Abstract
BACKGROUND: Evaluations of critical bleeding and massive transfusion have focused on traumatic hemorrhage. However, most critical bleeding in hospitalized patients occurs outside trauma. The purpose of this study was to provide an in-depth description examining the critical administration threshold (CAT; ≥3 units red blood cells (RBCs) in a 1-h period) occurrences in nontraumatic hemorrhage. This will assist in establishing the framework for future investigations in nontraumatic hemorrhage. METHODS: This is an observational cohort study of adults experiencing critical bleeding defined as being CAT+ during hospitalization from 2016 to 2021 at a single academic institution. A CAT episode started with administration of the first qualifying RBC unit and ended at the time of completion of the last allogeneic unit prior to a ≥4-h gap without subsequent transfusion. The primary goal was to describe demographic, clinical and transfusion characteristics of participants with nontraumatic critical bleeding. RESULTS: 2433 patients suffered critical bleeding, most often occurring in the operating room (71.1%) followed by the intensive care unit (20.8%). 57% occurred on the initial day of hospitalization, with a median duration of 138 (36, 303) minutes. The median number of RBCs transfused during the episode was 5 (4, 8), with median total allogeneic units of 9 (4, 9). Hospital mortality was 19.2%. The most common cause of death was multi-organ failure (50.3%), however death within 24 h was due to exsanguination (72.7%). DISCUSSION: The critical administration threshold may be employed to identify critical bleeding in non-trauma settings of life-threatening hemorrhage, with a mortality rate of approximately 20%.