Articles: mechanical-ventilation.
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J Intensive Care Med · Dec 2016
Management of Acute Respiratory Failure in Patients With Hematological Malignancy.
Acute respiratory failure (ARF) is the leading cause of intensive care unit admission in patients with hematologic malignancies and is associated with a high mortality. The main causes of ARF are bacterial and opportunistic pulmonary infections and noninfectious lung disorders. Management consists of a systematic clinical evaluation aimed at identifying the most likely cause, which in turn determines the best first-line empirical treatments. ⋯ However, most of these studies did not control the time between onset of ARF to NIV implementation nor accounted for the etiology of ARF or the presence of associated organ dysfunction at the time of NIV initiation. Moreover, the benefits demonstrated with NIV in these patients were derived from studies with high mortality rates of intubated patients. Additional studies are therefore warranted to determine the appropriate patients with hematologic malignancy and ARF who may benefit from prophylactic or curative NIV.
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Annals of intensive care · Dec 2016
Effect of external PEEP in patients under controlled mechanical ventilation with an auto-PEEP of 5 cmH2O or higher.
In some patients with auto-positive end-expiratory pressure (auto-PEEP), application of PEEP lower than auto-PEEP maintains a constant total PEEP, therefore reducing the inspiratory threshold load without detrimental cardiovascular or respiratory effects. We refer to these patients as "complete PEEP-absorbers." Conversely, adverse effects of PEEP application could occur in patients with auto-PEEP when the total PEEP rises as a consequence. From a pathophysiological perspective, all subjects with flow limitation are expected to be "complete PEEP-absorbers," whereas PEEP should increase total PEEP in all other patients. This study aimed to empirically assess the extent to which flow limitation alone explains a "complete PEEP-absorber" behavior (i.e., absence of further hyperinflation with PEEP), and to identify other factors associated with it. ⋯ Expiratory flow limitation was associated with both high and complete "PEEP-absorber" behavior, but setting a relatively high respiratory rate on the ventilator can prevent from observing complete "PEEP-absorption." Therefore, the effect of PEEP application in patients with auto-PEEP can be accurately predicted at the bedside by measuring the respiratory rate and observing the flow-volume loop during manual compression of the abdomen.
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Intensive Care Med Exp · Dec 2016
EditorialLung stress, strain, and energy load: engineering concepts to understand the mechanism of ventilator-induced lung injury (VILI).
It was recently shown that acute respiratory distress syndrome (ARDS) mortality has not been reduced in over 15 years and remains ~40 %, even with protective low tidal volume (LVt) ventilation. Thus, there is a critical need to develop novel ventilation strategies that will protect the lung and reduce ARDS mortality. Protti et al. have begun to analyze the impact of mechanical ventilation on lung tissue using engineering methods in normal pigs ventilated for 54 h. ⋯ If the lung is fully inflated, a large Vt is not necessarily injurious. In conclusion, using engineering concepts to analyze the impact of the mechanical breath on the lung is a novel new approach to investigate VILI mechanisms and to help design the optimally protective breath. Data generated using these methods have challenged some of the current dogma surrounding the mechanisms of VILI and of the components in the mechanical breath necessary for lung protection.
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Parenchymal strain is a key determinant of lung injury produced by mechanical ventilation. However, imaging estimates of volumetric tidal strain (ε = regional tidal volume/reference volume) present substantial conceptual differences in reference volume computation and consideration of tidally recruited lung. We compared current and new methods to estimate tidal volumetric strains with computed tomography, and quantified the effect of tidal volume (VT) and positive end-expiratory pressure (PEEP) on strain estimates. ⋯ PEEP reduced tidal-strain estimates referenced to end-expiratory lung volumes, although it did not affect strains referenced to resting lung volume. These estimates of tidal strains in normal lungs point to middependent lung regions as those at risk for ventilator-induced lung injury. The different conditions and topography at which maximal strain estimates occur allow for testing the importance of each estimate for lung injury.
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Although increasingly recommended, compliance with low Vt ventilation remains suboptimal. Dyssynchrony induced by low Vts may be a reason for it. ⋯ Lower Vts during VC ventilation result in higher patient-ventilator dyssynchrony in most patients with or at risk for acute respiratory distress syndrome. The use of APC mode is an option to reduce dyssynchrony, but it requires careful monitoring to avoid larger-than-target delivered volumes.