Development of an optical technique for the non-invasive measurement of arterial compliance

The authors describe a simple and robust method for the measurement of pulse propagation velocity (PWV). Two probes each containing an infra-red emitting diode and a phototransistor are placed on the skin. The energy returning to each probe depends on the amount of blood the beam has passed through, and this varies as the vessel pulsates. The output from each probe is displayed in real time on a portable PC. PWV is estimated from the delay between the start of the systolic upswing in the signals from the two sites. Measurements on 6 volunteers showed that PVW values were reproducible throughout the day. In 21 subjects undergoing cardiac catheterisation, the authors found that PWV values obtained by the optical method did not differ significantly from those obtained from intra-arterial pressure measurements. A study on 213 subjects aged 45 to 55 years, in whom weight and body dimensions had been recorded at, birth, has revealed a correlation between PWV in the aorta and leg, and several indices of intrauterine growth. The authors conclude that their technique is a useful addition to the methods available for determining blood vessel elasticity. Its simplicity and ease of use make it suitable for large scale measurements in the `field´