BACTERIAL AND VIRAL REMOVAL EFFICIENCY, HEAT AND MOISTURE EXCHANGE PROPERTIES OF 4 FILTRATION DEVICES

Four devices used for filtration of microorganisms and/or for heating and moistening the ventilated air during mechanical ventilation were e valuated. This evaluation included measurement of bacterial and viral removal efficiency, heat and moisture exchange properties, dead space and air flow resistance. The devices included: Pall BB50T and DAR Ster ivent (filtration devices); DAR Hygrobac and Gibeck Humid-vent [heat a nd moisture exchangers (HMEs)]. The two devices which are primarily co nceived as filters had the highest bacterial and viral removal efficie ncy (titre reduction of 10(5)-10(6) for bacteria and of 10(4)-10(5) fo r viruses), while removal efficiencies of the HME devices were lower: titre reduction of 10(4) for bacteria and 10(1)-10(3) for viruses. As expected, heat and moisture output of HMEs was better than that of fil ters. In mechanical ventilation, dead space and air flow resistance ar e important properties of devices, which might disturb efficient venti lation. There were only minor differences in dead space and air flow r esistance. Resistance to airflow in the HMEs was increased by nebuliza tion of medication (mesna) unlike that of the filters.