Table 2.

Comorbidities predisposing to increased risk of delayed return of consciousness

Respiratory	Hepatic	Renal	Endocrine
Reduced central drive: •Obesity hypoventilation syndrome •COPD •Intracranial pathology •Obstructive sleep apnoea	Acute hepatic failure	Acute kidney injury	Hypothyroidism
Neuromuscular disorder: •Myasthenia gravis •Motor neurone disease •Guillain-Barré syndrome •Muscular dystrophy	Chronic hepatic failure	Chronic renal failure
Pulmonary pathology: •$\dot{V}/\dot{Q}$ mismatch