engleski

Circadian stability of some cardiac parameters

Along withcardiac parameters as dependent variable, their resting values are usually used as reference points to be compared with changes caused by the independent variables. However, the resting level parameters were frequently shown unreliable, due to environmental effects. The aim of this study was to examine the reliability and validity of resting level cardiac parameters, against their level during the delta phase of EEG (deep sleep). This study included 16 subjects, aged 19 to 22, whose cardiac R-R intervals were registrated hourly during 24 hours. After this, every subject was left to sleep, and when he was in the EEG delta phase (deep sleep), his cardiac R-R intervals were recorded. The comparison of the mean R-R intervals and their variability in the EEG delta phase of sleeping with the same parameters at the wake resting level showed marked differences, suggesting that cardiac parameters in the EEG sleep phase should be used as more reliable cardiac reference value than the resting level parameters, since the reliability of the latter changes in the course of the day.

R-R intervals; resting level parametars; EEG delta phase parametars; circadian changes

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