Critical care clinics
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For the ventilator-dependent patient, weaning should be accomplished by withdrawing support safely, efficaciously, and efficiently. Success depends largely on physiologic determinants of respiratory system function, avoidance of ventilator-associated complications, and attention to patient readiness. Recent clinical trials, predictors of weaning, current techniques of weaning, the concept of reloading the respiratory pump, and determinants of ventilator dependency are all discussed.
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Critical care clinics · Oct 1998
ReviewVentilation of patients with asthma and obstructive lung disease.
Mechanical ventilation in a patient with obstructive airway disease may be a lifesaving measure; however, it may also be associated with significant morbidity and mortality. It is important for a physician to be familiar with the potential complications of mechanical ventilation in this group of patients and to know how to avoid them by carefully applying safe ventilator strategies. The cornerstone of such strategies is to minimize minute ventilation, maximize time for expiration, and avoid hyperinflation of the lung. ⋯ In the event controlled hypoventilation is necessary, sedation with or without the use of muscle relaxants may be required. Unconventional therapies such as the use of Heliox, magnesium sulfate, ketamine, and inhalational anesthetics may be attempted in severe cases that do not respond to conventional management. With appropriate use of ventilator strategies, a reduction in the mortality and morbidity of patients with obstructive airway disease requiring mechanical ventilation has recently been noted.
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Ventilatory management of patients with acute lung injury (ALI), particularly its most severe subset, acute respiratory distress syndrome (ARDS), is complex. Newer lung protective strategies emphasize measures to enhance alveolar recruitment and avoid alveolar overdistention, thus minimizing the risk of ventilator-induced lung injury (VILI). ⋯ Novel techniques, including prone positioning, inverse ratio ventilation, tracheal gas insufflation, and high frequency ventilation, are considerations in severe ARDS. No single approach is best for all patients; adjustment of ventilatory parameters to individual characteristics, such as lung mechanics and gas exchange, is required.
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Critical care clinics · Oct 1998
ReviewPharmacologic adjuncts to mechanical ventilation in acute respiratory distress syndrome.
This article reviews pharmacologic approaches to treating acute respiratory distress syndrome (ARDS). The authors discuss the therapeutic effects of ketoconazole, antioxidants, corticosteroids, surfactant, ketanserin, pentoxifylline, bronchodilators, and almitrine in ARDS. Current animal data and proposed mechanics which may foster future pharmacologic therapies are also examined.
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Changes in the understanding of the pathophysiology of ARDS and effects of mechanical ventilation with high pressures have led to treatment strategies that resulted in improved survival rates. The central principle in these strategies is to avoid ventilation induced lung injury by allowing the lungs to rest. A number of promising new treatments emphasizing this principle are under investigation. Physicians caring for patients who develop ARDS should make every effort to avoid alveolar overdistention by ventilating patients in the compliant portion of pressure-flow loop and avoid peak inspiratory pressures in excess of 40 cm H2O.