Author + information
- Received May 20, 1994
- Revision received September 23, 1994
- Accepted September 28, 1994
- Published online March 1, 1995.
- Gary C. Butler, PhD1,
- Matthew T. Naughton, MB, BS, FRACP1,
- M. Atiar Rahman, MB, BS, PhD1,
- T. Douglas Bradley, MD, FRCPC2 and
- John S. Floras, MD, DPhil, FRCPC, FACC*
- ↵*Address for correspondence: Dr. John S. Floras, Division of Cardiology, Mount Sinai Hospital, Room 1615, 600 University Avenue, Toronto, Ontario MSG TX5, Canada.
Objectives. Our objective was to determine whether continuous positive airway pressure augments the low heart rate variability of congestive heart failure, a marker of poor prognosis.
Background. Nasal continuous positive airway pressure improves ventricular function in selected patients with heart failure.
Methods. In 21 sessions in 16 men (mean [±SE]age 56 ± 2 years) with New York Heart Association functional class II to IV heart failure, we assessed the effects of 45 min with (n = 14) and without (as a time control, n = 7) nasal continuous positive airway pressure (10 cm of water) on heart rate variability and endexpiratory lung volume. Coarse-graining spectral analysis was used to derive total spectral power (PT), its nonharmonic component (fractal power [PF]) and the low (0.0 to 0.15 Hz [PL]) and high (0.15 to 0.50 Hz [PH]) frequency components of harmonic power. Standard deviation of the RR interval, high frequency power and the PH/PTratio were used to estimate parasympathetic activity in the time and frequency domains, and the PH/PTratio was used to estimate cardiac sympathetic activity in the frequency domain.
Results. Use of continuous positive airway pressure increased end-expiratory lung volume by 445 ± 82 ml (p < 0.01) and both time (p < 0.006) and frequency domain indexes of heart rate variability: Total spectral power (p < 0.01), nonharmonic power (p < 0.023) and low (p < 0.04) and high (p < 0.05) frequency components of harmonic power all increased. Time alone had no effect on these variables. By comparison, the PH/PTratio increased during nasal continuous positive airway pressure (p < 0.004), whereas the PL/PHratio was unchanged. Breathing rate remained constant in both groups.
Conclusions. Short-term application of nasal continuous positive airway pressure increases heart rate variability and time and frequency domain indexes of parasympathetic activity without influencing cardiac sympathetic activity. This increase may occur reflexively, through stimulation of pulmonary mechanoreceptor afferents.
↵1 Drs. Butler, Naughton and Rahman are Fellows of the Medical Research Council of Canada.
↵2 Drs. Bradley and Floras are recipients of Career Scientist Awards from the Ministry of Health of the Province of Ontario, Toronto.
This study was supported by Operating Grant MT 11607 from the Medical Research Council of Canada, Ottawa.
- Received May 20, 1994.
- Revision received September 23, 1994.
- Accepted September 28, 1994.
- American College of Cardiology