Epidural and spinal anaesthesia

Question 1

Neuraxial blocks

Uses

Answer 1

• sympathetic, sensory, and motor block

- for surg, alongside general, epidural - post op pain relief

Question 2

spinal block

epidural

Answer 2

spinal - intrathetcal space

Epidural - epidural space

epidural space - blood vessels, nerves, spinal and sympathetic nerves
-runs from foremen magnum to the sacral hiatus

Question 3

where does the spinal cord end?

Answer 3

L1-L2

Question 4

how it works

Answer 4

inject local into epidural space

• this causes reverible blockaid of sodium channels
• blokade of nerve roots as they exit the spinal cord
• can work by blocking nerves as they pass throguh epidurla space, or by diffusing across the dura into spinal fluid and working like spinal anaesthesia

Question 5

Sympathetic nervous system

Answer 5

CVS

• SNS is derived from T1 to L2 with the first four thoracic roots involved with sympathetic innervation of the heart
• spinal and epidural blocks sympathetic nerves and give rise to a decreased blood pressure, this is due to a marked decrease in peripheral resistance so get pooling of blood and reduced venous return ot heart
• if block involves t4-t5 then can get reduced ability to increase HR and inotropy in response to drop on BP
• so they are given lots of fluid prior to this

Resp

• blocks dont often cause resp depression alone
• resp depression, phrenic nerve innovating diaphragm from c3,c4,c5
• opiods given - can cause resp depression

Gastro
-unopposde vagal activity due to sumpathetic lock can increase gut motility - improved gastric emptying and reduce postoperative ileus and reducing rate of anaestmoitci dehiscen of bowel surgery

Question 6

Insertion technique

Answer 6

placing a spinal needle into CSF like a lumbar puncture

• patient curl up in a ball
• needle advanced between spinous processes which are palpable in the back or from lateral to spinous processes
• want to see free flow of clear CSF

Insertion technique

• tuohy needle into epidural space, then pass cather down center, needle is removed leaving catheter in.
• is used by assessing resistance to injection of air or saline down the needle, as the latter is advacned throughout tissues
• get increased resistance and hten siden loss when go past ligamentum flavum and go into epdiural space

Question 7

useful

Answer 7

-lower limb surgery
-urology surgery
-herni repairs
-gynecological surgery
analgeisa for abdo surgery

Question 8

complications

Answer 8

• local anesthetic toxicity by injecting into epidural vein
• epidural dose given to csf
• high blocks with low BP
• neurological damage
• epidural haematoma or abscesses with paralysis
• infections including meningitis
• back pain