Neuraxial Anaesthesia

Front 1

What does the iliac crest correspond to?

What does the PSIS correspond to?

What does the inferior angle of scapula correspond to?

Back 1

iliac crest - S4

PSIS - S1

Inferior angle of scapula - T7

Front 2

identify the structures

Back 2

Front 3

describe epidural anaesthesia

Back 3

• Midline or Parammedian technique is utilized to insert the needle (17-18G Tuohy needle, 19-20G catheter), at L4-L5
  
• Epidural space is identified by loss of resistance technique
  
• a small catheter is then threaded into epidural space, 3-5 cm past needle tip
  
• The catheter is aspirated to ensure that no blood or CSF can be withdrawn
  
• 3 mL test dose of lidocaine with epinephrine 1:200,000 is attached
  
• If the catheter entered the bloodstream, there will be transient tachycardia on the monitors
  
• If there are no motor or sensory changes within 3 mins, the catheter is most likely not in the subarachnoid space
  

Front 4

describe spinal anaesthesia

Back 4

• Midline or Parammedian technique is utilized to insert the needle at L4-L5
  
• A distinct pop sound will be heard when the needle penetrates the ligamentum flavum
  
• The needle is confirmed to be in the subarachnoid space by the presence of a "CSF swirl"
  
• Ensure that there is no blood flowing out of syringe
  
• Inject LA over 3-5s, then aspirate again at the end to check for CSF swirl again
  

Front 5

What is midline approach?

Back 5

needle is placed midline, perpendicular to spinous process, aimed slightly cephalad

Front 6

What is paramedian approach?

Back 6

needle placed 1.5cm laterally and slightly caudad to the center of interspinous space, needle is aimed medially and slightly cephalad, passed lateral to supraspinous ligament. if lamina is contacted, redirect needle medial and cephalad

Front 7

What medications are injected into the subarachnoid/epidural space?

Back 7

Shorter duration, faster onset

Chloroprocaine

Lidocaine

Longer duration, slower onset

Bupivacaine

Ropivacaine

Front 8

Side effects of spinal and epidural anaesthesia

Back 8

1. Cauda equina syndrome

- a/w high dose of anaesthesia

- permanent bowel,bladder dysfunction, paralysis of lower limb

2. Transient neurologic symptoms

- a/w lithotomy position and lidocaine

- resolves within days

3. Cardiovascular changes

- hypotension, treated with ephedrine/phenylephrine

- bradycardia if T1-4 affected

4. Post dural puncture headache (epidural>spinal)

5. Urinary retention

6. Intravascular injection (requires emergent surgical decompression)

7. Epidural abscess

8. Total spinal anaesthesia

- Needs intubation, since respiratory centers are affected

- watch out for hypotension

Front 9

Contraindications of neuraxial anaesthesia

Back 9

Absolute:

- Injection in area of needle puncture

- Elevated intracranial pressure

- Uncontrolled bleeding

Relative:

- Bacteraemia

- pre-existing neurologic disease

- Cardiac disease

- Abnormal coagulation studies