title: Reproducibility of duplex ultrasonography and air plethysmography used for the evaluation of chronic venous insufficiency.
abstract: OBJECTIVE
  The purpose of this study was to determine the reproducibility of measurements on duplex ultrasonography (DU) and air plethysmography (APG) in subjects with post-thrombotic syndrome.
  
  
  METHODS
  Duplex ultrasonography and APG were used to measure indices of lower limb venous reflux in 15 limbs with a history of deep vein thrombosis and evidence of venous insufficiency as diagnosed by ultrasonography. Three limbs were in class 0; 4 were in classes 1 to 3; and 8 were in classes 4 to 6, according to clinical, etiologic, anatomic, and pathophysiologic clinical classification. Duplex ultrasonography was performed 3 times on the same day, and venous diameter, area, peak reflux velocity, reflux flow volume, and reflux duration measurements were obtained. Air plethysmography was performed on 2 days, 7 to 10 days apart, with 1 measurement on the first day and 2 measurements on the second day. Values obtained from APG included outflow fraction, venous filling index, ejection fraction, and residual volume fraction. The measurements were performed by a vascular technologist blinded to the previous test results. One-way analysis of variance, the Student paired t test, and Bland-Altman plots were used to examine the statistical differences of the DU and APG parameters for all measurements.
  
  
  RESULTS
  The mean coefficient of variation for within-subject measurements of all DU and APG parameters measured was less than 10%. Bland-Altman plots showed that there were no apparent trends with increasing values over a wide range for any of the DU parameters, nor were there any for the APG parameters.
  
  
  CONCLUSIONS
  Under ideal conditions, when measured by a highly trained technologist, both DU and APG showed satisfactory reproducibility.
authors.affiliation: Department of Vascular Sciences and Medicine, Monash University and Southern Health, Melbourne, Victoria, Australia.
authors.forename: Akram Mahmoud
authors.initials: AM
authors.lastname: Asbeutah
authors.forename: Andrea Zdena
authors.initials: AZ
authors.lastname: Riha
authors.forename: James Donald
authors.initials: JD
authors.lastname: Cameron
authors.forename: Barry Patrick
authors.initials: BP
authors.lastname: McGrath
mesh_terms: D000328:Adult; D000368:Aged; D000388:Air; D000704:Analysis of Variance; D001783:Blood Flow Velocity; D002908:Chronic Disease; D005260:Female; D006801:Humans; D007866:Leg / Q000098:blood supply*; D008297:Male; D008875:Middle Aged; D010991:Plethysmography; D015203:Reproducibility of Results; D018616:Ultrasonography, Doppler, Duplex; D014689:Venous Insufficiency / Q000175:diagnosis* / Q000000981:diagnostic imaging*