Expansion
AEIOU TIPS, covering the structural and metabolic causes
Expansion
AEIOU TIPS:
- A - Alcohol
- E - Epilepsy, Encephalopathy, Electrolytes, Endocrine
- I - Insulin: hypoglycaemia and hyperglycaemia
- O - Overdose and Opioids
- U - Uraemia
- T - Trauma and Temperature, both high and low
- I - Infection: meningitis, encephalitis, sepsis
- P - Psychiatric, Poisoning
- S - Stroke, Shock, Space occupying lesion, Subarachnoid haemorrhage
The immediately reversible causes come first: glucose, naloxone for pinpoint pupils and respiratory depression, thiamine in alcohol dependence or malnutrition, and oxygen.
Examination findings that localise
- Pupils: pinpoint suggests opioids or a pontine lesion; a unilateral fixed dilated pupil suggests uncal herniation; dilated and reactive suggests anticholinergics or sympathomimetics
- Fundoscopy for papilloedema and subhyaloid haemorrhage
- Lateralising signs suggest a structural cause; a symmetrical examination with intact brainstem reflexes suggests a metabolic one
- Cushing’s reflex (hypertension, bradycardia, irregular breathing) indicates critically raised intracranial pressure
Protect the airway if the GCS is 8 or less, and always exclude hypoglycaemia before attributing coma to anything else.