Current opinion in critical care
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Curr Opin Crit Care · Feb 2003
ReviewExtubation failure: magnitude of the problem, impact on outcomes, and prevention.
Extubation failure, defined as the need for reinstitution of ventilatory support within 24 to 72 hours of planned endotracheal tube removal, occurs in 2 to 25% of extubated patients. The pathophysiologic causes of extubation failure include an imbalance between respiratory muscle capacity and work of breathing, upper airway obstruction, excess respiratory secretions, inadequate cough, encephalopathy, and cardiac dysfunction. Compared with patients who tolerate extubation, those who require reintubation have a higher incidence of hospital mortality, increased length of ICU and hospital stay, prolonged duration of mechanical ventilation, higher hospital costs, and an increased need for tracheostomy. ⋯ Risk factors for extubation failure include being a medical, multidisciplinary, or pediatric patient; age greater than 70 years; a longer duration of mechanical ventilation; continuous intravenous sedation; and anemia. Tests designed to assess for upper airway obstruction, secretion volume, and the effectiveness of cough can help to improve prediction of extubation failure. Rapid reinstitution of ventilatory support in patients who fail extubation may improve outcome.
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Curr Opin Crit Care · Feb 2003
ReviewWhy protect the right ventricle in patients with acute respiratory distress syndrome?
Even a slight increase in pulmonary vascular resistance can overload a normal right ventricle, which ejects blood through a low-pressure circuit. In a clinical setting, a persistent increase in pulmonary vascular resistance produces acute cor pulmonale. From an echocardiographic point of view, may be defined as the combination of a paradoxical septal motion, reflecting systolic overload, with right ventricular enlargement, reflecting diastolic overload. ⋯ This prognosis has greatly improved with protective ventilation. At the same time, the incidence of acute cor pulmonale has diminished in acute respiratory distress syndrome, and the prognosis of this specific complication has also improved, suggesting that the right ventricle may develop some adaptation against persistent overload. Past lessons, however, have taught us that this potential may be limited and lead us to recommend right ventricular protection during mechanical ventilation.
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Curr Opin Crit Care · Feb 2003
ReviewHigh-frequency oscillatory ventilation in adults with acute respiratory distress syndrome.
The last decade has seen increased appreciation of ventilator-induced lung injury. The understanding that the process of mechanical ventilation can itself damage lungs has spurned the search for ventilation strategies that are more lung protective. ⋯ In the past year, a number of provocative and exciting studies have been published that contribute significantly to our understanding of high-frequency oscillatory ventilation, its role in preventing and reducing ventilator-induced lung injury, and its use in the support of adult patients with lung injury. In this article, we discuss the current understanding of high-frequency oscillatory ventilation and highlight the most recent literature addressing its application in adult patients with acute respiratory distress syndrome.
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Curr Opin Crit Care · Feb 2003
ReviewNew modes of mechanical ventilation: proportional assist ventilation, neurally adjusted ventilatory assist, and fractal ventilation.
Increased knowledge of the mechanisms that determine respiratory failure has led to the development of new technologies aimed at improving ventilatory treatment. Proportional assist ventilation and neurally adjusted ventilatory assist have been designed with the goal of improving patient-ventilator interaction by matching the ventilator support with the neural output of the respiratory centers. ⋯ Neurally adjusted ventilatory assist is an experimental mode in which the assistance is delivered in proportion to the electrical activity of the diaphragm, assessed by means of an esophageal electrode. Biologically variable (or fractal) ventilation is a new, volume-targeted, controlled ventilation mode aimed at improving oxygenation; it incorporates the breath-to-breath variability that characterizes a natural breathing pattern.
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Curr Opin Crit Care · Feb 2003
ReviewUsefulness of helium-oxygen mixtures in the treatment of mechanically ventilated patients.
The density of helium is markedly lower than that of air or any of its components, leading to a substantial decrease in airway resistance to flow when it is inhaled. In mechanically ventilated patients with obstructive airway disease, replacing the usual air-oxygen mixture with helium-oxygen has been shown to reduce dynamic hyperinflation and intrinsic positive end-expiratory pressure; to decrease lung inflation pressures, respiratory acidosis, and work of breathing; and to improve arterial blood gases. ⋯ However, interference with ventilator function and added costs are two major disadvantages of helium-oxygen. Hence, before its widespread use in mechanically ventilated patients can be recommended, studies are needed to determine whether these favorable short-term effects can influence patient outcome.