Postocclusive Hyperemia Measured with Laser Doppler Flowmetry and Transcutaneous Oxygen Tension in the Diagnosis of Primary Raynaud's Phenomenon: A Prospective, Controlled Study

Abstract

The aim of this study was to measure the sensitivity and specificity of transcutaneous oxygen tension and postocclusive hyperemia testing using laser Doppler flowmetry in patients with primary Raynaud's phenomenon. One hundred patients and one hundred controls were included in the study. Baseline microvascular blood flow and then time to peak flow following occlusion were measured using laser Doppler flowmetry. Afterwards, the transcutaneous oxygen tension was recorded. The sensitivities of baseline microvascular blood flow, postocclusive time to peak flow, and transcutaneous oxygen tension were 79%, 79%, and 77%, respectively. The postocclusive time peak flow had a superior specificity of 90% and area under the curve of 0.92 as compared to 66% and 0.80 for baseline microvascular flow and 64% and 0.76 for transcutaneous oxygen tension. Time to postocclusive peak blood flow measured by laser Doppler flowmetry is a highly accurate test for differentiating patients with primary Raynaud's phenomenon from healthy controls.

Figure 1

Position of the probes and measuring equipment on the hand: (a) TcPO₂ probe, (b) pressure cuff, (c) thermometer, and (d) LDF probe and probe holder.

Figure 2

Difference in values obtained for bMBF, tpMBF, and TcPO₂ between controls and patients with primary RP. bMBF: baseline microvascular blood flow; tpMBF: postocclusive time to peak microvascular blood flow; TcPO₂: transcutaneous oxygen tension.

Figure 3

ROC curves of the predictive power of basal microvascular blood flow, LDF measures of time to max blood flow following vascular occlusion, and TcPO₂ on the presence or absence of Raynaud's syndrome. bMBF: baseline microvascular blood flow; tpMBF: postocclusive time to peak microvascular blood flow; TcPO₂: transcutaneous oxygen tension.