neuroaxial anaesthesia

1. NEURAXIAL ANAESTHESIA DR ISMAIL AHMED ANAESTHESIA CONSULTANT MD ANAESTHESIA AND INTESIVE CARE AL AZHAR UNIVERSTY

2. Introduction • Neuraxial anesthesia is a type of regional anesthesia that involves injection of anesthetic medication in the fatty tissue that surround the nerve roots or into the cerebrospinal fluid which surrounds the spinal cord • Spinal anaesthesia • 1898 - August Bier - first planned spinal anesthesia • Epidural • 1921- Fidel Pagés performed lumbar epidural anesthesia • Caudal • 1901- Cathelin use the technique of caudal epidural injection

3. Outlines •  Anatomy •  Advantages •  Indications/ contraindications •  Physiologic effects •  Techniques •  Pharmacology •  Complications

4. anatomy There are 7 cervical, 12 thoracic and 5 lumbar vertebrae.  The sacrum is a fusion of 5 sacral vertebrae.  small rudimentary coccygeal vertebrae

5. SPINAL CORD • Spinal canal contains the spinal cord with the meninges-pia, arachnoid and dura mater Subdural and epidural spaces are potential spaces • Extends from foramen magnum •  At birth, spinal cord ends at lower border of L3 •  At 1 year- at L2 •  >12 years- at lower border of L1 (50%) upper border of L2 (40%) body of T12 (5-6%) upper border of L3 (3%) •  length- 45 cm (males) 42 cm (females)

6. Dural sac ; circular sac surrounding spinal cord Cranially attached to the circumference of foramen magnum Ends at S2 level( 35%) • LIGAMENTUM FLAVUM ; Yellow elastic tissue Between laminae of adjacent vertebrae Right and left halves fuse at midline

7. DERMATOMES • A dermatome is an area of skin innervated by sensory fibers from a single spinal nerve • T4 – nipples • T6 – xiphoid • T10 – umbilicus • T12, L1 – inguinal ligament , crest of ileum • S2-S4 – perineum Perineal and anal surgery S2 to S5 (saddle block) Upper abdominal surgery T4

8. ADVANTAGES Cost effective ,Less risk of pulmonary aspiration , Avoid periop. respiratory complications,Less post-op. thromboembolism ,Avoid systemic effects of GA drugs CONTRAINDICATIONS

9. PHYSIOLOGICAL EFFECTS CVS • Hypotension • Bradycardia With high sympathetic block, sympathetic cardiac accelerator fibers arising at T1-T4 are blocked, leading to bradycardia CNS • Sequence of blockage of nerve fibres Autonomic-> Sensory -> Motor • Recovery in reverse order Autonomic level is 2 segment higher than sensory which is 2 segment higher than motor - differential blockade Endocrine system • Decrease stress response to surgery Gastrointestinal • Contracted gut with sphincter relaxation • Nausea/vomiting Genitourinary system Penile engorgement retention

10. SPINAL ANAESTHESIA • INDICATIONS • Lower limb orthopaedic ,Abdominal surgeries • Urological ,Obstetric and gynaecological procedure • WHAT IS TUFFIER’S LINE? A line drawn between the highest points of both iliac crests will correspond to either the body of L4 or the L4-L5 interspace.

11. SPINAL NEEDLES • Quincke Babcock needle • Whitacre needle • Sprotte needle • Greene needle

12. PROCEDURE • Preparation of the patient, consent,Pre-medication,Anxiolytics, Monitors Intravenous line – pre/co-loading with fluids, Maintainstrictasepsis POSITIONS Lateral flexed position Sitting position TECHNIQUE Midline approach • Skin • Subcutaneous tissue • Supraspinous ligament • Interspinous ligament • Ligamentum flavum • Dura mater • Sub dural space • Arachnoid mater • Subarachnoid space

13. Paramedian approach • 2 cm lateral to inferior aspect of superior spinous process • advanced towards midline at 10-25° angulation • Needle lies lateral to supraspinous and interspinous • ligaments and penetrates ligamentum flavum • and dura mater in the midline

14. ASSESSMENT OF LEVELS OF BLOCK •  Sensory level Pin prick using sterile needle Temperature sensation • Motor block •  Modified Bromage scale

15. FACTORS AFFECTING SPREAD OF LA INSUBARACHNOID SPACE

16. EPIDURAL ANAESTHESIA • INDICATIONS •  Intra/post operative analgesia •  Thoracic/ abdominal surgeries with or without GA •  With spinal anaesthesia for prolong surgeries •  Painless labour •  Chronic pain management • ADVANTAGES •  Less hypotension •  No post spinal headache •  Level of block can be changed •  Duration of surgery can be prolonged

17. EPIDURAL SPACE ( EXTRADURAL OR PERIDURAL SPACE) It lies outside duramater. Extends from foramen magnum to sacral hiatus CONTENTS OF EPIDURAL SPACE  Anterior and posterior nerve root  Epidural veins (Batson venous plexus)  Spinal arteries  Lymphatics  Fat

18. Epidural needles •  Most common is Tuohy’s needle It is blunt bevel with curve of 15 to 30 degree at tip (Huber Tip) Blunt tip reduce the risk of accidental dural puncture and guide the catheter cephalad. •  Weiss – is winged •  Crawford – straight blunt bevel with no curve •  The catheter is made of a flexible, calibrated, durable, radiopaque plastic with either a single orifice or multiple side orifices near the tip

19. EPIDURAL TECHNIQUES • Patient preparation,Explain to the patient,Consent taking • monitoring and resuscitation equipment, intravenous access • Strict asepsis , Sterile drape • Patient position-sitting or lateral • Site of needle insertion depends on the extent of surgical field TECHNIQUES TO IDENTIFY EPIDURAL SPACE •  Loss of resistance technique – after piercing ligamentum flavum there is loss of resistance. •  Hanging drop technique ( Gutierrez’s sign)- drop of saline in hub sucked in due to negative pressure . •  MacIntosh extradural space indicator •  Odom’s manometer indicator Epidural catheter is passed through the needle and 3 to 4 cm of catheter should be in epidural space.

20. Test dose • A test dose is designed to detect both subarachnoid and intravascular injection . •  The classic test dose combines local anesthetic and epinephrine, typically 3 mL of 2% lignocaine with 1:200,000 epinephrine (0.005mg/mL). •  Lignocaine, if injected intra-thecal, will produce spinal anesthesia that should be rapidly apparent paresthesia •  Epinephrine, if injected intra-vascular, should produce a noticeable increase in heart rate (20% or more), with or without hypertension

22. CAUDAL ANAESTHESIA INDICATIONS • Lower limb/ abdominal surgeries along with GA or sedation in paediatric patients Intra/ post op. analgesia The caudal space is the sacral portion of the epidural space. Caudal anesthesia needle and/or catheter penetration of the sacrococcygeal ligament covering the sacral hiatus. The sacral hiatus is a defect in the lower part of the posterior wall of the sacrum formed by the failure of the laminae of S5 and/or S4 to meet and fuse in the midline. The hiatus may be felt as a groove or notch above the coccyx and between two bony prominences, the sacral cornua .

23. Contents of the Sacral canal • Dural sac which ends at the border of the 2nd sacral vertebra on a line joining the posterior iliac spine. • The pia mater is continued as the filum terminale. • Sacral nerves and the coccygeal nerve. • Venous plexus formed by the lower end of the internal vertebral plexus. • Areolar and fatty tissue The posterior superior iliac spines and the sacral hiatus define an equilateral triangle

24. TECHNIQUE • The patient is placed in the lateral or prone position with one or both hips flexed and the sacral hiatus is palpated. • After sterile skin,preparation, a needle intravenous cannula (18–23gauge) is advanced at a 45° angle cephalad until a pop is felt as the needle pierces the sacrococcygeal ligament,The angle of the needle is then flattened and advanced 1-2 cm • Aspiration for blood and CSF is performed, and, if negative, LA is injected. For continuous caudal block, a catheter can be placed.

25. DRUGS USED FOR CAUDAL BLOCK •  volume • 0.5ml/kg for lumbosacral block • 1ml/kg for thoraco-lumbar block • 1.25 ml//kg for midthoracic block •  Bupivacaine • Maximum dose 2.5 mg/kg (without Adr) & 3mg/kg (with Adr) • 0.25% for analgesia and 0.5% for motor block •  Lignocaine • Maximum dose 5mg/kg (without Adr) & 7.5mg/kg (with Adr) • 1% for analgesia and 2% for motor block

27. THANK YOU