Clinical Research On The Effects Of Patient Positioning And Eliciting Methods In The Evaluation Of Great Saphenous Vein Reflux By Ultrasonography

Objective: To investigate the effect of different patient positioning and elicitingmethods in the evaluation of great saphenous vein reflux by ultrasonography.Methods: Fifty great saphenous veins (GSV) with reflux (reflux group) and fifteenGSVs with no prior history of venous disease (healthy group) were examined by duplexscanning in the supine,20degrees reverse-trendelenburg (RT-20),40degreesreverse-trendelenburg (RT-40) and standing position. Two different eliciting methodswere used：Valsalva maneuver and distal pneumatic cuff maneuver. Pneumatic cuffcompression pressure of confined100mmHg was used onto the calf to elicit reflux.Each GSV was assessed for reflux at three venous sites: two centimeter below thesapheno-femoral junction (SFJ), the greater saphenous vein in the mid thigh (MGV) andthe greater saphenous vein in the upper calf (CGV). Pulse waveforms of reflux wererecorded. The main duplex-derived parameters assessed included the duration of refluxand the peak reflux velocity. Venous reflux was assumed to be present if the duration ofreflux was more than0.5s. The incidence of positive venous reflux was calculated. Thestatistical differences of the peak reflux velocity and duration of reflux in superiorpositions and advantageous eliciting methods were analyzedResults:(1) The influence of patient positioning on the evaluation of GSV reflux bydistal pneumatic cuff method: In healthy group, there were no false positive results ofreflux in supine, RT-20and RT-40positions. In reflux group, false negative results werefound at all venous sites when limbs were examined in supine position [false negativerate:59%(19/32),22%(11/50),24%(12/50)]. In RT-20and RT-40positions, theincidence of venous reflux reached100%at MGV and CGV, and false negative caseswere only detected at SFJ [false negative rate:12%(4/32),12%(4/32)].(2)The influenceof patient positioning on the evaluation of GSV reflux by Valsalva maneuver: In healthy group, false positive cases were detected at SFJ in supine[false positive rate:13.3%（2/15）] and RT-20positions[false positive rate:13.3%（2/15）]. In reflux group, bothfalse negative and false positive cases were detected in all positionings at SFJ. For SFJ,both the false negative and posititve rate in supine position were the highest[43.75%(14/32)、18.75%(6/32)], and RT-40were the lowest[both6.75%(2/32)]. ForMGV and CGV, there were only false negative case in four positionings, the rate ofwhich was14%(7/50)、8%(4/50)、8%(4/50)、8%(4/50) respectively at MGV and48%(24/50)、52%(26/50)、34%(17/50)、34%(17/50) at CGV.(3) The influence of patientpositioning on the analysis of the duration and the peak reflux velocity by distalpneumatic cuff method: The reflux time in standing, supine, RT-20and RT-40positionswere (7.75±3.23) s,(5.27±3.66) s,(8.67±3.72) s,(8.55±3.93) s respectively. There weresignificant differences among different positions in reflux time (F=56.9, P＜0.01). Indetail, no significant differences were identified between standing position and RT-20orRT-40position (q=1.51,1.33respectively, both P＞0.05), except for supine position(q=4.11, P＜0.01). Peak reflux velocity in standing, supine, RT-20and RT-40positionswere (55.26±22.24) cm/s,(22.87±12.03) cm/s,(38.46±16.30) cm/s,(45.13±19.21) cm/srespectively. There were also significant differences among different positions in peakreflux velocity (F=13.7, P＜0.01). Comparing the supine, RT-20and RT-40positionswith standing position, differences of the peak reflux velocity between them were allstatistically significant (q=12.71,6.59,3.98respectively, all P＜0.01).Conclusion:(1)RT-20and RT-40positions were effective to detect GSV reflux,especially for GSV at mid-thigh and upper calf, meaning that those positions weresuperior to examing GSV reflux.(2)Valsalva maneuver was inadvisable to be used as amethod to elicit reflux.(3) Assessing GSV reflux in spine position was inappropriate.(4)The reflux time elicited in reverse-trendelenburg positions was statistically same asstanding positions by the distal pneumatic cuff method. Although the peak velocity ofthis two positions was different, some regular patterns could be found.