| Abstract: | Using the modified 3-Hz oscillation method, the inhalation challenge test was performed with house dust allergen upon subjects while tidal breathing throughout the test. Their total respiratory resistance (Rrs) was continuously monitored with the inhalation of saline as a control, and 250-, 50-, and 10-fold diluted allergen solution to the inhalation of aerosolized metaproterenol. The starting point of the induced bronchoconstriction was checked and as soon as Rrs increased up to twice the base-line value, the subjects inhaled the aerosolized metaproterenol. From the dose-response curve of Rrs, the dose of inhaled allergen (minimum dose) as bronchial sensitivity was determined; also the decreasing rate of respiratory conductance, which was calculated from the slope of elevation of Rrs, as bronchial reactivity. It was found that the more diluted allergen required for a positive skin reaction, the more likely the patients were to have a subsequent positive bronchial inhalation challenge to house dust allergen. There was a relationship between the increased bronchial reactivity and the increased RAST score. These results indicate that this inhalation challenge test is specific, safe, and time-saving. |
