IOS is a new method for the evaluation of the bronchial airway narrowing. In comparison with conventional spirometery IOS is more convenient and needs less patient’s cooperation. The aim of this study is to evaluate the correlation between the IOS and spirometery parameters in patients with positive MCT.
42 patients with respiratory symptoms suggesting asthma and positive MCT were studied. All of them had performed an IOS test with MS Jeager device which measures both IOS and spirometery parameters. After administration of different concentrations of methacholin IOS and spirometery parameters were measured. After at least 20% fall in the serial FEV1s, the case considered positive for MCT. The crude and percent changes for X5, Z5, R5, R20, R central and R peripheral of IOS and FEV1, PEFR, MMEF, FEF25%, FEF50% and FEF75% were measured and compared with each other.
Percent changes of predicted MMEF and FVC were not correlated significantly with any IOS parameter mentioned above. Significant correlations between the percent changes FEF25%, FEF50%, FEF75% and PEFR and some IOS parameters was not clinically significant (r < 0.5). Changes in the percent of predicted FEV1 were correlated with percent changes of the predicted and crude values of R5 and R20, all with r < 0.5.
This study shows although there are some correlations between IOS and spirometery parameters, these are not clinically significant. It might be because of technical considerations to do a correct IOS test and standardization of that.
Results of IOS test in determining airway narrowing have a low correlation with conventional spirometery.
Ali Moghimi, None.