title: Forced-air warming design: evaluation of intake filtration, internal microbial buildup, and airborne-contamination emissions.
abstract: Forced-air warming devices are effective for the prevention of surgical hypothermia. However, these devices intake nonsterile floor-level air, and it is unknown whether they have adequate filtration measures to prevent the internal buildup or emission of microbial contaminants. We rated the intake filtration efficiency of a popular current-generation forced-air warming device (Bair Hugger model 750, Arizant Healthcare) using a monodisperse sodium chloride aerosol in the laboratory. We further sampled 23 forced-air warming devices (same model) in daily hospital use for internal microbial buildup and airborne-contamination emissions via swabbing and particle counting. Laboratory testing found the intake filter to be 63.8% efficient. Swabbing detected microorganisms within 100% of the forced-air warming blowers sampled, with isolates of coagulase-negative staphylococci, mold, and micrococci identified. Particle counting showed 96% of forced-air warming blowers to be emitting significant levels of internally generated airborne contaminants out of the hose end. These findings highlight the need for upgraded intake filtration, preferably high-efficiency particulate air filtration (99.97% efficient), on current-generation forced-air warming devices to reduce contamination buildup and emission risks.
authors.affiliation: Northumbria Healthcare NHS Trust, United Kingdom.
authors.forename: Mike
authors.initials: M
authors.lastname: Reed
authors.forename: Oliver
authors.initials: O
authors.lastname: Kimberger
authors.forename: Paul D
authors.initials: PD
authors.lastname: McGovern
authors.forename: Mark C
authors.initials: MC
authors.lastname: Albrecht
mesh_terms: D000391:Air Microbiology; D004866:Equipment Contamination / Q000517:prevention & control*; D004867:Equipment Design; D005374:Filtration; D006361:Heating / Q000295:instrumentation*; D006801:Humans; D007035:Hypothermia / Q000517:prevention & control*; D017053:Infection Control; D007431:Intraoperative Complications / Q000517:prevention & control*; D009873:Operating Rooms; D014691:Ventilation / Q000295:instrumentation