AUTOMATED CRITICAL CARE LIFE SUPPORT.

Source: The Combat Casualty Care Research Program website, www.usacc.org.

Rationale for Investment
Care and maintenance of battlefield casualties after initial stabilization, after definitive care, and while awaiting and during evacuation is complex and difficult in the haze and chaos of the battlefield and during evacuation in land and air vehicles. Vital signs are difficult to obtain reliably and patients may drift into irretrievable agonal states before interventions can be applied or recognized as needed. A portable, lightweight, self-contained system that provides capability for continuous monitoring of casualty status, including early markers of deterioration; for automatic alarming, and for closed-loop, automatic control of life support equipment and interventions would be of value to medical personnel after casualty stabilization and during evacuation.

Overarching Objective:
Conduct basic and applied research to support the discovery, adaptation, and development of new devices that can be integrated into a lightweight, semi-autonomous critical care system capable of monitoring and regulating patients pre-and post-surgery at echelons 2 and 3.

Development Strategy:
Current efforts include defining and developing an En Route Care System (ERCS) to provide a wide variety of life support capabilities during transport between echelons of care. Central to this effort is the design of algorithms and sensors for automated delivery of oxygen, ventilation, and fluids through closed loop systems. An ad hoc coordinating group with representatives from interested parties in the Army, Air Force and Navy is drafting a development plan that will incorporate Tri-Service requirements. Ideally, the ERCS will optimize ventilator settings to improve oxygen saturation and minimize oxygen flow required to maintain blood oxygen saturation at > 94%. Combining digitally controlled orifice controls with oxygen conservation devices using sequential re-breathing techniques will result in a large reduction in oxygen required for transport and in the size of the oxygen generation system required.

Such a system will improve patient care via continuous adjustment of flow rates, enable providers to concentrate on tasks requiring human intervention, and substantially reduce the volume of fluids and oxygen the logistics system must deliver.

The focus of this effort is to automate three life support functions which include; 1) oxygen administration, 2) fluid administration and 3) ventilatory support. This effort is to primarily facilitate the en route care mission of the 91W medic as the principle user. However, this automation of life support will also facilitate the mission of the Intensive Care Unit (ICU) nurse as a secondary target and the nurse anesthetist, respiratory specialist or anesthesiologist. The algorithm development will survey and leverage prior published work in the area of closed loop control and identify research requirements where knowledge gaps exist. These gaps will first be explored using animal models designed to emulate the medical management challenges encountered in the en route care environment. The control algorithms for oxygen administration, ventilation and fluid administration will be tuned to their individual end-points first and then combined to assess their interaction in these animal models. Each of the 3 individual algorithms will then be moved into appropriate clinical settings once the performance in animal models has been determined to be adequate by a panel of subject matter experts. Once the algorithms have been pre-clinically and clinically validated using prototypical hardware hosts, the algorithm will be transitioned to advanced development for competitive bidding from hardware suppliers based on the specifications developed within this effort. Individual, stand-alone products may also spin out in this process, such as a closed loop fluid resuscitation pump based on a blood pressure target alone, closed loop oxygen controller based on pulse oximetry or a ventilator that automatically sets itself up and adjusts to minimize the work of breathing and optimize blood oxygenation. These 3 components working together will be required to optimally empower the en route care medic to effectively attend the critically injured patient while minimizing oxygen and fluid requirements.

Future Direction:
In the next two years, complete demonstration of effectiveness of closed loop ventilation and oxygen delivery systems in animal models of lung injury, low inspired oxygen (altitude) and shock, complete data collection for closed loop fluid resuscitation for the integrated platform for Investigational Device Exemption (IDE) and begin clinical evaluations of closed loop fluid infusion, complete the pre-clinical data collection for oxygen delivery and ventilation control loops within the integrated platform and complete clinical validation of closed loop fluid infusion. This product transitions to U.S. Army Medical Materiel Development Activity for advanced development in FY07.

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