Venous pulse wave velocity

Central venous pressure and volume status are relevant parameters for the characterization of the patient's haemodynamic condition and for the management of fluid therapy however, their invasive assessment is affected by various risks and complications while non-invasive approaches provide only imprecise and subjective indications. Aim of the present study is to explore the possibility to assess changes in venous pressure from changes in the venous pulse wave velocity (vPWV). In 9 healthy subjects, pressure pulses were generated artificially in the veins by a PC-driven rapid inflation of a pneumatic cuff (300mmHg in <1sec) placed around a foot. Passage of the pulse wave in the superficial femoral vein distally to the inguinal ligament was detected by Doppler flowmeter and the latency from the pressure stimulus was measured. The vPWV was then calculated as the ratio between traveling distance and latency. Changes in leg venous pressure were obtained by raising the trunk of the subject from the initial supine position by 30 and 60 deg. In each position 15 pressure pulses were delivered every 30 s, at the end-expiratory phase for vPWV assessment. Venous pressure in the leg was non-invasively estimated by assessing the point of collapse of the jugular or axillary vein. The vPWV increased from 1.64±0.06(supine) to 2.13±0.26 (60 deg) (Student’s t- test, p<.01) and exhibited a very strong correlation with leg venous pressure (overall r=0.76). Differences in vPWV among the three positions were statistically significant also on an individual basis in 8/9 subjects (ANOVA + Tukey's HSD post-hoc, p<.01). These preliminary results show that vPWV may be easily assessed in healthy subjects and may constitute a good non-invasive indicator of venous pressurechanges.