Blood lactate after pre-hospital blood transfusion for major trauma by helicopter emergency medical services

Background and Objectives: The appropriate use of blood components is essential for ethical use of a precious, donated product. The aim of this study was to report in-hospital red blood cell (RBC) transfusion after pre-hospital transfusion by helicopter emergency medical service paramedics. A secondary aim was to assess the potential for venous blood lactate to predict ongoing transfusion. Materials and Methods: All patients who received RBC in air ambulance were transported to a single adult major trauma centre, had venous blood lactate measured on arrival and did not die before ability to transfuse RBC were included. The association of venous blood lactate with ongoing RBC transfusion was assessed using multi-variable logistic regression analysis and reported using adjusted odds ratios (aOR). The discriminative ability of venous blood lactate was assessed using area under receiver operating characteristics curve (AUROC). Results: From 1 January 2016 to 15 May 2019, there were 165 eligible patients, and 128 patients were included. In-hospital transfusion occurred in 97 (75.8%) of patients. Blood lactate was associated with ongoing RBC transfusion (aOR: 2.00; 95% confidence interval [CI]: 1.36–2.94). Blood lactate provided acceptable discriminative ability for ongoing transfusion (AUROC: 0.78; 95% CI: 0.70–0.86). Conclusions: After excluding patients with early deaths, a quarter of those who had prehospital RBC transfusion had no further transfusion in hospital. Venous blood lactate appears to provide value in identifying such patients. Lactate levels after pre-hospital transfusion could be used as a biomarker for transfusion requirement after trauma.