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 χ(2) 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.