American journal of respiratory and critical care medicine
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Am. J. Respir. Crit. Care Med. · Aug 2018
GuidelineAssessment of Right Ventricular Function in the Research Setting: Knowledge Gaps and Pathways Forward. An Official American Thoracic Society Research Statement.
Right ventricular (RV) adaptation to acute and chronic pulmonary hypertensive syndromes is a significant determinant of short- and long-term outcomes. Although remarkable progress has been made in the understanding of RV function and failure since the meeting of the NIH Working Group on Cellular and Molecular Mechanisms of Right Heart Failure in 2005, significant gaps remain at many levels in the understanding of cellular and molecular mechanisms of RV responses to pressure and volume overload, in the validation of diagnostic modalities, and in the development of evidence-based therapies. ⋯ This statement provides a roadmap to further advance the state of knowledge, with the ultimate goal of developing RV-targeted therapies for patients with RV failure of any etiology.
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Am. J. Respir. Crit. Care Med. · Aug 2018
Natural History of Chronic Obstructive Pulmonary Disease Exacerbations in a General Practice-based Population with Chronic Obstructive Pulmonary Disease.
Acute exacerbations of chronic obstructive pulmonary disease (AECOPDs) are important adverse events in the natural history of chronic obstructive pulmonary disease (COPD). ⋯ A large proportion of patients with COPD do not exacerbate over a maximum 10 years of follow-up. AECOPD frequency in a single year predicts long-term AECOPD rate. Increasing frequency and severity of AECOPDs is associated with risk of death and highlights the importance of preventing AECOPDs.
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Am. J. Respir. Crit. Care Med. · Aug 2018
Positive End-Expiratory Pressure Ventilation Induces Longitudinal Atrophy in Diaphragm Fibers.
Diaphragm weakness in critically ill patients prolongs ventilator dependency and duration of hospital stay and increases mortality and healthcare costs. The mechanisms underlying diaphragm weakness include cross-sectional fiber atrophy and contractile protein dysfunction, but whether additional mechanisms are at play is unknown. ⋯ Mechanical ventilation with PEEP results in longitudinal atrophy of diaphragm fibers, a response that is modulated by the elasticity of the giant sarcomeric protein titin. We postulate that longitudinal atrophy, in concert with the aforementioned cross-sectional atrophy, hampers spontaneous breathing trials in critically ill patients: during these efforts, end-expiratory lung volume is reduced, and the shortened diaphragm fibers are stretched to excessive sarcomere lengths. At these lengths, muscle fibers generate less force, and diaphragm weakness ensues.