Peak expiratory flow rate in Sri Lankan schoolchildren of Sinhalese ethnic origin.

Normal values for lung function indices are not available for Sri Lankan children. Reference standards for peak expiratory flow rate (PEFR) in non-smoking Sri Lankan schoolchildren belonging to the Sinhalese ethnic group have been derived. A total of 1206 schoolchildren of age range 5-19 years was studied. The mini-Wright peak flow meter was used to measure peak expiratory flow rates. The highest of three readings was taken as the correct value. The results were correlated with age, standing height, weight and surface area. The flow rate was only marginally higher in pre-pubertal boys than in girls. Girls reached a maximum at 15 years of age. The boys continued to show an increase in the PEFR until, at the age of 19 years, they had values about 150 l min-1 higher than females of the same age. Up to a height of 150 cm, a weight of 35 kg and l.1 m2 surface area, the two sexes showed similar gradients of increase of PEFR. Beyond these limits, the relationships changed abruptly, the boys showing an increase and the girls, a decrease in the gradient. There was a high correlation between PEFR and the anthropometric measurements studied. The peak flow rates compared favourably with those of other ethnic groups. Prediction formulae were developed with age and height as the independent variables. A nomogram based on these equations was constructed. These results would be useful in obtaining predicted normal values in Sinhalese school children with respiratory dysfunction.