Spinal Anaesthesia

INTRODUCTION:

Spinal anesthesia is also called as spinal block or subarachnoid block (sab).
SAB is a regional anesthesia involving injection of a local anesthesia into the subarachnoid space which extends from the foramen magnum to S2 in adults and S3 in children.
Injection of LA below LI in adults and L3 in children helps to avoid direct trauma to the spinal cord , (anesthetic agents acts on the spinal nerve and not on the substance of the cord)

INDICATION:

Used both alone and in combination with either GA or sedation.
Lower limb orthopedic surgery on the pelvis, femur, tibia and ankle.
Total hip replacement.
Total knee replacement.
Lower limb vascular surgery.
Hernia (Ingunial or epigastric).
Haemorrhoidectomy, fistula, fissure.
Nephrectomy and cystectomy in combination with GA.
Transurethral resection of the prostate and transurethral resection of the bladder tumors.
Abdominal and vaginal hysterectomies
Laproscopic assisted vaginal hysterectomies(LAVH) combined with GA.
Caesarean sections.(LSCS)

CONTRAINDICATIONS:

Absolute	Relative
Raised intracranial pressure Patient refusal Shock: Hypotension and hypovolemia Infants and children- control of level is difficult. Bleeding disorders Patient’s on anticoagulants Infection of the local site and Septicemias Vertebral abnormalities (kyphosis, lordosis, etc.)	Aortic and mitral stenosis MI Heart block Spinal deformities Psychiatric and CNS disorders

SPINAL ANASTHESIA TECHNIQUE:

POSITIONS

LATERAL POSITION
TWO ASPECTS
Spinal canal should be on horizontal plane
Operator should fix his or her gaze on the horizontal plane.
Flexed lateral position- back should be parallel to the edge of the table, knees are flexed on the abdomen, neck flexed.
Jack knife position

SITTING POSITION

Patient sit with their elbows resting on their thighs or bedside table or they can hug a pillow.
Flexon of spine miximizes the target area between adjacent spinous processes and brings the spine closer to skin surface

PRONE POSITION

This position is used for anorectal procedures utilising a hypobaric anasthetic solution

TECHNIQUE:

Taylor technique:

Largest interspase L5-S1
12-cm needle directed upward , medially and forward at 500 , approximating forward at an angle that the dorsal aspect of the sacrum makes with the skin
The needle enters the lumbosacral space between the sacrum and the last lumbar vertebra.
Deposited between piamater & arachnoid

POSITION:

The lateral position is preferred with the table tilted and the head up at 100degree to faster filling of the lumber subarachnoid space.
The sitting position may also be used.
First fibres to be blocked in spinal anaesthesia is Sympathetic preganglionic
The puncture at L3 –L4 vertibra interspace for children of 1-18yrs and L5 for infants.
The spinal needle directed perpendicular to plane of the back.
A standard 24-26G needle is used.
Dosage-Minimum vol. of 0.2ml is necessary in the preterm or newborn infant
5% lignocaine is used for spinal anaesthesia.
Infant under 3000gm requires the largest doses because larger vol. of CSF and absorption doses upto 0.6mg/kg may be given to infant of 2-3kg of weight
For infant over 3kg the dose is stablised at 0.35 mg/kg upto 1yr of age.

COMPLICATIONS:

T1-4 segments

Bradycardia
Hypotension(can be prevented by Preloading with crystalloids)
Tingling or weakness in the hands or complaints of difficulty in breathing or talking.

C6-8: Hand paresthesia and weakness, likely to be effect on adequacy of breathing

C3-5: Diaphragmatic paralysis, with definite respiratory

Post spinal headache

Exam Question

In spinal anaesthesia drug is deposited between Piamater and arachnoid
First fibres to be blocked in spinal anaesthesia is Sympathetic preganglionic
Hypotension and Bradycardia is seen in patients given high spinal anaesthesia
A Lower Segment Caesarean section (LSCS) can be carried out under Spinal anaesthesia
The most effective method to prevent hypotension during spinal anaesthesia is Preloading with crystalloids
Headache after spinal anaesthesia is believed to be due to loss of CSF
Post spinal headache can last for 2 weeks
5% lignocaine is used for spinal anaesthesia.
Increased intracranial pressure is the contraindications Spinal anaesthesia

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