Effect of CPAP on intrinsic PEEP, inspiratory effort, and lung volume in severe stable COPD

Open Access
Publisher Website
Google Scholar
Abstract
Background: Intrinsic positive end expiratory pressure (PEEPi) constitutes an inspiratory threshold load on the respiratory muscles, increasing work of breathing. The role of continuous positive airway pressure (CPAP) in alleviating PEEPi in patients with severe stable chronic obstructive pulmonary disease is uncertain. This study examined the effect of CPAP on the inspiratory threshold load, muscle effort, and lung volume in this patient group. Methods: Nine patients were studied at baseline and with CPAP increasing in increments of 1 cm H2O to a maximum of 10 cm H2O. Breathing pattern and minute ventilation (V̇i), dynamic PEEPi, expiratory muscle activity, diaphragmatic (PTPdi/min) and oesophageal (PTPoes/min) pressure-time product per minute, integrated diaphragmatic (EMGdi) and intercostal EMG (EMGic) and end expiratory lung volume (EELV) were measured. Results: Expiratory muscle activity was present at baseline in one subject. In the remaining eight, PEEPi was reduced from a mean (SE) of 2.9 (0.6) cm H2O to 0.9 (0.1) cm H2O (p2O.s/min to 112.9 (21.7) cm H2O.s/min). EELV increased by 1.1 (0.3) l (pConclusion: High levels of CPAP reduce PEEPi and indices of muscle effort in patients with severe stable COPD, but only at the expense of substantial increases in lung volume.