Response to Painful Stimuli
Profound sedation in the presence of a reasonable blood pressure suggests TCAs, neuroleptics, anticonvulsants (e.g. carbamazepine, phenytoin), opioids or barbiturates.
It is unusual for benzodiazepines or alcohol alone to lead to deep coma (grades 2-4). More serious toxins such as TCAs and anticonvulsants are more likely.
| Alert | no signs of CNS depression |
| Drowsy | all patients between alert & stuporous |
| Stuporous | responds to verbal or tactile stimuli |
| Coma 1 | responds to painful stimuli only, normal BP & Respiration |
| Coma 2 | no response to painful stimuli, normal BP & Respiration |
| Coma 3 | no response to painful stimuli, abnormal respiratory pattern &/or low but adequate BP |
| Coma 4 | no response to painful stimuli, apnoea or inadequate respiration &/or inadequate BP |
Plum F, Posner JB. The diagnosis of stupor and coma. Contemp Neurol Ser 1972;10:1-286 PMID4664014