Critical care : the official journal of the Critical Care Forum
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Mortality is the most widely accepted outcome measure in randomized controlled trials of therapies for critically ill adults, but most of these trials fail to show a statistically significant mortality benefit. The reasons for this are unknown. ⋯ Investigators of therapies for critical illness systematically overestimate treatment effect size (delta) during the design of randomized controlled trials. This bias, which we refer to as "delta inflation", is a potential reason that these trials have a high rate of negative results."Absence of evidence is not evidence of absence."
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Studies in intensive care unit (ICU) patients have suggested that anemia and blood transfusions can influence outcomes, but these effects have not been widely investigated specifically in surgical ICU patients. ⋯ In this group of surgical ICU patients, anemia was common and was associated with higher morbidity and mortality. Higher hemoglobin concentrations and receipt of a blood transfusion were independently associated with a lower risk of in-hospital death. Randomized control studies are warranted to confirm the potential benefit of blood transfusions in these subpopulations.
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Biography Historical Article
Clinical review: Guyton--the role of mean circulatory filling pressure and right atrial pressure in controlling cardiac output.
Arthur Guyton's concepts of the determinative role of right heart filling in cardiac output continue to be controversial. This paper reviews his seminal experiments in detail and clarifies the often confusing concepts underpinning his model. ⋯ Further concerns have been raised in regard to the artificial experimental preparations that Guyton used. Recently reported measurements in humans support Guyton's theoretical and animal work.
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The human fetus develops in a profoundly hypoxic environment. Thus, the foundations of our physiology are built in the most hypoxic conditions that we are ever likely to experience: the womb. This magnitude of exposure to hypoxia in utero is rarely experienced in adult life, with few exceptions, including severe pathophysiology in critical illness and environmental hypobaric hypoxia at high altitude. ⋯ Many of these mechanisms act to modify the process of oxygen consumption rather than oxygen delivery in order to maintain adequate tissue oxygenation. The successful activation of such processes may provide a new chapter in the clinical management of hypoxemia. Thus, strategies employed to endure the relative hypoxia in utero may provide insights for the management of severe hypoxemia in adult life and ventures to high altitude may yield clues to the means by which to investigate those strategies.
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Comparative Study
Effects of hydrogen sulfide on hemodynamics, inflammatory response and oxidative stress during resuscitated hemorrhagic shock in rats.
Hydrogen sulfide (H2S) has been shown to improve survival in rodent models of lethal hemorrhage. Conversely, other authors have reported that inhibition of endogenous H2S production improves hemodynamics and reduces organ injury after hemorrhagic shock. Since all of these data originate from unresuscitated models and/or the use of a pre-treatment design, we therefore tested the hypothesis that the H2S donor, sodium hydrosulfide (NaHS), may improve hemodynamics in resuscitated hemorrhagic shock and attenuate oxidative and nitrosative stresses. ⋯ NaHS is protective against the effects of ischemia reperfusion induced by controlled hemorrhage in rats. NaHS also improves hemodynamics in the early resuscitation phase after hemorrhagic shock, most likely as a result of attenuated oxidative stress. The use of NaHS hence appears promising in limiting the consequences of ischemia reperfusion (IR).