The relationship between exhaled nitric oxide measured with an off-line method and airway reversible obstruction in Japanese adults with asthma.
BACKGROUND
Exhaled nitric oxide (eNO) is a useful marker of eosinophilic airway inflammation in asthma patients. There is no study to show the relationship between the eNO measured by using an off-line method and the degree of reversibility of airflow limitation in Japanese asthma patients. We sought to investigate the relationship between the eNO level measured by using an off-line method and the degree of reversibility of bronchial constriction in Japanese asthma patients.


METHODS
The study population comprised 97 asthma patients in our outpatient clinic with some patients in both groups who received inhaled corticosteroid treatment. We measured eNO levels, forced expiratory volume in one second (FEV1) before and after treatment, reversible airway obstruction (DeltaFEV1) after inhalation of bronchodilator, and other parameters.


RESULTS
eNO was significantly correlated with peripheral blood eosinophil counts in asthma patients (in steroid-naïve asthma patients, r=0.544, p<0.0001; in asthma patients treated with inhaled corticosteroid, r=0.463, p=0.026), and subjects with severe eosinophilia in sputum showed high levels of eNO (mild eosinophilia versus severe, p=0.0152). Among patients with obstructive impairment, eNO levels were correlated with DeltaFEV1 regardless of whether patients received (r=0.527, p=0.0435) or did not receive (r=0.64, p = 0.0056) inhaled corticosteroid. In subjects with normal pulmonary function, there was no significant relationship between eNO and DeltaFEV1 with or without inhaled corticosteroid.


CONCLUSIONS
In patients with obstructive impairment, eNO reflects the degree of reversible airflow limitation. In subjects with normal pulmonary function, eNO may facilitate the diagnosis and management of asthma, rather than indicate reversible bronchial obstruction. eNO measurement by off-line methods is applicable as a potential tool for the diagnosis of asthma and management of asthma patients.
Tsuburai
Takahiro
T
Clinical Research Center for Allergy and Rheumatology, National Hospital Organization, Sagamihara National Hospital, Kanagawa, Japan. t-tuburai@Sagamihara-hosp.gr.jp
Tsurikisawa
Naomi
N
Taniguchi
Masami
M
Morita
Sonoko
S
Ono
Emiko
E
Oshikata
Chiyako
C
Ohtomo
Mamoru
M
Maeda
Yuji
Y
Ikehara
Kunihiko
K
Akiyama
Kazuo
K
D000305:Adrenal Cortex Hormones / Q000627:therapeutic use; D000368:Aged; D000402:Airway Obstruction / Q000188:drug therapy* / Q000209:etiology; D001249:Asthma / Q000150:complications / Q000188:drug therapy* / Q000503:physiopathology*; D001944:Breath Tests / Q000379:methods; D001993:Bronchodilator Agents / Q000627:therapeutic use; D004802:Eosinophilia / Q000209:etiology / Q000276:immunology; D045853:Exhalation; D005260:Female; D005541:Forced Expiratory Volume; D006801:Humans; D008297:Male; D008875:Middle Aged; D009569:Nitric Oxide / Q000032:analysis / Q000378:metabolism*; D013183:Sputum / Q000166:cytology
D000305:Adrenal Cortex Hormones; D001993:Bronchodilator Agents; D009569:Nitric Oxide