Magnitude of acute exposures to vibration and finger circulation

Changes in finger circulation were studied during and after acute exposure to increasing magnitudes of hand-transmitted vibration.

Finger skin temperature (FST) and finger blood flow (FBF) were measured in the middle fingers of both hands of 10 healthy men. The right hand was exposed for 15 minutes to 125-Hz vibration with acceleration magnitudes of either 5.5, 22, 44, or 62 m/s2 root-mean-square. The measures of finger circulation were taken before the vibration, at fixed intervals during exposure, and during a 45-minute recovery period.

The FST did not change during vibration exposure, whereas vibration of any magnitude provoked significant reductions in the FBF of the vibrated finger when compared with the preexposure FBF and the contralateral (nonvibrated finger) FBF. Vasoconstrictor aftereffects (i.e., during recovery) were observed in both fingers after the end of exposure to vibration magnitudes greater than 22 m/s2 root-mean-square. The higher the vibration magnitude, the stronger the reduction of FBF in either finger during both vibration exposure and the recovery period. This effect was stronger in the vibrated finger than in the nonvibrated finger during both periods.

Acute exposure to 125-Hz vibration can reduce FBF in both the vibrated and the nonvibrated finger, and the degree of digital vasoconstriction is related to the magnitude of the vibration. The pattern of the hemodynamic changes during and after vibration exposure suggests that complex vasomotor mechanisms are involved in the response of digital vessels to acute vibration.