Raynaud's phenomenon and cold stress testing: a new approach.

There are a number of methods of evaluating digital blood flow in the vascular laboratory but none fulfills the criteria of providing a quick and reproducible diagnostic test for Raynaud's phenomenon. We present our experience with the use of high frequency ultrasound to provide direct real time imaging of the digital arteries. Using this method and a standardised cold challenge test, consisting of exposure of the hand to a temperature of 10 degrees C for 5 minutes, it is possible to distinguish patients with Raynaud's phenomenon from normal controls on the basis of extent of digital artery closure. The mean fall in digital artery diameter on cold challenge, expressed as a percentage of the original diameter, was 92.4% (S.D. = 16.4, S.E.M. = 2.1) in patients with Raynaud's phenomenon as against 8.7% (S.D. = 11.5, S.E.M. = 2.5) in a group of normal volunteers. Using a 45% fall in digital artery diameter as the diagnostic cut-off point, the test has a specificity of 100% and a sensitivity of 96.6% in differentiating patients with Raynaud's phenomenon from controls. It is suggested that the test could be used as objective confirmation of a clinical diagnosis and to assess the efficacy of therapeutic interventions.