[Development of an improved system for monitoring the peripheral circulation and its application. Part 2. Its application to the cold water immersion test in workers using vibratory tools].

Using an improved system for measuring skin blood flow by the thermal clearance curve, the change of the skin blood flow in the finger (finger blood flow) of the workers using vibratory tools induced by 10 degrees C cold water immersion for 10 min was observed in order to clarify the pathogenesis of vibration-induced white finger (VWF) from the aspect of peripheral circulatory function and simultaneously to demonstrate the efficiency of the system. The subjects constituted a group of 10 workers with VWF (VWF group) and 10 healthy workers without a history of hand-arm symptoms (control group). Ages and years of exposure to vibration in the two group were almost equal. The results were as follows. 1) While the finger blood flow in the control group was remarkably decreased at 1 min after the immersion, the decrease in the VWF group was low as compared with that in the control group. This result shows that vasoconstriction just after the immersion in VWF patients is not as great as that in the control group. 2) The finger blood flow in the control group at 5 min after the immersion was increased. In contrast no increase in the VWF group was observed. These results showed that cold-induced vasodilatation (CIVD) in VWF patients diminished. 3) An increase of the finger blood flow at 1 min after stopping the immersion was observed in the VWF group. These results suggest that the property of reaction to cold in VWF patients is not excessive vasoconstriction as has been hypothesized, but the diminution of CIVD. Apart from 10 workers of VWF group, observing the change of the finger blood flow in a case in which VWF was provoked by the immersion, the author found an abnormal decrease of the finger blood flow at 5 min after the immersion. This finding supports the hypothesis that the diminution of CIVD plays an important role in VWF attack as well. Concerning the characteristics of peripheral circulatory function in VWF patients, it can therefore be considered that its reaction in VWF attack is vasospasms, while the reaction to cold is the diminution of CIVD in the non-attack phase. The cold water immersion test using the system was recognized to be useful for diagnostic examination because the estimation of finger blood flows at both measuring points, 1 min and 5 min after the immersion, could fairly well discriminate VWF patients from healthy workers.(ABSTRACT TRUNCATED AT 400 WORDS)