SPINAL ANAESTHESIA Dr. Pradnya - PowerPoint Presentation

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SPINAL ANAESTHESIA

Dr.

Pradnya

S. Joshi

Associate Prof.

Dept.

Of Anesthesia

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LEARNING OBJECTIVES

At the end of the lecture, the student shall be able to

Describe anatomy of spinal cord

Enumerate physiological effects of spinal anaesthesia on various systems

Enumerate indications & contraindications of spinal anaesthesia

Enumerate advantages & disadvantages of spinal anaesthesia

Enumerate complications of S.A.

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ANATOMY OF SPINE

Spine : composed vertebral bones &

fibro cartilaginous discs

.

There are : 7 cervical

: 12 thoracic

: 5 lumbar

: sacrum which is a fusion of 5

sacral vertebrae

: Coccyx 4-5

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VERTEBRAL COLUMN

Four curves:Cervcial &lumbar convex anteriorly (lordosis).Thoracic & sacral concave anteriorly (kyphosis)Spinal nerves:8 cervical 12 thoracic5 lumbar5 sacral1coccygeal.Total 31

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SPINAL CORD

Spinal cord continues

cephalad

with brain stem through foramen magnum and terminates distally in the

conus

medullaris

at

lower border of L1 in adults and upper border of L3 in children

.

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SPINAL CORD

Meningeal

coverings

:

From with in to periphery

Pia

mater

Arachanoid

membrane

Dura mater

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SUBARACHANOID SPACE

Lies between

pia

mater and

arachnoid

mater, ends at S2

Contents

:

CSF

Spinal nerves

Blood vessels supplying spinal cord

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CIRCULATION OF CSF

Choroid plexus in lateral ventricles Foramen of Monroe 3rd ventricle Aqueduct of Sylvius 4th ventricle Foramen of Luschke and Magendie Subarachanoid space.Re absorption of CSF occurs in arachanoid villi.

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August Bier 1885

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AUTONOMIC NERVOUS SYSTEM

Has 2 components:

Sympathetic fibers

Arises from T1 - L2 segment.

Parasympathetic fibers

From craniosacral segment

Cranial nerves giving rise to parasympathetic fibers: 3,7,9,10

Sacral fibers arises from S2,S3,S4 spinal segment.

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S.A. results in predominantly sympathetic blockade ,because parasympathetic fibers carried by vagus have higher origin

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MECHANISM OF ACTION

Site of action for neuraxial blockade in sub arachnoid space: nerve roots

Blockade of posterior nerve roots interrupts somatic and visceral sensation.

Blockade of anterior nerve root fibers prevents efferent motor and autonomic outflow.

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ORDER OF BLOCKING NERVE FIBRES

Autonomic fibers

Temperature fibers

Pain fibers

Touch fibers

Somatic motor fibers

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T4---Nipple

T5---

Inframammary

fold

T6---

Xiphoid

T10---Umbilicus

L1---Groin

S2-4---Perineum.

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CVS CHANGES

HYPOTENSION

Occurs because of venous and arterial dilatation

BRADYCARDIA

Blockade of cardiac sympathetic fibers ->

decrease in H.R.

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EFFECTS ON GIT

Nausea and vomiting

caused by unopposed parasympathetic (vagal) activity

This also results in small contracted gut which provide excellent operative conditions.

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URINARY TRACT MANIFESTATIONS

Blockade of both sympathetic and parasympathetic control of bladder function results in urinary retention.

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ADVANTAGES

Low cost

Decrease blood loss

Less metabolic derangement

Better for severe respiratory impairment

Allows verbal communication

Postoperative Analgesia

Avoid complications of G.A.

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DISADVANTAGES

Discomfort in prolonged surgeries

Potential of nerve damage

Introduction of infection in CSF

Post operative leg weakness & urinary

retention

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INDICATIONS

Primary anesthetic technique in lower abdominal procedures(LSCS), inguinal hernia repair,

urogenital

, rectal and lower extremity surgeries.

S.A. preferable in

geriartic

age group for peripheral

orthopaedic

,vascular and urological procedures.

Obstetric patients with full stomach

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ABSOLUTE CONTRAINDICATIONS

Patient refusal

Infection at injection site

Coagulopathy

or bleeding diathesis

Low fixed cardiac output states:

Severe constrictive

pericarditis

, cardiac

tamponade

, severe M.S., severe A.S.

Severe

hypovolemia

Raised ICT

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RELATIVE CONTRAINDICATIONS

Sepsis

Uncooperative patient

Spinal deformity:

congenital, traumatic, post

laminectomy

Severe anemia

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TECHNIQUE OF S.A.

Equipment

Spinal needle - small needles reduce the incidence of post

dural

puncture headache.

Drugs

Lidocaine

(5%)

Bupivacaine(0.5%)

Ropivacaine(0.5%) available in isobaric form only

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Spinal Needle

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Sitting Position

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LATERAL POSITION

SITING POSITION

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Holding for Spinal

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INTRAOPERATIVE COMPLICATIONS

Due to exaggerated physiological responses

Hypotension

Management:-

Maintain O2 supply

IV fluids bolus 0.5-1L

RAISE LEGS

Use of

vasopressor

drugs like Ephedrine or

Mephenteramine

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Bradycardia

When PR. < 60/Min

P.R.< 50 - Inj. Atropine 0.6mg

Inj. Epinephrine 50-100µg

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TOTAL SPINAL BLOCK:

Level of block extend above T1 involving cervical segments

Nausea, vomiting, difficulty in breathing, hypotension,

bradycardia

.

Management

:

Maintain adequate airway & ventilation with 100%O2 supply.

Immediately do intubation

Maintain circulation with iv fluids.

Vasopressor

drugs :

Inj.

Phenylephrine

, Dopamine .

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Urinary retention

Nausea &vomiting

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POSTOPERATIVE COMPLICATIONS

Postdural

puncture headache

occurs 12-72 hrs post operatively.

Cause -

Loss of CSF through

dural

puncture -> decreased ICP -> traction on

dura

& blood vessels

Bilateral frontal or retro orbital or occipital headache.

Increases in sitting & relieves in lying down

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Management

Prevention

:

use smaller size needle

Prevention of dehydration

Treatment

:

Recumbent position, analgesics

I.V or oral fluid administration

I.V. caffeine

Epidural blood patch.

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Delayed complications

Transient neurological symptoms

Cranial nerve disturbances

Visual and auditory disturbances

Paralysis of 6

th

cranial nerve

Backache

Spinal

haematoma

Meningitis or

arachnoiditis

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