Abstract
Autonomic nervous system (ANS) is severely altered in COPD patients and is improved after pulmonary rehabilitation. It was also shown that heart rate recovery (HRR)≥12 beats one minute after exercise was a good index of parasympathetic tone.
We studied 33 COPD patients before and after a 2-month pulmonary rehabilitation (PR) and recorded HRR at the first minute following a symptom limited cycling exercise and ANS measured from a night ECG recording. Quality of life was assessed by the CAT questionnaire. Daily physical activity was evaluated using an actimeter.
At baseline, the group with a HRR≥12 (10 patients, 30%), did not differ from HRR<12 group for global ANS activity (SDNN) and parasympathetic index (PNN50 and rMSSD). After PR, HRR tends to increase from 8.3±9.0 to 11.2±9.5 (P=0.06). In the HRR≥12 group only, SDNN, PNN50 and rMSSD improved significantly (all p=0.01). CAT score was also significantly better and steps count increased in this group. In the whole population, we found weak but significant correlations between HRR after PR and night parasympathetic tone (PNN50, r=0.39, p=0.03; rMSSD, r=0.41, p=0.03). CAT score was inversely related to HRR (r=0.45, p=0.01) and steps count increased with HRR (r=0.55, p=0.008).
We conclude that HRR≥ 12 is not a reliable index of parasympathetic tone in COPD patients before PR but reflects the improvements of ANS index, quality of life and daily physical activity induced by PR.
- © 2014 ERS