RESULTS	Applied during PSV , the LSF method leads to gross underestimation of Rrs ( -10.4 + / - 2.3 cmH2O / ( l/s ) ) and overestimation of Crs ( +35.2 + / - 33 ml/cmH2O ) whenever the set pressure support level is low and the activity of the respiratory muscles is high ( P0 .1 was 4.6 + / - 3.1 cmH2O ) .\