Specific and non-specific nasal provocation tests in children with perennial allergic rhinitis.

BACKGROUND nasal provocation tests (NPT) have been extensively used in clinical practice to evaluate chronic rhinopathies, mainly allergic rhinitis (AR). METHODS we submitted 10 perennial AR children (aged from six to 15 years) to histamine (H), Dermatophagoides pteronyssinus (Dp) and Blomia tropicalis (Bt) NPT. All children were sensitized (positive skin prick test, mean wheal > 3 mm) to both mites. Dp and Bt specific NPT were realized in two occasions, apart one week, always preceeded 24 hours by H challenge. Increased concentrations were applied to the nasal mucosa during each NPT: H (0,03 to 16 mg/ml), Dp (1/100,000 to 1 /2.5) and Bt (1/125,000 to 1/10). NPT were evaluated by clinical and rhinomanometric parameters (total score, TS), and by lung function tests. NPT was considered positive, when total nasal resistance (TNR) doubled in relation to basal value. RESULTS H NPT was positive twice in 8/10 patients. Concordance between H concentration that induces a positive NPT measured by TNR or TS was observed. Regarding to specific NPT, 90 % of patients were positive to Dp and 60 % to Bt. There was no concordance between the allergen concentration that induces a positive SPT and a positive NPT, considering the different concentrations. There were no modification in lung function tests during both specific and non-specific provocation tests. CONCLUSIONS NPT with H is an objective and reproducible method which allow evaluate nasal reactivity. Specific NPT have restricted indications, mainly when there where doubts about AR's etiology.