Use of Non-Invasive Methods to Determine Stroke Volume

Quantitative estimation of blood loss in wounded battlefield casualties must be promptly transmitted to medics for corrective actions. Yet heart rate and blood pressure measures are often inadequate, and the more accurate invasive measures of stroke volume as well as derived measures from the ventricular volume curve (obtained with echo-Doppler) cannot be employed logistically. Real-time, battlefield monitoring of such parameters can be achieved with a non-invasive inductive plethysmographic sensor (thoracocardiograph) and ECG. By fitting casualties with these easy-to-apply sensors (one non-constricting elastic band transversely around the chest near the xiphoid process and three ECG chest electrodes), wireless transmission of continuous hemodynamic data can be received on a small, handheld monitoring device with onboard signal processing software for waveform and numerical displays as well as an automatic alarm function when problems are detected. To further support casualty monitoring, these sensors can be easily integrated with others such as blood pressure, etc., all of which could be transmitted wirelessly to the same handheld display and monitoring device along with expert systems data reduction. These features could then be integrated into a more comprehensive, battery-powered physiological monitoring device worn by warfighters to gather and track both pre- and post-injury heath status data.