Digital photoplethysmography and light reflection rheography. A clinical comparison.

BACKGROUND: Light reflection rheography (LRR) is appropriate for the global assessment of calf-pump insufficiency regardless of whether it is caused by varicosity, the post-phlebitic syndrome, or deep venous thrombosis. The instrument has been increasingly used by many phlebologists. Digital photoplethysmography (D-PPG) is a further development of this well-established LRR. With this D-PPG instrument it is possible, in contrast to LRR, to calibrate the reflected light. OBJECTIVE AND METHODS: To compare the venous refilling times of both the LRR and the D-PPG when measured at the same time on the same leg. We also evaluated the practical use of both instruments. In total we performed 152 simultaneous measurements with both instruments. RESULTS: We found a statistically significant correlation when we compared the venous refilling time of both LRR and D-PPG (r = .664; P < .001). The observed agreement between both instruments for detecting a disturbed venous refilling time (< or = 25 seconds) is 92%. CONCLUSION: Both instruments seems to correlate as has been shown in this and other studies. The D-PPG has the advantage of being more handy. Furthermore the reflected light is calibrated, which enables to compare intra- and interindividual measurements.