Pd40 Sgaw With Deep Inhalation As Alternative For Pd20 Fev1

Introduction: Bronchial challenge testing is used in te assessment of airway hyper responsiveness. PD20 FEV1 is considered the gold standard. However, some patients are not able to perform a reliable FEV1. PD40 sGaw might serve as an alternative in these patients; however, compared to PD20 FEV1, PD40 sGaw appears to overestimate the presence of hyperreactivity (resulting in high false positivity). We hypothesized that the apparent difference in test performance is related to the bronchodilatation effect of the deep inhalation needed to perform a FEV1. Methods: 38 patients (22 F, age 45±31) performed routinely bronchial challenge test which were extended with a measurement of sGaw without and with a deep inhalation, at each provocation step until PD20 was reached, even though PD40 was reached. Results: There was a significant difference between sGaw before and after deep inhalation (0.77±0.31 vs. 0.87±0.27 1/kPa/sec; p<0.001), which resulted in a significant difference in PD40 (0.49±0.67 vs. 0.66±0.57 mg; p=0.026). Sensitivity for PD40 sGaw without prior deep inhalation was high (92%) with very low specificity (23%) compared to PD20 FEV1 as gold standard. This implies a high level of false positive tests. PD40 sGaw with deep inhalation had a lowet sensitivity (76%, which might be underestimated by study design) but a specificity of 100%. Discussion: We conclude that a deep inhalation before bronchial challenge testing using PD40 sGaw better represents the values achieved with the gold standard PD20 FEV1 then a PD40 sGaw without a deep inhalation. Based upon this preliminary study, we suggest that this test can be used as an alternative to assess airway hyperreactivity in patients whoa are unable to perform a reliable FEV1.