Assessment of Peripheral Circulatory Function among Workers Exposed to Hand-Arm Vibration using Laser Doppler Perfusion Imager

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Laser Doppler perfusion imaging(LDPI) is a new technique for mapping cutaneous blood flow. The method employs a two-dimensional horizontal scanning of the flow in a specific tissue, and makes it possible to visualize the spatial variation over the region of interest. The aim of this study was to clarify the usefulness of the LDPI technique in the assessment of peripheral circulatory functions among workers exposed to hand-arm vibration.In the preliminary study, we measured the finger skin blood perfusion of 8 young healthy male volunteers (34.1±2.9 years) using LDPI in various testing conditions. The skin blood perfusion decreased markedly under the room temperature of 21℃ compared to 23℃ and 25℃ conditions. Significant differences in the perfusion values were observed between the three levels of room temperature. In addition, the finger skin blood perfusion tended to be low during the hand was immersed in water, irrespective of the water temperature. However, the decrease of perfusion … More during the immersion was slight and showed similar values independent of the depths under the water. It is, therefore, suggested that the LDPI technique enables a monitoring of skin blood perfusion of the hand being immersed in cold water and that the assessment of skin blood perfusion requires a strictly controlled condition of ambient temperature.In the experimental study, the changes in the finger skin blood perfusion in response to cold water immersion test (10℃, 10min) were evaluated in 47 male volunteers aged 27 to 63 years (42.5±8.4 years). None of the subjects had complications relating to peripheral circulatory impairments of the hands. The finger blood perfusion reduced sharply as a result of immersion of the hand in cold water. However, the perfusion value increased gradually until the end of the immersion. After removal of the hand from the cold water, the finger blood perfusion recovered rapidly and nearly reached the baseline value. The blood perfusion values were significantly correlated with age, and subjects in the 50 years group had significantly lower values than the 30 years group. These results indicate that the changes in finger skin blood perfusion in response to cold water immersion are different by age group and thus the age-related variation should be considered in the assessment of peripheral circulatory function of workers exposed to hand-arm vibration.In addition, we examined 16 subjects, aged 46 to 59 years (52.9±3.4 years), who were selected from workers operating vibrating tools such as chainsaws and bush cleaners in private forestry enterprises. When compared to the control subjects of similar age, the vibration-exposed subjects had lower finger skin blood perfusion at baseline. The blood perfusion of the exposed subjects remained unchanged at the lowest level over the period of cold water immersion, while that of the control subjects showed a gradual increase. At the recovery phase following the immersion, the blood perfusion of exposed subjects had no tendency to recover as the time span increased. There were significant differences in the perfusion values of the two groups of subjects at baseline, the latter phase of the cold water immersion, and throughout the recovery period after statistical adjustments for the effects of age and room temperature.In conclusion, the findings of this study suggest that the LDPI technique enables visualizing and quantifying the peripheral vascular effects of cold water immersion on the finger skin blood perfusion and thus has the potential of providing more detailed and accurate information that may help detect the peripheral circulatory impairment in the fingers of vibration-exposed workers. Less