Copyright ©The Author(s) 2019. Published by Baishideng Publishing Group Inc. All rights reserved.
World J Clin Pediatr. Apr 9, 2019; 8(2): 15-22
Published online Apr 9, 2019. doi: 10.5409/wjcp.v8.i2.15
Applications of lung clearance index in monitoring children with cystic fibrosis
Andrew Fretzayas, Konstantinos Douros, Maria Moustaki, Ioanna Loukou
Andrew Fretzayas, School of Medicine, University of Athens, Athens 11527, Greece
Andrew Fretzayas, Department of Pediatrics, Athens Medical Center, Athens University Medical School, Maroussi 15125, Greece
Konstantinos Douros, Respiratory Unit, Third Department of Pediatrics, Athens University Medical School, “Attikon” University Hospital, Haidari 12464, Greece
Maria Moustaki, Ioanna Loukou, Department of Cystic Fibrosis, “Agia Sofia”, Children’s Hospital, Athens 11527, Greece
Author contributions: Each author did equally to this work.
Conflict-of-interest statement: The authors state that they have no conflicts of interest.
Open-Access: This article is an open-access article which was selected by an in-house editor and fully peer-reviewed by external reviewers. It is distributed in accordance with the Creative Commons Attribution Non Commercial (CC BY-NC 4.0) license, which permits others to distribute, remix, adapt, build upon this work non-commercially, and license their derivative works on different terms, provided the original work is properly cited and the use is non-commercial. See:
Corresponding author: Andrew Fretzayas, MD, Doctor, Department of Pediatrics, Athens Medical Center, Athens University Medical School, 5-7 Distomou str, Maroussi 15125, Greece.
Telephone: +30-210-6157269 Fax: +30-210-6862376
Received: December 5, 2018
Peer-review started: December 5, 2018
First decision: January 21, 2019
Revised: February 3, 2019
Accepted: February 19, 2019
Article in press: February 19, 2019
Published online: April 9, 2019

A sensitive, reproducible and feasible measure of lung function for monitoring the respiratory health is a prerequisite for the optimization of management of the patients with cystic fibrosis (CF). Spirometry has been considered the method of choice, although it is applicable only in children older than 6 years of age, as good cooperation is necessary for its proper performance. However, over the last 15 years, scientific interest in gas dilution techniques and particularly in multiple breath wash out (MBW) method has been revived. The most commonly reported index of MBW is lung clearance index (LCI). The aim of this review is to present the most recent developments in the application of LCI as a monitoring index of respiratory status of CF patients. LCI is a sensitive and reproducible marker of ventilation inhomogeneity. It is more sensitive than spirometry and, unlike spirometry; it can be performed across the whole pediatric age range. Since it is dependent on body size, until at least the age of 6 years, the relative and not the absolute changes are more appropriate for providing clinically meaningful conclusion on ventilation inhomogeneity. Until now, MBW has been mainly used as a research tool. Based on the currently available data LCI cannot safely predict high-resolution computed tomography findings in children with CF, especially in infants. It can be used as an end-point measure for the assessment of beneficial effect of interventions. However, its utility as an outcome measure for the efficacy of therapeutic interventions seems to be dependent on the pathophysiologic mechanisms that underlie each intervention. It seems that more studies, especially longitudinal ones, are required in order to fully clarify the clinical usefulness of LCI, not only in the research setting, but also in every day practice of CF clinic.

Keywords: Cystic fibrosis, Respiratory health, Lung clearance index, Ventilation inhomogeneity

Core tip: We herein present an overview of the applications of lung clearance index (LCI) in monitoring the respiratory health status of children with cystic fibrosis (CF). LCI is a more sensitive marker than spirometry and unlike spirometry it can be performed across the entire pediatric age range. At present, it is mostly used in research settings. However, as more data become available from longitudinal studies, it may be proved to be a very useful marker of respiratory status monitoring in children with CF, able to identify early those who are at risk for deterioration and allowing the early application of more aggressive interventions.