When we started using air plethysmography for assessment of lower extremity venous function, a question arose as to how to analyze the wide pressure change that appeared when an examined subject started to stand up from the horizontal position. To work out this question, we tried to use a tilt bed and contrived a noiseless method to support a subject from the horizontal position to the standing position. Finally, the “on the box” method was contrived to facilitate the examination. The aim of this study was to compare the method using a tilt bed (five normal limbs), the noiseless method (five normal limbs), and the on the box method (fourteen normal limbs) with Nicolaides’ technique, that has been widely used to assess lower extremity venous function. We also compared the lower extremity venous functions of normal limbs (38), primary varicose limbs(PVL, 62) and deep vein thrombosis (DVT, 24) using the “on the box” method.

There were no pressure changes at the time the examined subject started to stand up from the horizontal position using a tilt bed. The values of venous volume (VV) using the tilt bed were lower than the values with Nicolaides’ technique. There was no difference between the venous filling index (VFI) values using the tilt bed and those using Nicolaides’ technique. There was good correlation between the values using the tilt bed and the values using Nicolaides’ technique.Th ere was no difference between the values of the noiseless method and those of Nicolaides’ technique in VV.T he values of VFI with the noiseless method were higher than those with Nicolaides’ technique. There was good correlation between the values with the noiseless method and those with Nicolaides’ technique. Using the statistical method of Bland-Altman, the values with the “on the box” method were better than those with Nicolaides’ technique from the viewpoint of reproducibility in VV, VFI, ejection fraction (EF), and residual volume fraction (RVF).

With the “on the box” method, the values of the outflow fraction of PVL were significantly higher than those of normal limbs and DVT,a nd the values of normal limbs were sigt1ificantlyh igher than the values of DVT. The values of VV of PVL were significantly higher than those of normal limbs and DVT. The values of VFI of PVL and DVT were significantly higher than those of normal limbs, and the values of PVL were higher than those of DVI. The values of EF of PVL and DVT were significantly lower than those of normal limbs. The values of RVF of PVL and DVI were significantly higher than those of normal limbs, and the values of DVT were significantly higher than those of PVL. These results suggest that, the wide pressure change that occurs when moving from the horizontal to the standing position should be tolerated for record analysis. They also show that the “on the box” method is useful for assessment of lower extremity venous function using air plethysmography.