SPINAL AND EPIDURAL

ANAESTHESIA

PRESENTED BY ---- Dr. KHAWER MUNEERMODERATOR ---- Dr. JAVED IQBAL

OBJECTIVES

2

HAVE A BASIC UNDERSTANDING OF

• Anatomic structure of spine and vertebra•Anatomic structure of spinal cord•Blood supply of spinal cord•Features of neuraxial blockade•Indications/ contraindications•Patient evaluation and preparation•Techniques•Local anesthetics and factors effecting spread•complications

BRIEF HISTORY OF SPINAL ANAESTHESIA CSF DISCOVERED ---- by Domenico Catugno 1764

CSF CIRCULATION---- by F . Magendie 1825 FIRST SPINAL ANALGESIA--- by J Leonard Corning 1885 FIRST PLANNED SPINAL ANAESTHESIA--- by

August Bier in 1891 The epidural space was first described by Corning

in 1901, and Fidel Pages first used epidural anaesthesia in humans in 1921.

ANATOMY

•cervical vertebrae (7) •thoracic vertebrae (12) •lumbar vertebrae (5) •sacral vertebrae (5) •coccygeal vertebrae (4 )

LUMBAR VERTEBRA

SPINAL CORDADULTS– approx L1CHILDREN--approx L3

ARTERIAL SUPPLY OF SPINAL CORD

DERMATOMESA dermatome is an area of skin innervated by sensory fibers from a single spinal nerve

DERMATOMAL LEVELS OF SPINAL ANESTHESIA FOR COMMON SURGICAL PROCEDURES

Procedure Dermatomal Level

Upper abdominal surgery T4

Intestinal, gynecologic, and urologic surgeryTransurethral resection of the prostate

T6

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)

PHYSIOLOGICAL EFFECTS OF NEURAXIAL BLOCKADE

• Vasomotor tone determined by sympathetic fibers arising from T5 to L1 innervating arterial & venous smooth muscle.

• A ↓ in blood pressure that may be accompanied by ↓ in heart rate.

• With high sympathetic block, sympathetic cardiac accelerator fibers arising at T1-T4 are blocked, leading to ↓ cardiac contractility.

• Bezold-Jarisch reflex has been implicated as a cause of bradycardia, hypotension and cardiovascular collapse after central neuraxial anaesthesia, in particular spinal anaesthesia.

CARDIOVASCULAR EFFECTS:

PULMONARY EFFECTS:

Even with high thoracic levels, tidal volume is unchanged.

A small decrease in vital capacity due to paralysis of abdominal muscles necessary for forced exhalation & not due to decrease in phrenic nerve or diaphragmatic function.

Effective coughing & clearing of secretions may get affected with higher levels of block.

Rare respiratory arrest associated with spinal anaesthesia due to hypoperfusion of respiratory centers in brain stem.

GASTROINTESTINAL FUNCTION:

Nausea and vomiting in upto 20% patients due to gastrointestinal hyperperistalsis caused by unopposed parasympathetic(vagal) activity.

Vagal tone dominance results in small contracted gut with active peristalsis & can provide excellent operative conditions for some laproscopic procedures when used as an adjunct to GA.

Hepatic blood flow will ↓ with reductions in mean arterial pressure.

RENAL FUNCTION:

Renal function has a wide physiological reserve. ↓ in renal blood flow is of little physiological importance.

Neuraxial blocks are a frequent cause of urinary retention which delays discharge of outpatients & necessitates bladder catheterization in inpatients.

COMMON INDICATIONS OF NEURAXIAL ANAESTHESIA

SPINAL 1. lower extremities 2. pelvic /lower abdomen 3. pain mgmt intra/post operative (narcotics)

EPIDURAL 1. similar surgeries as spinal 2. labour and delivery 3. post op pain mgmt 4. chronic pain mgmt 5. in combination with GA for abdominal & thoracic procedures.

CONTRAINDICATIONS

ABSOLUTE 1. patients refusal 2.coagulopathy 3. infection at local

site 4. severe hypovolemia

5. increased ICT 6. allergy to drugs 7. shock 8. sever AS or MS

RELATIVE 1. uncoperative pt 2. preexisting

neurological deficits 3. demyelinating lesions 4. severe spinal

deformity 5. infection at site

remote from infection 6. sepsis

SEQUENCE OF ONSET

Principal site of action is the nerve root. Sequence of onset depends on conc. of LA

achieved, duration of contact, size & myelination of nerve fibers.

CLINICALLY OBSERVED SEQUENCE1. Sympathetic nervous system fibers (B

fibers: vasodilation, skin temp ↑)2. Temperature & pain conduction (A & C

fibers)3. Proprioception & touch (Aγ & Aβ fibers)4. Motor function (A fibers)

SUMMARYMedicatio

nPreparation Dose

Lower Limbs

DoseLower

Abdomen

Dose Upper

Abdomen

Procaine 10% Solution 75 mg 125 mg 200 mg

Lidocaine 5% Solution in 7.5% dextrose

25-50 mg 50-75 mg 75-100 mg

Tetracaine 1% Solution in 10% glucose or as niphanoid crystals

4-8 mg 10-12 mg 10-16 mg

Bupivacaine

0.5-0.75% Isobaric Solution

0.5-0.75% Hyperbaric

Solution in 8.25% Dextrose

Hypobaric Solution

4-10 mg 12-14 mg 12-18 mg

Ropivacaine

0.2—1% solution 8-12mg 12-16 16-18

DOSAGE AND ACTIONS OF COMMONLY USED SPINAL ANESTHETIC DRUGS

FACTORS AFFECTING THE LEVEL OF SPINAL ANESTHESIAMOST IMPORTANT FACTORS

Baricity of the drug

Position of the patient Drug dosage Site of injection OTHER FACTORS

Age

Csf

Curvature of Spine

Intraabdominal Pressure

Needle direction

Patient Height

Pregnancy

Weight of pt

PROCEDURE PREPERATION

Remove your jewellery/watches Wash your hands I.V access/fluids bolus if needed Emergency drugs /equipment Position Sedation if needed Monitoring NIBP/SPO2/ECG• Verbal contact with pt

POSITIONING 1. Sitting 2. Lateral 3. Prone

TECHNIQUES FOR SPINAL 1. Midline 2. Paramedian 3. Taylor approach

The structures that will be passed in spinal : Skin , subcutaneous tissue, supraspinous ligament , interspinous ligament , lagementum flavum , dura mater , subdural space , arachnoid matter,subarachnoid space in midline approach

SPECIFIC TECHNIQUES FOR EPIDURAL LOSS OF RESISTANCE HANGING DROP

AGENTS FOR EPIDURAL ANAESTHESIAAGENT CONCENT

RATIONONSET SENSORY

BLOCKMOTOR BLOCK

CHLOROPROCAINE

2%3%

FastFast

AnalgesicDense

Mild to moddense

LIDOCAINE <1%1.5%2%

IntermediateIntermediateIntermediate

AnalgesicDenseDense

MinimalMild to moddense

BUPIVICAINE <0.25%0.5%0.75%

SlowSlowSlow

AnalgesicDenseDense

Minimal Mild to mod Mod to dense

ROPIVICAINE 0.2%0.5%0.75%--1.0%

SlowSlowSlow

AnalgesicDenseDense

Minimal Mild to mod Mod to dense

EPIDURAL NEEDLES

SPINAL NEEDLES

COMPLICATIONS/SIDE EFFECTS OF NEURAXIAL ANESTHESIA

Systemic toxicity Hypotension Postdural Puncture Headache High Spinal Anesthesia Total spinal anaesthesia Neurological complications Arachnoiditis / Meningitis Spinal / Epidural Hematoma Formation Epidural Abscess Backache Urinary retension Pruritus

POSTDURAL PUNCTURE HEADACHE ONSET= 12—72 hrs it is postural and it is often fronto--occipital associated with stiff neck , nausea,

vomiting , dizziness and photophobia. CAUSE---loss of CSF at a faster rate than it can be produced causing traction

on the structures supporting brain, particularly dura and tentorium. INCIDENCE---25% FACTORS---that increase the risk are young age,female,pregnancy,large gauge

needle, multiple punctures It is aggravated by sitting or standing and decreased or relieved by lying down

flat. TREATMENT----- conservative t/t involves recumbent position, analgesics, i.v

or oral fluids and caffeine.

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EPIDURAL BLOOD PATCH

The epidural blood patch consists of injecting 5-20 mLs of autologous blood into the epidural space, in the region of the suspected dural 'hole.'

Autologous blood is typically drawn in a sterile fashion, and then injected as a bolus into the epidural space.

In 90% of cases, the response is positive and immediate. Subsequently, long-term relief of PDPH occurs in the majority of cases

HIGH NEURAL BLOCKADE ,HIGH SPINAL AND TOTAL SPINAL ANAESTHESIA

Can occur both with spinal and epidural Admins . Of an excessive dose,failure to reduce doses

in selected pts (elderly,pregnant,obese , very short) or unusual sensitivity or spread of LA maybe responsible

SA ascending into cervical level causes severe hypotension,bradycardia and respiratory insufficiency and even apnea

Total spinal can occur following attempted epidural/caudal anesthesia if there is inadvertent intrathecal injection

TREATMENT---vasopressors,atropine ,fluids,oxygen ,assisted ventillation and even intubation and mechanical ventillation may be needed

TRANSIENT NEUROLOGICAL SYMPTOMS AND CAUDA EQUINA SYNDROME

TNS or transient radicular irritation refers to pain ,dysesthesia or both in the legs or buttocks after spinal anesthesia, resolving spontaneously within several days

Most common with hyperbaric lidocaine and after surgery in lithotomy position

CES characterized by bowel and bladder dysfunction together with evidence of multiple nerve root injury, assoc with use of continous spinal catheters and 5% lidocaine

NEURAXIAL BLOCKADE IN SETTING OF ANTICOAGULANTS AND ANTIPLATELET AGENTS---AMERICAN SOCIETY FOR REGIONAL ANESTHESIA RECOMMENDATIONS

Pts taking NSAIDS or receiving subcutaneous unfractioned heparin for DVT prophylaxsis are not viewed as being at increased risk of spinal hematoma

DISCONTINUE---ticlopidine 2 weeks, clopidogrel for 1 week ,abciximab 24 to 48 hrs, eptifibate and tirofiban 4 to 8 hrs before performing central neuraxial block.

Pt who are fully anticoagulated or who are receiving thrombolytic or fibrinolytic theraphy should not receive central neuraxial block except in very unusual circumstances where other options are not viable.

Delay atleast 10 -12 hrs after last dose of LMWH Post op t/t with LMWH delay 12hrs after compl of surgery Removal of epi ,spi catheters should take place 10—12hrs

after last dose with subs dosing delay for atleast 2hrs.

ADVANTAGES OF SPINAL ANESTHESIA (SPA)

1. Cost. The costs associated with SPA are minimal.

2. Patient satisfaction. the majority of patients are very happy with this technique. 

3. Respiratory disease. SPA produces few adverse effects on the respiratory system as long as unduly high blocks are avoided.

4. Patent airway. As control of the airway is not compromised, there is a reduced risk of airway obstruction or the aspiration of gastric contents.

5. Diabetic patients. There is little risk of unrecognised hypoglycaemia in an awake patient.

ADVANTAGES OF SPA CONTD

6. Muscle relaxation. SPA provides excellent muscle relaxation for lower abdominal and lower limb surgery.

7. Bleeding. Blood loss during operation is less than when the same operation is done under general anaesthesia

8. Splanchnic blood flow. Because of its effect on increasing blood flow to the gut, spinal anaesthesia reduces the incidence of anastomotic dehiscence

9. Visceral tone. The bowel is contracted by SPA and sphincters relaxed although peristalsis continues. Normal gut function rapidly returns following surgery.

10. Coagulation. Post-operative deep vein thromboses and pulmonary emboli are less common following spinal anaesthesia.

DIFFERENCES BETWEEN SPINAL AND EPIDURAL ANESTHESIA

Spinal anaesthesia Epidural Anaesthesia

Level: below L1/L2, where the spinal cord

ends

Level: at any level of the vertebral column.

Injection: subarachnoid space i.e punture

of the dura mater

Injection: epidural space (between

Ligamentum flavum and dura mater) i.e

without punture of the dura mater

Identification of the subarachnoid space:

When CSF appears

Identification of the Peridural space: Using

the Loss of Resistance technique.

Dosis: 2.5- 3.5 ml bupivacaine 0.5% heavy Doses: 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. 37

REGIONAL VS GENERAL ANAESTHESIA

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