Pulse Wave Velocity and Blood Pressure Change: Calibration and Applications

An adaptation of the technique for measuring pulse wave velocity is described in which the interval between the R wave of the ECG and the radial pressure pulse is monitored. The resulting transit time (TT) is suitable for use as an indirect measure of blood pressure change. The reliability of the measure was assessed in 5 subjects who volunteered for arterial cannulation on 2 occasions. Simultaneous recordings of intra-arterial pressure and TT were taken during a variety of maneouvres, including mental arithmetic, isometric exercise, and amyl nitrite inhalation. The dependence of changes in TT on arterial pressure was confirmed for all procedures except amyl nitrite inhalation. Linear correlations between TT and mean arterial pressure were high, varying between ?.913 and ?.98. The regression coefficients were reproducible and similar in all individuals. The reasons for the anomalous amyl nitrite response are discussed, together with the limits of application of the measure.