METHOD TO DETERMINE INDICES OF VENTILATION INHOMOGENEITY E.G.LUNG CLEARANCE INDEX (LCI) OF A PAEDIATRIC TEST SUBJECT

摘要

The present invention relates to a method to determine the lung clearance index (LCI) or other indices of ventilation inhomogeneity of the lungs of a paediatric test subject. Wash-in is used to wash-in the inert tracer gas and the wash-out is conducted by inhaling atmospheric air from the surroundings and exhaling to a confined space such as a collection bag until the end-tidal tracer gas concentration has fallen below a predetermined fraction of the starting concentration. The LCI of a paediatric test subject is calculated as the ratio between the cumulative expired volume (V CE ) required to clear the inert tracer gas concentration from the lungs of the paediatric test subject below a predetermined fraction of the starting concentration and the functional residual capacity (FRC) where FRC is determined by dividing the net volume of inert tracer gas exhaled by said paediatric test subject with the difference in end-tidal fractional concentration of the inert tracer gas at the start and end of the wash-out period; and where V CE is determined by measuring the total volume in the collection bag after completed wash-out period. Furthermore the present invention relates to a corresponding system and computer-readable medium.