Feasibility and Usability of a Combat Medical Early Warning System for Simulated Mass Casualty Triage During a Naval Exercise – a pilot study.

Introduction:Mass casualty incidents (MASCAL) in modern naval large-scale combat operations (LSCO) present unique triage challenges due to the confined environments, operational constraints, and saturation of medical resources.Combat Medical Early Warning Systems (CMEWS)integrating wearable biosensors with automated early warning scores (EWS)-may support dynamic triage, but their use in a naval military setting has not been previously studied. Materials and Methods:This prospective observational pilot study was conducted aboard a French Navy amphibious helicopter carrier during the POLARIS 25 naval LSCO simulation (May-June 2025).The tested CMEWS combined new-generation autonomous OXYFLEX biosensors with a traumaadapted EWS, displayed via color-coded LEDs.Biosensors collected heart rate (HR), J o u r n a l P r e -p r o o f respiratory rate (RR), oxygen saturation (SpO), and transcutaneous hemoglobin (SpHb) every 10 seconds.Simulated scenarios included onboard and task force-level MASCAL events with aeromedical evacuation.Primary endpoints were data quality-defined by the proportion of valid physiological data points-and usability, evaluated using the System Usability Scale (SUS), Computer System Usability Questionnaire (CSUQ), and After Scenario Questionnaire (ASQ).Data quality assessment focused on technical feasibility and signal robustness under operational conditions rather than measurement accuracy against a reference standard. Results:Twenty-two simulated combat casualties were monitored, including 10 during helicopter evacuation.Over 34 hours of monitoring yielded 12,476 data points per variable.Newgeneration biosensors provided 79% valid data-indicating technically feasible physiological signal acquisition under operational conditions.HR showed the highest proportion of valid data (91.2%) and RR the lowest (59.6%).Lower proportions of valid data were observed during helicopter evacuation.Usability feedback was favorable (N = 21): SUS 86 (7.6) (Grade A), CSUQ 1.9 (0.9), ASQ 1.6 (0.6).Participants reported ease of use, improved situational awareness, and enhanced triage efficiency.Reported limitations included absence of blood pressure monitoring and a basic interface. Conclusion:CMEWS deployment in a naval MASCAL setting proved technically feasible, logistically achievable, and well-accepted by users.While biosensor performance was robust in static conditions, further technical optimization and clinical validation in real operational and clinical settings are needed for broader operational use.