Critical care : the official journal of the Critical Care Forum
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Comparative Study Clinical Trial Controlled Clinical Trial
Helium-oxygen mixture does not improve gas exchange in mechanically ventilated children with bronchiolitis.
STATEMENT OF Varying concentrations of helium-oxygen (heliox) mixtures were evaluated in mechanically ventilated children with bronchiolitis. We hypothesized that, with an increase in the helium:oxygen ratio, and therefore a decrease in gas density, ventilation and oxygenation would improve in children with bronchiolitis. Ten patients, aged 1-9 months, were mechanically ventilated in synchronized intermittent mandatory ventilation (SIMV) mode with the following gas mixtures delivered at 15-min intervals: 50%/50% nitrogen/oxygen, 50%/50% heliox, 60%/40% heliox, 70%/30% heliox, and return to 50%/50% nitrogen/oxygen. The use of different heliox mixtures compared with 50%/50% nitrogen/oxygen in mechanically ventilated children with bronchiolitis did not result in a significant or noticeable decrease in ventilation or oxygenation.
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Cost is a key concern in fluid management. Relatively few data are available that address the comparative total costs of care between different fluid management regimens in particular clinical indications. Relevant costs of fluid-associated morbidity and mortality, including those incurred after intensive care unit or hospital discharge, also need to be considered in evaluating the cost-benefit ratios of administered fluids. Rigorously designed pharmacoeconomic studies are needed to delineate the costs and benefits of various approaches to fluid management.
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Although many promising objective methods (measuring systems) are available, there are no truly validated instruments for monitoring intensive care unit (ICU) sedation. Auditory evoked potentials can be used only for research in patients with a deep level of sedation. Other measuring systems require further development and validation to be useful in the ICU. ⋯ The Glasgow Coma Score modified by Cook and Palma (GCSC) achieves good face validity and reliability, which assures its clinical utility for routine practice and research. Other scales, in particular the Ramsay Scale, can be recommended preferably for clinical use. An accurate use of available instruments can improve the sedative treatment that we deliver to our patients.
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Review
Fluid balance and colloid osmotic pressure in acute respiratory failure: emerging clinical evidence.
Available evidence suggests that both hydrostatic and osmotic forces are important in the development of acute respiratory distress syndrome (ARDS) or, more broadly, acute lung injury (ALI). More than 80% of ARDS patients in a large-scale randomized controlled trial (RCT) exhibited, at least intermittently, pulmonary artery wedge pressures (PAWP) above 18 mmHg. Retrospective analyses have shown that PAWP elevation is associated with increased mortality. ⋯ These results provide evidence that combined therapy with furosemide and albumin is effective in augmenting serum albumin and STP levels, promoting weight loss, and improving oxygenation and longer-term hemodynamic stability. Although mortality did not differ between groups, the RCT showed a trend toward reduced duration of mechanical ventilation and length of stay in the intensive care unit in patients receiving furosemide + albumin. The findings of the RCT further highlight the importance of both hydrostatic and osmotic forces in hypoxemic respiratory failure, a subject that requires further investigation.
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Physiological background concerning mechanics of the respiratory system, techniques of measurement and clinical implications of pressure-volume curve measurement in mechanically ventilated patients are discussed in the present review. The significance of lower and upper inflection points, the assessment of positive end-expiratory pressure (PEEP)-induced alveolar recruitment and overdistension and rationale for optimizing ventilatory settings in patients with acute lung injury are presented. Evidence suggests that the continuous flow method is a simple and reliable technique for measuring pressure-volume curves at the bedside. In patients with acute respiratory failure, determination of lower and upper inflection points and measurement of respiratory compliance should become a part of the routine assessment of lung injury severity, allowing a bedside monitoring of the evolution of the lung disease and an optimization of mechanical ventilation.