Increased effort during partial ventilatory support is not associated with lung damage in experimental acute lung injury

Abstract: BACKGROUND Patient-ventilator asynchrony during mechanical ventilation may exacerbate lung and diaphragm injury in spontaneously breathing subjects. We investigated whether subject-ventilator asynchrony increases lung and/or diaphragmatic injury in a porcine model of acute respiratory distress syndrome (ARDS). METHODS ARDS was induced in adult female pigs by lung lavage and injurious ventilation, before mechanical ventilation by pressure assist-control for 12h. Mechanically ventilated pigs were randomised to spontaneously breath with, or without, induced subject-ventilator asynchrony, or neuromuscular blockade (n=7/group). Subject-ventilator asynchrony was produced by ineffective, auto- or double-triggering of spontaneous breaths. The primary outcome was mean alveolar septal thickness (where thickening of the alveolar wall indicates worse lung injury). Secondary outcomes included distribution of ventilation (electrical impedance tomography), lung morphometric analysis, inflammatory biomarkers (gene expression), lung wet-to-dry ratio and diaphragmatic muscle fibre thickness. RESULTS Mean alveolar septal thickness was similar in pigs randomised to subject-ventilator asynchrony (mean (SD):29.5% (10.8) asynchronous breaths of total breaths; n=7) compared to synchronous spontaneous breathing (asynchronous breaths 1.8% (2.9) of total breaths; n=7). There was no difference in mean alveolar septal thickness throughout upper and lower lungs lobes between pigs randomised to subject-ventilator asynchrony versus synchronous spontaneous breathing (87.3-92.2μm after subject-ventilator asynchrony, compared to 84.1-95.0 μm in synchronised spontaneous breathing; P=0.956). There were also no differences between groups in wet-to-dry ratio, diaphragmatic muscle fibre thickness, atelectasis, lung aeration, and mRNA expression levels for inflammatory cytokines pivotal in ARDS pathogenesis. CONCLUSION Subject-ventilator asynchrony during spontaneous breathing did not exacerbate lung injury and dysfunction in experimental ARDS.

TL;DR: In this article, the authors evaluated different degrees of effort during Biphasic positive airway pressure (BIVENT) on lung and diaphragm damage in experimental pneumonia, though largely used in clinical setting.

TL;DR: In this paper, a decrease in frequency of controlled breaths during biphasic positive airway pressure (BIVENT), associated with an increase in spontaneous breaths, whether pressure support (PSV)-assisted or not, would mitigate lung and diaphragm damage in mild experimental acute respiratory distress syndrome (ARDS).

TL;DR: In this paper , subject-ventilator asynchrony during spontaneous breathing did not exacerbate lung injury and dysfunction in experimental porcine ARDS, and there were no differences between groups in wet-to-dry weight ratio, diaphragmatic muscle fibre thickness, atelectasis, lung aeration, or mRNA expression levels for inflammatory cytokines pivotal in ARDS pathogenesis.

TL;DR: In patients with severe ARDS, early administration of a neuromuscular blocking agent improved the adjusted 90-day survival and increased the time off the ventilator without increasing muscle weakness.

TL;DR: The probable causes of mechanical ventilation injury and ways to prevent it are reviewed.

TL;DR: Findings are consistent with increased diaphragm-biopsy specimens from case subjects showing decreased cross-sectional areas of slow-twitch and fast-twitch fibers and a 200% higher ratio of atrogin-1 messenger RNA (mRNA) transcripts to MBD4 (a housekeeping gene) during inactivity.

TL;DR: Evaluating the association of higher vs lower PEEP with patient-important outcomes in adults with acute lung injury or ARDS who are receiving ventilation with low tidal volumes found that higher levels were associated with improved survival among the subgroup of patients with ARDS, but lower levels were not associated withImproved hospital survival.