Autonomic and cerebro-vascular abnormalities in mild copd are worsened by chronic smoking

¹ Dept of Internal Medicine, University of Pavia and IRCCS Ospedale S.Matteo, Pavia, Italy
² Dept of Sport Science, Medical Section, University of Innsbruck, Austria
³ Clinical research Laboratory, Hypoxia Medical Academy, Moscow, Russia

^* To whom correspondence should be addressed. E-mail: lbern1ps{at}unipv.it.

	Abstract

Patients with chronic obstructive pulmonary disease (COPD) may develop hypercapnia and hypoxia, two main determinants of cerebral blood flow. We tested whether cerebrovascular regulation were: altered in mild COPD, modified by manoeuvres acutely improving autonomic cardiovascular modulation, influenced by smoking habit.

In 15 eucapnic normoxic mild COPD patients (8 smokers) and 28 age-matched controls (14 smokers) we monitored mid-cerebral artery flow velocity (MCFV), end-tidal carbon dioxide (CO₂-et), oxygen saturation (SaO₂%), electrocardiogram and blood pressure at rest, during progressive hypercapnic hyperoxia, isocapnic hypoxia, slow breathing, oxygen administration. MCFV, arterial baroreflex, and dynamic MCFV- blood pressure relationship (by phase analysis), were compared.

COPD- and control smokers showed higher MCFV (when corrected for CO₂), lower cerebrovascular resistance index and lower sensitivity to CO₂, with equal sensitivity to SaO₂ and phase analysis. Arterial baroreflex was depressed in all COPD. Slow breathing and oxygen administration improved baroreflex sensitivity and reduced MCFV in all COPD.

Patients with mild COPD show autonomic dysfunction. Chronic smoking induces cerebral vasodilation and impairs cerebrovascular control. All abnormalities can be partly corrected by improving the cardio- and cerebrovascular autonomic modulation, suggesting functional autonomic abnormalities present already at an early stage.

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