The diagnosis of deep venous thrombosis using laser Doppler skin perfusionmeasurements

Compression ultrasonography (CUS) falls short in the diagnosis of deep veno us thrombosis in asymptomatic patients and thrombi limited to the calf vein s. Alternatively, laser Doppler fluxmetry (LDF) may be useful for this purp ose, as it can measure the peripheral vasoconstriction response upon an inc rease in venous pressure, which is hypothetically preactivated upon venous damming by a thrombus. We investigated the merits of LDF: in the diagnosis of DVT. In 81 outpatients, referred with clinically suspected unilateral DV T, skin perfusion in the symptomatic and contralateral legs was measured in the big toe by measuring resting flux (RF) before and during an increase i n venous pressure by inflating an ankle cuff to SO mm Hg. The percentage of LDF reduction (LDFr) was used as a parameter to detect DVT and compared wi th an independent gold standard (a combination of CUS, D-dimer testing, and 3-month clinical follow-up). The prevalence of DVT was 31%. LDFr in sympto matic legs with DVT [24%; interquartile range (IQR) 8-44%] was significantl y (P < 0.001) lower than in symptomatic legs without DVT (60%; IQR 44-70%). Assessment of the diagnostic accuracy of LDF yielded an area under the ROC curve of 0.79. The optimum cutoff value resulted in a sensitivity and a sp ecificity of 80 and 72%, respectively. LDFr is reduced in legs with DVT, su pporting the hypothesis of preactivation of the peripheral vasoconstriction response. The diagnostic value of LDF measurements is not likely to surpas s that of CUS in symptomatic patients, but may be of additional use in situ ations where CUS is less sensitive. (C) 2000 Academic Press.