August 2013

Research published in the August issue of AANA Journal revealed that 96% of Bair Hugger forced-air warming (FAW) blowers studied were generating “significant levels of contamination.”  The researchers, including two UK orthopedic surgeons, measured up to 110,000 particles per cubic foot–82,500 particles per second.  More than 70% of the blowers “had hose-end airflows with higher contamination levels than in intake airflows.”

The contaminates, therefore, were incubated inside the Bair Hugger blowers.

The problem, researchers concluded, arises from the blowers’ inadequate air filtration. Originally designed to provide 93.8% efficient intake filtration, the current-model Bair Hugger filters perform at only 63.8% efficiency.  This poor filtration, the authors stated, suggests “that inadequate FAW device intake filtration…led to a significant buildup of internal microbial contamination in the FAW blowers sampled.”

Air path swabs revealed the presence of viable microorganisms in 100% of FAW blowers.  Referring particularly to coagulase-negative staphylococci, the authors noted:  “the composition of identified microbes in current-generation FAW blowers favored pathogens associated with surgical site infection.…”

The researchers stated that their findings question the common assumption that “all forced-air warming [blowers] include filters that essentially eliminate bacteria in the heated air.”  This oft-quoted statement was attributed to Dr. Daniel Sessler, a member of the Advisory Board of 3M, manufacturer of Bair Hugger.

To address these design deficiencies, the authors urged the manufacturer to redesign the blowers to make decontamination possible, to increase inlet filtration efficiency to HEPA quality (99.97% efficiency) and to add a filter at the distal end of the hose.

The full version of the study in AANA Journal can be found here on page 275 of the journal, or 29 of the pdf.