An imbalance between oxidative stress and antioxidative capacity is thought to piay an important role in the development and progression of chronic obstructive pulmonary disease (COPD). To assess the lung oxidative status in patients with COPD, we studied whether exhaled hydrogen peroxide (H2O2) is increased in breath condensate of patients with stable COPD (n = 12, mean FEV1 51% pred) and in patients with exacerbated COPD (n = 19, actual FEVi 36% pred) compared with a healthy control group (n = 10, FEVi 108% pred). Expired breath condensate during 15 min of tidal breathing was collected by cooling. The concentration of H2O2 was measured spectrophotometrically by means of horse radish peroxidase-catalyzed oxidation of tetramethylbenzidine. Concentrations of H2O2 (mean ± SEM) were significantly elevated at 0.205 ± 0.054 nM in patients with stable COPD compared with 0.029 ± 0.012 n.M in the control group (p < 0.05) and were further increased to 0.600 ± 0.075 nM in patients with acutely exacerbated COPD (p < 0.001 compared with patients with stable COPD). Patients with pulmonary infiltrates on chest radiograph showed similar values compared with patients without obvious infiltrates. These findings demonstrate that patients with stable COPD exhibit increased oxidant production in the airways and that oxidant production increases further during exacerbations.

In the present study, we hypothesized that exhaustive exercise in patients with chronic obstructive pulmonary disease (COPD) results in glutathione oxidation and lipid peroxidation and that xanthine oxidase (XO) contributes to free radical generation during exercise. COPD patients performed incremental cycle ergometry until exhaustion with (n = 8) or without (n = 8) prior treatment with allopurinol, an XO inhibitor. Reduced (GSH) and oxidized glutathione (GSSG) and lipid peroxides [malondialdehyde (MDA)] were measured in arterial blood. In nontreated COPD patients, maximal exercise (approximately 75 W) resulted in a significant increase in the GSSG-to-GSH ratio (4. 6 +/- 0.9% at rest vs. 9.3 +/- 1.7% after exercise). In nontreated patients, MDA increased from 0.68 +/- 0.08 nmol/ml at rest up to 1. 32 +/- 0.13 nmol/ml 60 min after cessation of exercise. In contrast, in patients treated with allopurinol, GSSG-to-GSH ratio did not increase in response to exercise (5.0 +/- 1.2% preexercise vs. 4.6 +/- 1.1% after exercise). Plasma lipid peroxide formation was also inhibited by allopurinol pretreatment (0.72 +/- 0.15 nmol/ml preexercise vs. 0.64 +/- 0.09 nmol/ml 60 min after exercise). We conclude that strenuous exercise in COPD patients results in blood glutathione oxidation and lipid peroxidation. This can be inhibited by treatment with allopurinol, indicating that XO is an important source for free radical generation during exercise in COPD.

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Background-It is important to diagnose asthma at an early stage as early treatment may improve the prognosis in the long term. However, many patients do not present at an early stage of the condition so the physician may have diYculty with the diagnosis. A study was therefore undertaken to compare the proportion of patients who underpresented their respiratory symptoms with the proportion of underdiagnosed cases of asthma by the general practitioner (GP). A secondary aim was to investigate whether bad perception of dyspnoea by the patient was a determining factor in the underpresentation of asthma symptoms to the GP. Methods-A random sample of 1155 adult subjects from the general population in the eastern part of the Netherlands was screened for respiratory symptoms and lung function and the results were compared with the numbers of asthma related consultations registered in the medical files of the GP. In subjects with reduced lung function the ability to perceive dyspnoea was investigated during a histamine provocation test in subjects who did and did not report their symptoms to their GP. Results-Of the random sample of 1155 subjects 86 (7%) had objective airflow obstruction (forced expiratory volume in one second (FEV 1 ) below the reference value corrected for age, length, and sex minus 1.64SD on two occasions) and had symptoms suggestive of asthma. Of these 86 subjects only 29 (34%) consulted the GP, which indicates underpresentation by 66% of patients. Of all subjects with objective airflow obstruction who presented to their GP with respiratory symptoms, 23 (79%) were recorded in the medical files as having asthma, indicating underdiagnosis by the GP in 21% of cases. Of the subjects with objective airflow obstruction who visited the GP with respiratory symptoms 6% had bad perception of dyspnoea compared with 26% of those who did not present to the GP in spite of airflow obstruction ( 2 = 3.02, p = 0.08). Conclusions-Underpresentation to GPs of respiratory symptoms by asthmatic patients contributes significantly to the problem of underdiagnosis of asthma. Underdiagnosis by the GP seems to play a smaller role. Furthermore, there are indications that underpresentation of symptoms by the patient is at least partly explained by a worse perception of dyspnoea. (Thorax 2000;55:562-565)

This study investigated the influence of the use of different types of inhalers on the adequacy of inhalation technique among adult asthmatics. Three hypotheses were tested: first, patients using only one type of inhaler will demonstrate adequate inhalation technique more often than those with two or more types. Secondly, patients using a combination of dry powder inhalers (DPIs) will demonstrate correct inhalation technique more often than those using the combination of a metered dose inhaler (MDI) and a DPI. Thirdly, some inhalers or combinations of inhalers are more prone to erroneous inhalation technique than others.Adult outpatients with asthma who regularly used inhaled steroid therapy (n=321) participated in the study. The inhalers investigated were MDIs on the one hand, and the DPIs Turbuhaler1, Diskhaler1, Cyclohaler1, Inhaler Ingelheim1 and Rotahaler1 on the other.Of 208 adult asthmatics with only one inhaler, 71% made no inhalation errors versus 61% of 113 patients with two or more different inhalers. Of patients with a combination of DPIs 68% performed all essential checklist items correctly, versus 54% of patients with the combination of "regular" MDI and DPI. Patients using only the Diskhaler1 made fewest errors.Whenever possible, only one type of inhaler should be prescribed. If a combination is unavoidable, combinations of DPIs are preferable to MDI and DPI. The Diskhaler seems to be the most foolproof device.