Circadian Rhythm of Peak Expiratory Flow Rate in Asymptomatic Childhood Asthma

Im, Hwi Kyu; Han, Byung Mu; Park, Seok Won; Kim, Jong Soo

Abstract

PURPOSE
Asthmatic patients show marked circadian variation in disease severity, with bronchospasm far worse between midnight and 8 a.m. than at other times of the day. And many studies have demonstrated that symptoms are much relieved in the day-time while they worsen at night. Our study was conducted to examine the circadian variation of peak expiratory flow rate (PEFR) in asymptomatic asthmatic children after proper treatment by mini-Wright peak flow meter. METHODS: Thirty four asthmatic patients who have had no respiratory symptoms for the past one month were enrolled to our study. Control group included 25 patients who were admitted to Wonju Christian Hospital for inguinal hernia, aseptic meningitis, etc., but without respiratory symptoms. RESULTS: The mean age was 6.3 years, ranging from 4 to 11 years, in the stable asthmatic group. In control group, the mean age was 8.7 years ranging from 4 to 14 years. PEFR was checked at every 2 hours from 8 a.m. to 10 p.m. for 4 days. There were no significant differences in PEFR checked at all times between the asthma group and the control group except for the PEFR checked at 8 a.m. in moderate persistent asthma group. PEFR reached the nadir at 8 a.m. in both asthma and control groups. It rose to the highest level in the afternoon, then, it slightly fell in the evening and at night. There were significant differences between the PEFR checked at 8 a.m. and the PEFR checked at any other period of the day in each group (P< 0.05). The circadian variation in moderate persistent asthma group is much greater than that of other groups. CONCLUSION: Our study indicates that the moderate persistent asthma group with no current symptoms of asthma has an increased circadian variability. It is recommended, therefore, that special attention be paid to preventive treatment for the moderate persistent asthma group.