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Background: In patients with severe chronic obstructive pulmonary disease (COPD), pursed-lips breathing (PLB) improves the pulmonary gas exchange and hyperinflation measured by electro-optic coupling. The response to PLB in inspiratory lung function tests is not known. Objectives: The purpose of this study was to measure the effect of PLB on inspiratory parameters. Methods: Thirty-five subjects with stable COPD and a forced expiratory volume in first second (FEV₁) <50% of the predicted value were tested for the following primary parameters before and immediately after PLB, and 5 min later: forced inspiratory vital capacity, inspiratory capacity (IC), forced inspiratory volume in first second, maximal inspiratory flow at 50% of vital capacity, and peak inspiratory flow. Patients were also tested for the following secondary parameters: vital capacity, FEV₁, breathing frequency, end-tidal CO₂ tension, and oxygen saturation. Results: Of all the primary parameters only IC (p = 0.006) improved significantly; with regard to the secondary parameters, the mean oxygen saturation was improved by 1% (p = 0.005) and the mean end-tidal CO₂ tension and breathing frequency decreased significantly (p < 0.0001 for both) to 3.2 mm Hg and 3.1 breaths/min, respectively. After 5 min the effects diminished. Conclusion: Improved IC after PLB indicates less hyperinflation in patients with severe COPD; there was no effect on parameters of flow.

The present study demonstrates that ILPs improved significantly after using either device. Although significant correlations were found between the VAS and FIF(50) and PIF for the nebulizer, in stable COPD patients, the pMDI plus spacer is a better route of administration than a nebulizer.

BackgroundIn chronic obstructive pulmonary disease (COPD), the response of the forced expiratory volume in 1 second (FEV1) after bronchodilator application is weak. Inspiratory parameters like the forced inspiratory volume in 1 second (FIV1) and inspiratory capacity (IC) can be responsive to bronchodilators. In an individual patient with COPD, a significant bronchodilator response must at least exceed the random variation for that parameter. Therefore, it is important that the type of scatter is homoscedastic, as the chance of underestimating or overestimating the random variation for low or high parameter values is minimized. The aim of this study is to investigate the random variation (type and quantity) of inspiratory parameters.MethodsIn 79 stable COPD patients, spirometry was performed.The forced inspiratory volume in 1 second (FIV1), inspiratory capacity (IC), maximal inspiratory flow at 50% (MIF50) and peak inspiratory flow (PIF) were measured five times in one day and again within two weeks of the first measurement. The values of these parameters, taken within one hour, within one day and between two different days, were compared. The coefficient of repeatability (CR) was calculated, and, in addition, linear regression was performed to investigate the type of scatter (homo- or heteroscedastic) of the measured parameters.ResultsThe type of scatter was heteroscedastic for all of the parameters when the differences were expressed as absolute values; however, when the differences were expressed as the percent change from the initial values, we found a more homoscedastic scatter. The CR within one hour of each parameter expressed as the percent change from the initial value was: IC, 19%; FIV1, 14%; PIF, 18%; MEF50, 21%.ConclusionsTo obtain a more homoscedastic scatter, percentage changes in FIV1, IC and MIF50 are more appropriate than absolute changes.In an individual patient with COPD, a significant improvement for a particular parameter must at least exceed the above-mentioned CR.

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