Standardized allergen provocation test. Variation in bronchial response

Standardized bronchial allergen provocation with the same individual allergen dose was performed 3-9 times in 20 symptomless adult asthmatic patients at intervals of 1 week or more during 1/2-22 months in order to study variations in bronchial response. The immediate type reaction was recorded by monitoring FEV1, FVC, PEFR and MEF50% for 30-40 min after provocation. FEV1 was highly significantly correlated to the other variables. The coefficient of variation corresponding to maximum decrease in FEV1 was 23%. All provocations were followed by a bronchial reaction within clinically acceptable limits. There was no indication of hypo- or hypersensitization. It is concluded that although many different factors influence the bronchial response, careful standardization of the provocation procedure leads to a moderate variation in bronchial response, making the allergen provocation test suitable for pathophysiological studies and clinical evaluation of anti-asthmatic drugs.

[Methodologic problems concerning pharmacology effect on bronchomotricity in asthma (Raw, V/V) (author's transl)]

Study of spirometric, flow-rate and Raw modifications in three groups of 5 to 8 asthmatic patients (stage I or II) before and after acetylcholine and pneumallergen (dust) action is made. The same modifications were studied on the action of dust before and after a chemical protector effect. In two control groups the following parameters were verified: 1) the stability of Raw and V/V (normal subjects: 8); 2) the reproductibility of the acetylcholine bronchospasm, before and after the action of chemical protector (asthmatic patients: 11). Some considerations about the methodology in the practice of bronchomotricity data are submitted.

Airway responsiveness to cold air and hyperpnea in normal subjects and in those with hay fever and asthma

Multiple aspects of pulmonary mechanics were measured before and after bronchial challenges consisting of hyperpnea with cold air inhalation in 20 normal control subjects, 16 subjects with hay fever, and 44 asymptomatic asthmatics. These challenges had no effect on the lung function of the normal subjects. In the hay fever group, however, postchallenge mechanics changed a small, but significant, amount, e.g., mean decrease in forced expiratory volume in one second (FEV1) was -5.1 +/- 1.7% (SEM). The asthmatics had a much more marked response (mean fall in FEV1, -32.7 +/- 2.6%). There was considerable overlap between the responses of the normal subjects and those with hay fever, but no overlap at all between asthmatic and normal subjects. The only subjects with hay fever whose responses overlapped the asthmatic response were those who had histories of occasional episodes of wheezing. This pattern of response suggests that the use of hyperpnea and subfreezing air is a very sensitive and highly specific means of detecting increased air reactivity.

PGF2 alpha challenge test in asthma and chronic bronchitis

PGF2 alpha challenge tests were performed in twenty-three patients with bronchial and six patients with chronic bronchitis; two patients with allergic rhinitis and four healthy volunteers also participated in the trial. FEV1 measurements were used in assessing the reactions. PGF2 alpha challenge proved safe and practical in clinical use. A wide scattering in PGF2 alpha reactivity was seen, but sensitivity to PGF2 alpha did not correlate to several clinical criteria. Comparison with an ordinary histamine challenge revealed that the sensitivity of the patients to PGF2 alpha and histamine was not uniform.

Bronchial provocation studies in farmers allergic to storage mites

In an investigation of the relationship between storage mites and symptoms of allergic respiratory disease in farmers exposed to hay and grain dust, the clinical responses suggested an immediate type-I hypersensitivity. This study confirmed that farmers are exposed to large numbers of mites, particularly while feeding cattle. Storage mites may be an important cause of asthma in the farming community and should also be considered in the differential diagnosis of farmers lung.

Measurements of responsiveness in bronchoprovocation testing

The relative sensitivity and usefulness of FEV1 and SGaw measurements in determining airway responsiveness to stimuli causing changes in bronchomotor tone depend to a great extent on the population studied. Though neither test provides a great deal of information regarding the site of airway obstruction, when used together they provide a reliable and sensitive indicator of airway responsiveness.

Comparison of histamine bronchial challenges with the Wright nebulizer and the dosimeter

In twenty adult asthmatics studied in a stable state, histamine bronchial challenges were carried out at one-week intervals with the Wright nebulizer and with the dosimeter-DeVilbiss apparatus. Dose-response curves were analysed for sensitivity, defined as the minimal histamine dose causing a 20% fall in FEV1 (PC20), and for reactivity, defined as the slope of the dose-response curve once the reaction starts to occur. A significant relationship (r=0.80) was found for the sensitivity obtained with the two nebulizers. PC20 was indeed reproducible within a two folds concentration of histamine in sixteen of the twenty patients. A significant difference (P less than 0.01) was found in the reactivity to the two different apparatus, reactivity being greater with the Wright nebulizer in twelve out of fifteen patients so tested. Sensitivity and reactivity showed a borderline relationship (r=0.47) with the Wright nebulizer but not with the dosimeter. A significant correlation (P less than 0.05) was found to exist between the initial FEV1 (in % of the predicted value) and the observed sensitivity and reactivity as assessed with the Wright nebulizer, but not as assessed with the dosimeter. We conclude that histamine bronchial challenges with the Wright nebulizer and with the dosimeter yield reproducible results if the threshold of a 20% fall in FEV1 is taken as positive. However, the two methods produce different results in terms of reactivity.

Bronchial and intravenous provocation tests with indomethacin in aspirin-sensitive asthmatics

In an attempt to elucidate the mechanisms involved in analgesic-induced asthma, I performed bronchial and intravenous challenge tests with indomethacin in 5 aspirin-sensitive asthmatics. Bronchial challenge with less than 2 mg of indomethacin elicited bronchoconstriction that developed immediately in most cases, reached its macimum at a mean time of 64 min, and was over within 2 to 4 h. The time sequence of the reaction after intravenous challenge was similar to that after bronchial challenge, except that to obtain a comparable degree of bronchoconstriction it was necessary to administer at least twice the inhaled dose. Inhalation of disodium cromoglycate during bronchoconstriction inhibited the reaction within 8.6 +/- 5.7 min, regardless of the route of challenge. This suggests that sequential mast cell degranulation with liberation of chemical mediators is the mechanism responsible for bronchoconstriction in analgesic-induced asthma.

Bronchial provocation tests in etiologic diagnosis of asthma

Several methods of bronchial challenging have been described in literature. The comparison of the results obtained in different departments is, of course, very difficult. The Authors have been interested in the standardization of inhalation challenge techniques and they present in this work their method and the results obtained. The standardized method has a good specificity, because of the agreement between B.P.T. and other diagnostic tests. The bronchial reaction generally developes after the exposition to low doses of allergen extract, and this confirms the specificity of the method. Its precision, depending on the standardization of allergen extract activity by RAST and of inhalation procedures, is good. The reproducibility is of 100 per cent. The safety is high (rare untword reactions).

IN CONCLUSION

this standardized method of bronchial challenging is useful in etiologic diagnosis of asthma.

[Recommendations for performance and evaluation of the acetylcholine test as an ultrasonic aerosol method (author's transl)]

As a task in the research project Chronic Lung Diseases the method of testing bronchial reactivity by provocation with acetylcholine as an ultrasonic aerosol was developed. Indications for an uniform standardized application and policy are given.