title: Influence of age on venous physiologic parameters.
abstract: OBJECTIVE
  The incidence of deep venous thrombosis increases significantly with age. Attempts to explain this association have failed to identify factors that could be contributory. We hypothesized that age-related changes in venous physiologic parameters might contribute to an increased risk of deep venous thrombosis.
  
  
  METHODS
  Air plethysmography was used to measure a number of physiologic parameters in two sets of patients. Group A consisted of 17 subjects (33 limbs), age range 23 to 40 years. Group B consisted of 11 subjects (22 limbs), age range 60 to 83 years. No subject in either group had peripheral vascular disease or a history of deep venous thrombosis. Parameters measured were venous volume, venous filling index, ejection volume, ejection fraction, residual volume fraction, and outflow fraction.
  
  
  RESULTS
  Venous volume and ejection fraction were significantly reduced in Group B compared with Group A. Residual volume fraction was significantly increased in Group B compared with Group A. There were no statistically significant differences in outflow fraction, venous filling index, or ejection fraction between the two groups.
  
  
  CONCLUSIONS
  These results suggest that the efficiency of the calf muscle pump diminishes with increasing age, possibly contributing to the increased incidence of deep venous thrombosis in the elderly.
authors.affiliation: Section of Vascular Surgery, Pennsylvania State University, College of Medicine, Milton S. Hershey Medical Center, Hershey 17033.
authors.forename: M J
authors.initials: MJ
authors.lastname: Schina
authors.forename: M M
authors.initials: MM
authors.lastname: Neumyer
authors.forename: D A
authors.initials: DA
authors.lastname: Healy
authors.forename: R G
authors.initials: RG
authors.lastname: Atnip
authors.forename: B L
authors.initials: BL
authors.lastname: Thiele
mesh_terms: D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D000375:Aging / Q000502:physiology*; D001810:Blood Volume; D005260:Female; D006801:Humans; D007866:Leg / Q000098:blood supply; D008297:Male; D008875:Middle Aged; D010991:Plethysmography; D011446:Prospective Studies; D012307:Risk Factors; D013924:Thrombophlebitis / Q000503:physiopathology; D014680:Veins / Q000502:physiology*