Open AccessComparison of baroreflex sensitivity determined by cross-spectral analysis at respiratory and 0.1 Hz frequencies in man
Author(s) -
Pavla Bothová,
Nataša Honzíková,
Bohumil Fišer,
Eva Závodná,
Zuzaováková,
Dale Robert Kalina,
Klára Honzíková,
Růžena Lábrová
Publication year - 2010
Publication title -
physiological research
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.647
H-Index - 70
eISSN - 1802-9973
pISSN - 0862-8408
DOI - 10.33549/physiolres.932009
Subject(s) - baroreflex , blood pressure , breathing , medicine , respiratory system , cardiology , spectral analysis , anesthesia , metronome , respiratory rate , heart rate , rhythm , physics , quantum mechanics , spectroscopy
Non-invasive methods of determination of baroreflex sensitivity(BRS, ms/mmHg) are based on beat-to-beat systolic bloodpressure and inter-beat interval recording. Sequential methodsand spectral methods at spontaneous breathing include transientsuperposition of breathing and 0.1 Hz rhythms. Previously, across-spectral method of analysis was used, at constantbreathing rate using a metronome set at 0.33 Hz, enablingseparate determination of BRS at 0.1 Hz (BRS0.1Hz) andrespiratory rhythms (BRS0.33Hz). The aim of the present study wasto evaluate the role of breathing in the spectral method of BRSdetermination with respect to age and hypertension. Suchinformation would be important in evaluation of BRS atpathological conditions associated with extremely low BRS levels.Blood pressure was recorded by Finapres (5 minutes, controlledbreathing at 0.33 Hz) in 118 healthy young subjects (YS: meanage 21.0±1.3 years), 26 hypertensive patients (HT: mean age48.6±10.3 years) with 26 age-matched controls (CHT: mean age46.3±8.6 years). A comparison of BRS0.1Hz and BRS0.33Hz wasmade. Statistically significant correlations were found betweenBRS0.1Hz and BRS0.33Hz in all groups: YS: r=0.52, p<0.01, HT:r=0.47, p<0.05, and CHT: r=0.70, p<0.01. The regressionequations indicated the existence of a breathing-dependentcomponent unrelated to BRS (YS: BRS0.33Hz=2.63+1.14*BRS0.1Hz;HT: BRS0.33Hz=3.19+0.91*BRS0.1Hz; and CHT: BRS0.33Hz=1.88++1.01*BRS0.1Hz; differences between the slopes and the slope ofidentity line were insignificant). The ratios of BRS0.1Hz to BRS0.33Hzwere significantly lower than 1 (p<0.01) in all groups (YS:0.876±0.419, HT: 0.628±0.278, and CHT: 0.782±0.260). Thus,BRS evaluated at the breathing rate overestimates the realbaroreflex sensitivity. This is more pronounced at low values ofBRS, which is more important in patients with pathologic lowBRS. For diagnostic purposes we recommend the evaluation ofBRS at the frequency of 0.1 Hz using metronome-controlledbreathing at a frequency that is substantially higher than 0.1 Hzand is not a multiple of 0.1 Hz to eliminate respiratory baroreflexnon-related influence and resonance effect on heart ratefluctuations.