When does 1:1 resuscitation really matter? An analysis of 4,858 patients from four traumatic hemorrhage studies.

BACKGROUND: While supported by a randomized trial and America College of Surgeon Trauma Quality Improvement Program(TQIP) guidelines, the inflection point in transfusion volumes at which balanced ratios (1:1) begin to affect mortality has not been fully explored. We sought to evaluate transfusion volumes at which a difference in mortality is observed.

METHODS: Four studies of bleeding trauma patients were analyzed: two conducted before whole blood (WB) availability; a single institution experience (Pre-WB Single Center, 2010-2016) and a randomized, multicenter trial [Pre-WB Pragmatic Randomized Optimal Platelet and Plasma Ratios (PROPPR), 2012-2013] and two conducted with WB use; one single institution experience (WB Single Center 2017-2021) and a prospective, multicenter study [WB Shock, Whole blood And Traumatic brain injury (SWAT), 2018-2021]. Patients were divided into balanced [1:1 or less, red blood cell (RBC):plasma] and unbalanced (>1:1) cohorts. RBC units transfused in the first four hours were evaluated (0-6, 7-10, then 10-unit intervals). Primary outcome was 30-day mortality. Secondary outcomes were four-hour and 24-hour mortality.

RESULTS: The Pre-WB Single Center (n = 730 1:1 or less, n = 536 >1:1) and Pre-WB PROPPR (n = 342, n = 338) noted mortality differences once >10 units of RBCs were transfused (11-20 units: 26% vs. 32%, p = 0.151 and 20% vs 30%, p = 0.090; 21-30 units: 43% vs. 71%, p = 0.013 and 32% vs. 61%, p = 0.017). The WB Single Center study (n = 1,239, n = 879) and WB SWAT (n = 447, n = 587) noted outcome separation >6 units (7-10 units: 14% vs. 22%, p = 0.139 and 14% vs. 18%, p = 0.198; 11-20: 28% vs. 41%, p = 0.118 and 17% vs. 31%, p = 0.030). Absolute differences tended to widen with greater units transfused. Differences remained at 24-hours for 7 to 10 units for Pre-WB Single Center and 11 to 20 units for Pre-WB PROPPR, WB Single Center, and WB SWAT studies.

CONCLUSIONS: In this analysis of almost 5,000 patients, balanced resuscitation had a protective effect during or after the second transfusion cooler (>6 or >10 units of RBCs). This highlights the need for early 1:1 resuscitation with suspicion for massive hemorrhage, utilizing early WB to stay balanced and storing more immediately available plasma.

LEVEL OF EVIDENCE: Therapeutic/Care Management; Level IV.