Abstract

Multiple-breath washout (MBW)-derived lung clearance index (LCI) is a sensitive measure of ventilation inhomogeneity in patients with cystic fibrosis (CF), but LCI measurement is time consuming. We systematically assessed ways to shorten LCI measurements.

In 68 school-aged children (44 with mild CF lung disease) three standard nitrogen (N₂) MBWs were applied. We assessed repeatability and diagnostic performance of (1) LCI measured earlier from three MBW runs and (2) LCI measured at complete MBW (1/40th of starting N₂ concentration) from two runs only.

Compared with the standard LCI from three complete MBW runs, the new LCI based on three N₂MBW runs until 1/20th, or two complete runs until 1/40th, provided similar or better repeatability as well as sensitivity and specificity for CF lung disease. Alternative ways to measure LCI reduced test duration in children with CF by 30% and 41%, respectively.

LCI measurements can be reliably shortened in children. These new MBW protocols may advance the transition of LCI from research into clinical settings.