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

Abstract

We have studied the effects of positi\re expiratory pressurc (PEP). continuous positive airway pressure (CPAPj 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 PO2 (Rc0,i. PCO, ( PtcC02) and SO2 (SpOz) and arterial blood gas measurements. The lrariseutaneous rneasiirements showed that the PEP treatment reduced the PtcCO,, in COPD patients by 0.S kPa and the CPAP treatment reduced it by 0. I kPa (p<0.05). The hyperventilation maneuver caused a decrease in the RcC02 of 0.7 kPa. The nocturnal treatments and measurements were all siinilar to the daytime measurements; the PtcCO? decreased by 0.4 kPa using PEP mid by 0.3 kPa using C'PAP (p<0.01). 'This indicated that all 3 methods reduced the PtcCO,. but only in the short term as the effects iasted 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 ( L.2 kPa) and a decrease in Pa02 and Sa02 during the night (1 1 prn to 7 am) without treatment. After 3 days of trcatrnent 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 therc is nojustifica!ion for treating stable hypercapnic COPD patients with these methods.