The effect of cooling on toe systolic pressures in subjects with and without Raynaud's syndrome in the lower extremities.

The effect of changes in local and body temperature on the toe systolic pressures was studied in 20 subjects with and 30 without Raynaud's syndrome in the toes. The pressures were significantly lower in the group with Raynaud's syndrome under all experimental conditions (P less than 0.01). The pressures were significantly lower during body cooling than during body warming in both groups (P less than 0.01). The mean decrease with body cooling was 58 mmHg in the group with Raynaud's syndrome and 24 mmHg in the control subjects (P less than 0.01). During body cooling pressures fell to less than 30 mmHg in 70% of subjects with Raynaud's syndrome and in 3% of the controls. Local cooling from 30 to 10 degrees C during body cooling resulted in a significant mean decrease in pressure of over 40 mmHg in both groups (P less than 0.01) and the pressure fell below 30 mmHg in over 90% of the group with and in 26% of those without Raynaud's attacks. The results indicate the importance of body cooling and local temperature in the mechanism of vasospasm in the toes. They are also relevant to the diagnosis of Raynaud's syndrome in the lower limbs and have implications for the testing of patients with arteriosclerotic occlusion since erroneously low pressure values could be obtained in tests when the feet are cold.