Marco Romanelli

University of Torino

Marco Romanelli, a graduate student at the University of Torino in Italy, is exploring venous pulse wave velocity (vPWV) as a non-invasive indicator of blood volume changes. Assessing volemic status is a critical clinical challenge, and this study examined how vPWV responds to hypovolemic stress induced by lower body negative pressure (LBNP). Results showed that vPWV decreased significantly with LBNP, demonstrating greater sensitivity to blood volume changes than the commonly used collapsibility index of the inferior vena cava (IVC). These findings suggest vPWV could improve fluid status monitoring in clinical settings. Marco will present this research at the 40th Congress of the International Union of Physiological Sciences (IUPS) in September.

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Abstract

Reliable assessment of the volemic status is a primary clinical need and a still open challenge.

Venous pulse wave velocity (vPWV), has recently been reassessed as a possible non-invasive-indicator of blood volume changes (1), being related to the stiffness of vessel wall, in turn affected by venous filling.

This study aims to investigate the dependence of vPWV on the magnitude of simulated hypovolemic stimuli produced by lower-body negative pressure (LBNP) and to compare vPWV with ultrasound monitoring of the inferior vena cava (IVC) in assessing changes in volume status.

Seventeen subjects (age 21.8±2.5) underwent a randomized sequence of LBNP stimuli (10-40 mmHg, 90-s duration) while monitoring vPWV (in the left arm) and IVC ultrasound B-mode imaging. Periodic assessment of vPWV was based on generating a pressure pulse at the wrist by pneumatic cuff compression and detecting the propagated wave in the basilic vein by Doppler ultrasound (2). Continuous monitoring of IVC diameter was extracted frame-by-frame from long-axis IVC imaging, by a dedicated software (3–5).

The results showed a decrease of vPWV (p<0.001) by 19±9 and 34±12% and of IVC diameter (p<0.001) by 21±2 and 53±12% and non-significant increase of the collapsibility index (CI) (p=0.081) from 41±18 to 44± 18 and 50.3±16% at LBNP of -10 and -40 mmHg, respectively.

The vPWV demonstrated high sensitivity to hypovolemic challenges outperforming the widely employed CI. Studies on patient populations will be necessary to verify its applicability in clinical conditions and test its usefulness to monitor fluid therapies in patients.

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