Non-specific nasal provocation in children with chronic allergic rhinitis.

Twenty-three children with chronic allergic rhinitis (Group A) and eleven normal non-atopic subjects (group C) were submitted to non-specific nasal provocation tests with histamine (0.03; 0.06; 0.125; 0.25; 0.5; 1.0; 2.0 and 4.0 mg/ml), and one week later with methacholine (0.025; 0.1; 0.25, 0.5; 1.0; 2.5; 5.0 and 10.0 mg/ml). Measurements of total nasal resistance were performed by active anterior rhinomanometry (Berger, S.A.) and symptoms were recorded. Challenges were carried out in the morning with all children in an acclimatized room (25 degrees C/77 degrees F). Concentrations of the tested drugs were increasingly instilled, and after 5 min were followed by total nasal resistance, FEV, and FVC measurements. Considering as positive those tests in which total nasal resistance had a 100% increase, we observed that both histamine and methacholine caused an increase in total nasal resistance as instilled drug concentration rose; histamine provocations were significantly more positive among group A than group C patients (91% sensitivity, 80.8% positive predictive value). This was not observed with methacholine (55% sensitivity, 75% positive predictive value). In neither provocation was there correlation between the concentration that induced a positive response and symptoms. There were no changes in spirometric values during the tests. Nasal provocations with histamine and methacholine are safe and well tolerated. Histamine seems to be more adequate for differentiating children with allergic rhinitis from normal controls.