RESUMO
INTRODUCTION: There are many potential factors that can modulate bronchial reactivity, including exposure to allergens, viral infections, and medications. The aim of this study was to analyze the effect of grass pollination intensity on the bronchial reactivity in seasonal allergic rhinitis (SAR) patients subjected to subcutaneous allergenic immunotherapy (SCIT). MATERIAL AND METHODS: This study, performed between 2005 and 2008, included 41 patients with confirmed sensitivity to grass pollens and predominating symptoms of SAR, randomly assigned to desensitization by pre-seasonal or maintenance SCIT. Bronchial provocation challenge with histamine was performed before the onset of immunotherapy, and repeated three times after each pollen season covered by this study. Bronchial reactivity was analyzed with regard to grass pollination intensity in 2005-2008 (air concentration of grass pollen grains, seasonal number of days when air concentration of grass pollen reached at least 20 or 50 grains per 1 m(3)). RESULTS: After 3 years of SCIT, a significant decrease in bronchial responsiveness was observed in the analyzed group as confirmed by an increase in PC20 FEV1 histamine values (p = 0.001). An inverse tendency was observed after 2 years of SCIT, however. This second year of SCIT corresponded to the 2007 season, when a significantly higher number of days with at least 50 grains of pollen per 1 m(3) of air was recorded. CONCLUSIONS: FLUCTUATIONS IN POLLINATION INTENSITY OBSERVED DURING CONSECUTIVE YEARS OF IMMUNOTHERAPY CAN INFLUENCE BRONCHIAL REACTIVITY IN PATIENTS SUBJECTED TO SCIT (ISRCTN REGISTER: ISRCTN 86562422).
RESUMO
OBJECTIVE: The aim of this study was to compare the usefulness of mannitol provocation test to that of classical histamine challenge in children with PC(20)FEV(1) histamine lower than 4 mg/ml. METHODS: Twenty-two adolescent patients (mean age of 15.4 ± 4.1 years) with established asthma (PC(20)FEV(1) histamine below 4 mg/ml) were included in this study. Bronchial challenge with mannitol was performed 1-2 days after the test with histamine. RESULTS: The fraction of positive results of mannitol test was markedly lower when compared with the histamine challenge (72.7% vs. 100%, p = .015). The test was discontinued in one case due to severe coughing after inhalation of 315 mg of mannitol. Coughing during inhalation of dry mannitol powder occurred in most patients, although drinking water after subsequent doses alleviated this symptom in nearly all of them. Of note, triboelectrification of the inhaler and capsules was observed during the administration of consecutive mannitol doses, markedly hindering the delivery of this provoking agent. The relative decrease in FEV(1) resulting from bronchial provocation was significantly lower following mannitol delivery when compared with the histamine test (70.3% vs. 81.6% of resting value, p < .001). Significant correlation was not observed between the values of PC(20)FEV(1) histamine and PD(15)FEV(1) mannitol levels. CONCLUSIONS: Bronchial challenge with mannitol can be used as a screening test in everyday practice, but one cannot exclude bronchial hyperresponsiveness based on its negative results. Moreover, its usefulness is limited by the influence of static on the delivery of sequential mannitol doses and coughing which can be often associated with mannitol inhalation.
