The frequency response of external transducer blood pressure measurement systems: a theoretical and experimental study.

An electrical transmission line model of the class of blood pressure measurement systems that consists of a needle, or cannula, a manometer line and a transducer, is described. Transducer compliance and manometer line compliance and hysteresis losses of systems have been determined experimentally, and viscous resistance and inertance components have been calculated. Correlations between observed and theoretical frequency responses, predicted using these parameters, have shown the theory to be adequate to at least 100 Hz. The model is a useful tool for predicting the best frequency response that may be expected of a particular measurement system.