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Slow breathing reduces sympathoexcitation in COPD

¹ Depts of Cardiology and Pneumology, ² Anaesthesiology II and Intensive Care, Georg-August University Göttingen, Göttingen, ³ Dept of Clinical Pharmacology, Hanover Medical School, Hanover, and ⁶ Specialist Lung Clinic Immenhausen, Immenhausen, Germany, ⁴ Dept of Internal Medicine, University of Pavia, and ⁵ Istituto di Ricovero e Cura a Carattere Scientifico (IRCCS) San Matteo, Pavia, Italy.

CORRESPONDENCE: S. Andreas, Lungenfachklinik Immenhausen, Robert-Koch-Strasse 3, D-34376 Immenhausen, Germany. Fax: 49 5673501101. E-mail: sandreas{at}lungenfachklinik-immenhausen.de

Keywords: Baroreflex, chronic obstructive pulmonary disease, slow breathing, sympathetic activity

Received: August 21, 2007
Accepted March 10, 2008

Neurohumoral activation has been shown to be present in hypoxic patients with chronic obstructive pulmonary disease (COPD). The aims of the present study were to investigate whether there is sympathetic activation in COPD patients in the absence of hypoxia and whether slow breathing has an impact on sympathoexcitation and baroreflex sensitivity.

Efferent muscle sympathetic nerve activity, blood pressure, cardiac frequency and respiratory movements were continuously measured in 15 COPD patients and 15 healthy control subjects. Baroreflex sensitivity was analysed by autoregressive spectral analysis and the alpha-angle method.

At baseline, sympathetic nerve activity was significantly elevated in COPD patients and baroreflex sensitivity was decreased (5.0±0.6 versus 8.9±0.8 ms·mmHg^–1). Breathing at a rate of 6 breaths·min^–1 caused sympathetic activity to drop significantly in COPD patients (from 61.3±4.6 to 53.0±4.3 bursts per 100 heartbeats) but not in control subjects (39.2±3.2 versus 37.5±3.3 bursts per 100 heartbeats). In both groups, slow breathing significantly enhanced baroreflex sensitivity.

In conclusion, sympathovagal imbalance is present in normoxic chronic obstructive pulmonary disease patients. The possibility of modifying these changes by slow breathing may help to better understand and influence this systemic disease.