CPAP and EPAP elicit similar lung deflation in a non-equivalent mode in GOLD 3-4 COPD patients

Lung hyperinflation is associated with inspiratory muscle strength reduction, nocturnal desaturation, dyspnea, altered cardiac function and poor exercise capacity in advanced COPD.

We investigated the responses of inspiratory capacity (IC) and inspiratory muscle strength (PImax), comparing continuous positive airway pressure (CPAP) and expiratory positive airway pressure (EPAP) with the main hypothesis that there would be similar effects on lung deflation.

Eligible patients were submitted to 10 cmH₂ O CPAP and EPAP on different days, under careful ECG (HR) and peripheral oxygen saturation (SpO₂ ) monitoring.

Twenty-one eligible COPD patients were studied (13 male/8 female, FEV₁ % predicted of 36.5 ± 9.8). Both CPAP and EPAP demonstrated significant post-pre (Δ) changes for IC and PImax, with mean ΔIC for CPAP and EPAP of 200 ± 100 mL and 170 ± 105 mL (P = .001 for both) in 13 and 12 patients (responders) respectively. There were similar changes in % predicted IC and PImax (∼7%, P = .001 for both) for responders and poor responder/non-responder agreement depending on CPAP/EPAP mode (Kappa = .113, P = .604). There were no differences in CPAP and EPAP regarding intensity of lung deflation (P =.254) and no difference was measured regarding HR (P = .235) or SpO₂ (P = .111)_. CONCLUSIONS: Both CPAP and EPAP presented a similar effect on lung deflation, without guaranteeing that the response to one modality would be predictive of the response to the other.