IOS reactance measurements are more closely related than resistance measurements to other pulmonary function measurements in COPD patients. The IOS reactance measurements appear to be indicative of changes in pulmonary compliance caused by airflow obstruction.
Multiple flow rates of exhaled nitric oxide (eNO) fraction (Fe,NO) data can be modelled to estimate airway wall concentration of nitric oxide (Caw,NO), diffusing capacity of nitric oxide (Daw,NO), alveolar nitric oxide concentration (Calv,NO) and total maximal flux of nitric oxide in the airway compartment (J9aw,NO).Fe,NO at 10, 30, 50, 100 and 200 mL?s -1 from 50 chronic obstructive pulmonary disease (COPD) patients and 35 healthy controls (smokers and nonsmokers) modelled using five different methods was compared and the effect of the number of flow rates was investigated.All methods showed that current smoking reduced Caw,NO in COPD patients, with some methods showing that smoking reduced J9aw,NO. Smoking did not affect Calv,NO or Daw,NO. The methods gave similar results for Caw,NO but there was variability between methods for J9aw,NO, Calv,NO and Daw,NO. The median error by least squares fitting between modelled and actual data was significantly lower for the nonlinear method (1.96) compared with the mixed methods (3.31 and 3.62). Parameters calculated using the nonlinear method using five and four flow rates were significantly different. The ratio (95% confidence interval) of Caw,NO was 2.02 (1.45-2.83).Nitric oxide models give different results, although airway conductance of nitric oxide is relatively model independent. Nonlinear modelling has the least error, suggesting it is the best method. The number of flow rates should be standardised.
BackgroundMany of the systemic manifestations of chronic obstructive pulmonary disease (COPD) are mediated through increased systemic levels of inflammatory proteins. We assessed the long term repeatability of Interleukin-6 (IL-6), tumor necrosis factor-α (TNF-α), and C-reactive protein (CRP) over one year and examined the relationships between these systemic markers in COPD.MethodsFifty-eight stable COPD patients completed a baseline and one-year visit. Serum IL-6, plasma CRP, and plasma TNF-α were measured. Repeatability was expressed by intraclass correlation coefficient (Ri) and the Bland–Altman method. Pearson correlations were used to determine the relationships between the systemic markers at both visits.ResultsThere was moderate repeatability with a very high degree of statistical significance (p ≤ 0.001) between the two visits for all the systemic biomarkers (IL-6, CRP, and TNF-α). CRP was significantly associated with IL-6 at both visits (r = 0.55, p = 0.0001, r = 0.51, p = 0.0002, respectively). There were no other significant associations between the systemic markers at either of the visits.ConclusionsSystemic inflammatory biomarkers IL-6, CRP, and TNF-α were moderately repeatable over a twelve month period in COPD patients. We have also shown that a robust and repeatable association between IL-6 and CRP exists.
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.