کد مقاله | کد نشریه | سال انتشار | مقاله انگلیسی | نسخه تمام متن |
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6062728 | 1201843 | 2016 | 7 صفحه PDF | دانلود رایگان |

BackgroundIn asthmatic patients undergoing airway challenge, fraction of exhaled nitric oxide (Feno) levels decrease after bronchoconstriction. In contrast, model simulations have predicted both decreased and increased Feno levels after bronchodilation, depending on the site of airway obstruction relief.ObjectiveWe sought to investigate whether β2-agonists might induce divergent effects on Feno values in asthmatic patients as a result of airway obstruction relief occurring at different lung depths.MethodsFeno, FEV1, and the slope of phase III of the single-breath washout test (S) of He (SHe) and sulfur hexafluoride (SSF6) were measured in 68 asthmatic patients before and after salbutamol inhalation. SHe and SSF6 decreases reflected preacinar and intra-acinar obstruction relief, respectively. Changes (Î) were expressed as a percentage from the baseline.ResultsNo Feno change (|ÎFeno| ⤠10%) was found in 16 patients (mean [SD]: 2.5% [5.2%]; ie, Feno= group); a ÎFeno value of greater than 10% was found in 23 patients (31.7% [20.3%]; ie, the Feno+ group); and a ÎFeno value of less than â10% was found in 29 patients (â31.5% [17.3%]; ie, the Fenoâ group). All groups had similar ÎFEV1 values. In the Feno= group neither SHe nor SSF6 changed, in the Feno+ group only SHe decreased significantly (â21.8% [SD 28.5%], P = .03), and in the Fenoâ group both SHe (â29.8% [24.0%], P < .001) and SSF6 (â27.2% [23.3%], P < .001) decreased.DiscussionThree Feno behaviors were observed in response to β2-agonists: a decrease likely caused by relief of an intra-acinar airway obstruction that we propose reflects amplification of nitric oxide back-diffusion, an increase likely associated with a predominant dilation up to the preacinar airways, and Feno stability when obstruction relief involved predominantly the central airways. In combination, these results suggest a new role for Feno in identifying the site of airway obstruction in asthmatic patients.
Journal: Journal of Allergy and Clinical Immunology - Volume 137, Issue 3, March 2016, Pages 806-812