振動障害における冷水浸漬テストにおよぼす季節影響について

抄録

For early diagnosis of vibration syndrome, peripheral circulation and sensory tests after cold water immersion of the upper extremities are being performed widely in Japan. The authors studied the seasonal effect on the immersion test and its influence on diagnosis of vibration syndrome. Eight healthy male subjects, aged from 28 to 39, were examined. The immersion tests were conducted in winter (February), spring (May), summer (August) and autumn (November) in Ube city, Japan (Table 1). The room temperatures were maintained at 10°C, 20°C and 30°C during the tests at each season. As to the exposure-to-cold test, the left hand of subject was immersed in stirred water at 10°C for ten minutes, and the changes of peripheral circulatory function and sensory function were measured. Peripheral circulatory function was assessed by the skin temperature of middle finger and the value of the nail press test on the index finger. Sensory function was assessed by 125 Hz vibratory sense threshold and pain threshold of the middle finger. The finger skin temperature was lower in autumn and winter, followed by spring, and highest in summer. In particular, the finger skin temperature in autumn was lower than that in winter at the condition of room temperature at 30°C, which is considered to be less effected by heat content in the body (Fig.1, Table3). The frequency of the appearance of cold induced vasodilation was also lower in autumn than that in winter (Table2). These findings suggest that the tonus of the vasoconstrictor in the skin vessels of finger is strongest in autumn, followed by winter. It is also suggested that the tonus remains slightly strong in spring and is weakest in summer. Furthermore, the seasonal variations in the value of the nail press test, vibratory sense threshold and pain threshold were observed at some points of measuring time during immersion test (Figs. 2-4). Of these, the variations in the value of the nail press test and vibratory sense threshold were considered to be secondary to the seasonal variation of peripheral circulatory function (Fig.6). The variation in pain threshold was considered to result from paresthesia developing in the lower room temperature at 10°C. The pain of finger during immersion test was also effected by season but the range of variation was not significant (Fig.5). The cold water immersion test as the medical examination for the workers exposed to vibration is said to be conducted in the room temperature at 20-23°C. The seasonal variations in the finger skin temperature, the value of the nail press test and vibratory sense threshold under the room temperature at 20°C were not negligible in the present experiment. Especially in summer, the effect should be taken into consideration when evaluating the examination data. If the period of medical examination must be fixed to be performed in the four seasons, autumn and winter are advisable because the tonus of vasoconstrictor is stable for relatively long time.