Non-specific nasal provocation test with histamine. Analysis of the dose-response curve

Non-Specific Nasal Hyper-reactivity (NSNH) is described as a clinical condition characterized by the presence of rhinitic symptoms that are a consequence of non-specific stimulations. Because of its effects on vascular, epithelial, and glandular receptors, NSNP Test (NSNPT) with histamine allows the study of NSNH. The aims of this study are 1. to analyze the behavior of NSNH both in non-allergic chronic vasomotory patients and in healthy control subjects 2. to correlate total nasal resistance(TNR) to each dosage of histamine to derive the dose/response curves and 3. to study these curves to analyze and possibly define different stages according to the intensities of response of NSNH. We have studied 26 subjects affected by non-allergic vasomotor rhinitis and 10 healthy control subjects. We sprayed a NSNPT with histamine-phosphate (0.2-0.3-0.4-0.5-0.6-0.8 mg) in different sessions to avoid accumulation phenomena. Five minutes before and five minutes after each challenge, TNR was determined by active anterior rhinomanometry. TNR was correlated to the doses of histamine by an empirical equation. The most important results of this study are as follows: a) the variation of TNR follows a model of exponential curve, b) it is possible to classify NSNH, as a function of the regression b coefficient belonging to the empirical equation used, in reactivity classes, c) from one reactivity class to another, post-stimulation TNRs double; 0.5 mg of histamine of the NSNPT is the optimal dose, d) there is an overlap between the responses of some normal subjects and rhinopathic patients that will be the subject of a further study. Finally, our data suggest that, in a future perspective, it is possible to use the NSNPT with histamine for diagnostic, prognostic and therapeutic control purposes.