R. Lurf, R. Semerad, M. Meindl, C. Mayer, B. Hametner, T. Weber, S. Wassertheurer:
"Frequency Response of Blood Pressure Cuffs based on Step Response and forced sinusoidal harmonic Excitation";
Background. Pulse wave analysis (PWA) using cuff based methods emerged
within the last years. Compared to traditional sensors used in PWA like catheters and piezo gauges very little is known on the frequency response of cuff based systems according to standard measurement and systems theory. Therefore the aim of this work is the investigation of the capability of blood pressure cuffs to register the dynamical behavior of the arterial pulse appropriately.
Methods. To evaluate the dynamic behavior of cuff based sensor chains we performed both tests on step response (similar to "pop test") as well as forced sinusoidal harmonic excitation by the means of a fully automated and standardized custom testing bench. The stepwise variation of cuff pressures and/or bladder volumes and cuff sizes was intended to account for various anatomical situations faced in clinical practice.
Results. The resonant frequencies of the evaluated systems are in the range of 110 Hz (Fig. 1a). Similar results have been obtained for both step response method and harmonic excitation. This behavior did not vary over a pressure range from 80 to 200 mmHg. Nevertheless we observed that pressure-volume relation had significant influence on the cuffs frequency response. In particular too tightly fitted cuffs lead to chaotic results (Fig. 1b). Too loosely fitted cuffs causes a loss in resolution.
Conclusions. Based on our actual data blood pressure cuffs provide acceptable capabilities to cope with the dynamics of the arterial pulse for PWA use. This is only valid for properly fitted and inflated cuffs.
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