Optimizing finger systolic blood pressure measurements with laser Doppler: Validation of the second phalanx site.

OBJECTIVE Finger systolic blood pressure measurement (FSBP) has been shown helpful in the detection of distal arterial insufficiency in upper limbs. This work assesses the possibility to measure FSBP on the 2nd phalanx instead of the first one in order to improve its sensitivity and to verify this would not alter the repeatability of the measurement. METHODS In this multicenter study, FSBP was measured twice in all fingers but the thumbs in consecutive systemic sclerosis patients on the first phalanx and the second phalanx in alternate order using laser-Doppler flowmetry. RESULTS Thirty-seven patients were enrolled. The repeatability of FSBP was excellent and similar on the first and 2nd phalanxes with coefficients of variation respectively of 7.1% and 7.6%. While the correlation between the FSBP at the two sites was fair (Pearson coefficient 0.69; p < 0.001). The agreement was poor, with a mean difference of 14 mm Hg between the two sites. Significantly higher differences were found in fingers with digital ulcers. The ROC curves showed a better prediction of the 2nd phalanx measurements. CONCLUSION FSBP has an excellent repeatability whatever the site of phalanx. However, measurements performed on the 2nd phalanx have a better sensitivity for the prediction of digital ulcers.