Pros And Cons Of Spinal Anesthesia

INTRODUCTION

Spinal anesthesia is the most commonly used technique for lower abdominal and lower limb surgeries as it is very economical and easy to administerIntrathecal α2 agonist when used as adjunct potentiates the effect of local anaesthetics and allows a decrease in required doses..

Different drugs have been used as adjuvants to prolong the duration of intraoperative and postoperative analgesia adrenaline being the first drug used and latest being dexmedetomidine.

These adjuvants have their own advantages and limitations. Efforts to find a better adjuvant are underway since long. The addition of opioid does provide a dose sparing effect of local anaesthetic and superior analgesia but there is always a possibility of an increased incidence

The rest of the spinal cord depends on segmental medullary and radicular arteries running along the spinal nerve roots for circulation.

Mautes et al 7 described the radicular artery continuing along the nerve root and dividing into an anterior radicular artery and a posterior radicular artery which join the 3 major arteries on the surface of the spinal cord to provide the blood supply to those areas.

A large, unilateral artery called as the artery of Adamkiewicz is a radicular artery arising from the aorta found mostly on the left side provides blood supply to the lower anterior 2/3rds of the spinal cord is responsible for anterior spinal artery syndrome if injuried. figure 5;Blood Supply to the Spinal Cord

SUBARACHNOID SPACE 8

The subarachnoid space is a continuous space which starts at the formen magnum and ends with the conus medullaris at the sacral hiatus, extends from the cerebral ventricles down to

• Sensory

Sensory nerves transmit sensations such as touch and pain to the spinal cord and from there to the brain,

• Autonomic.

Autonomic nerves control the caliber of blood vessels, heart rate, gut contraction and other functions not under conscious control.

Local anesthetic solution injected into the subarachnoid space blocks conduction of impulses along all nerves with which it comes in contact, Dorsal sensory roots are blocked more easily than the smaller anterior roots due to the organization of the dorsal root into bundles which expose a larger surface area to local anesthetic solutions.

Autonomic and pain fibers are blocked first and motor fibers last, this physiology has many important consequences like the vasodilation and drop in blood pressure which occurs when the autonomic fibers are blocked and the patient may be aware of touch and yet feel no pain when surgery starts.

 Positions of neuraxial anesthesia

• Sitting Position o No torque o Chin on chest o Arms resting on knees o Footstool/Table to support