Physiologic Waveform Analysis for Early Detection of Hemorrhage during Transport and Higher Echelon Medical Care of Combat Casualties

摘要

Early detection of hemorrhage is crucial for managing combat casualties. However, mean arterial blood pressure (ABP) and other vital signs are late indicators of a bleed. By contrast, cardiac output (CO), stroke volume (SV), ventricular end-diastolic volume (EDV), and autonomic nervous system (ANS) activity can provide timely warning of blood loss. However, existing methods for their measurement are invasive and/or require an operator. On the other hand, a peripheral ABP waveform can be measured non-invasively and automatically with commercial devices that are amenable to most combat casualties during evacuation and medical care thereafter. We have conceived techniques to track CO, SV, EDV, and ANS activity by mathematical analysis of a peripheral ABP waveform and simpler non-invasive waveforms. Our objective was to prove the efficacy of these techniques during hypovolemia. We investigated the techniques based on existing data from conscious humans exposed to lower body negative pressure (LBNP) a model of early bleeding. Our most significant results were that the techniques can estimate relative changes in CO and SV accurately and better than previous techniques during progressive LBNP and recovery. We also transitioned the techniques from academia to a ventured backed start-up company. The techniques could ultimately be used to help manage combat casualties during transport and higher echelon care.