Effects of Positive Expiratory Pressure (PEP), Continuous Positive Airway Pressure (CPAP) and Hyperventilation in COPD Patients with Chronic Hypercapnea Merja Herala.

Abstract

We have studied the effects of positive expiratory pressure (PEP), continuous positive airway pressure (CPAP) and hyperventilation on 9 hypoxemic and hypercapnic chronic obstructive pulmonary disease (COPD) patients. All the patients were in a stable condition and received continuous oxygen. PEP and nasal CPAP were each given for 3 days in random order once every hour during the day and 3 times overnight. The effects of treatment were compared with a 3-day period in which the patients had no treatment for C02 elimination. The effects were based on transcutaneous measurements of P02 (PtcOi), PC02 (PtcC02) and S02 (Sp02) and arterial blood gas measurements. The transcutaneous measurements showed that the PEP treatment reduced the PtcCOo in COPD patients by 0.5 kPa and the CPAP treatment reduced it by 0.1 kPa (p<0.05). The hyperventilation maneuver caused a decrease in the PtcCO-. of 0.7 kPa. The nocturnal treatments and measurements were all similar to the daytime measurements; the PtcC02 decreased by 0.6 kPa using PEP and by 0.3 kPa using CPAP (p<0.01). This indicated that all 3 methods reduced the PtcCOo. but only in the short term as the effects lasted for less than 4 min. COPD patients had no “late response” after any form of treatment. Arterial blood gases in COPD patients showed an elevation in PaC02 (1.2 kPa) and a decrease in Pa02 and SaQ2 during the night (11 pin to 7 am) without treatment. After 3 days of treatment with PEP and CPAP, the same pattern was noticed. The PaC02 increased with both therapies, 1.3 kPa with PEP and 0.6 kPa with CPAP. Our data indicate that the effects were not of clinical significance and there is no justification for treating stable hypercapnic COPD patients with these methods. © 1995, Informa UK Ltd. All rights reserved.