Physiologic Waveform Analysis for Early Detection of Hemorrhage during Transport and Higher Echelon Medical Care of Combat Casualties
Annual rept. 15 Oct 2010-14 Oct 2011
MICHIGAN STATE UNIV EAST LANSING
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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 stroke volume SV, cardiac end-diastolic volume EDV, and autonomic nervous system ANS activity can provide timely warning of blood volume loss. However, existing methods for their measurement are invasive andor require a point-of-care 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 SV, EDV, and ANS activity by mathematical analysis of a peripheral ABP waveform and simpler non-invasive waveforms. Our objective is to prove the efficacy of these techniques in the context of early hypovolemia detection. We are investigating the techniques based on existing data from healthy humans exposed to lower body negative pressure LBNP a model of early bleeding in conscious subjects. Our most significant results to date are that the techniques can accurately estimate relative changes in cardiac volumes during progressive LBNP and recovery and that these estimates can provide a sensitive marker of the degree of LBNP. With further research, the techniques may potentially be used to help manage combat casualties during transport and higher echelon care.
- Medicine and Medical Research