Clinics in chest medicine
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Clinics in chest medicine · Sep 1996
ReviewEvolving concepts in the ventilatory management of acute respiratory distress syndrome.
With few modifications, a high tidal volume, normoxic, normocapnic ventilation paradigm developed as the standard approach to supporting most critically ill patients. Large tidal volumes, high end-tidal (plateau) alveolar pressures, and low levels of positive end-expiratory pressure are still common in many ICUs during ventilation of acute respiratory distress syndrome (ARDS). ⋯ A relatively small but growing number of practitioners are shifting their first priority from optimizing oxygen exchange, oxygen delivery, or respiratory system compliance to ensuring adequate lung protection. This article reviews the basis for concern about traditional ventilatory support in ARDS and develops an approach based on current evidence and newer options for management.
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Clinics in chest medicine · Sep 1996
ReviewNoninvasive positive-pressure ventilation in patients with acute respiratory failure.
This article provides a systematic review of the literature on the application of noninvasive ventilation in various forms of hypercapnic and hypoxemic respiratory failures. A description of the underlying pathophysiology is followed by a review of physiologic data explaining the mechanisms of action of noninvasive ventilation. A critical review of clinical studies is presented with specific suggestions. The methodology of correctly implementing and monitoring noninvasive ventilation in patients with acute respiratory failure, critical to success, is detailed.
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Resumption of spontaneous unassisted breathing after an episode of acute respiratory failure often is achieved without major difficulty. In a significant number of patients however, weaning from mechanical ventilation is a long and difficult process that markedly increases the duration of mechanical ventilation and consumes a significant fraction of critical care resources. Some criteria have been suggested to predict early and more accurately the moment the patient is ready to be separated from the ventilator. ⋯ Although their conclusions were different regarding the best method of weaning, however, two recent clinical trials suggest that ventilatory management has a major influence on the outcome of weaning from mechanical ventilation in difficult-to-wean patients. The global management of such patients requires a systematic approach with consideration of all factors involved in the process of separation from the ventilator. New computer-assisted systems already are tested and, in the future, may provide a significant advantage in the management of weaning from mechanical ventilation.
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Clinics in chest medicine · Sep 1996
ReviewAuto-positive end-expiratory pressure and dynamic hyperinflation.
PEEP is indicated in patients with COPD only to unload the respiratory muscles from the auto-PEEP resulting from expiratory flow limitation. If auto-PEEP is not caused by flow limitation, application of PEEP will cause further hyperinflation, worsening respiratory mechanics, muscle activity, and hemodynamics. To assess the presence of expiratory flow limitation correctly, to measure auto-PEEP correctly, and to identify the maximal PEEP level to be used, measurements of flow and opening pressure must be obtained during a brief period of suspended respiratory muscle activity (obtained by sedation) with the patient's own breathing pattern reproduced accurately.
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Airway management of critically ill patients has been enhanced by the recent introduction of several new types of artificial airways and laryngoscopes. New drugs for sedation and neuromuscular blockade have been developed to facilitate care of the intubated patient. Guidelines for management of the difficult airway have been introduced. ⋯ A consensus is evolving that TLI and tracheotomy each have clear advantages and disadvantages in prolonged airway maintenance and that multiple factors, not simply the duration of TLI, must be considered in the optimal timing of tracheotomy for each patient. Complex medicolegal and ethical issues directly impact intubation, perhaps more so than any other practice in critical care medicine. Physicians who care for critically ill patients should be familiar with these recent developments and concepts in airway management.