Tympanogram gradient and width in Children 4 to 6 years-old

Background: Impedanciometry is a sensitive test that allows the diagnosis of intratimpanie effusion. Both tympanogram gradient (TG) and tympanogram width (TW) can be obtained from it. Usually, international reference values for these variables are used, but their distribution in chilean pediatric population remains uncertain. Objective: Establish normal values for these parameters in chilean children 4 to 6 years-old. Method: This study was performed at the Otorhinolaryngology Service of Hospital Militar in Santiago, contemplating all chilean army personnel children, both sexes, 4 to 6 years-old who assisted to the center between March and June 2003. 180 children were evaluated by anamnesis, otoscopy, audiometry and impedanciometry. Results: Normal values for TG were determined with a 95% confidence interval. These were 0,21 to 0,62 for girls and 0,22 to 0,57 for boys. Percentiles were determined for TW, where its normal value can be estimated in our population by means of its inverse, with significative correlation with TO, Conclusion: These normal values will improve impedanciometry accuracy in the diagnosis of intratimpanic effusion, at the moment based on timpanometric shape and compliance peak.