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A practical approach to the theoretical models to calculate NO parameters of the respiratory system.
MedLine Citation:
PMID:  24565997     Owner:  NLM     Status:  Publisher    
Abstract/OtherAbstract:
Expired nitric oxide (NO) is used as a biomarker in different respiratory diseases. The recommended flow rate of 50 mL s(-1) (FENO0.05) does not reveal from where in the lung NO production originated. Theoretical models of NO transfer from the respiratory system, linear or nonlinear approaches, have therefore been developed and applied. These models can estimate NO from distal lung (alveolar NO) and airways (bronchial flux). The aim of this study was to show the limitation in exhaled flow rate for the theoretical models of NO production in the respiratory system, linear and nonlinear models. Subjects (n = 32) exhaled at eight different flow rates between 10-350 mL s(-1) for the theoretical protocols. Additional subjects (n = 32) exhaled at tree flow rates (20, 100 and 350 mL s(-1)) for the clinical protocol. When alveolar NO is calculated using high flow rates with the linear model, correction for axial back diffusion becomes negligible, -0.04 ppb and bronchial flux enhanced by 1.27. With Högman and Meriläinen algorithm (nonlinear model) the corrections factors can be understood to be embedded, and the flow rates to be used are ≤20, 100 and ≥350 mL s(-1). Applying these flow rates in a clinical setting any FENO can be calculated necessitating fewer exhalations. Hence, measured FENO0.05 12.9 (7.2-18.7) ppb and calculated 12.9 (6.8-18.7) ppb. In conclusion, the only possibility to avoid inconsistencies between research groups is to use the measured NO values as such in modelling, and apply tight quality control to accuracies in both NO concentration and exhaled flow measurements.
Authors:
M Högman; A Thornadtsson; G Hedenstierna; P Meriläinen
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Publication Detail:
Type:  JOURNAL ARTICLE     Date:  2014-2-24
Journal Detail:
Title:  Journal of breath research     Volume:  8     ISSN:  1752-7163     ISO Abbreviation:  J Breath Res     Publication Date:  2014 Feb 
Date Detail:
Created Date:  2014-2-25     Completed Date:  -     Revised Date:  -    
Medline Journal Info:
Nlm Unique ID:  101463871     Medline TA:  J Breath Res     Country:  -    
Other Details:
Languages:  ENG     Pagination:  016002     Citation Subset:  -    
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