Patients presenting unconscious may reasonably be categorized as suffering from a metabolic or structural condition.

The objective was to investigate if some routinely recorded clinical features may help to distinguish between these 2 main forms of coma in the emergency department (ED).

Adults admitted to an ED in Stockholm between February 2003 and May 2005 with a Glasgow Coma Scale (GCS) score less than 11 were enrolled prospectively. The GCS score was entered into a protocol that was complemented with available data within 1 month.

The study population of 875 patients was classified into 2 main groups: one with a metabolic (n = 633; 72%) and one with a structural disorder (n = 242; 28%). Among the clinical features recorded in the ED, 3 were found to be strongly associated with a metabolic disorder, namely, young age, low or normal blood pressure, and absence of focal signs in the neurological examination. Patients younger than 51 years with a systolic blood pressure less than 151 mm Hg who did not display signs of focal pathology had a probability of 96% for having a metabolic coma. The mean GCS score on admission was identical in the groups. Hospital mortality was 14% in the metabolic and 56% in the structural group.

These findings indicate that unconscious young adults who present without a traumatic incident with a low or normal blood pressure and without signs of focal pathology most probably suffer from a metabolic disorder, wherefore computed tomography of the brain may be postponed and often avoided.