Blood transfusions in mass casualty events: recent trends

The US AABB disaster task force recommends estimating 3 RBC units per admission (UPA) for mass casualty events (MCEs). In a previous analysis, median MCE UPA were 2·7 RBCs, 1·2 plasmas and 0·27 platelet doses (Vox Sang 2017; 112:648). Additional recent data were sought from the current era of balanced massive transfusion protocols (bMTPs).

Publications in English from 1980 to 2020 were reviewed for MCEs using ≥50 RBCs/event and with numbers of admissions available. MCE reports were stratified by era and event-wide or trauma-centre source. The bMTP era included all MCEs since 2010 plus a 2008 bMTP military report.

Mann-Whitney test.

Thirty-two MCEs met analysis criteria. Event-wide reports used medians [interquartile ranges] of 1·8 [1·2-3·9] RBC, 0·6 [0·3-0·9] plasma and 0·14 [0·06-0·26] platelet-dose UPA. Trauma centres transfused 3·4 [2·7-6·3] RBC, 2·4 [1·3-4·1] plasma and 0·41 [0·34-0·50] platelet-dose UPA, all P < 0·05 vs event-wide. Same-event median post-day-1 transfusions were 50% of day-1 use for RBC, 28% for plasma and 16% for platelets. Compared to prior years, the median plasma/RBC transfusion ratio rose from 0·28 to 0·67 in the bMTP era (P < 0·01). In recent mass shootings, trauma centres transfused up to 42 platelets (range 0·45-0·57 UPA) on day 1.

Based on available mass casualty data, we recommend planning for 3 RBC, 1 plasma and one-fourth platelet-dose units per admission for blood centres (event-wide), and 6, 4 and one-half UPA, respectively, for trauma centres, which have seen rising plasma usage and large mass-shooting platelet needs.