Related Articles

Endoscopic lung volume reduction (ELVR) is an emerging therapy for emphysematous COPD. However, any resulting changes in lung perfusion and ventilation remain undetermined. Here, we report ELVR-mediated adaptations in lung perfusion and ventilation, as investigated by means of pulmonary scintigraphy.

METHODS: In this observational study, we enrolled 26 patients (64.9±9.4 yrs, 57.7% male) with COPD heterogeneous emphysema undergoing ELVR with endobronchial valves (Zephyr, Pulmonx, Inc.). Mean baseline FEV1 and RV were 32.9% and 253.8% predicted, respectively. Lung scintigraphy was conducted prior to ELVR and eight weeks thereafter. Analyses of perfusion and ventilation shifts were performed and complemented by correlation analyses between paired zones.

RESULTS: After ELVR, target zone perfusion showed a mean relative reduction of 43.32% (p<0.001), which was associated with a significant decrease in target zone ventilation (p<0.001). Perfusion of the contralateral untreated zone and of the contralateral total lung exhibited significant increases post-ELVR (p = 0.002 and p = 0.005, respectively); both correlated significantly with the corresponding target zone perfusion adaptations. Likewise, changes in target zone ventilation correlated significantly with ventilatory changes in the contralateral untreated zone and the total contralateral lung (Pearson's r: -0.42, p = 0.04 and Pearson's r: -0.42, p = 0.03, respectively). These effects were observed in case of clinical responsiveness to ELVR, as assessed by changes in the six-minute walk test distance.

DISCUSSION: ELVR induces a relevant decrease in perfusion and ventilation of the treated zone with compensatory perfusional and ventilatory redistribution to the contralateral lung, primarily to the non-concordant, contralateral zone.

Lire la suite...

Related Articles

It remains difficult to differentiate between chronic obstructive pulmonary disease (COPD) and asthma in clinical practice, especially in a primary care setting. The purpose of this study was to develop a new scoring system for differentiating between COPD and asthma, and to evaluate its effectiveness.

METHODS: First, to identify important variables differentiating COPD from asthma, the data of 197 patients with COPD and 138 patients with asthma were assessed retrospectively. Secondly, a scoring system that was based on these variables was then developed, and its performance was internally validated using a bootstrapping-based method. Thirdly, the scoring system was externally validated using prospectively collected data from patients with COPD (n = 104) or asthma (n = 96).

RESULTS: The final scoring system was composed of the four variables: age of onset of breathlessness (<40 years, 0 points; 40-60 years, 2 points; >60 years, 4 points), continuous breathlessness (no, 0 points; yes, 1 point), diurnal variation of breathlessness (yes, 0 points; no, 1 point) and emphysematous change in chest X-ray (no, 0 points; yes, 1 point). The patients were classified by their total score into three categories: 0-2 points, probable asthma; 3-4 points, difficult-to-differentiate; 5-7 points, probable COPD. The new scoring system performed well in the external validation dataset (area under the curve, 0.86; 95% confidence interval: 0.813-0.911; P < 0.001).

CONCLUSIONS: The new scoring system that was developed in this study may be a useful tool for differentiating between COPD and asthma in primary care.

Lire la suite...

Related Articles

Chronic obstructive pulmonary disease (COPD) is characterized by a mixture of emphysema and airway disease. The forced oscillation technique (FOT) has been applied to COPD patients to clarify changes in respiratory mechanics; dynamic changes in respiratory resistance (Rrs) during breathing (within-breath changes in Rrs, ΔRrs) are characteristic of COPD. However, the pathophysiological significance of these changes is unknown. The aim of this study was to assess how emphysema and airway disease influence ΔRrs in COPD patients.

METHODS: In this cross-sectional study, stable COPD patients were recruited and underwent respiratory impedance measurements with a commercially available FOT device. Rrs was recorded during tidal breathing and then analyzed as whole-breath Rrs (Rrs at 5 Hz, R5; Rrs at 20 Hz, R20; and their difference, R5-R20) or as ΔRrs, the difference between the expiratory and inspiratory Rrs (ΔR5, ΔR20 and ΔR5-R20). The percentage of the low attenuation area (LAA%) and airway wall area (WA%) was quantified by computed tomography analysis, and their contributions to ΔRrs were examined.

RESULTS: Seventy-five COPD patients were recruited. LAA% was negatively correlated with ΔR5 and ΔR5-R20 (P = 0.0002 and P = 0.0033, respectively); meanwhile, WA% in B(10) was positively correlated with ΔR5 and ΔR5-R20 (P = 0.0057 and P < 0.0001, respectively). Multivariate analysis revealed that the contribution of both LAA% and WA% in B(10) to ΔRrs was independent of the severity of airflow limitations.

CONCLUSION: This study shows that emphysema suppresses ΔRrs in COPD patients, while airway disease increases ΔRrs in these patients.

Lire la suite...

Several studies in mild COPD have shown higher than normal ventilatory equivalent for carbon dioxide (VE/VCO2) during exercise. Our objective was to examine pulmonary gas exchange abnormalities and the mechanisms of high VE/VCO2 in mild COPD and its impact on dyspnea and exercise intolerance.

METHODS: Twenty-two subjects (11 GOLD grade-1B COPD patients, 11 age-matched healthy controls) undertook physiological testing and a symptom-limited incremental cycle exercise test with arterial blood gas collection.

RESULTS: Patients (post-bronchodilator FEV1: 94±10 %predicted; mean±SD) had evidence of peripheral airway dysfunction and reduced peak oxygen uptake compared to controls (80±18 versus 113±24 %predicted; p<0.05). Arterial blood gases were within the normal range and effective alveolar ventilation was not significantly different from controls throughout exercise. The alveolar-arterial O2 gradient was elevated at rest and throughout exercise in COPD (p<0.05). VE/VCO2, dead space-to-tidal volume ratio (VD/VT), and arterial-to-end tidal CO2 difference were all higher (p<0.05) in COPD than controls during exercise. In COPD versus controls, there was significant dynamic hyperinflation and greater tidal volume constraints (p<0.05). Standardized dyspnea intensity ratings were also higher (p<0.05) in COPD versus controls in association with higher ventilatory requirements. Within all subjects, VD/VT correlated with the VE/VCO2 ratio during submaximal exercise (r=0.780, p<0.001).

CONCLUSION: High VD/VT was the most consistent gas exchange abnormality in smokers with only mild spirometric abnormalities. Compensatory increases in minute ventilation during exercise maintained alveolar ventilation and arterial blood gas homeostasis but at the expense of earlier dynamic mechanical constraints, greater dyspnea and exercise intolerance in mild COPD.

Lire la suite...