Abstracts: ISEE 22nd Annual Conference, Seoul, Korea, 28 August–1 September 2010: Air Pollution - Exposure Characterization and Health Effects
Peak expiratory flow rate (PEFR), a lung function parameter is a reliable indicator of variability in airway caliber. It follows a specific pattern of variability in asthmatics as well as in healthy individuals. Variability in PEFR (PEFvar) could be due to susceptibility to increased bronchial responsiveness and it may be influenced by external factors. This study was aimed at comparing the diurnal variation in the PEFR of healthy subjects and asthmatics.
PEFR was measured in 24 healthy subjects and 26 asthmatics using Wright's peak flow meter twice daily for a 4-week period in the month of September. On each day, 3 measurements were carried out at 6 am in the morning and at 6 pm in the evening and best of the 3 measurements were taken for calculating the PEFR variability. Amplitude percent mean (A%M), is the index used for expressing the PEFR diurnal variability in this study. A%M is a common index used in several previous studies (Higgins 1997).
The PEFvar was significantly higher in asthmatics (6.67) when compared to healthy individuals (4.39). Similar result was observed in the child panel too. PEFvar of the asthmatic children (11.07) was significantly high when compared with healthy children (5.755). Among the asthmatic panel, males (13.22) had higher PEFR variability than females (8.85).
Measurement of diurnal variability of PEFR serves as a valuable and reliable tool for asthma screening, diagnosis, and prognosis. Daily PEFR monitoring is a useful measure for clinician for providing appropriate dose of the asthma medication. This study results are being used in an ongoing study for evaluating the effects of ozone on exacerbation of asthma. This study has provided the insights required for choosing and sustaining the panel of asthmatics for the ongoing air pollution study.