EPIDURAL ANAESTHESIA Dr P V Bhale Prof Anesthesia

EPIDURAL ANAESTHESIA Dr. P V. Bhale Prof. Anesthesia Dept. Of Anesthesia.

ANATOMY OF EPIDURAL SPACE �Extends from foramen magnum to sacral hiatus. �Lies between the visceral and parietal layer of dura mater (lines the periosteum of vertebral canal) �Diameter varies from cervical to sacral level. (Largest at lumbar & smallest at cervical level) �Contents – Loose areolar tissue, fatty tissue, venous plexus, ant. & post. nerve roots with coverings

ANATOMY BOUNDED: Anteriorly : posterior longitudinal ligament Laterally : Pedicles & intervertebral foramina Posteriorly: Anterior surface of lamina Ligamentum flavum.

NEGATIVE PRESSURE IN EXTRADURAL SPACE �Relative to atmospheric pressure epidural pressure is negative (lumbar 0. 5 -1 cm. H 2 O and thoracic 1 -3 cm. H 2 O) Causes: �Dimpling of dura by needle. �Transfer of negative pressure from thorax via para vertebral spaces (especially in thoracic region)

SITE OF ACTION �Nerve roots in extradural space �Nerve roots in paravertebral spaces �Nerve roots in intradural or subarachnoid space after inward diffusion of drug across the dura. �Sensory block is complete & motor paralysis is less (depending upon the concentration of local anaesthetic)

SPREAD OF SOLUTION Depends on : 1) Volume of solution injected 2) Age : Old pt. require less dose due to a decrease in the size and compliance of the epidural space, Less lat. spread 3) Height : Taller patients may require higher dose. 4) Level of injection 5) Length of vertebral column.

ADVANTAGES 1. Well defined area of anaesthesia – segmental anaesthesia 2. Duration of anaesthesia can be prolonged as per the duration of surgery by giving repeated bolus drug through the epidural catheter. 3. Minimize infections of spinal cord 4. Less incidence of nausea and vomiting

5. Less problem of urinary retention 6. Provide post op. analgesia. 7. Less danger of neurological sequel. 8. Suitable in pts. with asthma, bronchitis or emphysema

DISADVANTAGES 1. Technically difficult 2. Incomplete muscle relaxation 3. Large volumes of LA injected. 4. Chances of accidental dural puncture & injecting large amount of drug in subarachnoid space -> resulting in total spinal block. 5. Risk of entering veins during catheter insertion > inadvertent I. V. injection -> L. A toxicity. 6. Spread of block may be non uniform and segmented 7. Back pain

INDICATIONS �Lower limb surgeries �Hip and knee surgery : E. A. reduces the blood loss. Incidence of DVT is reduced �Obstetrics. Epidural labour analgesia is indicated in preeclampsia, valvular heart disease �In lower abdominal operations

POSTOPERATIVE PERIOD �Epidural analgesia minimizes the effects of surgery on cardiopulmonary reserve �Prevents diaphragmatic splinting and the inability to cough adequately due to pain �Helpful in patients with compromised respiratory function like patients with COPD , morbid obesity & elderly. �Epidural analgesia allows earlier mobilization, reduces the risk of DVT & allows better cooperation with chest physiotherapy preventing chest infections.

CONTRAINDICATIONS Absolute �Patient refusal �Coagulopathy. �Therapeutic anticoagulation. �Skin infection at injection site. �Raised intracranial pressure. Accidental dural puncture in a patient with raised ICP may lead to brainstem herniation (coning). � Severe Hypovolaemia. �Low fixed cardiac output states Severe constrictive pericarditis, cardiac tamponade, severe M. S. , Severe A. S.

Relative �Uncooperative patients �Pre-existing neurological disorders like multiple sclerosis �Spinal deformity : congenital, traumatic, post laminectomy �Mild to moderate stenotic valvular heart diseases.

Epidural needle Tuohy’s needle: 16 -18 gauge , 8 cm long with surface markings at 1 cm interval & blunt bevel with a gentle curve of 15 -30 degree at tip (Huber’s tip)

EPIDURAL CATHETERS Epidural catheters : single end-hole or a number of side holes at the distal end. Incidence of inadequate analgesia is less with multiport catheters.

DRUGS �Lignocaine - 1 -2% �Bupivacaine - 0. 25 -0. 5% �Ropivacaine - 0. 2%- 0. 5% �Adrenaline: Used as 1 in 200000 solution. Causes less systemic absorption of local anaesthetic drug. Prolongs the duration of action. May cause more intense blockade of nerve fibres.

Position �Sitting position �Lateral position �Caudal epidural anaesthesia Prone position in adults and lateral decubitus position in children. APPROACH �Median �Paramedian

TECHNIQUE �Loss of resistance technique: Insert needle into ligamentum flavum & attach syringe filled with normal saline at hub of needle. Advance with repeated attempts at injection. Needle enters epidural space sudden loss of resistance flow of solution without resistance. �Hanging drop technique : After removing the stylet, hub of needle filled with solution so that a drop hangs from the opening. Needle enters epidural space negative pressure drop immediately sucked in the needle hub.

Test dose �After introduction of needle in to the space, aspirate and confirm negative aspiration and Test dose given to avoid subarachanoid or intravascular injection. � 3 ml of 1. 5% lidocaine with 1: 200000 epinephrine (5 mcg/ml). After test dose, monitor PR/BP/RR/CNS if no significant changes , give the entire dose of L. A solution.

Complications Due to catheters: � 1. Misplacement � 2. Kinking � 3. Occlusion � 4. damage of catheter � 5. Shearing damage on bevel of needle � 6. Migration of catheter

COMPLICATIONS �Hypotension & CVS depression. �Inadequate or patchy block �Total spinal block �Local anaesthetic toxicity -> disorientation, twitching, convulsions or apnoea �Hypoapnea: due to medullary depression by L. A. �Epidural haematoma / abscess

Difference between Spinal and Epidural block. �The dose of L. A is high in epidural and less in spinal. �The volume of drug is more in epidural than spinal. �In epidural there are chances of intravascular inj which are not there in spinal. �Epidural is technically difficult than spinal. �As epidural block is slow in onset than spinal the degree of hypotension seen is less. �Chances of the rare complication of total spinal are there in epidural but not in spinal.

Caudal epidural anaesthesia

ANATOMY �Failure of fusion of lamina of 4 th & 5 th sacral vertebrae leads to formation of sacral hiatus(triangular shaped opening) �Sacral hiatus covered by sacrococcygeal membrane pierced by coccygeal & 5 th sacral nerves. �Apex formed by 4 th sacral spine & sacral cornu on each side below & laterally.

INDICATIONS �One of the most commonly used regional anaesthetic procedure in paediatric age group. �Haemorrhoidectomy & other perianal surgeries in adults �Combined with general anesthesia to provide intraoperative & postoperative analgesia. �Surgery below umbilicus can be performed under caudal anaesthesia in children.

Drugs Local anaesthetic agents �Lignocaine - 1 -2% �Bupivacaine - 0. 25 -0. 5% DOSE: 0. 5 - 1 ml/kg �Ropivacaine - 0. 25% Dose -1 ml/kg Adjuvants �Ketamine: 0. 25 mg/kg �Clonidine – 1 mcg/kg