments; arthritic spine Consider paramedian approach

80. Inability to advance catheter False loss of resistance; narrow epidural space ; needle too close to dura mater; obstructed needle orifice Fluid predistention ; rotate needle bevel; use stiffer catheter ; attempt new placement, withdraw and readvance Heme in catheter Epidural vein cannulation; needle entry too lateral; engorged epidural veins Withdraw catheter 1–2 cm and flush with saline; perform new placement if heme persists ; Warm, clear fluid return in needle or catheter Accidental dural puncture; intrathecal placement continuous spinal or new placement at different interspace Pain/paresthesia on catheter insertion Catheter advanced > 6 cm into epidural space ; Withdraw catheter, perform new placement if pain persists Inability to palpate spinous processes Obesity; severe arthritis; patient with previous back surgery use ultrasonography Inability to flex spine Elderly; arthritis; patient with previous spinal instrumentation Consider paramedian approach; Curvature of spine Scoliosis Use ultrasonography;

81. RECENT ADVANCES Optical Coherence Tomography

82. Hytrel coated probe ( HCP)

83. Haptic Simulators

84. Fiber Bragg Grating Force Device

85. Technology Merits Drawbacks Ultrasound-guided epidural needle -Real-time and pre-procedural ultrasound guiding of the procedure -The depth of the EDS and the angle of the needle insertion can both be determined by ultrasound. -Relatively expensive; -Technical complications, epidural needle for the needle to be fully automated; -Lack of measured data for force/pressure feedback Haptic feedback-based devices -Enclosed in portable cases; -Connect to laptops with graphic displays. -Lack of measured data for force/pressure feedback Epidural pressure measurement-based devices -Monitor and record needle-inserted pressure; -Compact system. -Different tissues are not identified through insertions; -Needs to be calibrated. FBG-based devices -Dynamic data of force variation on the spinal needle with a high resolution. -Require specific design of the FBGs. OCT-based devices -Image the tissue in front of the needle tip; -Deep learning models can be applied to automatically process the imaging data for needle localization. -Relatively expensive.

86. THANK YOU