Table 1

 Common causes of unconsciousness

CauseClinical clues
    Intracerebral bleed• History of preceding sudden onset headache
    Subarachnoid haemorrhage• Focal neurological signs
    Hypoglycaemia• History of diabetes mellitus
    Severe hyperglycaemia• Always check the glucose
    (hyperosmolar non ketotic coma)
    Severe hyponatraemia
    Opiates• History of illicit drug use, alcoholism or mental health problems
    Tricyclics• Presence of empty pill bottles
    Benzodiazepines• Pin-point pupils (opiates)
    Carbon monoxide (accidental or deliberate)• Dilated pupils (tricyclics or benzodiazepines)
Head injury• History of falls
• Scalp laceration, bruising or swelling
• Periorbital bruising
Epilepsy• Previous history of fits
    Status epilepticus (non-convulsive)
Infection• History of prodromal illness
    Meningitis• Rash
    Encephalitis• Pyrexia
    Sepsis• Signs of septic shock (peripheral vasodilatation, tachycardia, hypotension)
Hypothermia• Temperature <35°C