Enhancing Far-Forward Resuscitation: A Quantitative Laboratory Analysis of Blood Warmer Devices Used in Austere Environments.

Abstract

Objectives: It is well known that hypothermia increases organ dysfunction and mortality in traumatically injured patients. While several small, portable blood warmers are commercially available, comparative data on their warming efficiency and flow dynamics remain limited. Thus, the objective of this study was to identify optimal blood warming devices for far-forward austere trauma resuscitation.

Methods: This prospective experimental study assessed six blood warming devices: QinFlow Warrior Lite^™, MWarmer^™, Buddy Lite^™, Thermal Angel^®, the LifeWarmer Quantum^™, and the Ready Heat Blanket^™, using whole blood stored at 4 °C. Devices were tested in triplicate under two pressure conditions (0 and 300 mmHg). Flow was measured volumetrically and converted into average (Qavg), ideal (Qi), and maximum (Qmax) flow rates. Temperature was measured at the distal end of intravenous tubing and analyzed using average (Tavg), ideal (Ti), and maximum (Tmax) definitions. Time-to-one-unit (TT1U) was calculated as a clinically meaningful metric. Two-way ANOVA with interaction terms and post hoc Tukey testing were used for statistical comparison, with significance defined as multiplicity-adjusted p < 0.05.

Results: The Quantum exhibited the highest Qi at both pressure levels, achieving a TT1U of 1.55 ± 0.10 min at 300 mmHg, significantly faster than all other devices. However, its warming performance declined significantly with increased pressure, with Ti decreasing from 34.7 °C to 25.6 °C (p < 0.0001). In contrast, the MWarmer demonstrated the highest and most consistent warming performance across all pressure conditions, maintaining Ti of 40-41 °C (p < 0.0001) at both pressure conditions. The Buddy Lite showed poor warming performance with pressure-related degradation, while Ready Heat provided negligible warming capacity with flow comparable to control.

Conclusions: This is an independent quantitative comparison of portable blood warming devices using cold-stored whole blood under clinically relevant pressure conditions. Results suggest that the MWarmer offers the most favorable balance of thermal performance and flow for far-forward resuscitation.