title: Obesity and impaired venous function.
abstract: OBJECTIVE
  The clinical severity of venous disease is often worse in obese patients. The objectives of this study were to compare lower limb venous physiology assessed by air plethysmography in a large group of obese and normal-weight patients; to consider the effect of posture on these measures and on foot vein pressure in a smaller cohort.
  
  
  METHODS
  Venous function was assessed using air plethysmography and duplex scanning in 934 consecutive patients presenting for assessment of venous disease. These were grouped into obese or non-obese categories. A smaller group of twenty patients with a range of body weights were randomly selected from a database of patients with varicose veins. Foot vein pressures and femoral vein diameter were measured standing, sitting, lying and ambulating.
  
  
  RESULTS
  Venous disease was more clinically severe in the obese limbs (CEAP C5&6 non-obese group 20.5%, obese group 35.4%, p<0.001 chi(2)). Venous reflux was worse in the obese but measures of muscle pump function were better. Residual volumes and fractions were better in the obese (mean residual volume, non-obese 60 SD 36, obese 50 SD 42, p<0.001 t test). In the smaller study group weight correlated with the diameter of the superficial femoral vein (r=0.50), ambulatory venous pressure (r=0.45), venous filling index (r=0.49) and the ejection volume (r=0.38, p<0.05). The foot venous pressure was significantly greater in the obese in all positions.
  
  
  CONCLUSIONS
  The CEAP clinical stage of venous disease is more advanced in obese patients than non-obese patients with comparable anatomical patterns of venous incompetence. This may be the result of raised intra-abdominal pressure reported in previous studies, leading to greater reflux, increased vein diameter and venous pressures.
authors.affiliation: Department of Surgery, Dunedin School of Medicine, University of Otago, Dunedin, New Zealand. andre.vanrij@stonebow.otago.ac.nz
authors.forename: A M
authors.initials: AM
authors.lastname: van Rij
authors.forename: C S
authors.initials: CS
authors.lastname: De Alwis
authors.forename: P
authors.initials: P
authors.lastname: Jiang
authors.forename: R A
authors.initials: RA
authors.lastname: Christie
authors.forename: G B
authors.initials: GB
authors.lastname: Hill
authors.forename: S J
authors.initials: SJ
authors.lastname: Dutton
authors.forename: I A
authors.initials: IA
authors.lastname: Thomson
mesh_terms: D000328:Adult; D015992:Body Mass Index; D016022:Case-Control Studies; D005260:Female; D005268:Femoral Vein / Q000503:physiopathology; D005528:Foot / Q000098:blood supply; D006801:Humans; D035002:Lower Extremity / Q000098:blood supply*; D008297:Male; D008875:Middle Aged; D009119:Muscle Contraction; D018482:Muscle, Skeletal / Q000503:physiopathology; D009765:Obesity / Q000150:complications / Q000000981:diagnostic imaging / Q000503:physiopathology*; D010991:Plethysmography; D011152:Popliteal Vein / Q000503:physiopathology; D011187:Posture; D012501:Saphenous Vein / Q000503:physiopathology; D012720:Severity of Illness Index; D018616:Ultrasonography, Doppler, Duplex; D014648:Varicose Veins / Q000000981:diagnostic imaging / Q000209:etiology* / Q000503:physiopathology; D014690:Venous Pressure