Broad-band spectral analysis of 24 h continuous finger blood pressure: comparison with intra-arterial recordings.
The present study compares the spectral characteristics of 24-h blood pressure variability estimated invasively at the brachial artery level with those estimated by measurement of blood pressure at the finger artery using the non-invasive Portapres device. Broad-band spectra (from 3x10(-5) to 0.5 Hz) were derived from both finger and intra-brachial pressures recorded simultaneously for 24 h in eight normotensive and twelve hypertensive ambulant subjects. At frequencies lower than 0.07 Hz, higher spectral estimates were obtained by Portapres than by intra-brachial measurements. The maximum overestimation occurred in systolic pressure at around 10(-2) Hz, where the amplitude of the oscillations was two times greater when measured by Portapres. A less pronounced overestimation was found for diastolic pressures. The maximum overestimation was greater during daytime than during night-time. At around 0.1 Hz, invasive and non-invasive spectra were similar. At the respiratory frequencies (0.15-0.50 Hz), the power spectra were overestimated by Portapres during daytime, and underestimated at night. These results provide reference information for the correct interpretation of Portapres data in the estimation of 24-h blood pressure spectral power.
LaRC, Centro di Bioingegneria, Fondazione Don C. Gnocchi and Politecnico di Milano, via Gozzadini 7, I-20148 Milan, Italy.
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Di Rienzo
D000328:Adult; D000375:Aging / Q000502:physiology; D018660:Blood Pressure Monitoring, Ambulatory / Q000379:methods*; D001916:Brachial Artery; D002940:Circadian Rhythm / Q000502:physiology; D005385:Fingers / Q000098:blood supply*; D006801:Humans; D006973:Hypertension / Q000175:diagnosis*; D008875:Middle Aged; D012016:Reference Values; D012815:Signal Processing, Computer-Assisted