Seminars in respiratory and critical care medicine
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For many critically ill patients admitted to an intensive care unit, the insertion of an endotracheal tube and the initiation of mechanical ventilation (MV) can be lifesaving procedures. Subsequent patient care often requires intensivists to manage the complex interaction of multiple failing organ systems. The shift in the intensivists' focus toward the discontinuation of MV can thus occur late in the course of critical illness. ⋯ Many difficult aspects of pulmonary pathophysiology encroach on weaning management. Accordingly, weaning commands sophisticated, individualized care. Few other responsibilities of an intensivist require a more analytical effort and carry more promise for improving patient outcome than the application of physiologic principles in the weaning of patients.
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Semin Respir Crit Care Med · Aug 2014
ReviewNoninvasive Ventilation for Patients with Hypoxemic Acute Respiratory Failure.
Noninvasive ventilation (NIV) has an established efficacy to improve gas exchange and reduce the work of breathing in patients with hypoxemic acute respiratory failure. The clinical efficacy in terms of meaningful outcome is less clear and depends very much on patient selection and assessment of the risks of the technique. The potential risks include an insufficient reduction of the oxygen consumption of the respiratory muscles in case of shock, an excessive increase in tidal volume in case of lung injury, and a risk of delayed or emergent intubation. ⋯ In all cases, there is both a time window and a severity window for NIV to work, after which delaying endotracheal intubation may worsen outcome. The preventive use of NIV seems promising in this setting but needs more research. An emerging interesting new option is the use of high flow humidified oxygen, which seems to be intermediate between oxygen alone and NIV.
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Ventilator-associated pneumonia (VAP) is an iatrogenic pulmonary infection that develops in tracheally intubated patients on mechanical ventilation for at least 48 hours. VAP is the nosocomial infection with the greatest impact on patient outcomes and health care costs. Endogenous colonization by aerobic gram-negative pathogens, that is, Pseudomonas aeruginosa, and methicillin-resistant Staphylococcus aureus play a pivotal role in the pathogenesis of VAP. ⋯ In patients with clinical suspicion of VAP, respiratory samples should be promptly collected. The empiric treatment should be based on the local prevalence of pathogens, duration of hospital stay, and prior antimicrobial therapy. The antibiotics can be stopped or adjusted to more narrow-spectrum once cultures and susceptibilities are available.
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Chronic obstructive pulmonary disease (COPD) is characterized by expiratory flow limitation (EFL) due to progressive airflow obstruction. The various mechanisms that cause EFL are central to understanding the physiopathology of COPD. At the end of expiration, dynamic inflation may occur due to incomplete emptying the lungs. ⋯ When invasive MV is used, settings should be adjusted in a way that minimizes hyperinflation, while providing reasonable gas exchange, respiratory muscle rest, and proper patient-ventilator interaction. Further, weaning from MV may be difficult in these patients, and factors amenable to pharmacological correction (such as increased bronchial resistance, tracheobronchial infections, and heart failure) are to be systematically searched and treated. In selected patients, early use of NIV may hasten the process of weaning from MV and improve outcomes.
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Semin Respir Crit Care Med · Aug 2014
ReviewExtracorporeal Support for Severe Acute Respiratory Failure.
Extracorporeal membrane oxygenation (ECMO) and extracorporeal CO(2) removal (ECCO(2)R) techniques have increasingly been applied in patients with severe acute lung injury refractory to conventional mechanical ventilatory support. The objectives of this article are to review current concepts of extracorporeal life support techniques (ECMO and ECCO(2)R systems) and provide the rationale for their application in patients with acute respiratory distress syndrome, chronic obstruction pulmonary disease, and as adjunctive therapy for bridging patients to lung transplantation.