The Effect Of Chronic Obstructive Pulmonary Disease Induced Increases In Lung Volume On Upper Airway Patency

Author(s):  
Peter R. Grossman ◽  
Jason P. Kirkness ◽  
Christian Reinke ◽  
Ashley T. Thai ◽  
Susheel P. Patil ◽  
...  
Thorax ◽  
2001 ◽  
Vol 56 (9) ◽  
pp. 713-720
Author(s):  
J Hadcroft ◽  
P M A Calverley

BACKGROUNDBronchodilator reversibility testing is recommended in all patients with chronic obstructive pulmonary disease (COPD) but does not predict improvements in breathlessness or exercise performance. Two alternative ways of assessing lung mechanics—measurement of end expiratory lung volume (EELV) using the inspiratory capacity manoeuvre and application of negative expiratory pressure (NEP) during tidal breathing to detect tidal airflow limitation—do relate to the degree of breathlessness in COPD. Their usefulness as end points in bronchodilator reversibility testing has not been examined.METHODSWe studied 20 patients with clinically stable COPD (mean age 69.9 (1.5) years, 15 men, forced expiratory volume in one second (FEV1) 29.5 (1.6)% predicted) with tidal flow limitation as assessed by their maximum flow-volume loop. Spirometric parameters, slow vital capacity (SVC), inspiratory capacity (IC), and NEP were measured seated, before and after nebulised saline, and at intervals after 5 mg nebulised salbutamol and 500 μg nebulised ipratropium bromide. The patients attended twice and the treatment order was randomised.RESULTSMean FEV1, FVC, SVC, and IC were unchanged after saline but the degree of tidal flow limitation varied. FEV1 improved significantly after salbutamol and ipratropium (0.11 (0.02) l and 0.09 (0.02) l, respectively) as did the other lung volumes with further significant increases after the combination. Tidal volume and mean expiratory flow increased significantly after all bronchodilators but breathlessness fell significantly only after the combination treatment. The initial NEP score was unrelated to subsequent changes in lung volume.CONCLUSIONSNEP is not an appropriate measurement of acute bronchodilator responsiveness. Changes in IC were significantly larger than those in FEV1and may be more easily detected. However, our data showed no evidence for separation of “reversible” and “irreversible” groups whatever outcome measure was adopted.


2011 ◽  
Vol 110 (4) ◽  
pp. 1036-1045 ◽  
Author(s):  
George Cremona ◽  
Joan A. Barbara ◽  
Teresa Melgosa ◽  
Lorenzo Appendini ◽  
Josep Roca ◽  
...  

Lung volume reduction surgery (LVRS) improves lung function, respiratory symptoms, and exercise tolerance in selected patients with chronic obstructive pulmonary disease, who have heterogeneous emphysema. However, the reported effects of LVRS on gas exchange are variable, even when lung function is improved. To clarify how LVRS affects gas exchange in chronic obstructive pulmonary disease, 23 patients were studied before LVRS, 14 of whom were again studied afterwards. We performed measurements of lung mechanics, pulmonary hemodynamics, and ventilation-perfusion (V̇a/Q̇) inequality using the multiple inert-gas elimination technique. LVRS improved arterial Po2 (PaO2) by a mean of 6 Torr ( P = 0.04), with no significant effect on arterial Pco2 (PaCO2), but with great variability in both. Lung mechanical properties improved considerably more than did gas exchange. Post-LVRS PaO2 depended mostly on its pre-LVRS value, whereas improvement in PaO2 was explained mostly by improved V̇a/Q̇ inequality, with lesser contributions from both increased ventilation and higher mixed venous Po2. However, no index of lung mechanical properties correlated with PaO2. Conversely, post-LVRS PaCO2 bore no relationship to its pre-LVRS value, whereas changes in PaCO2 were tightly related ( r2 = 0.96) to variables, reflecting decrease in static lung hyperinflation (intrinsic positive end-expiratory pressure and residual volume/total lung capacity) and increase in airflow potential (tidal volume and maximal inspiratory pressure), but not to V̇a/Q̇ distribution changes. Individual gas exchange responses to LVRS vary greatly, but can be explained by changes in combinations of determining variables that are different for oxygen and carbon dioxide.


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