Chest
Hypoxic Pulmonary Vasoconstriction and Gas Exchange During Exercise in Chronic Obstructive Pulmonary Disease
Section snippets
Patients
Eight male patients ( ± SEM, 62 ±1 year) with the standard clinical criteria of COPD and with previous functional confirmation of nonreversible chronic airflow limitation (FEV1, 1.15 ±0.12 L [36 ±3 percent predicted]) were selected from the outpatient clinic of our institution. None of them had clinical evidence of overt right heart failure. Type B COPD was present in five patients whereas the three remaining patients had predominantly type A COPD. Consent was obtained after the
RESULTS
Airflow obstruction was severe in all but patient 8, and all but one subject (patient 2) showed marked air trapping (Table 1). Hyperinflation was noticed only in patient 5. The Dco was reduced in four subjects (patients 2, 3, 5, and 6) (Table 1). Table 2 provides the metabolic, hemodynamic, and gas exchange data at rest and during exercise, before and after nifedipine. Nifedipine was well tolerated by all the patients and did not produce any symptomatic adverse side effect.
DISCUSSION
Our study documents that exercise can improve / mismatching in COPD. In addition, it confirms that nifedipine releases HPV in these patients1 and lowers right ventricular afterload during exercise.2, 3, 4 To our knowledge, however, no previous information regarding the role of HPV in modulating gas exchange during exercise in COPD has yet been raised. Our results show that the release of HPV induced by nifedipine clearly interferes with the ability of the pulmonary circulation
ACKNOWLEDGMENTS
The authors thank C. Gistau for her chromatographic work; F.A. Lopez, F. Burgos, T. Lecha, M. Simo, and C. Argaña for their skillful technical assistance; A. Cobos (Department of Statistics, University of Barcelona) for his statistical advice; and the Medical Staff of our Service for their cooperation and care of the patients.
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Supported in part by Grant CCA 8309185 from the Joint US-Spain Committee, and CICYT PA 82–1787 and PA 86–0345.
Presented in part at the American Thoracic Society Meeting, Las Vegas, May 8–11, 1988.
Recipient of a Postdoctoral Research Fellowship Award of the Fondo de Investigaciones de la Seguridad Social (FISss IIE/88), Spain
Former Research Fellow, Universitat de Barcelona (FPI/85)
Manuscript received March 20; revision accepted July 13.