Associations of airway tree to lung volume ratio on computed tomography with lung function and symptoms in chronic obstructive pulmonary disease

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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Computed tomography-derived area and density of pectoralis muscle associated disease severity and longitudinal changes in chronic obstructive pulmonary disease: a case control study

Respiratory Research ◽

10.1186/s12931-019-1191-y ◽

2019 ◽

Vol 20 (1) ◽

Cited By ~ 5

Author(s):

So Hyeon Bak ◽

Sung Ok Kwon ◽

Seon-Sook Han ◽

Woo Jin Kim

Keyword(s):

Computed Tomography ◽

Chronic Obstructive Pulmonary Disease ◽

Lung Function ◽

Pulmonary Function ◽

Pulmonary Disease ◽

Disease Severity ◽

Chronic Obstructive ◽

Pectoralis Muscle ◽

Obstructive Pulmonary Disease ◽

Longitudinal Changes

Abstract Background Muscle wasting is associated with prognosis in patients with chronic obstructive pulmonary disease (COPD). The cross-sectional area of skeletal muscles on computed tomography (CT) could serve as a method to evaluate body composition. The present study aimed to determine the ability of CT-derived pectoralis muscle area (PMA) and pectoralis muscle density (PMD) to determine the severity of COPD and change in longitudinal pulmonary function in patients with COPD. Methods A total of 293 participants were enrolled in this study, a whom 222 had undergone at least two spirometry measurements within 3 years after baseline data acquisition. PMA and PMD were measured from a single axial slice of chest CT above the aortic arch at baseline. The emphysema index and bronchial wall thickness were quantitatively assessed in all scans. The generalized linear model was used to determine the correlation between PMA and PMD measurements and pulmonary function. Results PMA and PMD were significantly associated with baseline lung function and the severity of emphysema (P < 0.05). Patients with the lowest PMA and PMD exhibited significantly more severe airflow obstruction (β = − 0.06; 95% confidence interval: − 0.09 to − 0.03]. PMA was statistically associated with COPD assessment test (CAT) score (P = 0.033). However, PMD did not exhibit statistically significant correlation with either CAT scores or modified Medical Research Council scores (P > 0.05). Furthermore, neither PMA nor PMD were associated with changes in forced expiratory volume in 1 s over a 3-year periods. Conclusions CT-derived features of the pectoralis muscle may be helpful in predicting disease severity in patients with COPD, but are not necessarily associated with longitudinal changes in lung function.

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