Critical care : the official journal of the Critical Care Forum
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The importance of chest wall elastance in characterizing acute lung injury/acute respiratory distress syndrome patients and in setting mechanical ventilation is increasingly recognized. Nearly 30% of patients admitted to a general intensive care unit have an abnormal high intra-abdominal pressure (due to ascites, bowel edema, ileus), which leads to an increase in the chest wall elastance. ⋯ Consequently, for a given applied pressure, the increase in pleural pressure implies a decrease in transpulmonary pressure (airway pressure - pleural pressure), which is the distending force of the lung, implies a decrease of the strain and of ventilator-induced lung injury, implies the need to use a higher airway pressure during the recruitment maneuvers to reach a sufficient transpulmonary opening pressure, implies hemodynamic risk due to the reductions in venous return and heart size, and implies a possible increase of lung edema, partially due to the reduced edema clearance. It is always important in the most critically ill patients to assess the intra-abdominal pressure and the chest wall elastance.
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Intravascular fluid therapy is a common critical care intervention. However, the optimal type of resuscitation fluid, crystalloid or colloid, remains controversial. Despite the many theoretical benefits of human albumin administration in critically ill patients, there has been little evidence to support its widespread clinical use. ⋯ The results of these subgroups, as well as the use of higher albumin concentrations and other synthetic colloids (dextrans, starches), require rigorous evaluation in clinical trials. Finally, the Saline versus Albumin Evaluation trial represents a methodological milestone in critical care medicine, due to its size, its efficient trial design, and its logistical coordination. Future studies are still required, however, to establish a therapeutic niche for albumin and other colloids.
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Positive end-expiratory pressure (PEEP) improves oxygenation and can prevent ventilator-induced lung injury in patients with acute respiratory distress syndrome (ARDS). Nevertheless, PEEP can also induce detrimental effects by its influence on the cardiovascular system. The purpose of this study was to assess the effects of PEEP on gastric mucosal perfusion while applying a protective ventilatory strategy in patients with ARDS. ⋯ PEEP of 10-20 cmH2O does not affect gastric mucosal perfusion and is hemodynamically well tolerated in most patients with ARDS, including those receiving adrenergic drugs.
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In order to improve the efficiency of heat moisture exchangers (HMEs), new hybrid humidifiers (active HMEs) that add water and heat to HMEs have been developed. In this study we evaluated the efficiency, both in vitro and in vivo, of a new active HME (the Performer; StarMed, Mirandola, Italy) as compared with that of existing HMEs (Hygroster and Hygrobac; Mallinckrodt, Mirandola, Italy). ⋯ This study showed that active Performer may provide adequate conditioning of inspired gases, both as a passive and as an active device.
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This review introduces methods of analyzing data arising from studies where the response variable is the length of time taken to reach a certain end-point, often death. The Kaplan-Meier methods, log rank test and Cox's proportional hazards model are described.