title: Density dependence of maximal expiratory flows in normal subjects: influence of sex, age, body build and spirographic variables.
abstract: We studied the correlation between density-dependence parameters (delta He, volume of isoflow) and age, body build, spirography and forced expiratory fows in 69 healthy non-smokers (16 females) aged 18 to 51 years. Density dependence variables showed no significant differences between young (less than 35 years) males and females. Volume of isoflow per cent of forced vital capacity (Viso V % FVC) was poorly significantly related to age (r = +0.25 P less than 0.05) and weight (r = +0.27 P less than 0.05). Significant correlations were found between density dependence at low lung volume and the FEV1/VC ratio (r = 0.31, P = 0.01 for delta He 25%; r = -0.40, P less than 0.001 for Viso V% FVC) or the forced expiratory flows with air (Viso V% FVC vs. FEF 25% r = -0.42, P less than 0.001). These correlations were closer in females as compared to males. Volume of isoflow was well related to delta He 25% (r = -0.64, P less than 0.001), but the relationship with delta He 50% was weaker (r = -0.38; P less than 0.01).
mesh_terms: D000293:Adolescent; D000328:Adult; D000375:Aging; D001835:Body Weight; D005260:Female; D005540:Forced Expiratory Flow Rates; D006801:Humans; D008297:Male; D008448:Maximal Expiratory Flow Rate; D008449:Maximal Expiratory Flow-Volume Curves; D012129:Respiratory Function Tests; D012737:Sex Factors; D014797:Vital Capacity