Correlations between exhaled nitric oxide levels and pH-metry data in asthmatics with gastro-oesophageal reflux.
BACKGROUND
In gastro-oesophageal reflux (GER), micro-aspirations of gastric fluid may damage the epithelial surface of the airways, an important source of endogenous nitric oxide (NO).


OBJECTIVE
The aim of the study was to evaluate the possible influence of GER on fractional exhaled nitric oxide (FE(NO)) release.


METHODS
FE(NO) levels were compared in two age-matched groups of allergic children: (1) 20 with mild asthma, responding to standard anti-asthma pharmacologic therapy (asthmatic children) and (2) 12 with mild 'asthma-like symptoms' and GER.


RESULTS
No differences in pulmonary functions parameters (FEV(1), FVC and FEF(25-75%)) were found between the two groups of children (p > 0.1); FE(NO) levels were higher in asthmatic children compared with GER children (p = 0.0001). GER children underwent 24-hour oesophageal pH-metry, and possible correlations between pH-metry data, pulmonary functions and FE(NO) levels were evaluated. No correlations were found between pulmonary functions and pH-metry data (p > 0.05, each correlation). In contrast, correlations were observed between FE(NO) levels and pH-metry data, including (1) percentage of study time with pH < 4 (r = -0.80, p = 0.008), (2) number of episodes with pH < 4 (r = -0.76, p = 0.012), and (3) number of episodes >5 min with pH < 4 (r = -0.69, p = 0.02).


CONCLUSIONS
Thus, FE(NO) levels are lower in allergic children with 'asthma-like symptoms' and GER as compared to asthmatic children. The correlations between FE(NO) levels and pH-metry data suggest that inhalation of acid gastric content may interfere with NO production in the airways.
Silvestri
M
M
Pulmonary Department, G. Gaslini Institute, Genoa, Italy.
Mattioli
G
G
Defilippi
A-C
AC
Fregonese
B
B
Battistini
E
E
Jasonni
V
V
Rossi
G A
GA
D001249:Asthma / Q000453:epidemiology / Q000503:physiopathology*; D001944:Breath Tests; D002648:Child; D015897:Comorbidity; D005764:Gastroesophageal Reflux / Q000453:epidemiology / Q000503:physiopathology*; D006801:Humans; D006863:Hydrogen-Ion Concentration; D009569:Nitric Oxide / Q000032:analysis* / Q000096:biosynthesis; D012129:Respiratory Function Tests; D012137:Respiratory System / Q000378:metabolism
D009569:Nitric Oxide