Use of amplitude-modulated breathing for assessment of cardiorespiratory frequency response within subrespiratory frequencies

Abhijit Patwardhan, Susmitha Vallurupalli, Joyce Evans, Charles Knapp, Eugene Bruce

Research output: Contribution to journalArticlepeer-review

7 Scopus citations

Abstract

We present a new technique which uses amplitude-modulated breathing patterns to obtain estimates of frequency response between respiration and heart rate within subrespiratory frequencies. Frequency response between respiration and heart rate has been previously estimated using broadband respiration and metronomic breathing. However, the estimates obtained using these techniques show low coherence between respiration and heart rate within the subrespiratory frequencies (<0.12-0.15 Hz). The advantages of amplitude- modulated breathing are: enhancement in the degree of perturbation within subrespiratory frequencies us indicated by relatively higher coherencies between respiration and heart rate (≃0.7), and the subjects do not have to breathe at very low breathing frequencies or resort to breath holds. Use of a squared sine wave carrier modulated by sinusoidal functions enabled us to obtain energy distributions at subrespiratory frequencies without using demodulation. Results obtained at eight subrespiratory frequencies from ten subjects show that the new technique is easy to implement and produces relatively higher coherence between respiration and heart rate. The advantage of the new technique in terms of enhancing the level of perturbations within subrespiratory frequencies is particularly important, because it is in this frequency range that the interpretation of variability in heart rate in terms of autonomic origins is incompletely understood and is confounded by respiratory interactions.

Original languageEnglish
Pages (from-to)268-273
Number of pages6
JournalIEEE Transactions on Biomedical Engineering
Volume45
Issue number2
DOIs
StatePublished - Feb 1998

Bibliographical note

Funding Information:
Manuscript received April 3, 1996; revised August 12, 1997. This work was supported by the Kentucky Space Grant Consortium/NASA. Asterisk indicates corresponding author. *A. Patwardhan is with the Center for Biomedical Engineering, University of Kentucky, Lexington, KY 40506-0070 USA (e-mail: abhijit@cbme.uky.edu).

Keywords

  • Cardiorespiratory interaction
  • Heart rate spectrum
  • Transfer function

ASJC Scopus subject areas

  • Biomedical Engineering

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