Chest
Clinical Investigations: COPDDecreased Heart Rate Variability in Patients With Chronic Obstructive Pulmonary Disease
Section snippets
Aim of the Study
The aim of this study was to evaluate by HRV analysis the presence of autonomic dysfunction in patients with COPD and to determine whether the pattern of HR variability in this population is different from the normal population.
Study Population
Informed consent was obtained from 31 male inpatients with a history of COPD, as defined by the American Thoracic Society,18 and 32 aged-matched control subjects. The patients were between 31 and 68 years of age (mean=55 ± 10), normoxemic (mean PaO2=70.85 ± 13.93 mm Hg) and with a forced expiratory volume in 1 s (FEV1) of less then 65 percent of the predicted value (mean=52 ± 8.3 percent). Exclusion criteria were as follows: coronary artery disease; hypertension; encephalopathy; and diabetic
Results
Table 1 shows the mean values and SDs of measured and computed parameters at rest, during controlled breathing, and in passive head-up tilt.
In patients with COPD, the mean RR interval decreased after passive tilt (858 ± 127 ms vs 738 ± 130.76 ms), whereas there were no statistically significant changes during controlled breathing. Although the mean RR was slightly higher in the normal subjects during the whole test, this was not statistically significant. Significant differences between groups
Discussion
In this study, we have examined the differences in autonomic nervous control of heart rate in 31 patients with COPD compared with an age- and sex-matched control group under standardized conditions, to obtain an index of both static and dynamic neurovegetative balance, ie, at rest and during known autonomic stimuli.
The vagus nerve is known to modulate the rate of sinoatrial discharge. The possibility exists that an abnormality in the parasympathetic control of airway caliber may be reflected by
Conclusion
The complexity of the pulmonary effects of the autonomic nervous system is considerable, and our knowledge in this field remains elementary. Our results suggest that in patients with COPD, there is an imbalance in autonomic nervous system activity. This is apparently driven at rest by an increase in vagal activity and through the lack of responsiveness to sympathetic stimulation. This altered balance could contribute to the airways obstruction in COPD.
More studies are needed to increase our
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