[Assessment of the mechanical properties of peripheral arteries using photosensors and its application]

I have carried out fundamental experiments to observe the mechanical properties of peripheral arteries in healthy subjects using photosensors. To assess the mechanical properties, I measured them and evaluated the severity of peripheral vascular disturbances in 33 chain saw workers. On the basis of the intrinsic volume-pressure relationship in normal arteries, the elasticity was evaluated through the vascular volume ratio (V/V0) at which transmural pressure (Ptr) was 30mmHg. Furthermore, nonlinearity with a clear onset and the maximum point of the AC component of the intensity of transmitted light (delta I), with a rapid increase of vascular volume around this point, were observed through changes in V/V0. This nonlinearity was also observed through changes in relative vascular volume (V/VP40) for the reduction rate of cuff pressure (Pc) from systolic blood pressure to 40mmHg. The significantly low value of V/V0 (Ptr = 30mmHg) in old healthy subjects compared with young subjects suggested that V/V0 (Ptr = 30mmHg) tended to decrease with aging. It was impossible to calculate V/V0 because the normal nonlinearity was not observed in many measurements for chain saw workers. The arterial properties observed in these workers were classified into four types based on nonlinear changes: the normal type (Type N); Type I, in which the onset and maximum points of delta 1 were detected but V/V0 showed an abnormal value; Type II, in which the maximum point was not detected, and Type III, in which it was difficult to detect even the onset point. These four types were separated from changes in V/VP40 with the reduction of Pc. The classification of severity due to arterial opening delay, which was evaluated by changes in V/VP40, corresponded to the alternations in nonlinearity in arteries. The results obtained in this study indicate that the peripheral vascular disturbance in chain saw workers is to be understood as an arterial opening disturbance with the loss of normal nonlinearity, in connection with an organic abnormality of arteries.