Peak expiratory flow variability adjusted by forced expiratory volume in one second is a good index for airway responsiveness in asthmatics.
BACKGROUND
The lowest peak expiratory flow (PEF) over a week, expressed as a percentage of the highest PEF (Min%Max PEF) has been reported to be the index that most closely correlates with airway hyperresponsiveness (AHR) in asthmatics. However, both fluctuation of the airway caliber and airflow limitation are regarded as physiological properties of asthma closely related to AHR. An accurate index that shows the degree of AHR may be obtained by combining the index of airway lability with the parameters that represent airway caliber.


METHODS
Ninety-two steroid-naive and twenty-eight steroid-treated asthmatic patients were enrolled. Using the physiological parameters obtained from spirometry and PEF monitoring, we investigated the indices which correlate accurately with airway responsiveness measured by the inhalation challenge test.


RESULTS
Although the methacholine threshold was related to all parameters that represent airway caliber and lability, Min%Max PEF had the strongest correlation with AHR. When Min%Max PEF was adjusted by the airway geometric factors, the normalization of Min%Max PEF with forced expiratory volume in one second as a percentage of the predicted value (%FEV(1)) improved the relationship between Min%Max PEF and AHR.


CONCLUSIONS
Min%Max PEF adjusted by %FEV(1) showed a good correlation with airway responsiveness measured by the inhalation challenge test, and may be useful as a convenient alternative index of AHR in asthmatic patients.
The Third Department of Internal Medicine, Wakayama Medical University, School of Medicine, Wakayama.
Kazuto
K
Matsunaga
Masae
M
Kanda
Atsushi
A
Hayata
Satoru
S
Yanagisawa
Tomohiro
T
Ichikawa
Keiichiro
K
Akamatsu
Akira
A
Koarai
Tsunahiko
T
Hirano
Hisatoshi
H
Sugiura
Yoshiaki
Y
Minakata
Masakazu
M
Ichinose
D000328:Adult; D001249:Asthma / Q000175:diagnosis / Q000503:physiopathology*; D016535:Bronchial Hyperreactivity / Q000175:diagnosis / Q000503:physiopathology*; D001985:Bronchial Provocation Tests; D003430:Cross-Sectional Studies; D005260:Female; D005541:Forced Expiratory Volume / Q000502:physiology*; D006801:Humans; D008297:Male; D008875:Middle Aged; D010366:Peak Expiratory Flow Rate / Q000502:physiology*; D013147:Spirometry / Q000379:methods*