Seminars in respiratory and critical care medicine
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Semin Respir Crit Care Med · Feb 2019
ReviewAcute Respiratory Distress Syndrome: Respiratory Monitoring and Pulmonary Physiology.
The high prevalence of acute respiratory distress syndrome (ARDS), its morbidity and mortality continue to fare a huge burden in the intensive care unit. More than 40 years ago, experimental studies have highlighted that, albeit essential, mechanical ventilation could be harmful to lungs and more recently to the diaphragm. Despite life-saving advances in mechanical ventilation (such as low tidal-volume ventilation, neuromuscular blockers agents, or prone positioning), a recent international observational study reported that most ARDS patients were not appropriately monitored. ⋯ To achieve this goal, it is of paramount importance to better understand the complex relationship between the patient and the ventilator: the impact of ventilator settings on lungs during passive controlled ventilation, but also of patient's breathing efforts on lungs during assisted ventilation. In this review we present available tools to monitor respiratory mechanics at the bedside aiming at optimizing and personalizing mechanical ventilation. Hopefully, this careful management can decrease mortality of patients with ARDS in the future.
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Semin Respir Crit Care Med · Feb 2019
ReviewProne Positioning in Acute Respiratory Distress Syndrome.
Prone positioning is nowadays considered as one of the most effective strategies for patients with severe acute respiratory distress syndrome (ARDS). The evolution of the pathophysiological understanding surrounding the prone position closely follows the history of ARDS. ⋯ Indeed, the positive effects on oxygenation and CO2 clearance of the prone position are to be ascribed to a more homogeneous inflation-ventilation, to the lung/thoracic shape mismatch, and to the change of chest wall elastance. In the past 20 years, five major trials have tried, starting from different theories, hypotheses, and designs, to demonstrate the effectiveness of the prone position, which finally found its definitive place among the different ARDS supportive therapies.
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The acute respiratory distress syndrome (ARDS) phenotype was first described over 50 years ago and since that time significant progress has been made in understanding the biologic processes underlying the syndrome. Despite this improved understanding, no pharmacologic therapies aimed at the underlying biology have been proven effective in ARDS. Increasingly, ARDS has been recognized as a heterogeneous syndrome characterized by subphenotypes with distinct clinical, radiographic, and biologic differences, distinct outcomes, and potentially distinct responses to therapy. ⋯ Finally and most promisingly, biologic subphenotypes or endotypes have increasingly been identified using plasma biomarkers, genetics, and unbiased approaches such as latent class analysis. The potential of precision medicine lies in identifying novel therapeutics aimed at ARDS biology and the subpopulation within ARDS most likely to respond. In this review, we discuss the challenges and approaches to subphenotype ARDS into clinical, radiologic, severity, and biologic phenotypes with an eye toward the future of precision medicine in critical care.
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Semin Respir Crit Care Med · Feb 2019
ReviewRole of Pharmacologic Paralysis in Acute Respiratory Distress Syndrome.
The pharmacology and history of neuromuscular blockade in clinical care are complex, with multiple theoretical and observed potential benefits and potential harms. Past studies raised concern for long-term paresis, but more recent studies have not found evidence for harm, possibly due to changes in background care, neuromuscular blocking agent, and duration of blockade. Current use is highly variable, likely due to limited evidence for efficacy beyond short-term physiologic improvement and lingering concerns for harm. A recently completed large multicenter trial will provide further information on the role of pharmacologic paralysis in acute respiratory distress syndrome.
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Semin Respir Crit Care Med · Feb 2019
ReviewFluid Management in Acute Respiratory Distress Syndrome.
One of the defining features of acute respiratory distress syndrome (ARDS) is noncardiogenic pulmonary edema, resulting from increased permeability of the alveolar-capillary barrier and passage of protein-rich fluid into the interstitium and alveolar spaces. The loss of protein from the intravascular space disrupts the normal oncotic pressure differential and causes patients with ARDS to be particularly sensitive to the hydrostatic forces that correlate with intravascular volume. ⋯ These physiologic observations have led to a series of studies examining the impact of fluid management on the development of, resolution of, survival from, and long-term outcomes from ARDS. While questions remain, the current literature makes it clear that fluid management is an integral part of the care of patients with ARDS.