The empey index predicts upper airway obstruction in children

Abstract

Introduction. Reduced PEF in relation to FEV1 is associated with upper airway obstruction (UAO) in children. Children can present with tracheal stenosis, vocal cord dysfunction, subglottic stenosis, tracheobronchomalacia or persisting laryngomalacia. Stridor may be present. Bronchoscopy is often performed for diagnosis, monitoring and treatment. Forced expiration measured with spirometry, provides the Empey Index (EI) (FEV1 (ml) / PEF (L/min)), also expressed as the Expiratory Disproportion Index (EDI), (EI x 6). The usual cut-off for EI is 10. EI is raised in adults with UAO. Aim. To show the sensitivity of EI in identifying UAO in children. Method. A cohort of children with physician diagnosed UAO were identified between Aug 2016 and Aug 2018. EI was calculated in all retrospective spirometry measures for the entire cohort. Those with unacceptable spirometry by the ATS/ERS criteria were excluded. The defined EI cut-off of 10 was applied with a Bayesian analysis. Longitudinal data were further explored for interventions where available. Results. 2350 patients, 1294 male, (mean ± SD) age = 11.0 ± 3.6 yrs, were tested. 41 children with UAO were identified. 29 male, age = 11.6 ± 3.5 yrs.12 spirometries were excluded due to technique, leaving 29 tests to be analysed. 20 male, age 11.3 ± 3.1 yrs. EI measured in children using the cut-off index 10 has a Sensitivity 0.93, Specificity 0.98, PPV 0.41, NPV 0.99 for identifying UAO. Analysis of longitudinal data from 16 individuals revealed, improvements in the EI with surgical intervention to UAO. Conclusion. EI is a sensitive and specific test measure for UAO, and should be reported whenever UAO is suspected. Further investigation of its usefulness in measuring severity and monitoring progress is warranted.L6269393252019-04-02 <br />