title: Diurnal changes of lower leg volume in obese and non-obese subjects.
abstract: OBJECTIVE
  Obesity is a risk factor for chronic venous disease. However, the mechanisms behind this association are poorly understood. We tested the hypothesis that obese subjects have a higher diurnal leg volume increase compared with non-obese subjects.
  
  
  METHODS
  In this prospective cohort study including obese (body mass index, BMI ≥30 kg m(-)(2)) and non-obese (BMI ≤25 kg m(-)(2)) subjects without venous insufficiency, lower leg volume was assessed by optoelectronic volumetry in the morning and in the evening. All subjects underwent duplex ultrasound and light reflection rheography (venous pump power and venous refill time, VRT) to investigate lower extremity venous function. A pedometer was carried between the morning and evening visit to assess the daily number of footsteps. A backward multivariable linear regression model was used to determine factors associated with diurnal lower leg volume increase.
  
  
  RESULTS
  Forty-two limbs in 24 obese subjects and 29 limbs in 15 non-obese subjects were analyzed. Obese subjects had larger common femoral vein diameters (17.1±2.4 vs 15.5±2.4 mm, P<0.01) and slower peak, mean and minimal velocities (25.1±10.6 vs 44.3±14.3 cm s(-1); 6.8±2.4 vs 12.7±5.6 cm s(-1); -0.2±6.4 vs -6.3±11.9 cm s(-1); P<0.01 for all) than non-obese subjects. VRT was shorter in obese subjects (40.5±15.0 vs 51.0±12.1 s, P<0.01) and decreased significantly in the course of the day only in obese subjects (P<0.01). Obesity, male gender, CEAP (Clinical-Etiology-Anatomy-Pathophysiology) class, total time between the two visits and difference between morning and evening VRT were positively associated with higher lower leg volume increase; morning VRT and the total number of footsteps showed a negative association (P<0.04 for all).
  
  
  CONCLUSIONS
  Obesity was found to be an independent predictor of higher diurnal leg volume increase. One potential mechanism is a progressive failure of venous valve function in the course of the day in obese subjects.
authors.affiliation: Division of Clinical and Interventional Angiology, Swiss Cardiovascular Center, University Hospital of Bern, Bern, Switzerland.
authors.forename: R P
authors.initials: RP
authors.lastname: Engelberger
authors.affiliation: Division of Clinical and Interventional Angiology, Swiss Cardiovascular Center, University Hospital of Bern, Bern, Switzerland.
authors.forename: A
authors.initials: A
authors.lastname: Indermühle
authors.affiliation: Division of Clinical and Interventional Angiology, Swiss Cardiovascular Center, University Hospital of Bern, Bern, Switzerland.
authors.forename: F
authors.initials: F
authors.lastname: Baumann
authors.affiliation: Division of Clinical and Interventional Angiology, Swiss Cardiovascular Center, University Hospital of Bern, Bern, Switzerland.
authors.forename: J
authors.initials: J
authors.lastname: Fahrni
authors.affiliation: Division of Clinical and Interventional Angiology, Swiss Cardiovascular Center, University Hospital of Bern, Bern, Switzerland.
authors.forename: N
authors.initials: N
authors.lastname: Diehm
authors.affiliation: Division of Clinical and Interventional Angiology, Swiss Cardiovascular Center, University Hospital of Bern, Bern, Switzerland.
authors.forename: N
authors.initials: N
authors.lastname: Kucher
authors.affiliation: Division of General Internal Medicine, Bern, Switzerland.
authors.forename: U
authors.initials: U
authors.lastname: Egermann
authors.affiliation: Department of Endocrinology, Diabetes and Clinical Nutrition, University Hospital and University of Bern, Bern, Switzerland.
authors.forename: K
authors.initials: K
authors.lastname: Laederach
authors.affiliation: Division of Clinical and Interventional Angiology, Swiss Cardiovascular Center, University Hospital of Bern, Bern, Switzerland.
authors.forename: I
authors.initials: I
authors.lastname: Baumgartner
authors.affiliation: Division of Clinical and Interventional Angiology, Swiss Cardiovascular Center, University Hospital of Bern, Bern, Switzerland.
authors.forename: T
authors.initials: T
authors.lastname: Willenberg
mesh_terms: D000328:Adult; D002908:Chronic Disease; D002940:Circadian Rhythm; D015331:Cohort Studies; D054893:Cone-Beam Computed Tomography; D005260:Female; D005268:Femoral Vein / Q000503:physiopathology*; D006801:Humans; D007866:Leg / Q000098:blood supply*; D008297:Male; D009765:Obesity / Q000150:complications / Q000503:physiopathology*; D017156:Photoplethysmography; D011446:Prospective Studies; D011673:Pulsatile Flow; D012039:Regional Blood Flow; D012307:Risk Factors; D018616:Ultrasonography, Doppler, Duplex; D014689:Venous Insufficiency / Q000209:etiology / Q000503:physiopathology*
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