COPD patients with severe diffusion defect in carbon monoxide diffusing capacity predict a better outcome for pulmonary rehabilitation.

The aim of this study was to compare the effects of pulmonary rehabilitation (PR) on six-minute walk test (6mWT) between chronic obstructive pulmonary disease (COPD) patients with moderate or severe carbon monoxide diffusion defects. We also evaluated dyspnea sensation, pulmonary functions, blood gases analysis, quality of life parameters and psychological symptoms in both groups before and after pulmonary rehabilitation. Patients with COPD underwent a comprehensive 8-week out-patient PR program participated in this study. Patients grouped according to diffusion capacity as moderate or severe. Outcome measures were exercise capacity (6mWT), dyspnea sensation, pulmonary function tests, blood gases analysis, quality of life (QoL) and psychological symptoms. A total of 68 patients enrolled in the study. Thirty-two (47%) of them had moderate diffusion defect [TlCO; 52 (47-61)mmol/kPa] and 36 (53%) of them had severe diffusion defect [TlCO; 29 (22-34)mmol/kPa]. At the end of the program, PaO2 (p=0.001), Modified Medical Research Council dyspnea scale (p=0.001), 6mWT (p<0.001) and quality of life parameters improved significantly in both groups (p<0.05). Also the improvement in DlCO (p=0.04) value and FEV1% (p=0.01) reached a statistically significant level in patients with severe diffusion defect. When comparing changes between groups, dyspnea reduced significantly in patients with severe diffusion defect (p=0.04). Pulmonary rehabilitation improves oxygenation, severity of dyspnea, exercise capacity and quality of life independent of level of carbon monoxide diffusion capacity in patents with COPD. Furthermore pulmonary rehabilitation may improve DlCO values in COPD patients with severe diffusion defect.

Sahin H ，Naz I ，Varol Y ，Aksel N ，Tuksavul F ，Ozsoz A ... -  《-》

Improvements in Lung Diffusion Capacity following Pulmonary Rehabilitation in COPD with and without Ventilation Inhomogeneity.

Lung diffusing capacity (DLCO) and lung volume distribution predict exercise performance and are altered in COPD patients. If pulmonary rehabilitation (PR) can modify DLCO parameters is unknown. To investigate changes in DLCO and ventilation inhomogeneity following a PR program and their relation with functional outcomes in patients with COPD. This was a prospective, observational, multicentric study. Patients were evaluated before and after a standardized 3-week PR program. Functional assessment included body plethysmography, DLCO, transfer factor (KCO) and alveolar volume (VA), gas exchange, the 6-min walking test (6MWT) and exercise-related dyspnea. Patients were categorized according to the severity of airflow limitation and presence of ventilation inhomogeneity, identified by a VA/TLC <0.8. Two hundred and fifty patients completed the study. Baseline forced expiratory volume in 1 s (FEV1) % predicted (mean ± SD) was 50.5 ± 20.1 (76% males); 137 patients had a severe disease. General study population showed improvements in 6MWT (38 ± 55 m; p < 0.01), DLCO (0.12 ± 0.63 mmol × min-1 kPa-1; p < 0.01), lung function and dyspnea. Comparable improvements in DLCO were observed regardless of the severity of disease and the presence of ventilation inhomogeneity. While patients with VA/TLC <0.8 improved the DLCO increasing their VA (177 ± 69 ml; p < 0.01), patients with VA/TLC >0.8 improved their KCO (8.1 ± 2.8%; p = 0.019). The latter had also better baseline lung function and higher improvements in 6MWT (14.6 ± 6.7 vs. 9.0 ± 1.8%; p = 0.015). Lower DLCO at baseline was associated with lower improvements in 6MWT, the greatest difference being between subjects with very severe and mild DLCO impairment (2.7 ± 7.4 vs. 14 ± 2%; p = 0.049). In COPD patients undergoing a PR program, different pathophysiological mechanisms may drive improvements in DLCO, while ventilation inhomogeneity may limit improvements in exercise tolerance.

Santus P ，Radovanovic D ，Balzano G ，Pecchiari M ，Raccanelli R ，Sarno N ，Di Marco F ，Jones PW ，Carone M ... -  《-》

Usefulness of the desaturation-distance ratio from the six-minute walk test for patients with COPD.

Fujimoto Y ，Oki Y ，Kaneko M ，Sakai H ，Misu S ，Yamaguchi T ，Mitani Y ，Yasuda H ，Ishikawa A ... -  《International Journal of Chronic Obstructive Pulmonary Disease》

[Single-breath and rebreathing methods for measurement of pulmonary diffusing function: a comparative study].

Liu QX ，Zheng JP ，Xie YQ ，Guan WJ ，Jiang CY ，An JY ，Yu XX ，Liu WT ，Gao Y ... -  《-》

Diffusing Capacity of Carbon Monoxide in Assessment of COPD.

Diffusing capacity of the lung for carbon monoxide (Dlco) is inconsistently obtained in patients with COPD, and the added benefit of Dlco testing beyond that of more common tools is unknown. The goal of this study was to determine whether lower Dlco is associated with increased COPD morbidity independent of emphysema assessed via spirometry and CT imaging. Data for 1,806 participants with COPD from the Genetic Epidemiology of COPD (COPDGene) study 5-year visit were analyzed, including pulmonary function testing, quality of life, symptoms, exercise performance, and exacerbation rates. Dlco percent predicted was primarily analyzed as a continuous variable and additionally categorized into four groups: (1) Dlco and FEV1 > 50% (reference); (2) only Dlco ≤ 50%; (3) only FEV1 ≤ 50%; and (4) both ≤ 50% predicted. Outcomes were modeled by using multivariable linear and negative binomial regression, including emphysema and FEV1 percent predicted among other confounders. In multivariable analyses, every 10% predicted decrease in Dlco was associated with symptoms and quality of life (COPD Assessment Test, 0.53 [P < .001]; St. George's Respiratory Questionnaire, 1.67 [P < .001]; Medical Outcomes Study Short Form 36 Physical Function, -0.89 [P < .001]), exercise performance (6-min walk distance, -45.35 feet; P < .001), and severe exacerbation rate (rate ratio, 1.14; P < .001). When categorized, severe impairment in Dlco alone, FEV1 alone, or both Dlco and FEV1 were associated with significantly worse morbidity compared with the reference group (P < .05 for all outcomes). Impairment in Dlco was associated with increased COPD symptoms, reduced exercise performance, and severe exacerbation risk even after accounting for spirometry and CT evidence of emphysema. These findings suggest that Dlco should be considered for inclusion in future multidimensional tools assessing COPD.

Balasubramanian A ，MacIntyre NR ，Henderson RJ ，Jensen RL ，Kinney G ，Stringer WW ，Hersh CP ，Bowler RP ，Casaburi R ，Han MK ，Porszasz J ，Barr RG ，Make BJ ，Wise RA ，McCormack MC ... -  《-》