<p>Respiratory Mechanics and Diaphragmatic Dysfunction in COPD Patients Who Failed Non-Invasive Mechanical Ventilation</p>

Abstract

BackgroundAlthough non-invasive mechanical ventilation (NIV) is the gold standard treatment for patients with acute exacerbation of COPD (AECOPD) developing respiratory acidosis, failure rates still range from 5% to 40%. Recent studies have shown that the onset of severe diaphragmatic dysfunction (DD) during AECOPD increases risk of NIV failure and mortality in this subset of patients. Although the imbalance between the load and the contractile capacity of inspiratory muscles seems the main cause of AECOPD-induced hypercapnic respiratory failure, data regarding the influence of mechanical derangement on DD in this acute phase are lacking. With this study, we investigate the impact of respiratory mechanics on diaphragm function in AECOPD patients experiencing NIV failure.MethodsTwelve AECOPD patients with respiratory acidosis admitted to the Respiratory ICU of the University Hospital of Modena from 2017 to 2018 undergoing mechanical ventilation (MV) due to NIV failure were enrolled. Static respiratory mechanics and end-expiratory lung volume (EELV) were measured after 30 mins of volume control mode MV. Subsequently, transdiaphragmatic pressure (Pdi) was calculated by means of a sniff maneuver (Pdisniff) after 30 mins of spontaneous breathing trial. Linear regression analysis and Pearson’s correlation coefficient served to assess associations.ResultsAverage Pdisniff was 23.3 cmH2O (standard deviation 29 cmH2O) with 3 patients presenting bilateral diaphragm palsy. Pdisniff was directly correlated with static lung elastance (r=0.69, p=0.001) while inverse correlation was found with dynamic intrinsic PEEP (r=−0.73, p=0.007). No significant correlation was found with static intrinsic PEEP (r=−0.55, p=0.06), EELV (r=−0.4, p=0.3), airway resistance (r=−0.2, p=0.54), chest wall, and total elastance (r=−0-01, p=0.96 and r=0.3, p=0.36, respectively). Significant linear inverse correlation was found between Pdisniff and the ratio between Pdi assessed at tidal volume and Pdi sniff (r=−0.82, p=0.02).ConclusionThe causes of extreme DD in AECOPD patients who experienced NIV failure might be predominantly mechanical, driven by a severe dynamic hyperinflation that overlaps on an elastic lung substrate favoring volume overload.

Spontaneous Breathing and Evolving Phenotypes of Lung Damage in Patients with COVID-19: Review of Current Evidence and Forecast of a New Scenario

“…Indeed, the contractile capacity of the diaphragm is closely related to the length-tension relationship of the muscle. The active tension developed by the muscle during contraction is a function of the length of the muscle at rest before stimulation, which in turn is influenced by lung volume [ 55 ]. Ppl swing (i.e., DPes) following phrenic nerve stimulation decreases progressively, with increasing expiratory lung volume, by applying high levels of PEEP [ 52 , 56 , 57 ].…”

Diaphragmatic thickening fraction as a potential predictor of response to continuous positive airway pressure ventilation in Covid-19 pneumonia: A single-center pilot study

“…Ultrasound has been used for the assessment of diaphragm function in different clinical situations including respiratory failure requiring non-invasive ventilation. ( Cammarota et al, 2019 ; Marchioni et al, 2019 ; Ricoy et al, 2019 ) In particular the diaphragmatic thickening fraction (DTF) has been shown to correlate with pressure-generating capacity of the muscle ( Ueki et al, 1995 ), work of breathing and respiratory effort. ( Umbrello et al, 2015 ; Vivier et al, 2012 )…”

Accuracy of the dynamic signal analysis approach in respiratory mechanics during noninvasive pressure support ventilation: a bench study

“…One study investigated the effects of respiratory mechanics on the diaphragm function in patients with an acute exacerbation of chronic obstructive pulmonary disease (COPD) who were experiencing noninvasive ventilation (NIV) failure. 20 They stated that the ventilatory strategy and the pharmacological approach might be able to empty the lung. Therefore, the lung volume that was measured during controlled ventilation might represent static hyperinflation, but it does not correspond to the lung volume that was achieved during the spontaneous breathing trial, which is subject to dynamic hyperinflation.…”