Impulse oscillometry reference values and bronchodilator response in three- to five-year old children living at high altitude

Abstract

Introduction

Impulse oscillometry (IOS) is used to measure airway impedance. It is an effective tool for diagnosing and treating respiratory diseases, and it has the advantage that it does not require forced respiratory maneuvers. IOS reference values are required for each population group.

Objective

This study aimed to determine the IOS reference values and bronchodilator response in healthy preschool children living in Bogotá, Colombia.

Methods

We performed a cross-sectional study in preschool children who had no history of respiratory disease; 96 children fit the parameters for testing to determine normal values according to the American Thoracic Society and European Respiratory Society criteria.

Results

Values for respiratory resistance (Rrs) and reactance (Xrs) at 5, 10, and 20 Hz, respiratory impedance (Zrs, and resonance frequency (Fres) were established. Height was the most influential independent variable for IOS values; an increase in height led to a reduction in Rrs5 and Rrs20 and an increase in Xrs5. After the administration of 400 mcg of salbutamol the values for Rrs5(−17.48%), Rrs20(−8.63%), Fres (−10.68%), and area of reactance (−35.44%) were reduced, meanwhile Xrs5 (15.35%) was increased.

Conclusions

Normal IOS values before and after the administration of 400 mcg of salbutamol were determined for a population of children aged 3–5 years at 2,640 m. Reference IOS equations for these children are presented. A relative change of up to −28% and 36% after the use of salbutamol for respiratory resistance and reactance, respectively, should be considered as an upper limit of the normal range, and possible appropriate cut-off values for defining significant response for evaluating therapeutic interventions.

Keywords:

• oscillometry
• children
• reference values
• high altitude
• respiratory function tests
• cross-sectional studies

Acknowledgments

The authors thank the Pulmonary Function and Research Group from the Fundación Neumologica Colombiana for their support. They facilitated the availability of equipment for the tests and data collection. The authors also wish to thank the directors of the different educational institutes who allowed us to contact the children.

Author contributions

All authors contributed towards data analysis, drafting and critically revising the paper, gave final approval of the version to be published, and agreed to be accountable for all aspects of the work.

Disclosure

The authors report no conflicts of interest in this work.