振動障害における手指白ろう様変化発生の要因と爪圧迫テストについて

抄録

(1) Since 1964, I have mainly investigated vibration hazards of operators of gasoline powered chain-saws among forest workers. My study of the vibration hazards are divided into three themes, i.e., (i) dynamics of the peripheral blood circulation, (ii) pathological changes of the nervous function, (iii) pathological changes of the general function through disturbance of the central nervous system. In this paper, I report observations on the dynamics of the peripheral blood cicrulation.
(2) In Chubu District of Japan, I investigated 124 chain-saw operators who had experienced the appearance of white waxy changes of their fingers. It was found that (i) the primary factor of the occurrence of white waxy changes is the occurrence of the chill feeling and presumably, not any fall in the temperature of the finger skin, (ii) autobicycle riding contributed most frequently to the white waxy changes.
(3) The course of the occurrence of white waxy changes by autobicycle riding is shown in Fig. 1. I noticed white changes of the nail colour before chill feeling before the occurrence of white waxy changes. And I worked up the “nail press test” as means of a physiological examination of vibration hazards.
(4) The procedure of the “nail press test” is as follows. (i) Press the nail of the subject by the tester's thumb and 2nd finger for 10 seconds (Fig. 2). (ii) Start a stop watch to run immediately after the begining of the pressing. After 10 seconds, take quickly the tester's finger off from the subject's nail. White changes of the nail colour will gradually appear and red colour tone will recover gradually. And at last, red colour will spread in a moment over the whole area of the nail (Fig. 3). Just at that moment, stop running the watch. I called the time from the release of the press to the disappearance of white changes as the “value of nail press test”. Posture and the strain of the arm and the hand of the subject influence this value. It is important that subject should relax the arm, hand and finger in the posture as shown in Fig. 4. The value of nail press test depends on the vasospastic state of artelioles and the flow speed of the arterial blood into capillaries.
(5) The tendency is observed, that lowering of the temperatures and of the atmospheric environment as well as finger prolongs the time value of the nail press test. In workers suffering from vibration hazards, this tendency is more remarkable.
(6) Cooling test of the whole body was performed during the measurement of the temperature of finger skin and the nail press test. Subject were four chain-saw operators (A group) who experienced appearance of white waxy changes of their fingers every day, and four healthy forest workers without such experience (B group) as controls. (Table 1)
Experiment 1 : Standing outdoor for 40 min. at 5°C atmospheric temperature. Experiment 2 : Autobicycle riding for 20 min. at the speed of 30km/hr and after that standing for 20 min. outdoors.
Experiment 2 was performed when wearing thin clothes or when wearing thick clothes after warming of the body.
(7) Results of Experiment 1, 2 show that as chill feeling occured temperature of the finger skin of A group dropped more rapidly and remained at lower levels than in B group (Fig.5, Fig.6 (T) -A, Fig. 7 (T) -a). Raise the values of nail press test took place more rapidly than the fall of the temperature of the finger skin. The value increased to several tens of seconds before the appearance of white waxy changes (Fig. 5, Fig. 6 (N) -a, Fig. 7 (N) -a). White waxy changes appeared in four workers of A group (100%) on autobicycle riding wearing thin clothes.
(8) When white waxy changes appeared, no remarkable difference observed between the temperature of white waxy fingers and that of other fingers in every subject (Table. 2), (Fig. 7 (T) -a). This result showed that cold vasospastic reaction in the larger vessels, controlling