Comparison of spontaneous vs. metronome-guided breathing on assessment of vagal modulation using RR variability

Daniel M. Bloomfield, Anthony Magnano, J. Thomas Bigger, Harold Rivadeneira, Michael Parides, Richard C. Steinman

Research output: Contribution to journalArticlepeer-review

113 Scopus citations


R-R interval variability (RR variability) is increasingly being used as an index of autonomic activity. High-frequency (HF) power reflects vagal modulation of the sinus node. Since vagal modulation occurs at the respiratory frequency, some investigators have suggested that HF power cannot be interpreted unless the breathing rate is controlled. We hypothesized that HF power during spontaneous breathing would not differ significantly from HF power during metronome-guided breathing. We measured HF power during spontaneous breathing in 20 healthy subjects and 19 patients with heart disease. Each subject's spontaneous breathing rate was determined, and the calculation of HF power was repeated with a metronome set to his or her average spontaneous breathing rate. There was no significant difference between the logarithm of HF power measured during spontaneous and metronome-guided breathing [4.88 ± 0.29 vs. 5.29 ± 0.30 ln(ms2), P = 0.32] in the group as a whole and when patients and healthy subjects were examined separately. We did observe a small (9.9%) decrease in HF power with increasing metronome-guided breathing rates (from 9 to 20 breaths/min). These data indicate that HF power during spontaneous and metronome-guided breathing differs at most by very small amounts. This variability is several logarithmic units less than the wide discrepancies observed between healthy subjects and cardiac patients with a heterogeneous group of cardiovascular disorders. In addition, HF power is relatively constant across the range of typical breathing rates. These data indicate that there is no need to control breathing rate to interpret HF power when RR variability (and specifically HF power) is used to identify high-risk cardiac patients.

Original languageEnglish (US)
Pages (from-to)H1145-H1150
JournalAmerican Journal of Physiology - Heart and Circulatory Physiology
Issue number3 49-3
StatePublished - 2001
Externally publishedYes


  • Heart rate variability
  • Parasympathetic nervous system
  • Power spectral analysis
  • R-R interval

ASJC Scopus subject areas

  • Physiology
  • Cardiology and Cardiovascular Medicine
  • Physiology (medical)


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