Anaesthesia for Head Injury

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Traumatic brain injury (TBI) affects 700 per 100,000 population annually in Australia, with anaesthetic management focused on preventing secondary brain injury by optimizing cerebral oxygenation and perfusion. Pathophysiology: Primary injury (irreversible cellular damage at impact), secondary injury (hypotension, hypoxia, hypercapnia, hyperglycaemia, seizures causing additional damage). Intracranial pressure (ICP): Normal <15 mmHg, target <20-22 mmHg; Monro-Kellie doctrine requires reducing one component (CSF, blood, brain tissue) if another expands (haematoma, oedema). Cerebral perfusion pressure (CPP): MAP - ICP (or CVP), target 60-70 mmHg (avoid <50 or >70 initially); hypertension dangerous (increases cerebral oedema), hypotension dangerous (cerebral ischaemia). GCS assessment: Eye (1-4), Verbal (1-5), Motor (1-6); total 3-15; severe TBI GCS ≤8 (intubate for airway protection), moderate 9-12, mild 13-15. Anaesthetic goals: Avoid hypotension (SBP >90 mmHg), avoid hypoxia (SpO₂ >90%, PaO₂ >60 mmHg), avoid hypercapnia (PaCO₂ 35-40 mmHg, mild hyperventilation 30-35 only if acute herniation), maintain normoglycaemia (6-10 mmol/L), prevent seizures (phenytoin 15-20 mg/kg if severe), head elevation 30° (improves venous drainage). Induction: RSI with thiopental/propofol, fentanyl (avoid ketamine in severe TBI—traditionally contraindicated, but evidence may support safety), rocuronium; avoid succinylcholine if open eye injury or burns >24 hours old. Maintenance: Propofol or volatile <1 MAC (preserve cerebral autoregulation), remifentanil infusion, titrate to BIS 40-50; mannitol 0.25-1 g/kg for acute ICP elevation; hypertonic saline 3% 250 mL for refractory oedema; ventriculostomy for CSF drainage if available. Monitoring: ICP monitor (ventricular catheter or parenchymal probe) if severe TBI, CPP calculation, jugular venous saturation (SjO₂ 55-75%), brain tissue oxygen (PbtO₂). Emergence: Smooth emergence avoiding coughing/straining (raises ICP), ensure adequate analgesia and sedation in ICU. Indigenous patients: Higher TBI rates from motor vehicle accidents and violence; cultural considerations for family communication and end-of-life decisions. [1-10]