Effect of short-term, low-level nitrogen dioxide exposure on bronchial sensitivity of asthmatic patients.

Our purpose was to determine whether exposure to a realistic concentration of nitrogen dioxide (NO2) could increase the bronchial sensitivity of asthmatic patients to bronchoconstrictor agents. We established dose-response curves for changes in specific airway resistance (SRaw) in response to aerosolized carbachol in 20 asthmatics after each had spent 1 h in an exposure chamber breathing on one occasion unpolluted air and on a separate occasion 0.1 ppm NO2: sequence of exposures to unpolluted air and to low levels of NO2 were randomized in a single-blind fashion. NO2 induced a slight but significant increase in initial SRaw and enhanced the bronchoconstrictor effect of carbachol in 13 subjects: curves were shifted to the left and the mean dose of carbachol producing a twofold increase in initial SRaw was decreased from 0.66 mg to 0.36 mg (P less than 0.001). In contrast, NO2 neither modified the initial SRaw nor the bronchoconstrictor effect of carbachol in seven subjects. In 4 out of the 20 subjects, exposure to a higher concentration of NO2 (0.2 ppm) yielded variable results. Potentiation of the carbachol bronchoconstrictor response by NO2 could not be related to any physical or clinical characteristics of the subjects tested. Although the mechanisms underlying the NO2 effect remain controversial, the present results demonstrate that very low levels of NO2 can adversely affect some asthmatics.

[School health municipal service and health promotion in Villeurbanne]. / Service municipal de santé scolaire et promotion de la santé à Villeurbanne.

A school health municipal service has been in existence in Villeurbanne since its creation in 1935. It works throughout the city's schools, and in particularly in places which provide the last year of nursery school and all primary-level schools as well. In 1998 it was integrated into the office of the Directorate for Hygiene and Public Health, which provided an opportunity to reconsider its mission and reflect upon the priorities. The balance between screening and prevention was examined. Furthermore, its approach to thematic issues was put into question given the lack of a strategic overall programming methodology. The new health policy aimed at students was executed through a reorganization of evaluations, leading to the creation and implementation of a new programme called "I take care of myself" specifically targeting all first grade children. The results of this programme, which focuses on the development of a more comprehensive approach, are encouraging. Thanks to the programme, health has been reinstalled in its proper place in the schools, and it has become a matter of great importance for the children, their parents and the teachers. Furthermore, the school health service has consolidated and strengthened its role in this manner.

[Suicide mortality in Rhône-Alpes psychiatric sectors. Or the difficulties in a study]. / La mortalité par suicide selon les secteurs psychiatriques en Rhône-Alpes. Ou les difficultés d'une étude.

Mandated by the Social Welfare and Health Regional Office, the Regional Health Observatory realized a study on mortality by suicide in the psychiatric sectors. This work is based mainly on the definitions of a new map of the psychiatry, set on June 1994. Its objective was to give to each sector team a set of quantitative data on deaths due to suicide, happened on their area, both in term of progress (1982-1989) and of comparison (respective level of each sector compared to the "département" mean). This descriptive study is based on the regional cumulated mortality data from 1981-1983 and 1988-1990, given by the National Institute of Health and Medical Research (INSERM) and on the data of General population census in 1990. Epidemiological studies on suicide generally get as reference a delimitated geographical basis, accordingly to most of the important statistical databanks (nation wide, region wide...). The general psychiatric sectors are quite different, as the repartition is complex and their number is important (more than 80 for Rhône-Alpes Region) as well as the diversity of local needs and the organization in psychiatry. This repartition, responding to the needs of a medical and preventive practice, causes a great number of difficulties when one tries to approach this reality with statistics: the frontiers between sectors are determined with a degree of precision overtaking the one of demographical and epidemiological data sources. Taking into account the small size of the sectors, the number of deaths by suicide (mean of 10 to 20 by sector) does'nt enable to estimate the significance of the results. Despite the difficulty of different limitations, the data show inter-sectorial particularities, which could justify a regular epidemiologic survey (i.e.g., a growth in number of death by suicide in the "département" of Rhône between 1982 and 1989 is to be noticed more in urban areas). Such monitoring suggests a better acknowledgment of the feasibility of statistical surveys based on the sectors, and its use in the map of psychiatric services as well as the implementation of means, allowing data to be release quickly at the local level.

[Measurement of the effect of a bronchodilator using FEV1: how to express it?]. / Mesure d'un effet bronchodilatateur par le VEMS: comment l'exprimer?

An assessment of the effect of a bronchodilator on VEMS (FEV1) is based on a "before and after" comparison with the chosen drug. Most often the percentage rise in FEV1 compared to the initial value is calculated (I), and a minimum of 20% reversibility is expected for asthma. But the change of FEV1 expressed as a percentage of predicted theoretical value (II) may also be calculated. With the help of 50 cases of asthma selected by the first criteria (I) after an inhalation of an adrenergic stimulant the following changes were shown: That the first method (I) is biased, over estimating for low initial values; That the second method (II) was not inconvenient and furnished all the information derived. It shows in particular that 14/50 subjects have a variation of FEV1 less than 10% of their theoretical value, which has considerable therapeutic interest and merits further discussion.

[Respiratory function test, a key in the etiologic diagnosis of dyspnea or a simple quantitative test?]. / Exploration fonctionnelle respiratoire (EFR), clef du diagnostic étiologique de la dyspnée ou simple épreuve chiffrée?

When confronted with a case of dyspnoea, three questions must be asked: is the dyspnoea due to a pulmonary organic disease? How severe is it? What is its nature or its origin? In the majority of cases these questions are answered by elementary lung function tests (spirometry and measurement of the residual volume), but for these answers to be valid it must be borne in mind that respiratory function test (RFT) is primarily a physical exercise: no measurement is valid unless the operator is fully involved and the subject explored participates to the best of his possibilities. RFT also is a mental exercise: the data obtained can be well understood only if the operator is conversant with the data described in this article. RFT has multiple applications, and yet this examination is notoriously underestimated and underused by the medical profession. Good practice is its best publicity.

[Bronchodilator effects of an atropinic compound: oxitropium pressurized aerosol. Comparison with theophylline in asthma]. / Effets bronchodilatateurs d'un atropinique: l'oxitropium aérosol-doseur. Comparaison avec la théophylline dans l'asthme.

Oxitropium bromide (Tersigat pressurized aerosol) is a new anticholinergic agent. Two puffs of 100 micrograms given in 27 adult patients with asthma produced a 33% mean increase in FEVI, significantly bigger than the 20.9% increase obtained by an intra-muscular injection of theophylline (240 mg) in the same patients.

[Frequency dependance of compliance]. / Fréquence-dépendance de la compliance

Resistance of peripheral or "small" airways is only a small part of the total pulmonary resistance (Raw). Even considerable obstruction in these airways will have little effect on total resistance. Conversely this will lead to inequality in the time constants of units in parallel, and dynamic lung compliance (C dyn) shall fall as respiratory frequence increases. C dyn is measured from simultaneous recordings of transpulmonary pressure (esophageal balloon) and volume obtained from a volume displacement plethysmograph. If Raw and static compliance are found to be normal, the frequency dependance of compliance will result from peripheral airway obstruction only. Early stages of chronic airway obstruction can be established by this method. However this appear not suitable for wide-scale studies.

[Relationship between the initial dimensions of bronchial ring and its contraction after acetylcholine (author's transl)]. / Contraction par l'acétylcholine d'anneaux bronchiques isolés : influence du calibre initial

Contractions produced by comulative doses of acetylcholine were studied in isolated canine bronchical rings from 2 to 10 mm internal diameter. The maximal active tension achieved was directly related to the initial caliber of the ring and to the amount of smooth muscle. The maximal decrease in caliber was relatively greater (--39%) in the smaller than in the larger bronchi (--17%). However the corresponding increase in airway resistance may be predicted to be more important in the larger resistive bronchi.

[Paradoxical effect of forced inspiration: a new characteristic of asthmatic disease?]. / L'effet paradoxal de l'inspiration forcée : une nouvelle caractéristique de la maladie asthmatique?

In normal subjects, forced inspiration may dilate the bronchi and be considered as a defence or compensatory reaction in certain cases. In asthma, forced inspiration has the opposite effect. Bronchospasm occurs or becomes worse, usually moderately and transiently, but sometimes to a marked and lasting degree. These reactions may be prevented by anticholinergic and sympathomimetic drugs. They should be avoided and one should thus prohibit the manoeuvres which trigger them off. One should take them into consideration during respiratory function tests. This paradoxical effect of forced inspiration seems to exist to various degrees in most asthmatic patients, it may be considered as a diagnostic sign of asthma.

[Inadequate use of pressurized aerosols by asthmatic patients [author's transl]. / Mauvaise utilisation des aérosol-doseurs par les asthmatiques.

The purpose of this study was to determine in a population of asthmatics, the number of patients who correctly used the pressurized aerosols (bronchodilator drugs or steroids) spontaneously, or after training sessions. 115 asthmatics (in- or outpatients, 14-70 years old) were asked to use their inhaler in the presence of an observer. The inhalation technique was considered correct when (1) the puff release was coordinated with a deep inspiration and (2) when the inspiration was followed by a few seconds' breath-holding. The patients were divided into two groups: a trained group of 46 patients who were observed for 1 month or more after the two above-mentioned maneuvres had been demonstrated to them by a physician and the need for correct use strongly emphasized. The other group (the untrained group) comprised 69 patients who were presumably using their inhalers according to the manufacturer's instructions: (1) expiration; (2) inspiration and actuation, and (3) apnea. In the trained group 52% of the patients were classified by the observer as correct users, as compared to 28% in the untrained group. The results were not influenced by sex. age or occupational differences. These observations suggest that a majority of asthmatics probably derived incomplete benefit from the use of pressurized aerosols. Although training apparently results in a more efficient use of the canisters, this study shows that training sessions must be repeated, and the results checked at regular intervals by a member of the medical staff. In subjects who repeatedly fail to achieve a correct inhalation technique the drug should be given by another route.

[Induced beta-adrenergic stimulation and blockade in asthma bronchomotor effects (author's transl)]. / Stimulation et blocage beta-adrénergique dans l'asthme. Mise au point sur les effets bronchomotorurs

Patients with asthma, exhibiting spontaneous bronchial obstruction, from mild to medium severity, were examined by body plethysmography. Results were expressed as specific airway resistance (SRaw) in preference to specific conductance, the latter leading to errors, in particular in cases with dissimilar baseline values. After the inhalation of a beta-stimulating drug (salbutamol), the decreases in SRaw was directly related to initial SRaw, either in a group (n equal 30) or in individual cases. After the injection of a beta-blocking drug (propranolol), the increase in SRaw, found abnormal in 60% of the subjects, could be related to initial SRaw neither in a group (n equal 40) nor in individual cases. These findings indicate that submaximal bronchial obstruction in patients with asthma is mainly due to a bronchoconstriction, whatever the degree of the obstruction may be. On the opposite, there is an increased bronchodilator adrenergic influence in a majority of patients, not predictable after the degree of initial airway obstruction.

[Bronchial asthma and the beta adrenergic system]. / Asma bronquial y sistema simpático beta

The relationship between bronchial asthma and the beta adrenergic system is considered both from the physiopathologic and therapeutic point of view. A brief analysis of the sympathetic system is performed. The sympathetic nervous system is responsible for bronchodilation mediated through its beta-receptors. To evaluate this activity, beta adrenergic blockers such as propanolol are used. When this agent is administered, a descent of conductance is observed. On this condition, vagal stimulation brings about bronchoconstriction. At bronchial level, it seems that the beta-adrenergic system antagonizes vagal effect. From the physiopathologic point of view, Szentivanyi (1968) suggested a spontaneous beta block in the asthmatic. Other theories refer to a pathologic sensitivity of the peripheral bronchial receptors. The natural beta-adrenergics and the beta-adrenergic drugs enhance the synthesis of cAMP by stimulating the adenil cyclase system. This effect brings about relaxation of the bronchial smooth muscle. Considering the therapeutic effects, a comparative study of bronchodilators is performed. From all, Salbutamol has an intense broncholytic effect with little effect on heart dynamics. When sympathomimetics are bound to use in asthma, drugs such as Salbutamol and Terbutalina should be preferred because of its low cardiogenic effects. Its administration per os has rendered doubtful results.

[Bronchomotor tonus: per-operative bronchospasm]. / Le tonus bronchomoteur; le bronchospasme per-operatoire

The comprehension of the occurrence of bronchospasm during surgery is based on the knowledge of the factors which control bronchomotility: parasympathetic or cholinergic system, essentially bronchoconstrictor; sympathetic adrenergic system, with beta-2 effect, bronchodilator, and with alpha-bronchoconstrictor effect. It is also worth bearing in mind the chemical midiators, in particular, histamine contained in the mast cells, "slow reacting substance of anaphylaxis" which is a bronchoconstrictor substance of slow and prolonged action, Serotonin whose role is more modest. The last mediators known, prostaglandins, play an important role in the regulation of bronchomotility, PGE' are bronchodilators, PGF 2 alpha are bronchoconstrictors. With reference to the development of bronchospasm during anesthesia, one must bear in mind the background, and in particular of the allergy, of a past history of asthma and of the pre-operative functional respiratory condition. One must also bear in mind the anaesthesia, and the pharmacodynamic action of the substances used which can interfere with the phenomena controlling bronchomotor tone.