Arterial volume distensibility – the relative change in blood volume for a known change in arterial transmural pressure – provides an indirect measure of the structural properties of the artery wall. The measured arterial properties can offer useful diagnostic information. For example, a local decrease in arterial compliance is related to an increased risk of cardiovascular disease.

In the Physiological Measurement paper, Zheng and Murray develop a simple, non-invasive method for measuring arterial volume distensibility and use it to investigate the effect of age on peripheral arm arteries. The study quantified age-related changes at different transmural pressures, induced using a specialized long pressure cuff on the whole arm.

The technique involves recording electrocardiogram and finger and ear photoplethysmograms simultaneously at five arterial transmural pressures, induced by inflating the cuff to 0, 10, 20, 30 and 40 mmHg (thus reducing the transmural pressure by the same amount). These data were then used to calculate arm pulse propagation time, arm pulse wave velocity and arterial volume distensibility. The researchers assessed the method using 100 healthy volunteers, divided into five age ranges.

Increasing the external cuff pressure caused nonlinear increases in the arm pulse propagation time and arterial volume distensibility, while the arm pulse wave velocity decreased nonlinearly. The greatest effects were seen at the highest pressure. Changing the cuff pressure from 0 to 40 mmHg increased the arterial volume distensibility from 0.102% to 0.232% mmHg–1, increased the arm pulse propagation time by 36% and reduced the arm pulse wave velocity by 33%.

Data revealed that arterial volume distensibility had a significant inverse relationship with age. This dependence was more pronounced at higher external pressures (lower transmural pressures) where the peripheral arm arteries are more complaint. At 40 mmHg cuff pressure, for example, arterial volume distensibility decreased by 47% for an age increase from 20 to 70 years; without external pressure, the decrease was just 21%.

Results also showed that arterial volume distensibility was inversely related to resting mean arterial pressure and diastolic blood pressure, again with increasing significance as cuff pressure increased. At 40 mmHg cuff pressure, arterial volume distensibility fell by 54% for a mean arterial pressure increase from 75 to 105 mmHg, and by 57% for a diastolic blood pressure increase from 60 to 90 mmHg.

"These findings have implications in non-invasive studies for differentiating normal from diseased arteries, for monitoring development of peripheral vascular diseases, for detecting changes in the endothelium and even for investigating long-term effect of drugs on disease treatment," explained Zheng. "Furthermore, this simple measurement technique could also be performed easily to study the effect of ageing, smoking and alcohol on arterial properties."

The researchers are now collaborating with colleagues from Newcastle University's Institute of Ageing and Health, to validate their novel arterial compliance measurement technique. "Winning the Martin Black Prize gives us a great feeling of achievement," Zheng told medicalphysicsweb. "This award is extremely valuable in that it recognizes a simple and creative technique."

Pick of the papers

The Martin Black award is an annual prize awarded by IOP Publishing, the publishers of Physiological Measurement, in association with the journal owners, the Institute of Physics and Engineering in Medicine (IPEM). The responsibility for deciding the ultimate winner falls to the Editorial and International Advisory Boards of the journal. A shortlist was constructed using referees' comments and ratings, and then the board members personally assessed and ranked the selected papers.

The shortlisted papers for the 2011 Martin Black award are listed below in alphabetical order.