M. JAVORKA, I. ŽILA, K. JAVORKA, A. ČALKOVSKÁ

^{Department of Physiology, Jessenius Faculty of Medicine, Comenius University, Martin, Slovak Republic}


Received January 18, 2001
Accepted October 11, 2001

Summary
The aim of this study was to ascertain the persistence of heart rate and blood pressure oscillations at the onset of voluntary apnea in humans and to assess the dependence of the fluctuations` parameters on the chemoreceptor activity. In 24 young subjects (10 males, 14 females, mean age 20.4 years) heart rate (represented by its reciprocal value - RR-intervals), systolic blood pressure (SBP) and diastolic blood pressure (DBP) during controlled breathing (CB) of atmospheric air and oxygen followed by apnea were recorded continuously. The cosine functions were then fitted by nonlinear regression analysis to the heart rate, SBP and DBP oscillations during CB and at the onset of apnea. The parameters of oscillations were different during atmospheric air breathing compared to oxygen breathing. During oxygen breathing there was an increase of the RR-interval oscillations - relative bradycardia and enhanced magnitude of respiratory sinus arythmia. During apnea, the base level of the blood pressure oscillations was higher after breathing of atmospheric air compared o oxygen breathing. At least one cosine-like wave oscillation was present at the onset of apnea in the heart rate, SBP and DBP and the second wave was present in all assessed parameters in at least 70 % of recordings. The oscillations in RR-intervals are, to some extent, independent of blood pressure oscillations. No significant gender differences were found either in the duration of breath holding or in the RR and SBP oscillations parameters.
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Key words
Apnea · Respiratory sinus arrhythmia · Heart rate · Blood pressure · Oscillations

Reprint requests
Michal Javorka, M.D., Department of Physiology, Jessenius Medical Faculty, Comenius University, Malá Hora 4, 037 54 Martin, Slovak Republic.

ISSN 0862 - 8408