Reappraisal of the Utility of the Tilt-table in the Investigation of Venous Disease†

Abstract

Without gravity opposing drainage, most venous diseases would not exist. Therefore, manoeuvres that assess venous function should include gravity. The aim was to "dose" gravity in subjects using static positions and dynamic angulations on a tilt-table and to assess its effects with air plethysmography (APG) and duplex ultrasound over the femoral vein. Three groups (providing n=11 legs each) were compared. (a) A control group, without clinical or duplex evidence of venous disease. (b) An obstruction group, with past iliofemoral deep vein thrombosis. (3) A reflux group, with primary varicose veins. A manually operated tilt-table ranging from -70° to 40° in the Trendelenburg position provided rapid tilting (<3s). The changes in calf volume at -70° (almost standing), -45° (reclining), and 40° (legs-up) were recorded with APG, as well as the rate and duration of the changes. The minor diameter of the femoral vein was recorded at the three tilt positions. The results were expressed as median (interquartile range). The total working venous volume (mL) in the reflux group was significantly increased: 202 (180-240)mL versus the controls at 138 (119-198)mL, p=.008, and versus the legs with obstruction at 117 (80-154)mL, p<.0005. The venous drainage index (VDI) in mL/second in the obstructed group was significantly reduced: 7 (6-9.6)mL/second, versus the controls at 17.4 (13.9-27.2)mL/second, p<.0005, and versus the legs with varicose veins at 28.1 (25.4-34.4)mL/second, p<.0005. The venous filling index (VFI) in mL/second in the reflux group was significantly increased: 8.1 (4.2-10)mL/second versus the controls at 1.8 (1-2.1)mL/second, p<.0005. The VDI cut-off point discriminating obstruction was ≤10.8mL/second and the VFI discriminating reflux was ≥ 2.9mL/second. The femoral vein diameter was reduced significantly with increasing leg elevation. Manoeuvres using APG on a tilt-table have the potential to quantify the contributions of global obstruction and reflux (mL/second) in patients with venous disease.