Lung Clearance Index
Also written as: LCI — Lung Clearance Index
A measure of ventilation inhomogeneity derived from multiple-breath washout testing, reflecting how efficiently a gas (typically nitrogen or sulfur hexafluoride) is cleared from the lungs.
Full Definition
The Lung Clearance Index is calculated as the cumulative expired volume required to clear a tracer gas to 1/40th of its starting concentration, divided by the functional residual capacity. In pediatric pulmonology, it is particularly valued because it can detect early small-airway disease in conditions such as cystic fibrosis before spirometric changes are apparent. It is effort-independent, making it suitable for use in young children and infants who cannot reliably perform forced maneuvers. Editors should render it as 'Lung Clearance Index' on first use, followed by the parenthetical abbreviation '(LCI)'.
Usage
Usage note: Always expand on first use. Do not confuse LCI with FRC; they are related but distinct measurements. LCI is a ratio, not a volume.
In Context
- "The patient's elevated Lung Clearance Index (LCI) of 10.2 indicated significant ventilation inhomogeneity despite a normal FEV1." — Clinical case report
- "Multiple-breath washout testing yielded an LCI consistent with early small-airway involvement." — Pediatric pulmonology research article