New horizons (Baltimore, Md.)
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Multicenter Study
Application of total body bioimpedance to the critically ill patient. Brazilian Group for Bioimpedance Study.
In the past several years, considerable interest has developed in the study of total body bioimpedance analysis (TBBIA) and body composition in healthy subjects. This simple and noninvasive technique uses derived and regression equations to validate data comparative to the gold standards of total body water determination and body composition. However, this approach has not proved to be of value in the critically ill patient with distorted body composition under the effects of multiple drugs and interventions. ⋯ Some authors have demonstrated that this relation Xc/R is highly correlated with mortality and could be used for the staging of critically ill patients throughout their stay in the ICU. The role of TBBIA as a simple and noninvasive technique, and its implications for the management of critically ill patients are presented and discussed. Areas for future investigations, with single and multiple frequency, have the potential to clarify many aspects of this emergent technology at the bedside.
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Patients undergoing prolonged, complex oncological surgery are at increased risk of developing the adult respiratory distress syndrome (ARDS) and other organ failures. Our hypothesis is that maintaining adequate tissue perfusion and oxygenation may prevent tissue hypoxia and acidosis in pulmonary, peripheral, and splanchnic microcirculations. Experimental evidence suggests that the hypoxic, acidotic endothelium stimulates the release of cytokines, kinins, and other mediators. ⋯ Nitroglycerin and fluids were used to maintain tissue perfusion and prevent tissue hypoxia as reflected by transcutaneous oxygen tension values. In 155 high-risk patients, none developed ARDS. We conclude that maintenance of tissue perfusion and oxygenation in high-risk surgical patients decreases the incidence of ARDS.
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During shock resuscitation, a combination of fluids, vasopressors, vasodilators, and inotropes is administered in order to achieve a cardiac output or overall oxygen delivery as per guidelines of individual clinicians. The measurement of ventricular end-diastolic pressure allows a clinician to describe a therapeutic goal of optimum cardiac output response to changes in end-diastolic pressure. This concept has formed the backbone of resuscitative strategies in many forms of shock. ⋯ It is now clear that a significant gradient between pulmonary capillary pressure and PAOP may be present in inflammatory disorders which are not present in noninflammatory states, and that pulmonary capillary pressure may be measured at the bedside of critically ill patients. Bedside measurement of pulmonary capillary pressure may allow for added precision in our therapeutic goals in resuscitation from inflammatory shock. If further studies confirm the reliability and reproducibility of bedside measurement, pulmonary capillary pressure may become an invaluable part of the hemodynamic profile in the critically ill patient in shock.
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Near-infrared spectroscopy (NIRS) is a relatively new tool that allows continuous noninvasive monitoring of in vivo oxygenation in selected tissues such as muscle and brain. Since hemoglobin, myoglobin, and cytochrome c oxidase are the only biological compounds to exhibit variable absorption of near-infrared (NIR) light in response to changes in oxygen availability, NIRS can determine changes in tissue oxygenation. ⋯ As a comprehensive monitor of regional oxygen metabolism, NIRS has been applied in certain clinical and research settings. Despite technical limitations and the lack of definite "gold standards" to allow validation of results, NIRS remains a promising technology with applications in both the critical care environment and the research laboratory studying mechanisms of oxygen metabolism.
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The management of severe sepsis includes the use of agonists of alpha- and beta-adrenergic, as well as of dopaminergic, receptors. Data suggest that the severe inflammatory immune response seen in sepsis can be modulated by stimulation and inhibition of these receptors both in vitro and in vivo. ⋯ Since the vasopressor and inotrope support of sepsis is not well standardized, variability in the resulting inflammatory mediator response may have consequences to the efficacy of new immunotherapies. This article provides an overview of the effect of the sympathetic nervous system activity and of receptor manipulation on cytokine response to endotoxin, and adds to the perspective on inhibition of phosphodiesterase in the therapy of septic shock.