Inflammation and airway function in the lung periphery of patients with stable asthma.
BACKGROUND
An important role for exhaled nitric oxide (NO) measurement could be in the distinction between proximal and peripheral lung contributions to inflammation, with a particular interest for the alveolar lung zone and its implication on airway function.


OBJECTIVE
We aimed to isolate the acinar lung zone contribution to both inflammation and airway function to seek a relationship between them.


METHODS
In 30 patients with asthma with an asthma control test score exceeding 20, indices of conductive and acinar ventilation heterogeneity (Scond, Sacin) were obtained from a multiple breath washout. NO production in the conductive airways (J'aw(NO)), alveolar NO concentration (CA(NO)), and the standard exhaled NO at 50 mL/s (FENO(50)) were obtained from exhaled NO.


RESULTS
Scond was consistently abnormal in all patients with stable asthma, but without any correlation to inflammation abnormality in that compartment (J'aw(NO)). Sacin was particularly abnormal in the asthma subgroup receiving >500 microg budesonide equivalent, and a correlation was found between Sacin and CA(NO) (r = 0.61; P = .015); in this subgroup, a weak association was found between Scond and J'aw(NO) or FENO(50) (r = 0.50; P = .059 for both).


CONCLUSIONS
The persistent functional abnormality of small conductive airways in patients with stable asthma is largely independent of inflammation as measured by exhaled NO. In the alveolar compartment, a functional correlate of alveolar NO was found in a subgroup of patients with stable asthma on moderate-to-high maintenance doses of inhaled steroids. These patients in particular could benefit from novel therapies specifically aimed at improving airway functionality at the level of the acinar entrance and beyond.
Respiratory Division, University Hospital UZ Brussel, Brussels, Belgium. sylvia.verbanck@uzbrussel.be
Sylvia
S
Verbanck
Daniel
D
Schuermans
Walter
W
Vincken
D000328:Adult; D001249:Asthma / Q000503:physiopathology*; D001944:Breath Tests / Q000379:methods; D045853:Exhalation; D005260:Female; D006801:Humans; D007249:Inflammation / Q000503:physiopathology*; D008297:Male; D008875:Middle Aged; D009569:Nitric Oxide / Q000032:analysis*; D011650:Pulmonary Alveoli / Q000503:physiopathology; D012123:Pulmonary Ventilation / Q000502:physiology; D012129:Respiratory Function Tests / Q000379:methods; D055815:Young Adult
D009569:Nitric Oxide