Systolic Blood Pressure Lower than Heart Rate upon Arrival at and Departure from the Emergency Department Indicates a Poor Outcome for Adult Trauma Patients

BACKGROUND Hemorrhage is a leading cause of preventable trauma death. In this study, we used the reverse shock index (RSI), a ratio of systolic blood pressure (SBP) to heart rate (HR), to evaluate the hemodynamic stability of trauma patients. As an SBP lower than the HR (RSI < 1) may indicate hemodynamic instability, the objective of this study was to assess the associated complications in trauma patients with an RSI < 1 upon arrival at the emergency department (ED) (indicated as (A)RSI) and at the time of departure from the ED (indicated as (L)RSI) to the operative room or for admission. METHODS Data obtained from all 16,548 hospitalized patients recorded in the trauma registry system at a Level I trauma center between January 2009 and December 2013 were retrospectively reviewed. A total of 10,234 adult trauma patients aged ≥20 were enrolled and subsequently divided into four groups: Group I, (A)RSI ≥ 1 and (L)RSI ≥ 1 (n = 9827); Group II, (A)RSI ≥ 1 and (L)RSI < 1 (n = 76); Group III, (A)RSI < 1 and (L)RSI ≥ 1 (n = 251); and Group IV, (A)RSI < 1 and (L)RSI < 1 (n = 80). Pearson's χ² test, Fisher's exact test, or independent Student's t-test was conducted to compare trauma patients in Groups II, III, and IV with those in Group I. RESULTS Patients in Groups II, III, and IV had a higher injury severity score and underwent a higher number of procedures, including intubation, chest tube insertion, and blood transfusion, than Group I patients. Additionally, patients of these groups had increased hospital length of stay (16.3 days, 14.9 days, and 22.0 days, respectively), proportion of patients admitted to the intensive care unit (ICU) (48.7%, 43.0%, and 62.5%, respectively), and in-hospital mortality (19.7%, 7.6%, and 27.5%, respectively). Although the trauma patients who had a SBP < 90 mmHg either upon arrival at or departure from the ED also present a more severe injury and poor outcome, those patients who had a SBP ≥ 90 mmHg but an RSI < 1 had a more severe injury and poor outcome than those patients who had a SBP ≥ 90 mmHg and an RSI ≥ 1. CONCLUSIONS SBP lower than heart rate (RSI < 1) either upon arrival at or departure from the ED may indicate a detrimental sign of poor outcome in adult trauma patients even in the absence of noted hypotension.