Each parameter is converted to a coded value (0–4): GCS 13–15=4, 9–12=3, 6–8=2, 4–5=1, 3=0. SBP >89=4, 76–89=3, 50–75=2, 1–49=1, 0=0. RR 10–29=4, >29=3, 6–9=2, 1–5=1, 0=0. Then RTS = 0.9368×GCS(c) + 0.7326×SBP(c) + 0.2908×RR(c). Maximum score = 7.8408.

An RTS <7.84 (any coded value <4) suggests the patient should be transported to a designated trauma center. An RTS <4 indicates very severe injury with high mortality. The American College of Surgeons uses RTS as part of field triage criteria.

RTS measures physiologic response (how the body is responding) while ISS measures anatomic injury severity (what structures are damaged). Together they are used in the TRISS methodology for predicting trauma outcomes. RTS can be calculated quickly in the field, while ISS requires full injury cataloging.