In the Field
GCS gives more granular information than AVPU at the cost of taking longer and requiring more standardization to use reliably. The same patient can score 12 with one provider and 14 with another if the assessment criteria are not strictly applied. GCS is most useful for tracking neurologic trajectory over time: a casualty who arrives at 14, drops to 12 thirty minutes later, and is 9 at the hospital is decompensating and the trend matters as much as the absolute number. In the tactical environment, AVPU is faster and reliable; GCS comes online during prolonged casualty care and at role 2 and above.
Common Mistake
Reporting a single GCS without component scores. GCS 7 can be E1V1M5 or E2V2M3; the management implications differ. The other mistake is inaccurate scoring under stress. The motor component is the most predictive of outcome and the most often miscoded. Localizes to pain (M5) versus withdraws from pain (M4) is a subtle but important distinction. A third mistake is not noting modifying factors: intubation invalidates the verbal component (typically scored as 1T); intoxication or sedation invalidates the entire scale.
Technical Detail
Glasgow Coma Scale (Teasdale and Jennett, 1974). Eye opening: 4 spontaneous, 3 to voice, 2 to pain, 1 none. Verbal response: 5 oriented, 4 confused, 3 inappropriate words, 2 incomprehensible sounds, 1 none. Motor response: 6 obeys commands, 5 localizes pain, 4 withdraws from pain, 3 abnormal flexion (decorticate), 2 abnormal extension (decerebrate), 1 none. Total range 3 to 15. Severity classification: mild TBI 13 to 15; moderate 9 to 12; severe 3 to 8. Pediatric modification (Pediatric Glasgow Coma Scale) adjusts verbal and motor scoring for preverbal age. Modifiers: T (intubated, invalidates verbal); E (modifications for periorbital edema preventing eye opening). TCCC doctrine uses AVPU as the tactical field assessment because of speed and inter-rater reliability under stress.
