“…After institutional approval forty patients, 16 female, 24 male with a median age of 67 years (range 55 to 79 years) were randomly allocated to one of four groups (A, B, C, D) ten in each group, receiving either SHFJV by the Alexander 1 (group A and group B), or high frequency oscillation (HFO) by a VDR 4 (group C), or conventional mechanical ventilation (CMV) by an Evita (Group D). All patients were ventilated for more than 100 h because of respiratory insufficiency [ 1 ]. The relative humidity (RH) of the inspiration gas (FM-C1, E u E. Elektronic, Unterwiesen, Austria) and its temperature (temperature sensor line 21076 A, Hewlett Packard, Palo Alto, CA) were measured twice a day.…”