Critical care : the official journal of the Critical Care Forum
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Identification of risk factors for diminished cortisol response to adrenocorticotrophic hormone (ACTH) in the critically ill could facilitate recognition of relative adrenal insufficiency in these patients. Therefore, we studied predictors of a low cortisol response to ACTH. ⋯ In critically ill patients, low pH/bicarbonate and platelet count, greater severity of disease and organ failure are predictors of a low adrenocortical response to ACTH, independent of baseline cortisol values and cortisol binding capacity in blood. These findings may help to delineate relative adrenal insufficiency and suggest that adrenocortical suppression occurs as a result of metabolic acidosis and coagulation disturbances.
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This review summarizes key research papers published in the fields of cardiology and intensive care during 2006 in Critical Care and, where relevant, in other journals within the field. The papers have been grouped into categories: haemodynamic monitoring, vascular access in intensive care, microvascular assessment and manipulation, and impact of metabolic acidosis on outcome.
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Randomized Controlled Trial
Goal-directed fluid management based on pulse pressure variation monitoring during high-risk surgery: a pilot randomized controlled trial.
Several studies have shown that maximizing stroke volume (or increasing it until a plateau is reached) by volume loading during high-risk surgery may improve post-operative outcome. This goal could be achieved simply by minimizing the variation in arterial pulse pressure (deltaPP) induced by mechanical ventilation. We tested this hypothesis in a prospective, randomized, single-centre study. The primary endpoint was the length of postoperative stay in hospital. ⋯ Monitoring and minimizing deltaPP by volume loading during high-risk surgery improves postoperative outcome and decreases the length of stay in hospital.
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High-mobility group box-1 protein (HMGB1) has been known as a chromosomal protein for many years. HMGB1 has recently been shown to be a proinflammatory cytokine with a role in the immunopathogenesis of sepsis. Lipopolysaccharide-binding protein (LBP) has a central role in the innate immune response when the host is challenged by bacterial pathogens. Procalcitonin (PCT) has been suggested as a marker of severe bacterial infections and sepsis. The aim of the present study was to investigate levels of HMGB1, LBP and PCT in a well-characterised sepsis cohort. The study plan included analysis of the levels of the inflammatory markers in relation to the severity of infection, to the prognosis and to the ability to identify patients with bacteraemia. ⋯ Levels of HMGB1, PCT and LBP were higher in infected patients compared with those in healthy controls, and levels were higher in severe sepsis patients compared with those in sepsis patients. Levels of all studied inflammatory markers (HMGB1, LBP, PCT, IL-6) and infection markers (C-reactive protein, white blood cell count, neutrophils) were elevated among bacteraemic patients. PCT performed best as a diagnostic test marker for bacteraemia.
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Comparative Study
Variation in the PaO2/FiO2 ratio with FiO2: mathematical and experimental description, and clinical relevance.
Previous studies have shown through theoretical analyses that the ratio of the partial pressure of oxygen in arterial blood (PaO2) to the inspired oxygen fraction (FiO2) varies with the FiO2 level. The aim of the present study was to evaluate the relevance of this variation both theoretically and experimentally using mathematical model simulations, comparing these ratio simulations with PaO2/FiO2 ratios measured in a range of different patients. ⋯ The PaO2/FiO2 ratio depends on both the FiO2 level and the arterial oxygen saturation level. As a minimum, the FiO2 level at which the PaO2/FiO2 ratio is measured should be defined when quantifying the effects of therapeutic interventions or when specifying diagnostic criteria for acute lung injury and acute respiratory distress syndrome. Alternatively, oxygenation problems could be described using parameters describing shunt and ventilation/perfusion mismatch.