Effects of hypoxia on cardiorespiratory dynamic interaction within the low frequency region

S. Mullick, E. Bruce, A. Cross, A. Patwardhan

Research output: Contribution to journalArticlepeer-review


To investigate low frequency cardiorespiratory interaction we recorded ECG (Lead II), CO2 and ventilation in 10 awake subjects during broadband hypoxic stimulation with a mean F1O2 level of 16.5% and 12.5% Spectral broadening was obtained by pseudo random binary switching of inspired O2 level between 21% and either 12% or 4% Responses to changes in F1O2 in the low frequency region (< 1/2 breathing frequency) were estimated using parametric (prediction error method) and non-parametric methods (averaged penodograms) Cardio-respiratory responses during 16.5% mean F1O2 were small For 12.5% mean F1O2: mean R-R intervals decreased from 803 (+7-24.47) msec while breathing room air to 765 (+/-12.9) msec during hypoxia (p=0.035). Maximum gain of transfer function between F1O2 and R-R interval was 1.27 +/- 0.511 msec/torr. Parametric modeling yielded a model with four poles and two zeros as a best fit between F1O2 and R-R interval Partial coherences showed that fluctuations in ventilation and R-R interval were coherent in all subjects. This interaction may contribute to the cardiovascular effects of obstructive sleep apnea (OSA) where amplitude of oscillations in heart rate in the very low frequency (0.008-0.04 Hz) region increase.

Original languageEnglish
Pages (from-to)A472
JournalFASEB Journal
Issue number3
StatePublished - 1997

ASJC Scopus subject areas

  • Biotechnology
  • Biochemistry
  • Molecular Biology
  • Genetics


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