SPIROMETRIC AND FLOW STANDARDS FOR HEALTHY ADULT NONSMOKING SRI-LANKANS BELONGING TO THE SINHALESE ETHNIC-GROUP

The objective of this study was to establish reference norms for dynam ic lung volumes and forced expiratory hows applicable to the Sinhalese ethnic group in Sri Lanka. Respiratory function tests were carried ou t on 367 female and 328 male healthy nonsmoking Sinhalese adults of ag e range 17-65 years. Subjects included hospital and university staff, students of the Faculty of Medicine at Peradeniya and healthy relative s accompanying patients to outpatients clinics. An 8-litre rolling-sea l spirometer was used in conjunction with a X-Y recorder. Forced vital capacity (FVC) and forced expiratory volume in the first second (FEV( 1)) reached a peak at 30 years in males and 23 years in females. All m easurements except forced mid-expiratory flow (FEF(25-75%)) increased with increasing height. The flow-volume curve became progressively con cave towards the volume axis with advancing age. Lung function measure ments correlated best with age and height. Therefore prediction formul ae were developed with these two measurements as the independent varia bles. Nomograms based on these formulae were constructed. When standar dized for height and age, forced expiratory volumes were smaller than in Europeans, Negroes and Pakistanis, and were comparable to South Ind ian data. However, flows did not vary significantly from those of othe r ethnic groups. It can therefore be concluded that the Sinhalese have smaller lungs than Europeans and Negroes even after adjustment for di fferences in stature, but lung elastic recoil pressure and airway cali bre (which are determinants of forced expiratory flows) appear to be s imilar to those of other ethnic groups.