VALIDATION OF AIR PLETHYSMOGRAPHY, PHOTOPLETHYSMOGRAPHY, AND DUPLEX ULTRASONOGRAPHY IN THE EVALUATION OF SEVERE VENOUS STASIS

Purpose: The purpose of this study was to validate the diagnostic capa bilities of the most commonly used noninvasive modalities for evaluati on of chronic venous insufficiency. Methods: Twenty Limbs in 20 patien ts were studied with air plethysmography (APG), photoplethysmography ( PPG), and duplex ultrasonography. Ten limbs (group 1) were clinically without any venous disease. Group 2 consisted of 10 limbs with severe, class 3 venous stasis. Duplex ultrasonography, complemented with Dopp ler color-flow imaging was used to examine the superficial and deep ve nous systems to identify reflux. Results: Ultrasonography identified d eep venous reflux in eight of 10 limbs in group 2. Severe superficial reflux was identified in the two remaining limbs. Seven limbs with dee p reflux also demonstrated severe superficial reflux. Superficial veno us reflux was identified in one leg in group 1. APG accurately separat ed normal limbs from those with reflux. Parameters that were significa ntly different (p < 0.05) between the two groups were the venous filli ng index, (group 1 = 1.37 +/- 0.16 ml/sec, group 2 = 29.5 +/- 6.2 ml/s ec.), venous volume (group 1 = 107 +/- 10.1 ml, group 2 = 220 +/- 22.5 ml), ejection fraction (group 1 = 52.5% +/- 2.3%, group 2 = 32.5% +/- 4.6%), and residual volume fraction (group 1 = 21.4 +/- 2.0%, group 2 = 52.1% +/- 2.5%). PPG refill times were significantly shortened in g roup 2 versus those of group 1 (6.4 +/- 0.89 sec vs 20.2 +/- 1.1 sec). The sensitivity of PPG refill times to identify reflux was 100%, but the specificity was only 60%, whereas the sensitivity and specificity for the residual volume fraction was 100%. The venous filling index wa s able to identify reflux and determine whether only superficial reflu x was present with a sensitivity of 100% and a specificity of 90%. The kappa coefficient of agreement between duplex scanning and APG was 0. 83, whereas between duplex and PPG it was only 0.47. Conclusions: APG accurately identifies limbs with and without venous reflux when compar ed with duplex ultrasonography. APG is a better method of evaluating c linically significant venous reflux than PPG. PPG is a sensitive metho d of detecting reflux, but the specificity is poor, and PPG reflux tim es cannot accurately predict the location of reflux. The combination o f APG and duplex ultrasonography provides the best means of assessing venous reflux.