Critical care clinics
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Critical care clinics · Jul 1996
ReviewICU scoring systems allow prediction of patient outcomes and comparison of ICU performance.
Too much time and effort are wasted in attempts to pass final judgment on whether systems for ICU prognostication are "good or bad" and whether they "do or do not" provide a simple answer to the complex and often unpredictable question of individual mortality in the ICU. A substantial amount of data supports the usefulness of general ICU prognostic systems in comparing ICU performance with respect to a wide variety of endpoints, including ICU and hospital mortality, duration of stay, and efficiency of resource use. Work in progress is analyzing both general resource use and specific therapeutic interventions. ⋯ These systems do not dehumanize our decision-making process but, rather, help eliminate physician reliance on emotional, heuristic, poorly calibrated, or overly pessimistic subjective estimates. No decision regarding patient care can be considered best if the facts upon which it is based on imprecise or biased. Future research will improve the accuracy of individual patient predictions but, even with the highest degree of precision, such predictions are useful only in support of, and not as a substitute for, good clinical judgment.
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Critical care clinics · Jul 1996
ReviewDoes increasing oxygen delivery improve outcome in the critically ill? No.
The strategy of treating critically ill patients by increasing oxygen delivery and consumption to values previously observed among survivors of critical illness (supranormal values) is based on the belief that (1) tissue hypoxia may persist in critically ill patients despite aggressive early resuscitation to traditional endpoints of adequate tissue perfusion and (2) that increasing oxygen delivery can reverse tissue hypoxia. This article addresses the question of whether increasing oxygen delivery improves outcomes in critically ill patients by reviewing the relationship between whole-body oxygen delivery and consumption and by critically examining the randomized controlled trials that have increased oxygen delivery to supranormal values.
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Critical care clinics · Jul 1996
ReviewNutrition support is not beneficial and can be harmful in critically ill patients.
The introductory remark by Lucretius serves as a reminder that nutrient intake can have very different consequences in different subjects. In the patient with an acute or serious illness, metabolic derangements can transform a substance that is normally a source of energy into a source of metabolic toxins. The potential for organic nutrients to become organic toxins in the diseased host is a phenomenon that deserves more attention in the debate about the value of nutrition support in critically ill patients.
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Gastrointestinal tonometry is supposed to diagnose gut mucosal hypoxia using gastric luminal PCO2 and arterial bicarbonatemia, which are substituted in a modified Henderson-Hasselbach equation. This article reviews some of the problems inherent to the multiple assumptions underlying this technique. Tonometry is influenced by several local factors and by systemic acid-base imbalances that are unrelated to oxygenation. Tonometry is a rather crude and cumbersome method of gut capnometry, a technology that may provide valuable information regarding visceral perfusion, but not necessarily oxygenation.
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Increasing DO2 to supranormal levels, spontaneously or therapeutically, correlates with better survival in the critically ill patient, but not all patients who attain a DO2I greater than 600 mL/min/m2 survive. Conversely, there is often a 50% or greater survival rate in patients who do not reach normal DO2I values. No investigator has been able to show an incremental increase in survival with increasing DO2I; but studies have shown improved survival rates with increasing SVO2. ⋯ SVO2 should be normalized when low, again by increasing DO2. Data continue to support clinical interventions aimed at optimizing DO2. Does increasing DO2 increase the survival rates of critically ill patients? Sometimes.