A quantitative test for measuring reactivity to cold by the digital plethysmograph technique: application to 66...

The authors have developed a vascular reactivity test to cold using the digital plethysmograph technique with a mercury strain gauge. Three types of arterial reactivity were determined: local reactivity after immersion of the hand in 11 degrees C water, general reactivity after thorax ventilation, and cumulative reactivity associating both of these cooling modes. The method is based on measurement of the digital plethysmographic signal expressed as a ratio of a reference warm amplitude obtained after immersion of the hand in 45 degrees C water for 3 min. The method was tested and perfected in 66 control subjects before being applied to 65 patients with Raynaud's disease. Significant differences were noted between these 2 groups, especially in cumulative reactivity (p less than 10(-9)), which led to numerical expression of results in 5 types of increasingly important reactivity. It would appear that the test has diagnostic and prognostic value in the exploration of vascular acrosyndromes and their therapeutic follow-up.