Spinal epidural

Spinal anaesthesia

1. Spinal, Epidural and Caudal Anaesthesia Dr Sapna Nikhar Associate Professor Department of Anaesthesia and Intensive Care NIMS, Hyderabad

2. History James Leonard Corning- Pioneer of neuroaxial blockade 1891-Dural puncture described by Essex Wynter followed shortly by Heinrich Quincke . August Bier –on 16 th August 1898- performed surgery under spinal anaesthesia in Kiel. Fidel Pages- Explained the technique of Epidural anasethesia Dogliotti – first described “Loss of Resistance technique” 1901- First description of caudal anesthesia by CATHLEEN. 1907- ARTHUR BAKER emphasised use of hyperbaric spinal local anesthetic .

3. ADVANTAGES OF ‘ CNB’ OVER ‘ GA’ Preserves airway. Decreased metabolic changes following surgery. Decreased DVT rate for certain surgeries. Residual postoperative analgesia. Better recovery with less risk of airway obstruction and aspiration. Decreased blood loss in certain surgeries. Excellent muscle relaxation. Less expensive than many G.A techniques. 3

4. Anatomy

5. Vertebral column consists of 33 vertebrae. 7-cervical 12-thoracic 5-lumbar 5 –sacral 4-coccygeal 5

6. CLINICAL IMPLICATION- the vertebral column curves influence the spread of local anesthetics in the subarachnoid space. 6

7. SPINAL CORD The spinal cord is the downward continuation of medulla oblongata from the upper border of the posterior arch of first cervical vertebra(C1)to the lower border of the first lumbar vertebra(L1 ) ( IN ADULTS). [L3 in infants]. It terminates distally in the conus medullaris as FILUM TERMINALE (fibrous extension ) and the CAUDA EQUINA(neural extension) 7

8. Upto 3 rd month of intrauterine life spinal cord extends throughout the entire length of vertebral canal . Thereafter the vertebral column grows faster than the spinal cord. At birth – spinal cord ends at the level of lower border of L3. At 1 year- spinal cord ends at the level of L1-L2 CLINICAL IMPLICATION- lumbar puncture in adults can be done at L2 and below but in children it should be done at the level of L4-L5. 8

9. ANATOMIC DIFFERENCES

10. 10

11. Procedure Dermatomal Level Upper abdominal surgery T4 Intestinal, gynecologic, and urologic surgery T6 Transurethral resection of the prostate T10 Vaginal delivery of a fetus and hip surgery T10 Thigh surgery and lower leg amputations L1 Foot and ankle surgery L2 Perineal and anal surgery S2 to S5 (saddle block) Dermatomal levels of spinal anesthesia for common surgical procedures

12. 12

13. The spinous process of vertebra is important at the time of needle introduction in the I.V.space . Spinous process Cervical vertebra- Short and bifid ( with exception of C1&C7) and is directed almost horizontally to the body of vertebra. Spinous process of Thoracic vertebra- Long and inclined at an angle of 45˚-60° to the body of the vertebra. So the needle directed at an angle of 45 °-60° cranially to follow the upper border of spine to enter the ligamentum flavum . neonates and infants are more horizontal in position so - In less than 1 year of age, the needle insertion is perpendicular to the spinous process Spinous process lumbar vertebra- Directed horizontally back wards 90° to the body of vertebra & skin. VERTEBRA Cervical thoracic lumbar SPINOUS PROCESS Short and bifid,horizontal Long and inclined downwards Directed horizontally DIRECTION OF NEEDLE INSERTION Perpendicular to skin Slightly cephalad Perpendicular to skin

14. SUB ARACHNOID SPACE Space between the arachnoid and the piamater . Also called intrathecal space. Contents: CSF Spinal cord and nerve roots Blood vessels Incomplete trabecular network Virchow Robins space : Subarchnoid space communicates with the tissue spaces around the vessels in the piamater and accompanies them as they penetrate the cord. SPINAL ANAESTHESIA : Injection of local anaesthetic drug directly into CSF within the subarachnoid space. In the cervical and thoracic regions -3mm, lumbar region- 15mm 14

15. The absolute contraindications - lack of consent from the patient, elevated intracranial pressure (ICP), primarily due to intracranial mass infection at the site of the procedure (risk of meningitis). Relative contraindications - Preexisting neurological diseases (particularly those that wax and wane, e.g., multiple sclerosis) Severe dehydration ( hypovolemia ), any risk factors for hypotension Thrombocytopenia or coagulopathy (especially with epidural anesthesia, due to the risk of epidural hematoma) Other relative contraindications are severe mitral and aortic stenosis and left ventricular outflow obstruction as seen with hypertrophic obstructive cardiomyopathy.

16. MECHANISM OF ACTION LA IN DORSAL HORN, VENTRAL HORNS BLOCKS BOTH SODIUM AND POTASSIUM CHANNELS INHIBIT PAIN SIGNALS, MOTOR BLOCKADE RESPECTIVELY Uptake of LA from subarachnoid space to neural tissue depends on: Concentration of LA in CSF Surface area of nerve tissue exposed Lipid content of nerve tissue Blood flow to nerve tissue

17. LAYERS OF ANATOMY THAT ARE TRAVERSED DURING MIDLINE APPROACH OF SAB Skin Subcutaneous fat Supraspinous ligament Interspinous ligament Ligamentum flavum Epidural space Dura mater Subdural space Arachnoid mater Subarachnoid space From Posterior to Anterior

18. LAYERS OF ANATOMY THAT ARE TRAVERSED DURING PARAMEDIAN APPROACH Skin Subcutaneous fat Paraspinous muscle Ligamentum flavum Epidural space Dura mater Subdural space Arachnoid mater Subarachnoid space Supraspinous and interspinous ligaments are not traversed during paramedian approach

19. FACTORS AFFECTING LEVEL OF SAB Patient characteristics Age Height Weight Gender Intra-abdominal pressure Anatomic configuration of the spinal column Position Technique of injection Site of injection Direction of injection (needle) Direction of bevel Use of barbotage Rate of injection Characteristics of spinal fluid Volume Pressure (cough, strain, Valsalva maneuver) Density Characteristics of the anesthetic solution Density Amount (mass) Concentration Temperature Volume Vasoconstrictors

20. Contd … Factors Influencing Block Height Controllable Factors Dose (volume × concentration) Site of injection along the neuraxis Baricity of the local anesthetic solution Posture of the patient Factors Not Controllable Volume of cerebrospinal fluid Density of cerebrospinal fluid Factors Probably Unrelated to Height of the Spinal Anesthetic Block Added vasoconstrictor Coughing, straining, or bearing down (labor) Barbotage Rate of injection (except hypobaric) Needle bevel (except Whitacre needles) Gender Weight

21. STOUTS PRINCIPLE Height of anesthesia varies directly with concentration. Extent of anesthesia is inversely proportional to rapidity of spinal fixation & to the spinal fluid pressure Extent of anesthesia is directly proportional to speed of injection the volume of fluid specific gravity of hyperbaric solutions. With hypobaric solutions extent depends on position of the patient.

22. SPINAL NEEDLES The standard spinal needle 1) Hub 2) Cannula 3) Stylet with sizes ranging from 18 – 29 G. Length usually 9 cm. Pediatric needle-2.5-3cm in infants & 5cm in children Types of spinal needles : 1)CUTTING- Quincke’s and Pitkins . 2) PENCIL POINT- Sprotte and Whittacre . 3)NON-CUTTING- Greene’s 22

23. POSITIONING Lateral decubitus position Sitting position Prone position: jack knife position. Used with spinal anaesthesia for anorectal procedures with hypobaric solutions. Advantage of good position is to increase intervertebral space and reduce the failures

24. APPROACHES Approaches to intrathecal space include: Midline Paramedian Taylor Continuous spinal technique Approaches to epidural space include: Median Paramedian

25. Taylor approach

26. Taylor Approach The Taylor, or lumbosacral, approach to spinal anesthesia is a paramedian approach directed toward the L5–S1 interspace. Because this is the largest interspace, the Taylor approach can be used when other approaches are not successful or cannot be performed. As with the paramedian approach, the patient can be in any position for this approach: sitting, lateral, or prone. The needle should be inserted at a point 1 cm medial and inferior to the posterior superior iliac spine, then angled cephalad 45°–55° and medially. This angle should be medial enough to reach the midline at the L5–S1 interspace. 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. Figure 15 shows the Taylor approach to spinal anesthesia. Real-time ultrasound-guided prone spinal anesthesia via the Taylor approach has been described and may improve patient comfort and compliance during the procedure.

27. Effects of SAB

28. Dose , duration, and onset of local anesthetics used in spinal anesthesia Dose (mg) To T10 Dose (mg) to T4 Duration (minutes) Plain With Epinephrine Onset (minutes) Commonly used Bupivacaine 0.75% 8–12 14–20 90–110 100–150 5–8 Less commonly used • Lidocaine 5% • Tetracaine 0.5% • Mepivacaine 2% • Ropivacaine 0.75% • Levobupivacaine 0.5% • Chloroprocaine 3% 50–75 6–10 N/A 15–17 10–15 30 75–100 12–16 60–80 18–20 N/A 45 60–70 70–90 140–160 140–200 135–170 80–120 75–100 120–180 N/A N/A N/A N/A 3–5 3–5 2–4 3–5 4–8 2–4

29. Additives to Local Anesthesia Epinephrine Opioid mainly fentanyl Alpha 2 adrenergic agonist Midazolam Nalbuphine

30. Complications of SAB Minor Moderate Major • Nausea and vomiting • Mild hypotension • Shivering • Itch • Transient mild hearing impairment • Urinary retention • Failed spinal • Postdural puncture headache • Direct needle trauma • Infection (abscess, meningitis) • Vertebral canal hematoma • Spinal cord ischemia • Cauda equina syndrome • Arachnoiditis • Peripheral nerve injury • Total spinal anesthesia • Cardiovascular collapse • Death

31. EPIDURAL SPACE BOUNDARIES Superiorly : Foramen magnum Inferiorly: sacral hiatus Anteriorly : Posterior longitudinal ligament Posteriorly : Ligamentum flavum Laterally: Pedicles & intervertebral foramen CONTENTS Nerve roots Fat Loose areolar tissue Lymphatics & blood vessels including bateson’s venous plexus 32

32. EPIDURAL ANALGESIA ADVANTAGES DISADVANTAGES Area of anesthesia is well defined * Technically difficult Duration of anesthesia is longer than spinal *Incomplete muscle relaxation Side effects like headache , meningitis , *Need for large volumes of drug arachnoiditis are minimised GI complaints like nausea vomiting are * Risk of entering into subarachnoid space minimal Catheterisation incidence is small *Bleeding into epidural space *Spotty segmental block

33. EPIDURAL NEEDLES The epidural needle is typically 16-18G, 8-10cm long with surface markings at 1cm intervals. The Crawford with a straight needle allowing slightly easier insertion of catheter but with a greater risk of dural puncture. The more commonly used Tuohy needle whose curved end pushes the dura away after penetrating the ligamentum flavum .

34. DETECTION OF EPIDURAL SPACE Negative pressure techniques: Hanging drop sign of Gutierez : . After needles enters interspinous ligament hub is filled with saline. The needle advanced gently , On penetration of ligamentum flavum drop of needle is drawn into the epidural space Capillary tube method (Odom’s indicator ) : A small glass capillary tube attached to the needle containing fluid Manometer technique Loss of resistance techniques: Syringe technique- air/ saline Spring loaded syringe Balloon technique Brooks device Vertical tube of Dawkins

35. An equilateral triangle can be drawn to connect the posterior superior iliac spines and the sacral hiatus. Caudal Block

36. CAUDAL BLOCK Position : Lateral decubitus Prone with pillow under hips. Procedure -Sacral hiatus identified with non dominant hand. The sacral hiatus and the posterior superior iliac spines form an equilateral triangle pointing inferiorly. Needle should be entered in this space perpendicularly and angle should be decreased Aspirate the needle for CSF or blood for proper position Whoosh test

37. DRUG REGIMES Armitage regime: : 0.25% bupivacaine 0.5ml/kg for a lumbosacral block 1 ml/kg for a thoraco -lumber block 1.25 ml/kg for a mid thoracic block Also he recommended the following bupivacaine concentration: - For volume up to 20 ml. 0.25% bupivacaine is recommended. - For volume above 20 ml 0.19% bupivacaine is recommended (a part of 0.9% NaCl + three parts of 0.25% bupivacaine = 0.19% mixture). Scott regime: Calculates the dose from the child's age or weight

38. Thank you 40