Study objective: Shock index (SI) (heart rate/systolic blood pressure; normal range, 0.5 to 0.7) and conventional vital signs were compared to identify acute critical illness in the emergency department.
Design: Quasi-prospective study.
Patients: Two hundred seventy-five consecutive adults who presented for urgent medical care.
Interventions: Patients had vital signs, SI, and triage priority recorded on arrival in the ED and then their final disposition.
Results: Two groups were identified retrospectively by the SI; group 1 (41) had an SI of more than 0.9, and group 2 (234) had an SI of less than 0.9 on arrival in the ED. Although both groups had apparently stable vital signs on arrival, group 1 had a significantly higher proportion of patients who were triaged to a priority requiring immediate treatment (23 versus 45; P < .01) and required admission to the hospital (35 versus 105; P < .01) and continued therapy in an ICU (10 versus 13; P < .01).
Conclusion: With apparently stable vital signs, an abnormal elevation of the SI to more than 0.9 was associated with an illness that was treated immediately, admission to the hospital, and intensive therapy on admission. The SI may be useful to evaluate acute critical illness in the ED.