title: Timing of lowest and highest peak expiratory flow in patients with asthma: influence of anti-inflammatory treatment.
abstract: We sought to determine the optimal time for measuring peak expiratory flow rate (PEF) in patients with mild to moderate asthma, before and after treatment with inhaled beclomethasone dipropionate (BDP). After 2 weeks of observation, BDP (400 microg/d) was given to 22 patients with mild to moderate asthma. The dose of BDP (800-1200 microg/d) was increased every 2 weeks until PEF varied by no more than 20% each day. PEF was measured four times daily: on awakening, around noon, in the evening and at bedtime. Significant (P < 0.05) rhythms were detected by single cosinor analysis in all patients, both during observation and during treatment. Analysis by the population mean-cosinor method showed that the mean mesor was 378.8+/-59.1 lmin(-1), the mean amplitude was 53.9+/-13.4 lmin(-1), and the mean acrophase was at 16:26+/-0:32 before treatment. After treatment, the mean mesor was 528.0+/-61.9 l min(-1), the mean amplitude was 37.6+/-12.2 lmin(-1), and the mean acrophase was at 16:35+/-0:32. The mesor increased significantly (P<0.05), and the amplitude decreased significantly (P<0.05) after treatment. The acrophase did not change. These data indicate that PEF is lowest at 04:30 and highest at 16:30 in patients with mild to moderate asthma, both during observation and during treatment. We conclude that if one needs to assess PEF twice a day, this should ideally be done at 04:30 and 16:30, not only before but also after treatment with BDP.
authors.affiliation: Second Department of Medicine, Kyoto Prefectural University of Medicine, Japan. yiwasaki@koto.kpu-m.ac.jp
authors.forename: Y
authors.initials: Y
authors.lastname: Iwasaki
authors.forename: Y
authors.initials: Y
authors.lastname: Kubota
authors.forename: I
authors.initials: I
authors.lastname: Yokomura
authors.forename: M
authors.initials: M
authors.lastname: Ueda
authors.forename: S
authors.initials: S
authors.lastname: Hashimoto
authors.forename: H
authors.initials: H
authors.lastname: Hara
authors.forename: M
authors.initials: M
authors.lastname: Nakagawa
mesh_terms: D000293:Adolescent; D000328:Adult; D000368:Aged; D018927:Anti-Asthmatic Agents / Q000627:therapeutic use*; D001249:Asthma / Q000188:drug therapy / Q000503:physiopathology*; D001507:Beclomethasone / Q000627:therapeutic use*; D002940:Circadian Rhythm; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D010366:Peak Expiratory Flow Rate / Q000187:drug effects; D013997:Time Factors
chemical_list: D018927:Anti-Asthmatic Agents; D001507:Beclomethasone