Shock Index Identifies Compensated Shock in the ‘Normotensive’ Trauma Patient

Abstract

Introduction: Hemorrhagic shock is a life-threatening condition that requires rapid identification for timely intervention. Although shock is easily discernible in the hypotensive patient, compensated shock in the "normotensive" patient is not. This study aimed to evaluate the utility of shock index (SI) in trauma patients with compensated shock. Methods Patients with SBP > 90 mmHg on arrival were identified from our trauma center registry. SI was calculated by arrival heart rate divided by arrival SBP. Patients were stratified by SI using the following thresholds: < 0.7, > 0.7 to 0.9, > 0.9 to 1.1, > 1.1 to 1.3, and > 1.3. Logistic regression was used to estimate the odds of transfusion within 1 hour of arrival for each SI category with < 0.7 as the referent. Results 5964 trauma patients were included. Blood products were transfused within 1 hour of arrival in 221 (3.7%) patients. A main effect was observed for shock index with increased risk for required transfusion for patients with admission shock index > 0.7 (P < 0.001). In comparison to shock index of < 0.7, odds ratios were 2.4(1.6–3.6), 8.3(5.5–12.3), 24.7(15.1–40.5), 63.3(35.0–114.4) for each categorical increase in SI. Discussion SI can identify trauma patients with compensated shock; among patients presenting without hypotension, arrival SI was associated with an increase in odds of receiving transfusion within one hour. Arrival SI should be considered as a criterion for activation of massive transfusion protocol and highest level of trauma activation for non-hypotensive patients.