Patent ID: 8910633

Claim:
A method for estimating gas leakage from the ventilator circuit and patient interface that relies on breath-by-breath or time-to-time variability in the pattern of pressure delivery by the ventilator, which comprises: generating signals that correspond to pressure (P CIRCUIT ) and flow rate (Flow) in the ventilator circuit, integrating Flow (Integrated Flow), measuring the change in Integrated Flow (ΔV) over an INTERVAL extending from a selected point in the expiratory phase of a ventilator cycle to a selected point during the expiratory phase of a nearby ventilator cycle, repeating said measurement of ΔV in at least two said INTERVALs, processing P CIRCUIT to produce an index or indices that reflect(s) the pattern of pressure delivery by the ventilator during each of said INTERVALs, applying statistical methods to determine the relation between the differences in ΔV among INTERVALs and the corresponding differences in said index or indices of P CIRCUIT , and establishing from said relation the leak rate at specified P CIRCUIT values.