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

Remote lines

·     IVC and A-line: long, visible, same side as anaesthetist

·     Fluid warmer: connected pre-op

·     Drug-line connections: secure

·     Consider femoral CVC pre-op

·     Consider extra IVC in lower limb

Bleeding

·     BGHO +/- XM

·     ≥18g cannula x 2; consider lower limb PIVC

·     Fluid warmer + forced air warmer

·     Avoid hypertension

Microsurgery

·     High dose opioid

·     Relaxant infusion titrated to PTC 2

Rapid emergence

Strategy:

·     Minimise hypnotic (i.e. opioid + relaxant + BIS)

·     Fast offset drugs (i.e. desflurane + remifentanil + roc/sugammadex)

Beware if:

·     ↓GCS pre-op

·     Long anaesthetic

·     Major surgery

·     Posterior fossa surgery

 

Cerebral haemodynamics:

Goals

All patients:

·     Prevent rupture: avoid ↑mAP and ↓ICP

·     Prevent ischaemia: avoid ↓mAP and ↑ICP

If ruptured:

·     Before securement: SBP 140-160 mAP <110 (this high??)

·     After securement: mAP >90, CPP >70

Critical moments

·     Induction (↓BP)

·     Intubation (↑)

·     Pinning (↑)

·     Craniotomy (↑)

·     Dural incision (↑)

·     Extubation (↑)

·     Emergence (rebound ↑)

mAP management

·     Monitoring: A-line, IDC

·     Fluid: 0.9% NaCl, aim PPV <10% and UO >0.5mL/kg/h

·     Infusions: remifentanil (SNS’lyis), metaraminol (mitigate SNS’lysis)

·     Boluses: phentolamine, labetalol, adenosine

·     Available: adenosine

ICP management

·     Physical: head up, loose neck, ETT patent, no PEEP or cough

·     Physiological: normal O2, CO2, temp

·     Pharmacological: propofol, paralysis, anticonvulsant, osmotic

·     Surgical: drain CSF

Rupture management

Infusions:

·     ↑Propofol (and cease volatile)

·     ↑Opioid

·     ↓Metaraminol

Boluses:

·     Phentolamine 0.5mg (drawn up)

·     Labetalol 5mg (drawn up)

·     Adenosine 24mg (30 sec asystole, 1 min profound ↓BP)

 

Cerebral protection:

Supply

·     Temporary clip: mAP ↑20%, ≤5min on, ≥5min off

·     Perfusion: ↑mAP, ↓ICP

·     Oxygenation: ↑Hb, ↑SpO2

·     Lax brain: osmotic agents

Demand

·     Electrical: hypnotic, anti-convulsant, maybe thiopentone

·     Basal: hypothermia (but no difference in outcome)

Nimodipine

·     Dose: IV 10mg/h via CVC, PO 40mg q4h

·     AEs: ↓BP, ↑ICP, irritation, deranged LFT

·     CNS vasodilation

·     Anti-apoptosis

·     Anti-platelet

·     Rheologic effect

·     Later prevents vasospasm

Other

·     Avoid hyperglycaemia

·     NMDA antagonist (?)

·     Statin

 

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

·     A-line

·     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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