iVAPS delivered a lower median PS compared with standard PS ( 8.3 ( 5.6-10 .4 ) vs 10.0 ( 9.0-11 .4 ) cmH2 O ; P = 0.001 ) for the same ventilatory outcome ( mean overnight : SpO2 96 ( 95-98 ) vs 96 ( 93-97 ) % ; P = 0.13 and PtcCO2 6.5 ( 5.8-6 .8 ) vs 6.2 ( 5.8-6 .9 ) ; P = 0.54 ) .