A 20-year-old male with thoracic pain and a lower thoracic mass. Diagnosis: intrathoracal desmoid tumour with microscopically incomplete resection.
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Biomedical subjects
W R Douma
Publications and source records attributed to W R Douma.
Changes in peak expiratory flow indices as a proxy for changes in bronchial hyperresponsiveness. Dutch Chronic Non-Specific Lung Disease study group.
Guidelines for asthma management advocate home peak expiratory flow (PEF) monitoring. It is commonly stated that PEF variability is a good proxy of bronchial hyperresponsiveness (BHR), a hallmark of asthma. However, this has hardly been tested longitudinally, as required to monitor asthma. This study assesses which PEF index correlates best with BHR longitudinally and whether the correlation improves when correcting PEF values for the known nonlinearity of mini-Wright PEF meters. Every 6 months, for a period of 2 yrs, PEF diary cards were filled in and BHR to histamine was tested in 104 patients with BHR and reversible airways obstruction, who started treatment with bronchodilators with (n=33) or without (n=71) inhaled corticosteroids. Within each subject, PEF indices and BHR were correlated longitudinally. The highest median correlation coefficients were obtained in the group of patients using inhaled corticosteroids. The PEF indices providing the best correlation with BHR were: mean PEF bronchodilator response (rho=-0.50) and within-day variation (% mean or % maximum) (with postbronchodilator values, rho=-0.50; without postbronchodilator values, rho=-0.40). Using PEF data corrected for the nonlinearity of the PEF meters did not result in higher correlation coefficients. Since current guidelines on asthma management recommend only bronchodilators on demand, the most useful peak expiratory flow index for reflecting bronchial hyperresponsiveness longitudinally is mean within-day peak expiratory flow variation (% mean or % maximum) (without postbronchodilator values). Since the correlation coefficients are not very strong, the authors suggest that peak expiratory flow measurements are not used as a proxy for bronchial hyperresponsiveness longitudinally but as a measurement in its own right. The use of corrections of peak expiratory flows for the nonlinearity of mini-Wright peak expiratory flow meters does not improve the correlation between peak expiratory flow and bronchial hyperresponsiveness.
Administration, Inhalation↗
Risk of overtreatment with current peak flow criteria in self-management plans. Dutch CNSLD Study Group. Chronic Non-Specific Lung Disease.
Home peak expiratory flow (PEF) measurements have become the cornerstone of asthma self-management plans. However, the cut-off values for changing treatment have not been formally tested. This study focusses on the possible overtreatment brought about by the different cut-off values and denominators currently employed. Data from 133 clinically stable asthmatic patients from a 2.5 yr follow-up study were analysed. The results showed that strict adherence to current criteria would lead to severe overtreatment, with up to 30% of clinically stable patients crossing into the lowest (red) zone at least once a year when personal best is the denominator and when it has not been limited to a defined time of day or to defined prior bronchodilator use. As expected, the passage of clinically stable patients into the lower zones became less frequent when cut-off values were sharpened and when time- and treatment-specific PEFs were used as the denominators. Strict adherence to commonly used peak expiratory flow cut-off values would lead to considerable overtreatment. In order to avoid overtreatment, the morning peak expiratory flow before any (bronchodilator) treatment should be related to the personal best peak expiratory flow measured under the same conditions. The choice of the right cut-off value will also depend on studies being performed to test the amount of undertreatment with a given value.
Administration, Inhalation↗
Mini-Wright peak flow meters are reliable after 5 years use. Dutch CNSLD Study Group.
In studies with a long-term follow-up, peak expiratory flow (PEF) meters are often used to assess bronchial obstruction. The question arises whether data obtained with these frequently used meters are still reliable after several years of use, and whether the old meters should be renewed after a certain period. In the present study, we tested the reliability of PEF values measured with mini-Wright PEF meters that had been used frequently for 5 yrs. The values obtained with these meters were compared with values measured with identical but new meters, in 50 patients with obstructive airways disease. Though statistically significant, there was no clinically significant difference in mean PEF measured with the old and new meters in most patients (mean difference 10.2 L.min-1). However, on an individual basis, the differences between old and new meters could be large (upper and lower limits of agreement (mean +/- 2 SD) being 63.6 and -43.2 L.min-1, respectively). We conclude that mean peak expiratory flow values measured with frequently used mini-Wright peak expiratory flow meters are still reliable after 5 yrs. In long-term studies, renewal of peak expiratory flow meters should be restricted to cases of obvious malfunction.
Equipment Failure↗
Lack of correlation between bronchoconstrictor response and bronchodilator response in a population-based study.
Bronchodilator and bronchoconstrictor responsiveness have been considered physiological opposites in patients with obstructive airways disease. Provocation challenges have been replaced by bronchodilator tests in the assessment of cases of severe airways obstruction. The aim of this study was to examine the relationship between bronchoconstrictor and bronchodilator responsiveness, and their supposed interchangeability, in a general population. From the Vlagtwedde-Vlaardingen follow-up study, 101 adults were recruited (mean (SD) age 55 (11) yrs, 67 males and 34 females, and 31 were smokers). All completed a questionnaire on airways symptoms. Bronchoconstrictor and bronchodilator responsiveness were assessed with cumulative dose-response curves, using histamine and terbutaline, respectively. Thus, it was possible to relate histamine sensitivity of the airways (the concentration of histamine, at which forced expiratory volume in one second (FEV1) falls by 10% (PC10)) to the maximal bronchodilator response (delta FEV1) and the sensitivity to the bronchodilator (cumulative dose of inhaled terbutaline at which FEV1 increases by 10% (RD10)). Subjects with a bronchoconstrictor response (PC10 < or = 16 mg x mL(-1); n=38) had more respiratory symptoms than those without (n=63) (40 versus 21%) and also lower baseline FEV1 values (90 versus 96% predicted), but had comparable bronchodilator responsiveness. Subjects with a bronchodilator response (delta FEV1 > or = 9% of the predicted value; n=13) did not differ from those without (n=88) for all parameters, including symptoms, allergy and pulmonary function. In those with a bronchoconstrictor response, there was a weak but significant correlation between the PC10 and RD10 (rho=-0.32), but not between PC10 and delta FEV1. This study suggests that bronchoconstrictor and bronchodilator responsiveness are not highly correlated, even in subjects with airways obstruction. Symptoms were associated with the presence of a bronchoconstrictor, but not a bronchodilator, response. We conclude that bronchoconstrictor and bronchodilator responsiveness are two different phenotypic markers that are not interchangeable in epidemiological studies.
Administration, Inhalation↗