Basics | provocation
A hyperreactive bronchial system is typically found in patients with asthma bronchiale; it can however be detectable in connection with other pulmonary illnesses such as sarcoidosis or following a bronchopulmonary infection. Testing is possible using an inhalative provocation test, which is usually performed as a multi-concentration test.
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Besides informing and obtaining consent from the patient, the availability of antiobstructive medications, as well as a physician with experience in the acute treatment of possible adverse reactions and events, is absolutely essential. Any antiobstructive medications are to be temporarily discontinued beforehand, if necessary (rule of thumb).
Evaluatoin of bronchial hypersensitivity.
Contraindications may be present with
- obstructive ventilation disorder
- hypoxemia or hypercapnea
- acute bronchopulmonary infection
- cardiac diseases (recent myocardial infarction, bradycardic arrhythmias, ...)
- difficulty in treating adverse events due to concomitant diseases
(coronary heart disease, arterial aneurysm, ...)
- severe arterial hypertension
- epilepsy requiring treatment
Normal findings and normal values
The provocation test is considered to be positive when the FEV1 decreases by at least 20%, or when the resistance sRAWtot doubles, to at least 2.0 kPa*s. The quantification of the reaction takes place by recording the concentration or dosage of the inhaled provocation substance, at which the maximum effect was reached.
80-year-old male patient. Significant drop in FEV1 by 29% and rise in sRAWtot by 145%.
Findings: positive bronchial provocation test after inhalation of 0.12 mg metacholine and a cumulative dosage of 0.22 mg.
For temporarily suspending short-acting β2 sympathomimetic drugs, one should wait at least 6 hours before performing the provocation test; for long-acting β2 sympathomimetic drugs, this time period should increase to 24 hours; for anticholinergic drugs, this is 12(-24) hours; for antihistamines, 2 days and for β receptor blockers, 24 hours. Therapy with corticosteroids does not necessarily have to be discontinued; if necessary, they are to be temporarily discontinued 14 days in advance.