Seminars in respiratory and critical care medicine
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Semin Respir Crit Care Med · Aug 2014
Review Comparative StudyVentilator-Associated Lung Injury during Assisted Mechanical Ventilation.
Assisted mechanical ventilation (MV) may be a favorable alternative to controlled MV at the early phase of acute respiratory distress syndrome (ARDS), since it requires less sedation, no paralysis and is associated with less hemodynamic deterioration, better distal organ perfusion, and lung protection, thus reducing the risk of ventilator-associated lung injury (VALI). In the present review, we discuss VALI in relation to assisted MV strategies, such as volume assist-control ventilation, pressure assist-control ventilation, pressure support ventilation (PSV), airway pressure release ventilation (APRV), APRV with PSV, proportional assist ventilation (PAV), noisy ventilation, and neurally adjusted ventilatory assistance (NAVA). ⋯ Furthermore, during assisted MV, the following parameters should be monitored: inspiratory drive, transpulmonary pressure, and tidal volume (6 mL/kg). Further studies are required to determine the impact of novel modalities of assisted ventilation such as PAV, noisy pressure support, and NAVA on VALI.
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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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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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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.