May noninvasive mechanical ventilation and/ or continuous positive airway pressure increase the bronchoalveolar lavage salvage in patients with pulmonary diseases? Randomized clinical trial - Study protocol

PURPOSE

Bronchoalveolar lavage (BAL) procedure is a useful tool in the diagnosis of patients with interstitial lung disease (ILD) and is helpful in clinical research of chronic obstructive pulmonary disease (COPD) patients. Still little is known about predictors of poor BAL salvage. The trial aims to find the most efficient way to improve BAL recovery.

MATERIAL AND METHODS

Our study is a prospective, multicenter, international, two-arm randomized controlled trial. We aim to obtain BAL samples from a total number of 300 patients: 150 with ILD and 150 with COPD to achieve a statistical power of 80 ​%. Patients with initial BAL salvage <60 ​% will be randomized into the non-invasive ventilation (NIV) or continuous positive airway pressure (CPAP) arm. The NIV and CPAP will be set according to the study protocol. The influence on BAL salvage will be assessed in terms of BAL volume and content. Multivariable analysis of the additional test results to determine predictors for low BAL recovery will be conducted. In a study subgroup of approximately 20 patients per specific disease, a metabolomic assessment of exhaled air condensate will be performed. All procedures will be assessed in terms of the patient's safety. The trial was registered on clinicaltrials.gov (ID# NCT05631132). Interested experienced centers are invited to join the research group by writing to the corresponding author.

CONCLUSION

The results of our prospective study will address the currently unsolved problem of how to increase BAL salvage in patients with pulmonary diseases without increasing the risk of respiratory failure exacerbation.

A Real-World Multicenter Retrospective Observational Study on Polish Experience with Nintedanib Therapy in Patients with Idiopathic Pulmonary Fibrosis: The PolExNIB Study

Nintedanib is a disease-modifying agent licensed for the treatment of IPF. Data on Polish experience with nintedanib in IPF are lacking. The present study aimed to describe the safety and efficacy profiles of nintedanib in a large real-world cohort of Polish patients with IPF. This was a multicenter, retrospective, observational study of IPF patients treated with nintedanib between March 2018 and October 2021. Data collection included baseline clinical characteristics, results of pulmonary function tests (PFTs), and a six-minute walk test (6MWT). Longitudinal data on PFTs, 6MWT, adverse drug reactions (ADRs), and treatment persistence were also retrieved. A total of 501 patients (70% male) with a median age of 70.9 years (IQR 65-75.7) were included in this study. Patients were followed on treatment for a median of 15 months (7-25.5). The majority of patients (66.7%) were treated with the full recommended dose of nintedanib and 33.3% of patients were treated with a reduced dose of a drug. Intermittent dose reductions or drug interruptions were needed in 20% of patients. Over up to 3 years of follow-up, pulmonary function remained largely stable with the minority experiencing disease progression. The most frequent ADRs included diarrhea (45.3%), decreased appetite (29.9%), abdominal discomfort (29.5%), weight loss (32.1%), nausea (20.8%), fatigue (19.2%), increased liver aminotransferases (15.4%), and vomiting (8.2%). A total of 203 patients (40.5%) discontinued nintedanib treatment due to diverse reasons including ADRs (10.2%), death (11.6%), disease progression (4.6%), patient's request (6.6%), and neoplastic disease (2.2%). This real-world study of a large cohort of Polish patients with IPF demonstrates that nintedanib therapy is safe, and is associated with acceptable tolerance and disease stabilization. These data support the findings of previously conducted clinical trials and observational studies on the safety and efficacy profiles of nintedanib in IPF.

Therapeutic decisions in a cohort of patients with idiopathic pulmonary fibrosis: a multicenter, prospective survey from Poland

Background

Pirfenidone and nintedanib are considered as the standard of care in idiopathic pulmonary fibrosis (IPF), but there is no consensus as to which of these two agents should be regarded as first-line treatment.

Objective

To provide real-world data on therapeutic decisions of pulmonary specialists, particularly the choice of the antifibrotic drug in patients with IPF.

Methods

This was a multicenter, prospective survey collecting clinical data of patients with IPF considered as candidates for antifibrotic treatment between September 2019 and December 2020. Clinical characteristics and information on the therapeutic approach were retrieved. Statistical evaluation included multiple logistic regression analysis with stepwise model selection.

Results

Data on 188 patients [74.5% male, median age 73 (interquartile range, 68-78) years] considered for antifibrotic therapy were collected. Treatment was initiated in 138 patients, while 50 patients did not receive an antifibrotic, mainly due to the lack of consent for treatment and IPF severity. Seventy-two patients received pirfenidone and 66 received nintedanib. Dosing protocol (p < 0.01) and patient preference (p = 0.049) were more frequently associated with the choice of nintedanib, while comorbidity profile (p = 0.0003) and concomitant medication use (p = 0.03) were more frequently associated with the choice of pirfenidone. Age (p = 0.002), lung transfer factor for carbon monoxide (TL_CO) (p = 0.001), and gastrointestinal bleeding (p = 0.03) were significantly associated with the qualification for the antifibrotic treatment.

Conclusion

This real-world prospective study showed that dose protocol and patient preference were more frequently associated with the choice of nintedanib, while the comorbidity profile and concomitant medication use were more frequently associated with the choice of pirfenidone. Age, TL_CO, and history of gastrointestinal bleeding were significant factors influencing the decision to initiate antifibrotic therapy.

Risk factors of complications during noninvasive mechanical ventilation -assisted flexible bronchoscopy

PURPOSE

Flexible bronchoscopy (FB) causes airway narrowing and may cause respiratory failure (RF). Noninvasive mechanical ventilation (NIV) is used to treat RF. Until recently, little was known about noninvasive mechanical ventilation assisted flexible bronchoscopy (NIV-FB) risk and complications.

MATERIALS AND METHODS

A retrospective analysis of NIV-FB performed in 20 consecutive months (July 1, 2018-February 29, 2020) was performed. Indications for: FB and NIV, as well as impact of comorbidities, blood gas results, pulmonary function test results and sedation depth, were analyzed to reveal NIV-FB risk. Out of a total of 713 FBs, NIV-FB was performed in 50 patients with multiple comorbidities, acute or chronic RF, substantial tracheal narrowing, or after previously unsuccessful FB attempt.

RESULTS

In three cases, reversible complications were observed. Additionally, due to the severity of underlining disease, two patients were transferred to the ICU where they passed away after >48h. In a single variable analysis, PaO₂ 69 ​± ​18.5 and 49 ​± ​9.0 [mmHg] (p ​< ​0.05) and white blood count (WBC) 10.0 ​± ​4.81 and 14.4 ​± ​3.10 (p ​< ​0.05) were found predictive for complications. Left heart disease indicated unfavorable NIV-FB outcome (p ​= ​0.046).

CONCLUSIONS

NIV-FB is safe in severely ill patients, however procedure-related risk should be further defined and verified in prospective studies.

Ocena niedoborów witaminy D w grupie pacjentów z ciężką przewlekłą obturacyjną chorobą płuc w stadium przewlekłej niewydolności oddechowej

Wstęp: Celem pracy była ocena stężenia witaminy D w surowicy chorych z niewydolnością oddechową w przebiegu przewlekłej obturacyjnej choroby płuc POChP w porównaniu z grupą kontrolną złożoną ze zdrowych osób. Dodatkowym celem badania była analiza korelacji stężenia witaminy D w surowicy z wybranymi parametrami klinicznymi, gazometrycznymi i spirometrycznymi. Materiał i metody: Badaniem objęto 61 osób z POChP w stadium przewlekłej niewydolności oddechowej (45 mężczyzn oraz 16 kobiet) oraz 37 osób zdrowych w grupie kontrolnej (19 mężczyzn oraz 18 kobiet). W obydwu grupach wykonano następujące procedury: szczegółowy wywiad z uwzględnieniem aktywności ruchowej, diety i używek, spirometrię po leku rozszerzającym oskrzela, oznaczenie stężenia 25(OH)D w surowicy oraz w grupie badanej gazometrię krwi arterializowanej. Rekrutacja trwała od listopada do kwietnia. Analiza statystyczna została przeprowadzona za pomocą testu t-Studenta, testu U-Manna-Whitneya, korelacji porządku rang Spearmana i testu Chi-kwadrat. Wyniki: Stężenia 25(OH)D w surowicy krwi nie różniły się istotnie statystycznie pomiędzy grupą badaną a grupą kontrolną. Mediana (dolny i górny kwartyl) wyniosły odpowiednio: 24.75 nmol/L (16.9; 36.4) vs. 24.06 nmol/L (16.3; 37.2), p = 0.69. Niedobór witaminy D wystąpił u 60 chorych na POChP (98.3%) oraz 36 osób z grupy kontrolnej (97.3%), a różnica nie była znamienna statystycznie. Stężenie witaminy D nie korelowało istotnie statystycznie z żadnymi parametrami spirometrycznymi, gazometrycznymi, aktywnością, wiekiem, BMI ani paczkolatami palenia tytoniu. Natomiast oceniana aktywność korelowała dodatnio z parametrami spirometrycznymi i ujemnie z wiekiem oraz liczbą zaostrzeń. Wnioski: Wynik badania potwierdził, że w okresie jesienno-zimowym w Polsce niedobór witaminy D jest bardzo częsty nie tylko u chorych na POChP w stadium niewydolności oddechowej, ale także u osób zdrowych w podeszłym wieku. W przeciwieństwie do oczekiwań stężenia witaminy D w surowicy krwi u chorych na POChP z niewydolnością oddechową były podobne jak obserwowane w grupie kontrolnej złożonej z osób zdrowych.

Distribution and characteristics of COPD phenotypes - results from the Polish sub-cohort of the POPE study

Background

This study aimed to examine the distribution of predefined phenotypes, demographic data, clinical outcomes, and treatment of patients who were included in the Polish cohort of the Phenotypes of COPD in Central and Eastern Europe (POPE) study.

Patients and methods

This was a sub-analysis of the data from the Polish cohort of the POPE study, an international, multicenter, observational cross-sectional survey of COPD patients in Central and Eastern European countries. The study included patients aged >40 years, with a confirmed diagnosis of COPD, and absence of exacerbation for at least 4 weeks before study inclusion. A total of seven Polish centers participated in the study.

Results

Among the 430 Polish COPD patients enrolled in the study, 61.6% were non-exacerbators (NON-AE), 25.3% were frequent exacerbators with chronic bronchitis (AE CB), 7.9% were frequent exacerbators without chronic bronchitis (AE NON-CB), and 5.1% met the definition of asthma-COPD overlap syndrome (ACOS). There were statistically significant differences among these phenotypes in terms of symptom load, lung function, comorbidities, and treatment. Patients with the AE CB phenotype were most symptomatic with worse lung function, and more frequently reported anxiety and depression. Patients with the ACOS phenotype were significantly younger and were diagnosed with COPD earlier than those with other COPD phenotypes; those with the ACOS phenotype were also more often atopic and obese.

Conclusion

There is significant heterogeneity among COPD patients in the Polish population in terms of phenotype and clinical outcome. The non-exacerbator phenotype is observed most frequently in Poland, while the frequent exacerbator with chronic bronchitis phenotype is the most symptomatic.

[Zygomatic localization of Langerhans cell histiocytosis - a case report]

Langerhans cell histocytosis is a rare disease. LCH is reported mainly in children aged less than 15 years, however it may appear at any age. In this work, the case of 17-month boy is reported. The boy was admitted to the pediatric ophthalmology department in order to diagnose the swelling and bruising in the lower part of left orbit, which had lasted for one month before. The clinical status, various imaging techniques' results (MRI, TK and PET) and immunohistochemistry led to the final diagnosis of multisystem LCH (spread to masticator muscle and zygomatic bone). After the pharmacological therapy the total remission was achieved. Since four years the child is regularly controlled by oncologists and hematologists with no relapse reported.

Evaluation of COPD Progression Based on Spirometry and Exercise Capacity

Introduction: Chronic obstructive pulmonary disease (COPD) is characterized by an airflow limitation that is usually progressive. The progression of COPD expressed as the rate of an annual decline in FEV1 is very heterogeneous. Exercise capacity in COPD patients is often diminished and becomes worsened over the time. The purpose of the study was to examine how the change in FEV1 and exercise capacity would deteriorate over long-term observation. Material and Methods: A total of 22 men with COPD were examined. At the beginning the average age was 59 ± 8.1 years and the mean post-bronchodilator FEV1 was 52 ± 14.9% predicted. Pulmonary function testing was performed at entry and then each year for 10 years, and exercise testing on a cycle ergometer was performed at entry and after 10 years. Results: FEV1 and maximum oxygen uptake (VO2max), maximum mechanical work (Wmax), maximum minute ventilation (VEmax) and maximum tidal volume (VTmax) declined significantly over the observation time. The mean annual decline in FEV1 was 42 ± 37 mL, and the mean decline for VO 2max was 30 ± 15 mL/min/yr and 0.44 ± 0.25 mL/min/kg/yr. Regression analysis revealed that the changes in FEV1 do not predict changes in VO2max. We observed a correlation between the annual change in VEmax and annual change in VO2max (r = 0.51; p < 0.05). The baseline FEV1 (expressed as a percentage of predicted and in absolute values) is the predictor of FEV1 annual decline (r = 0.74 and 0.82; p < 0.05). Conclusions: We observed over time deterioration in exercise capacity in COPD patients which is independent of decline in airflow limitation. The long term follow-up of exercise capacity is important in monitoring of COPD patients in addition to pulmonary function.

Evaluation of COPD progression based on spirometry and exercise capacity

INTRODUCTION

Chronic obstructive pulmonary disease (COPD) is characterized by an airflow limitation that is usually progressive. The progression of COPD expressed as the rate of an annual decline in FEV 1 is very heterogeneous. Exercise capacity in COPD patients is often diminished and becomes worsened over the time. The purpose of the study was to examine how the change in FEV 1 and exercise capacity would deteriorate over long-term observation.

MATERIAL AND METHODS

A total of 22 men with COPD were examined. At the beginning the average age was 59 ± 8.1 years and the mean post-bronchodilator FEV 1 was 52 ± 14.9% predicted. Pulmonary function testing was performed at entry and then each year for 10 years, and exercise testing on a cycle ergometer was performed at entry and after 10 years.

RESULTS

FEV 1 and maximum oxygen uptake (VO2max), maximum mechanical work (W max ), maximum minute ventilation (V Emax ) and maximum tidal volume (V Tmax ) declined significantly over the observation time. The mean annual decline in FEV 1 was 42 ± 37 mL, and the mean decline for VO 2max was 30 ± 15 mL/min/yr and 0.44 ± 0.25 mL/min/kg/yr. Regression analysis revealed that the changes in FEV 1 do not predict changes in VO2max. We observed a correlation between the annual change in V Emax and annual change in VO2max (r = 0.51 p < 0.05). The baseline FEV 1 (expressed as a percentage of predicted and in absolute values) is the predictor of FEV 1 annual decline (r = 0.74 and 0.82; p < 0.05).

CONCLUSIONS

We observed over time deterioration in exercise capacity in COPD patients which is independent of decline in airflow limitation. The long term follow-up of exercise capacity is important in monitoring of COPD patients in addition to pulmonary function.

[Hemoptysis and dyspnea in a woman treated with acenocoumarol due to venous thrombosis]

A case report of young woman diagnosed as having microscopic polyangiitis (MPO) presenting with diffuse alveolar hemorrhage (DAH). DAH is a rare, but life-threatening disorder. The patients presented with dyspnea, cough, hemoptysis (not constant). The radiographic features are very characteristic and reveal the signs of diffuse, bilateral alveolar filling in chest HRCT especially in middle and lower zones. Anaemia with iron deficiency and hypoxic respiratory failure. Elevation of diffuse capacity (above 30% of predicted) is often recognized as a result of presence of blood in the alveoli. Broncho-alveolar lavage reveal haemosiderin laden macrophages. It may occurs most frequently as a secondary condition due to microscopic polyangiitis (MPA), Wegener's granulomatosis (WG), Goodpasture syndrome. Among the many conditions it can accompany connective tissue disorders, antiphospholipid antibody syndrome, some medicines or toxic exposures.

Role of C-C Chemokines in the Determination of Pleural Effusion Etiology

Introduction: Pleural effusion secondary to various diseases is associated with the presence of different inflammatory cells. The C-C chemokines (MCP-1 and MIP-1α), produced by pleural mesothelial cells, plays an important role in the recruitment of inflammatory cells to the pleural space. The purpose of the study was to evaluate predictive value of MCP-1 and MIP-1α in the differential diagnosis of pleural effusion. Material and methods: Based on Light’s criteria in 29 cases exudates and in 10 transudates were recognized. We investigated 39 patients with pleural effusion (congestive heart failure — 10, parapneumonic — 11, tuberculous — 6, malignant — 12). The C-C chemokines MCP-1 and MIP-1α levels in pleural effusion and serum were measured by ELISA. Results: The MCP-1 was significantly higher (p = 0.009) in the patient with exudates than in patients with transudates (2436 pg/ml and 794 pg/ml respectively). ROC curve analysis revealed however that this parameter has limited value in the differentiation of exudates an transudates (MCP-1 cut off value 1060 pg/ml, sensitivity 48%, specificity 90%, PPV 93%, NPV 37%). The chemokine MIP-1α were significantly higher (p = 0.001) in tuberculous than in the malignant effusion (405 pg/ml and 30 pg/ml respectively). Based on the ROC curve analysis, as a cut off value in the differentiation of tuberculous and malignant pleural effusion a value 120 pg/ml was accepted. The sensitivity of this test was 66% and specificity 99%, PPV 80%, NPV 84%. Conclusions: The chemokine MCP-1 has a limited value in the differentiation between transudate and exudates; MIP-1α could be helpful in the differentiation between tuberculous and malignant pleural effusion.

[Role of C-C chemokines in the determination of pleural effusion etiology]

INTRODUCTION

Pleural effusion secondary to various diseases is associated with the presence of different inflammatory cells. The C-C chemokines (MCP-1 and MIP-1alpha), produced by pleural mesothelial cells, plays an important role in the recruitment of inflammatory cells to the pleural space. The purpose of the study was to evaluate predictive value of MCP-1 and MIP-1alpha in the differential diagnosis of pleural effusion.

MATERIAL AND METHODS

Based on Light's criteria in 29 cases exudates and in 10 transudates were recognized. We investigated 39 patients with pleural effusion (congestive heart failure - 10, parapneumonic - 11, tuberculous - 6, malignant - 12). The C-C chemokines MCP-1 and MIP-1alpha levels in pleural effusion and serum were measured by ELISA.

RESULTS

The MCP-1 was significantly higher (p = 0.009) in the patient with exudates than in patients with transudates (2436 pg/ml and 794 pg/ml respectively). ROC curve analysis revealed however that this parameter has limited value in the differentiation of exudates an transudates (MCP-1 cut off value 1060 pg/ml, sensitivity 48%, specificity 90%, PPV 93%, NPV 37%). The chemokine MIP-1alpha were significantly higher (p = 0.001) in tuberculous than in the malignant effusion (405 pg/ml and 30 pg/ml respectively). Based on the ROC curve analysis, as a cut off value in the differentiation of tuberculous and malignant pleural effusion a value 120 pg/ml was accepted. The sensitivity of this test was 66% and specificity 99%, PPV 80%, NPV 84%.

CONCLUSIONS

The chemokine MCP-1 has a limited value in the differentiation between transudate and exudates; MIP-1alpha could be helpful in the differentiation between tuberculous and malignant pleural effusion.

[Role of c-c chemokines in the determination of pleural effusion etiology]

The purpose of the study was to evaluate predictive value of vascular endothelial growth factor (VEGF) in the differential diagnosis of pleural effusion.

MATERIAL AND METHODS

By Light's criteria in 29 cases exudates and 10 transudates was recognized. We investigated 39 patients with pleural effusion (congestive heart failure--10, parapneumonic--11, tuberculous--6, malignant--12, transudate--10).

RESULTS

The mean VEGF value were significantly higher (p = 0.002) in the effusion of lung cancer patient (3958.33 pg/ml) than in the serum (1030.33 pg/ml). The mean VEGF levels were significantly higher (p = 0.004) in patient with exudates (2711.10 pg/ml) than in transudates (683 pg/ml). Based on the receiver operating characteristic (ROC) curve analysis, cut off value in differentiation of exudates and transudates was accepted at the level of 560 pg/ml (sensitivity 80% and specificity 70%). The mean VEGF levels were significantly higher (p = 0.008) in the malignant effusion (3958.33 pg/ml) than in the tuberculous effusion (1308.90 pg/ml). Based on the ROC curve analysis, cut off value in differentiation of malignant and tuberculous effusion was accepted at the level of 2000 pg/ml (sensitivity 92% and specificity 83%). The positive correlation between pleural VEGF concentrations and pleural lactate dehydrogenase (LDH) level were observed (r = 0.67, p < 0.05).

CONCLUSION

We conclude that pleural effusion VEGF level could be useful in the differentiation between exudates and transudate and also between malignant and tuberculous exudates.

Możliwości wnioskowania o zdolności wysiłkowej chorych na przewlekłą obturacyjną chorobę płuc na podstawie krzywej maksymalnego przepływu i objętości

Wstęp: Chorzy na przewlekłą obturacyjną chorobę płuc (POChP) często wykazują upośledzoną tolerancję wysiłku. Wyrazem tego jest zmniejszona zdolność wysiłkowa, którą najlepiej określić wskaźnikiem maksymalnego zużycia tlenu (V’O2max). Zależność między spoczynkowymi wskaźnikami czynności płuc a wskaźnikami zdolności wysiłkowej była przedmiotem wielu badań, jednak dotychczas nie ustalono jednoznacznie wartości predykcyjnej tych wskaźników w przewidywaniu zdolności wysiłkowej u chorych na POChP. W miarę postępu POChP kształt krzywej MEFV się zmienia. Na skutek dynamicznej kompresji dróg oddechowych podczas natężonego wydechu krzywa ta staje się coraz bardziej wklęsła w kierunku osi objętości. Celem prezentowanej pracy była ocena przydatności nowego wskaźnika, jakim jest pole powierzchni pod krzywą maksymalnego przepływu wydechowego i objętości płuc [A(ex)], w przewidywaniu zdolności wysiłkowej (wyrażonej wskaźnikiem maksymalnego zużycia tlenu—V’O2max i maksymalnej pracy mechanicznej—Wmax). Materiał i metody: W badaniu wzięło udział 41 chorych na POChP w stadium od łagodnego do ciężkiego (FEV1 57.2 ± 15.3%N). U każdego pacjenta wykonano badanie spirometryczne, wyliczono wskaźnik A(ex), a następnie przeprowadzono limitowane objawami badanie wysiłkowe o wzrastającym obciążeniu, określając V’O2max i Wmax. Wyniki: Średnia wartość (± SD) A(ex) wynosiła 7.22 (± 4.37), a w grupie A i B odpowiednio 9.38 (± 4.54) i 4.20 (± 1.71). Wartości A(ex) między grupą A i B różniły się znamiennie (p < 0.0002). Stwierdzono istotną korelację między A(ex) i V’O2max (r = 0.57; p = 0.0009) w całej badanej grupie. U chorych na ciężką postać POChP stwierdzono istotną korelację między A(ex) i Wmax (r = 0.50; p = 0.04). Wnioski: Pole powierzchni pod krzywą maksymalnego przepływu wydechowego i objętości płuc [A(ex)] może być dodatkowym wskaźnikiem przydatnym w ocenie stopnia ciężkości oraz przewidywania zdolności wysiłkowej chorych na POChP.

[Prediction of exercise capacity in chronic obstructive pulmonary disease patients on the basis of maximum expiratory flow-volume curve]

INTRODUCTION

Patients with chronic obstructive pulmonary disease (COPD) often present reduced exercise tolerance. Limitation of exercise capacity in COPD is an essential feature, which can be accurately determined by incremental cycle ergometry. The relationship between resting lung function variables and exercise capacity has been studied extensively in COPD patients. A clear relationship between resting pulmonary function testing and exercise capacity has not been established. The present study was designed to assess the accuracy of new index such as area under the maximal expiratory flow-volume curve [A(ex)] in predicting exercise capacity (expressed by maximum oxygen uptake - V'O(2max) and maximal mechanical work - W(max)) in COPD patients.

MATERIAL AND METHODS

The study was performed on 41 patients with mild - to severe COPD (FEV1, 57.2 +/- 15.3% predicted). Each subject underwent resting spirometry (area under the maximal expiratory flow-volume curve - A(ex) was calculated). Subsequently, they performed maximal incremental cycle ergometer exercise for determination of V'O(2max), W(max).

RESULTS

Significant correlation was found between A(ex) and V'O(2max) (r = 0.57, p < 0.001). In the group of severe COPD significant correlation was found between A(ex) and W(max) (r = 0.50 p < 0.05).

CONCLUSIONS

In chronic obstructive pulmonary disease, the index - area under the maximal expiratory flow-volume curve - A(ex), could be useful in assesment of COPD severity and in predicting exercise capacity.