Studies on the Raynaud's Phenomenon of Occupational Origin : I. On the Provocation of Raynaud's Phenomenon and the Recovery Process of Its Appearance

Experiments were designed to provoke the Raynaud's phenomenon by immersion of hands into cold water (4°C) for 1 min. under three levels of conditions in order to observe changes of the skin temperature under these conditions and also to see the disappearance of this imitiation of the Raynaud's phenomenon. Subjects were used as two groups. One was the user of vibrating tools who complained Raynaud's phenomenon, the other was the control. The obtained results were as follows: (1) The ratio of provoked cases among the examinees was 0% under the room temperature 28°C, it was 14.2% under the air temperature of 6°C hands being kept at 25°C, and it was 78.5% under the air temperature of 6°C. These findings seemed to indicate that the Raynaud's phenomenon of occupational origin occured by the constriction of surface vessels, partly by a direct action of cold to the finger, and partly by the reflex action through the vasomotor nerves. (2) As the ratio of provoked cases was low under the condition which kept both hands warm, the prevention of attack would be realized by keeping hands warm. (3) It was also found that the Raynaud's phenomenon could be provoked by the provocation test to the user of vibrating tools who had not yet complained Raynaud's phenomenon. (4) The remarkable decrement of the skin temperature and the delay of its recovery to the former level were confirmed under the air condition of 28°C in a subject who had experienced the white finger 40-50 times during three years. This example suggested that the critical temperature which was sufficient to provoke the phenomenon had been changed according to the change of microcirculation function and that the threshold had been raised. (5) The skin temperature of finger which provoked Raynaud's phenomenon (appearance-finger) was not always lower than the control finger which did not (non-appearance finger). This means that blood volume in the arterioles and arteriae was showing almost no difference between them. And also, the temperature of the appearance-finger before the cold immersion was not necessarily be lower than the non-appearance finger. (6) The rapid increase of the skin temperature was observed at the non-appearance finger before disappearance of Raynaud's phenomenon, while at the appearance finger it occurred after disappearance. The degree of increase of skin temperature was by 8.9±1.9°C higher than the skin temperature before immersion. This was named "Rebound phenomenon of skin temperature" a