Craniotomy - aneurysm clipping

 

General issues:

Emergency surgery

·     Assume full stomach

·     Rx big dose opioid, minimise propofol, infuse metaraminol

·     Rx modified RSI; no bag-mask vent

Remote airway

·     Check ETT position at teeth

·     Auscultate

·     Secure with sleek + bilateral tegaderm

·     Ensure attachments locked well

·     Secure insp/exp tubing with artery forceps

Bleeding

·     BGHO +/- XM

·     ≥18g cannula x 2

·     Fluid warmer + forced air warmer

·     Avoid hypertension

Microsurgery

·     No movement, no coughing

·     High dose opioid

·     Relaxant at PTC 2

 

Neuro issues:

Risk of rupture

·     Preserve transmural gradient (mAP – ICP)

·     Avoid ↑↑mAP or ↓↓mAP

·     Rx high dose opioid + metaraminol infusion

Surgical access

General measures:

·     ↑Propofol

·     ↑Opioid

·     ↓Metaraminol

If disaster:

·     Phentolamine 0.5mg x n (drawn up); OR

·     Labetalol 5mg x n (drawn up)

·     Adenosine 6-12mg (30 sec asystole, 1 min profound ↓BP)
(out of the fridge)

Global perfusion

(tight brain)

Maintain mAP:

·     Fluid + pressor

·     Aim 80-90 once aneurysm secured

·     Transducer at tragus

Minimise ICP:

·     Physical: head up 30°, neck free, ETT patent, no PEEP, no cough

·     Physiological: ↑O2, ↓CO2, temp not high

·     Pharmacological: anaesthetic, relaxant, anti-epileptic, osmotic

o  Hypertonic: 3mL/kg ≈ 200mL

o  Mannitol: 0.5mg/kg = 2.5mL/kg ≈ 200mL

·     Surgical: EVD usually pre-clipping

Local perfusion

(clipping + retraction)

Surgery:

·     Temporary clip Max 5min on, Min 5min off

Anaesthesia:

·     ↑O2 supply: ↑mAP/↓ICP, ↑Hb, ↑SpO2

·     ↓O2 demand: hypnotic, anti-convulsant, normothermia

·     Lax brain for retraction: mannitol, hypertonic saline

·     Avoid hyperglycaemia

 

SAH complications:

CVS

SNS storm:

·     Myocardial ischaemia: Rx optimise O2 supply and demand

·     Neurogenic APO: Rx intubation, lung-protective ventilation

Rebound hypertension:

·     Expect ↑20-30% post-op

·     Rx draw up: phentolamine / labetalol / hydralazine

CNS

Early:

·     Seizures: Rx hypnotic, anticonvulsant

·     Hydrocephalus: Rx EVD

Late:

·     Vasospasm: ensure ↔Blood volume, ↔↑blood pressure

Metabolic

·     Sodium disorders: monitor ABG and UO

·     Mannitol side effects: euvolaemia, monitor ABG

 

Anaesthesia:

Preparation

Vascular access: (accessible!)

·     Big IV + chook foot + fluid warmer

·     A-line

·     Crossmatch

Airway:

·     Normal vs reinforced ETT

·     Secure with sleek + tegaderms

Drugs:

·     Infusions: propofol / remifentanil / metaraminol

·     Downers: phentolamine 0.5mg/mL OR labetalol 5mg/mL

Monitoring:

·     Standard

·     ABG

·     NMT

·     BIS

·     IDC

Induction

On table:

·     Propofol Cet 1mcg/mL

·     Remi Cet 2ng/mL

·     Metaraminol 1mL/h

Induction:

·     ↑Remi by 2ng/mL q1 min until LOC/apnoea at 6-10ng/mL

·     ↑Propofol to 3mcg/mL

·     ↑Metaraminol to 5mL/h (± 0.1mg boluses q1min)

·     Rocuronium 1.2mg/kg

·     ±Atropine 2.5-5mcg/kg if bradycardic + hypotensive

Maintenance

·     Propofol 3mcg/mL

·     Remi 6-10ng/mL

·     Metaraminol infusion titrated

·     Rocuronium infusion 0.6mg/kg/h titrated against PTC 2

Emergence

·     ↓Propofol 0mcg/mL

·     ↓Remifentanil 6ng/mL

·     ↓Metaraminol infusion titrated

·     Sugammadex 4mg/kg

·     Extubate when obeying command

·     Remifentanil 0ng/mL

·     Fentanyl 0.5-1mcg/kg

·     Labetalol / phentolamine / hydralazine PRN

 

 

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