- sedative drug effect – prolonged effect c/o altered kinetics (CSHT, decreased biotransformation or excretion), altered pharmacodynamics (potentiation of effect by other drugs or organ failure, sensitivity to effect of usual dosage)
- metabolic encephalopathy (renal or hepatic failure)
- endocrine problems – hypothyroidism, Addison, hypoglycaemia, hyperglycaemia…
- systemic sepsis
- neurological problems – cva (ischaemic, embolic, haemorrhagic), delirium, status epilepticus, increased ICP, intracranial haemorrhages, severe Guillain-Barré syndrome, critical illness polyneuropathy
- musculo-skeletal problems – myopathy, residual muscular paralysis
- neurological state prior to intubation, drugs administration, previous neurological problems.
- detailed neurological (global CNS, rule out locked in syndrome, myoneuropathy, PNS assessment, focal signs: pupils, tone, movement, reflexes).
- electrolytes, CK, renal and hepatic dysfunction, relevant endocrine tests
- other imaging as indicated: CT head, MRI
- EEG, EMG and LP
- antagonist challenge (flumazenil, naloxone)
- treat underlying cause