Non-invasive assessment of unstimulated forearm arterial compliance in human subjects. Impaired vasoreactivity in hypercholesterolaemia

NONINVASIVE DETERMINATION OF ARTERIAL PRESSURE-DEPENDENT COMPLIANCE IN YOUNG SUBJECTS USING AN ARTERIAL TONOMETER

The objective of this study is to determine the pressure-dependent compliance of human radial artery in young subjects. The arterial blood pressure and the change in vessel volume of the radial artery in ten normotensive volunteers were simultaneously measured with an arterial tonometer. The arterial global compliance was calculated as the division of change in vessel volume by the difference between the systolic and the diastolic blood pressures. The arterial global compliance measured from the ten young volunteers was found to be 4.645 ± 2.739 uL/mmHg. When the arterial pressure-volume relation was assumed to be of natural logarithm, a correlation coefficient of 0.996 was yielded by curve-fit methods. Similarly, when the arterial compliance-pressure relation was fit in a natural logarithmic form, a correlation coefficient of 0.998 was obtained. In conclusion, the arterial vessel volume varies with the arterial blood pressure logarithmicly and positively, whereas a logarithmic and negative relation between the arterial global compliance and arterial blood pressure is present in human radial arteries. Thus, it is for all time necessary to take the pressure level into account if we want to compare compliance values obtained from distinct physiological situations.

Time course of forearm arterial compliance changes during reactive hyperemia

Ultrasonic studies have shown that arterial compliance increases after prolonged ischemia. The objective of the present study was to develop an alternative plethysmographic method to investigate compliance, exploring validity and clinical applicability. Forearm pulse volume (FPV) and blood pressure (BP) were used to establish the FPV-BP relationship. Forearm arterial compliance (FAC) was measured, and the area under the FAC-BP curve (FAC(AUC)) was determined. The time course curve of compliance changes during reactive hyperemia was obtained by continuous measurements of FAC(AUC) for 20 s before and for 300 s after arterial occlusion. This technique allows us to effectively assess compliance changes during reactive hyperemia. Furthermore, the selected measurement protocol indicated the necessity for continuous measurements to detect "true" maximal FAC(AUC) changes. On multivariate analysis, preischemic FAC(AUC) was mainly affected by sex, peak FAC(AUC) was affected by sex and systolic BP, percent changes were affected by plasma high-density and low-density lipoprotein cholesterol, peak time was affected by age and body mass index, and descent time was affected by plasma triglyceride levels. The proposed technique is highly sensitive and well comparable with the generally accepted echotracking system. It may thus be considered as an alternative tool to detect and monitor compliance changes induced by arterial occlusion.