Chronic obstructive pulmonary disease (COPD) is associated with cardiac autonomic nervous system dysregulation. This study evaluates the effects of interval hypoxic training on cardiovascular and respiratory control in patients with mild COPD.
In 18 eucapnic normoxic mild COPD patients (age 51.7 ± 2.4 years, mean ± SEM), randomly assigned to either training or placebo group, and 14 age-matched healthy controls (47.7 ± 2.8 years), we monitored end-tidal carbon dioxide, airway flow, arterial oxygen saturation, electrocardiogram, and continuous noninvasive blood pressure at rest, during progressive hypercapnic hyperoxia and isocapnic hypoxia to compare baroreflex sensitivity to hypoxia and hypercapnia before and after 3 weeks of hypoxic training. In double-blind fashion, both groups received 15 sessions of passive intermittent hypoxia (training group) or normoxia (placebo group). For the hypoxia group, each session consisted of three to five hypoxic (15–12% oxygen) periods (3–5 min) with 3-min normoxic intervals. The placebo group inhaled normoxic air.
Before training, COPD patients showed depressed baroreflex sensitivity, as compared with healthy individuals, without evident chemoreflex abnormalities. After training, in contrast to placebo group, the training group showed increased (P < 0.05) baroreflex sensitivity up to normal levels and selectively increased hypercapnic ventilatory response (P < 0.05), without changes in hypoxic ventilatory response.
Eucapnic normoxic mild COPD patients already showed signs of cardiovascular autonomic abnormalities at baseline, which normalized with hypoxic training. If confirmed in more severe patients, interval hypoxic training may be a therapeutic strategy to rebalance early autonomic dysfunction in COPD patients.
aDepartment of Sport Science, Medical Section, University of Innsbruck, Innsbruck, Austria
bDepartment of Internal Medicine, University of Pavia and IRCCS Ospedale S.Matteo, Pavia, Italy
cPulmonologist Office, Innsbruck, Austria
dPrimary Care Physician Office, Innsbruck, Austria
eHypoxia Medical Academy, Moscow, Russia
fInstitute of Motor Sciences, University of Pavia and IRCCS Sopedale S.Matteo, Pavia, Italy
Received 17 April, 2008
Revised 30 January, 2009
Accepted 20 March, 2009
Correspondence to Luciano Bernardi, MD, Clinica Medica 2, Universita' di Pavia and IRCCS Ospedale S. Matteo, 27100 Pavia, Italy Tel: +39 0382 502979; fax: +39 0382 526259; e-mail: email@example.com