The mean inhaled gas absolute humidity was higher in HME than no-HME groups and higher in low-flow than high-flow groups ( [ HME1L : 25 1 mg H2OL ] > [ HME3L : 23 2 mg H2OL ] > [ 1L : 17 1 mg H2OL ] > [ 3L : 14 1 mg H2OL ] ; P < 0.0001 ) .