Choice of tests for vascular laboratory evaluation of venous reflux

The purpose of this study was to define the relative abilities of photoplethysmography (PPG), air plethysmography (APG), and duplex scanning (DS) in determining the presence or absence of venous reflux in patients with various clinical grades of venous insufficiency. This prospective study compared PPG-determined venous recovery times (VRT), APG-derived venous filling indices (VFI), and DS-determined venous reflux times as indicators of reflux in limbs with clinical grades 0-3 venous insufficiency. Data were analyzed for mean values of VRT and VFI, prevalence of abnormal VRT and VFI according to clinical grade, and ability of the presence of duplex-determined reflux to resolve discrepancies between clinical grade, and the results of VRT and VFI. One-hundred forty lower extremities in 76 patients were studied including 45 limbs that were clinically normal (clinical grade 0) and 95 limbs that were clinically abnormal (51 grade 1, 21 grade 2, 23 grade 3). In grade 0 limbs, VFI was abnormal in 8.7% and VRT was abnormal in 13% (p = NS). VRT was abnormal in 49% of grade 1, 38% of grade 2, and 100% of grade 3 limbs. VFI was abnormal in 47% of grade 1, 43% of grade 2, and 78% of grade 3 limbs. DS agreed with clinical classification of limbs as normal (grade 0) in 89% of examinations. When clinical grade was abnormal (grade 1-3), 73% of duplex examinations were also abnormal. In the 37 limbs where VFI or VRT were not consistent with clinical grade, DS findings of reflux correlated with clinical grade in only one-half of limbs. The ability of VRT or VFI to detect reflux was significantly improved when the standard for the presence of reflux was duplex scan results rather than clinical grading (59 vs. 83%, p = 0.008). In conclusion, VRT and VFI produce similar results in determining presence or absence of venous reflux in patients in all clinical grades. Many patients with clinical grade 1 venous insufficiency do not have reflux by VRT, VFI, or DS. The correlation of any method (PPG, APG, DS) to the results of clinical grading are similar and modest. The utility of the current clinical grading system as a standard to which noninvasive tests for reflux are to be compared is questionable.