Diurnal variation of peak expiratory flow rate in adolescents

Lung functions exhibit a circadian rhythm. Peak Expiratory Flow Rate (PEFR) is an easily measured and reproducible parameter for measuring lung functions. Limited information is available on the circadian variations in lung functions in south Indian adolescents. Hence, this study was undertakento evaluate the diurnal variation of PEFR in adolescents.This longitudinal study was conducted among 30 adolescent girls in the age group of 18-19 years recruited from a hostel in Chirala, Andhra Pradesh. Smokers, pregnant women and subjects with history of tuberculosis were excluded from the study. PEFR was measured using the Mini — Wright s, peak flow meter, four times a day (5.30 – 6.00 am, 12.00-1.00 pm, 5.00-6.00 pm, 9-10.00pm) and the diurnal variation of lung function was calculated. The PEFR values at different time points were analyzed using analysis of variance. Statistical significance was taken at 5% level of significance. Amplitude % Mean and Standard deviation % Mean were used to estimate diurnal variation of PEFR. The mean PEFR recorded at 5.30 am, 12.00 noon, 5.00 pm and 9.00 pm were 340, 347, 349 and 348 respectively. The mean of amplitude % mean and standard deviation % mean obtained in this study were 8.42 ± 3.65and 3.87±1 respectively.C The results of this study indicate that PEFR in adolescents exhibits a definite circadian rhythm, it being lowest early in the morning, progressively rises till late afternoon following which there is a slight fall in the night.