Revue de l'Institut d'hygiene des mines最新文献

Hyperreactivity of a pneumoconiotic origin may manifest itself either at the level of the lung parenchyma or at the bronchial site. It may induce either clinical patterns, such as those which occur in the bronchospastic disease in coal-miners, or be the cause of functional disturbances in particular positive responses to aspecific challenge tests with acetylcholine; finally it may produce some radiologic or endoscopic changes in the lungs. The precise role of the causal agent of pneumoconiosis is difficult to assess by comparison with the role of bronchitis, more precisely that of the small airway disease, or the action of the numerous air pollutants or eventually the intervention of an individual predisposition. Bronchial hyperreactivity in pneumoconiotics may not be assimilated to a purely immunological phenomenon. The various changes induced in the lungs by the pneumoconiosis, above all at the level of the bronchi, contribute to a multifactorial etiology of this hyperreactivity. A better understanding of the phenomenon might result from further biological investigation of the respiratory tract.

Two epidemiological surveys were made by the same research team on the prevalence and the aetiological factors of chronic bronchitis symptoms in coalminers. The first study was made in a coalminers' community of Belgian Limburg, the other one in a representative sample of coalminers regularly at work. In both surveys an excess of dyspnea complaints was observed in comparison to the prevalence of this symptom in controls. These dyspnea complaints often presented themselves as isolated symptoms, without chronic cough or phlegm production. Dyspnea in excess could not be explained by massive fibrosis. The prevalence of the symptom was not linked, neither to the spirometric values, nor to the results of respiratory challenge tests with acetylcholine, tobacco use, or the length of exposure at the coalface. When dyspnea was associated with cough and phlegm production there was on the contrary a statistically significant relation with the spirometric values and the effect of acetylcholine. It seems therefore reasonable to explain at least partially the isolated dyspnea complaints in coalminers by specific mechanisms not related to bronchitis but resulting from the pathological lesions characteristic of simple pneumoconiosis. Complaints of cough and phlegm production appear as a rule later in the coalminer's life. In the groups taken into consideration in the study they were linked with cigarette smoking which appeared as the predominant aetiological factor for these complaints; in a subgroup a synergic action of coaldust, tobacco use and air pollution could be discussed in this respect. Notwithstanding the pathogenic independence of some dyspnea complaints versus cough and expectoration, it is quite clear that when productive bronchitis develops and causes broncho-obstruction, it may aggravate pre-existing dyspneic patterns.

The usefulness of mucolytics for clinical purposes remains controversial. Although many authors agree with the opinion that some of these drugs, above all aerosols of acetylcysteine at convenient dosages, provided they are associated with beta 2-sympathomimetics, may be useful in the treatment of bronchial obstruction due to inspissated mucus in excess in the lumens, many specialists remain reluctant concerning the activity of mucolytics given by mouth. It seemed therefore interesting to organize an international meeting on this topic. First of all, I would like to pay honour to the initiative of the Zambon Laboratories who organized this symposium. I would also like to express my gratitude for having been involved in the preparation of the programme of these days and having been asked to present the general conclusions of the meeting. The following pages are devoted to these conclusions. We shall repeatedly make reference to the works which were presented in extenso during the meeting. The general report of the symposium will shortly appear in a special supplement of the European Journal of Respiratory Diseases. It seems however useful to give at the end of our text the complete list of the presented lectures.

The changes in FEV1 and in specific conductance induced by 200 micrograms oxitropium bromide given as pressurized aerosol were measured at 8 time intervals during 7 hours after inhalation in a group of 19 patients with reversible broncho-obstruction. The working of the drug was compared to the functional values observed at the same time intervals after placebo, 40 micrograms ipratropium bromide and 400 micrograms fenoterol. Both oxitropium and ipratropium were definitely and significantly superior to placebo at all time intervals. Oxitropium was superior to ipratropium at the 7th hour. At this time interval the difference was significant At the 7th hour oxitropium gave higher mean results than fenoterol, but this difference was not significant. The drug was also compared to its competitors regarding its subjective and cardiovascular tolerance. No unfavourable side-effects were observed.

We compared the effects of almitrine and doxapram on the arterial blood gases and ventilation of patients with chronic respiratory insufficiency and chronic hypercapnia and hypoxemia. Sixteen long-term in-patients were randomly allocated to one of the following treatment groups: the first group (8 patients) received IV almitrine 0.5 mg/kg and the second group (8 patients) IV doxapram 1 mg/kg by IV perfusion during 30 min. All gave their informed consent. Arterial blood gases and ventilation were measured 10 min and 5 min before treatment, at the 5th, 15th and 25th min of perfusion time, and 5, 10 and 15 min after infusion. There was a marked increase in paO2 in almitrine-treated patients, which was maximum at the 25th min of infusion (+ 14.6 mm Hg, p < 0.001), but only a slight improvement was observed in the doxapram group (+ 3.3 mm Hg, p < 0.05). After almitrine the maximum mean paCO2 decrease was at the 10th min after perfusion (-6.9 mm Hg, p < 0.001); after doxapram the maximum decrease, although highly significant, was much less (-2.8 mm Hg, p < 0.01). Thus, at the presently used and well-tolerated doses, almitrine is much more efficient than doxapram in improving gas exchange in patients with chronic hypoxemia and hypercapnia. However, complementary studies using higher dosage of doxapram are warranted.

RG 033 is a compound consisting of betametasone in resinic microcapsules which allow a slow and continuous dialysis of the active drug through the membrane in the digestive tract. The drug was studied with regard to its effects on the distribution of alveolar air and its gastric tolerance. In a preliminary study the drug release from the capsules in the pH-conditions of the digestive tract was studied by means of a physico-chemical model. Two groups of 15 patients with broncho-obstruction reversed by salbutamol, a potent beta 2-sympathomimetic, were included in the trial. One group received 1 mg and the other 2 mg of the drug. An alternate scheme was used for the treatments. The functional methods used to assess the ventilatory results were chosen according to the conclusions of a previous comprehensive study by one of the authors [7] [8]. The ventilatory results of both dosages were quite similar. This observation suggests that a maximum effect on alveolar air distribution was obtained with 1 mg. No unfavourable side-effect on the gastric mucosa was observed.

One of the authors observed an excess of dyspnea complaints in coalminers without bronchitis, massive fibrosis or emphysema in different epidemiological surveys. An abnormally high prevalence of dyspnea complaints in coalminers has also been reported by other investigators in different countries. It seems therefore necessary to study whether the type of complaints observed in our country can be validated by appropriate functional investigations. A research on this problem is in progress in our laboratory. In this preliminary publication a review of the literature concerning the mechanisms of dyspnea is presented. Such a study was necessary in order to make an adequate choice of the functional measurements usable for our validation study.

The present communication gives a general view of the methods of dust control in the Belgian coal mines at the beginning of 1979. The statistical data received from the mines are presented in tabular form. The length and the output of coal faces treated by the classical methods of pre-spraying of the wall, wet cutting and water infusion are given separately; in some cases two or more of these technics are used together on the same coal face. The number of stone drivages in which different methods of dust control are used, is also given.

The paper describes the research activities that have been accomplished in recent years in order to realise a computer controlled ventilation-system at Watershei Colliery (Kempense Steenkolenmijnen) in Belgium. Chapter I sums up the original objectives and describes some changes in the philosophy of this project, the objectives already reached, those nearly accomplished and some others that were abandoned. Chapter II contains relatively precise data concerning Waterschei Colliery; this is justified by the fact that local conditions obviously play an important role in the development of any such project. Chapter III and IV give extensive information about those parts of the research-project that have known a major development: i.e. the design, the installation and the remote control of the regulators, especially regulating doors, as well as the development of dialogue procedures between the regulators and the computer.