The application relates to methods aiming at fast equilibration in the lungs of inhaled tracer gases by inhalation of a bolus of gas mixture followed by rebreathing in a closed system. Possible applications of the methods include inert gas rebreathing for fast wash-in of tracer gas for multiple-breath washout measurements to determine the lung clearance index (LCI) or other indices of ventilation inhomogeneity of the lungs or for pulmonary blood flow and lung volume determination by rebreathing. Furthermore the present application relates to a corresponding system.
