Bilateral nasal allergen provocation monitored with acoustic rhinometry. Assessment of both nasal passages and the side reacting with greater congestion: relation to the nasal cycle

Background The effect of bilateral nasal provocation on nasal mucosa measured with the use of acoustic rhinometry (AR) can be assessed for both nasal passages or for the side responding with greater congestion. Assessment of changes in nasal congestion during the nasal provocation test (NPT) can be affected by the nasal cycle (NC). The aim of this study was to find out the most accurate method to evaluate changes observed during bilateral nasal provocation. Methods Cross-sectional areas (CSA) at the level of inferior nasal turbinate (CSA-2) were recorded by AR in 26 volunteers with allergic rhinitis during the NC for 5-7 h and subsequently during NPT. The risk of spontaneous total and unilateral CSA-2 decrease was established. Sensitivity of the NPT assessment for the total CSA-2 and for the side responding with greater congestion was evaluated at chosen thresholds. These thresholds were selected in a way that the risk levels of spontaneous decrease of unilateral and total CSA-2 were equal. Results The assessment of the total CSA-2 was found to be more sensitive than the assessment of the side responding with greater congestion. The highest sensitivity and specificity of the test was achieved by using a combination of both assessments. Optimum thresholds of the CSA-2 decrease for assessment at 15 min after provocation, with this method, were 27% and 40% for the side responding with greater congestion and for the total CSA-2, respectively. Conclusions Recognition of the risk of spontaneous unilateral and total CSA-2 decreases enables introduction of combined assessment of bilateral NPT. This assessment seems to be the most accurate method for evaluation of the test results.