Autonomic nervous activity during hand immersion in cold water in patients with vibration-induced white finger

Autonomic nervous function in response to cold was investigated in 21 patients with vibration-induced white finger (VWF) and 17 healthy controls of similar age, using power spectral analysis of heart rate variability. In a supine position, electrocardiogram and skin temperature of both index fingers were measured during immersion of right hand in cold water at 10 degrees C for 10 minutes. Autonomic nervous activity was evaluated from the power of the low-frequency component (LF: 0.02-0.15 Hz), the high-frequency component (HF: 0.15-0.40 Hz) and the ratio of the LF to the HF power (LF/HF ratio). The LF/HF ratio, an index of sympathetic nervous activity, significantly increased during the immersion in the VWF patients, but did not significantly increase in the controls. The LF/HF ratio was then significantly greater in the patients than in the controls during the first 1-2 minutes of the immersion. The HF power related to parasympathetic nervous activity did not change significantly in either group. Finger skin temperature of the immersed right hand was significantly lower in the VWF patients than in the controls during the last five minutes of the immersion and in the recovery period. The present results indicate that sympathetic nervous response to cold is significantly enhanced in VWF patients. The exaggerated sympathetic response to cold in these patients is considered to contribute to the enhanced vasoconstriction of their extremities.