Background -Several studies have shown that both objective and subjective measurements are related to exercise capacity in patients with chronic obstructive pulmonary disease (COPD) (Thorax 1994;49:468-472) Patients with chronic obstructive pulmonary disease (COPD) usually have a decreased exercise tolerance and a reduced quality of life. While spirometric measurements seem to be related to maximum ventilation in a bicycle ergometer performance,' in general they correlate weakly with less stressful tests such as the walking distance.2 5 Moreover, it has been shown that the transfer factor for carbon monoxide (TLCO) is positively correlated with the walking distance test.67Although dynamic and static lung volumes, compliance, and gas transfer (lung function) generally establish the level of impairment in COPD, Mahler and coworkers showed that maximal inspiratory pressure (MIP) provides additional information on impairment.8 Loiseau and coworkers9 also showed that exercise capacity in patients with COPD was related to the impairment of the inspiratory muscles. In addition, it has been shown in other studies that walking distance tests are related to psychosocial measurements, while no relation has been found between psychosocial measurements and bicycle ergometer tests.4 10 11Both objective and subjective measurements are related to exercise capacity in patients with COPD. However, we are not aware of any research on their relative effect on a walking distance test compared with a bicycle ergometer test. In this study we have therefore investigated the relative contribution of lung function, maximal inspiratory pressure, dyspnoea, and quality of life to the performance in a walking distance test as well as a bicycle ergometer test in patients with COPD. Methods PATIENTSForty patients with known COPD"2 (table 1) who started a rehabilitation programme were studied. Entry criteria were: (a) postbronchodilator FEV, (forced expiratory volume in one second) <60% predicted, and (2) postbronchodilator FEV,/IVC (inspiratory vital capacity) <50% (after two inhalations of 40,ug Rehabilitation Centre,

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The transfer factor of the lung for carbon monoxide (TL,CO) is decreased in patients with pulmonary hypertension. The pulmonary membrane diffusion capacity (Dm) and pulmonary capillary blood volume (Vc), were studied to establish: 1) the relative contribution of the components of the transfer factor to the decrease in TL,CO; 2) whether differences exist between primary pulmonary hypertension (PPH) and chronic thromboembolic pulmonary hypertension (CTEPH); and 3) the relationship between these parameters and haemodynamic parameters.Dm and Vc were determined in 19 patients with PPH and in eight patients with CTEPH. The patients had been referred for consideration for lung transplantation. Haemodynamic parameters were assessed by heart catheterization.In the PPH group, Vc was reduced in 12 of 19 patients (mean SD Vc 72 14% of the predicted value) and Dm in 17 of 19 patients (60 22% pred). In the CTEPH group, Vc was reduced in six of eight patients and Dm in seven of eight patients. The mean TL,CO Dm and Vc values were similar to those in the PPH group.The reduction in pulmonary membrane diffusion capacity was significantly greater than that in pulmonary capillary blood volume. No differences in pulmonary and cardiovascular functional values were found between the groups. Right atrial pressure showed a significant negative correlation with pulmonary capillary blood volume and an increased pulmonary vascular resistance was associated with a decrease in pulmonary membrane diffusion capacity. These results suggest pronounced functional impairment of the alveolocapillary membrane in these patients. Eur Respir J 2000; 16: 276±281.

It is not clear how airway pathology relates to the severity of airflow obstruction and increased bronchial responsiveness in cystic fibrosis (CF) patients. The aim of this study was to measure the airway dimensions of CF patients and to estimate the importance of these dimensions to airway resistance using a computational model.Airway dimensions were measured in lungs obtained from CF patients who had undergone lung transplantation (n=12), lobectomy (n=1), or autopsy (n=4). These dimensions were compared to those of airways from lobectomy specimens from 72 patients with various degrees of chronic obstructive pulmonary disease (COPD). The airway dimensions of the CF and COPD patients were introduced into a computational model to study their effect on airway resistance.The inner wall and smooth muscle areas of peripheral CF airways were increased 3.3-and 4.3-fold respectively compared to those of COPD airways. The epithelium was 53% greater in height in peripheral CF airways. The sensitivity and maximal plateau resistance of the computed dose/response curves were substantially increased in the CF patients compared to COPD patients.The changes in airway dimensions of cystic fibrosis patients probably contribute to the severe airflow obstruction, and to increased bronchial responsiveness, in these patients. Eur Respir J 2000; 15: 735±742.

Background-Nitric oxide (NO) is involved in inflammation and host defence of the lung. It has been found in increased concentrations in the airways in asthmatic subjects but its levels in patients with chronic obstructive pulmonary disease (COPD) have not been investigated. A study was undertaken to determine whether markers of NO metabolism (NO in exhaled air, iNOS expression in sputum cells, and nitrite + nitrate (NO 2 -/NO 3 -) in sputum supernatant) are increased in subjects with COPD, and whether they correlate with inflammatory indices in induced sputum. The associations of these markers with smoking were also assessed. Methods-Sixteen subjects with COPD (median age 66 years, median forced expiratory volume in one second (FEV 1 ) 63% predicted, eight current smokers) and 16 healthy subjects (median age 63 years, median FEV 1 113% predicted, eight current smokers) participated in the study. NO was measured during tidal breathing and sputum was induced by inhalation of hypertonic saline. Results-No