Journal of intensive care medicine
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J Intensive Care Med · Jan 1995
ReviewGastric tonometry: a new monitoring modality in the intensive care unit.
In many critically ill patients, systemic measures of hemodynamic and O2 transport variables may not be sufficiently sensitive to portray the complex interaction between energy requirements and energy supply in all tissues. Gastric or intestinal tonometry has been proposed as a relative noninvasive index of the adequacy of aerobic metabolism in the gut mucosa, a tissue that is particularly vulnerable to alterations in perfusion and oxygenation. The gut mucosa lacks some of the microvascular control mechanisms that allow other tissues, such as the heart, skeletal muscle, and the brain, to increase tissue perfusion during times of stress, and, just like the canary, it will display metabolic changes indicative of dysoxia earlier than those more "vital" tissues. ⋯ Increases in mucosal PCO2, or conversely, decreases in mucosal pH (pHi), are associated with the development of intestinal mucosa ischemia. The clinical utility of pHi to detect intestinal mucosal ischemia has been demonstrated in patients undergoing abdominal aortic surgery. Further, a low gastric mucosal pHi on admission to the ICU appears to be predictive of mortality and pHi-guided resuscitation may improve outcome in a subpopulation of patients admitted to the ICU with normal pHi, perhaps by preventing splanchnic ischemia and the development of a systemic oxygen deficit.
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J Intensive Care Med · Jan 1995
ReviewTreatment of hypothermia in trauma victims: thermodynamic considerations.
The relatively high specific heat of the human body makes hypothermia very difficult to treat. Although there are many treatment methods available, most evaluations of rewarming techniques are based on clinically observed rewarming rates, and they do not take into account initial core temperature, ambient temperature, the patient's own heat production, the effects of anesthesia, paralytic agents, and other variables. ⋯ A commercially available routine is used to solve the equations, which also include any heat exchange between the patient's body and the environment, as well as metabolic heat generation as a function of time and core temperature. This thermodynamic analysis of rewarming, based on computer modeling of heat transfer, provides a scientific basis on which to establish guidelines for appropriate selection of treatment strategies for hypothermia, and it indicates that direct blood warming or infusion of warm intravenous fluids are the most effective rewarming techniques.