At the time of the two exercise tests the relative humidity was 22 to 45 percent and the ambient temperature 22 to 24.5°C, as determined in 24 of the 48 experiments. Pretrial Examination Basal preexercise values for FEVi and VC were similar in the three groups, and all were within 75 percent of the predicted values. All patients with a history of EIA had decreases in FEVi of more than 15 percent following the pretrial
It is well known that 3-adrenoceptor blockade may cause bronchoconstriction and that -adrenoceptor stimulation induces bronchodilation in patients with bronchial asthma. There is also evidence (or the existence of a-adrenoceptors in human airways, the stimulation of which may induce contraction of human bronchial smooth muscle. Conversely, a-adrenoceptor blockade may counteract or reduce bronchoconstriction provoked by allergen, exercise, or histamine. Hence, adrenergic mechanisms seem to be important for the regulation of bronchial tone in patients with bronchial asthma. This raises two
In this study, disodium cromoglycate and Sch 1000 were found to be effective in the prevention of exercise-induced asthma in the majority of patients. While most studies agree that disodium cromoglycate is partially effective in the prevention of exercise-induced asthma, the reports on the effectiveness of administration of atropine are conflicting. The finding of this study that inhalation of Sch 1000 prevents exercise-induced asthma in the majority of patients is in agreement with the results
The baseline value for FEVi and the maximum percentage of change in FEVi after drug administration and after exercise are shown in Table 2. The FEVi measured before each study was very similar in each of the subjects. There was no change in FEVi after inhalation of placebo (mean changes, —0.2 percent). After inhalation of 20 mg of disodium cromoglycate, one patient (patient 6) developed acute bronchoconstriction , and the FEVi dropped by 55 percent; spontaneous recovery
Disodium cromoglycate has been shown in several studies to be partially effective in the prevention of exercise-induced asthma; however, the reports on the effectiveness of atropine are conflicting. While Sly et al showed that premedication with atropine failed to prevent exercise-included asthma in the majority of his patients, Simonsson and co-workers found that there was protection in six out of nine patients. Sch 1000 is a derivative of atropine (methyl bromide of N-isopropyl nortropine) and
The main finding of this study was that a sufficiently high dose of chlorpheniramine administered intravenously can protect against mild attacks of allergen-induced asthma on the basis of its Hi blocking properties. A second and quite unexpected finding was that regardless of the degree of bronchial reactivity to histamine, a fixed dose of chlorpheniramine given intravenously produced a comparable rate of protection against histamine-induced bronchoconstriction. The implication of the first finding is that in asthma,
The anthropometric and respiratory measurements of the subjects participating in this study are shown in Table 1. The same table shows the TDs of allergen, histamine, and when determined, acety-choline. The range of TDs of histamine was sixteenfold, between 0.08 and 1.28 mg. See articles in our site: https://onlineasthmainhalers.com/category/pathogenesis . The average change at the threshold level varied with the measurement: 3.0 to 8.0 percent for FVC, 11.3 to 18.6 percent for FEVi, and 16.0 to
Fifteen subjects with bronchial asthma were initially enrolled in the study, and selected according to the following criteria: age between 20 and 30, in an asthma-free interval, (ie, no attack of asthma in the last four weeks), clear cut history of attacks of asthma triggered by a well defined environmental allergen, and positive skin (prick) and radio-allergosorbent (RAST) tests to that allergen. Because 10 mg of intravenously administered chlorpheniramine dilates the bronchi only if FEV1 is low,
It is generally accepted that histamine is released in vivo when actively or passively sensitized fragments of lung, tracheobronchial strips, nasal polyps, or basophils are challenged with the appropriate allergen. In vivo, the blood level of histamine is increased during spontaneous or allergen-induced attacks of asthma. Moreover, at least in vivo, the asthmatic bronchi are hyperreactive to exogenous histamine, and thus, most likely to endogenous histamine as well. Yet, as repeatedly shown, the Hi blockers
The results obtained in this study indicate that terbutaline is an effective bronchodilator drug when given subcutaneously to children with acute exacerbations of bronchial asthma . The magnitude of clinical improvement was not significantly different from that obtained with epinephrine. Side effects were minimal with both drugs. Evaluation of the direct effect of a bronchodilator drug on heart rate may be difficult, since improvement in the dynamics of the airway may be accompanied by a slowing of the heart rate.
