J Trauma
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Effective resuscitation is critical in reducing mortality and morbidity rates of patients with acute burns. To this end, guidelines and formulas have been developed to define infusion rates and volume requirements during the first 48 hours postburn. Even with these standardized resuscitation guidelines, however, over- and under-resuscitation are not uncommon. ⋯ Because the system can self-adjust based on monitoring inputs, the technology can be pushed to environments such as combat zones where burn resuscitation expertise is limited. A closed-loop system can also assist in the management of mass casualties, another scenario in which medical expertise is often in short supply. This article reviews the record of fluid balance of contemporary burn resuscitation and approaches, as well as the engineering efforts, animal studies, and algorithm development of our most recent autonomous systems for burn resuscitation.
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Closed-loop algorithms and resuscitation systems are being developed to control IV infusion rate during early resuscitation of hypovolemia. Although several different physiologic variables have been suggested as an endpoint to guide fluid therapy, blood pressure remains the most used variable for the initial assessment of hemorrhagic shock and the treatment response to volume loading. Closed-loop algorithms use a controller function to alter infusion rate inversely to blood pressure. ⋯ Proportional-integral and fuzzy logic algorithms reduced mean fluid volume requirements compared with the nonlinear decision table; and (4) several algorithms have been constructed to the specific mechanism of injury and the volume expansion properties of different fluids. Closed-loop systems are undergoing translation from animal to patient studies. Future smart resuscitation systems will benefit from new noninvasive technologies for monitoring blood pressure and the development of computer controlled high flow intravenous pumps.
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Most prehospital medical interventions during civilian and military trauma casualty transport fail to utilize advanced decision-support systems for treatment and delivery of medical interventions, particularly intravenous fluids and oxygen. Current treatment protocols are usually based on standard vital signs (eg, blood pressure, arterial oxygen saturation) which have proven to be of limited value in detecting the need to implement an intervention before cardiovascular collapse. A primary objective of the US Army combat casualty care research program is to reduce mortality and morbidity during casualty transport from the battlefield through advanced development of a semiautomated decision-support capability for closed-loop resuscitation and oxygen delivery. ⋯ We propose that derived indices based on currently available technology for continuous monitoring of specific hemodynamic, autonomic, and/or metabolic responses could provide earlier recognition of hemorrhage than current standard vital signs and allow intervention before the onset of circulatory shock. Because of this, such indices could provide improved feedback for closed-loop control of patient resuscitation and oxygen delivery. These technological advances could prove instrumental in advancing decision-support capabilities for prehospital trauma care during transport to higher levels of care in both the military and civilian environments.
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Military operations, mass casualty events, and remote work sites present unique challenges to providers of immediate medical care, who may lack the necessary skills for optimal clinical management. Moreover, the number of patients in these scenarios may overwhelm available health care resources. Recent applications of closed-loop control (CLC) techniques to critical care medicine may offer possible solutions for such environments. ⋯ Some potential advantages of CLC in patient management include limiting task saturation when there is simultaneous demand for cognitive and active clinical intervention, improving quality of care through optimization of the titration of medications, conserving limited consumable supplies, preventing secondary insults in traumatic brain injury, shortening the duration of mechanical ventilation, and achieving appropriate goal-directed resuscitation. The uses of CLC systems in critical care medicine have been increasingly explored across a wide range of therapeutic modalities. This review will provide an overview of control system theory as applied to critical care medicine that must be considered in the design of autonomous CLC systems, and introduce a number of clinical applications under development in the context of deployment of such applications to austere environments.