Recent A & A study: “These findings warrant future research into the effects of forced air warming…during contamination-sensitive surgery.”

August 2013
 
Research in the August edition of Anesthesia & Analgesia, a publication of the International Anesthesia Research Society, and appearing under the name of the Anesthesia Patient Safety Foundation stated:

 “[F]orced air warming was found to establish convection currents that mobilized resident air from nonsterile areas (under the anesthesia drape) upward and into the surgical site.”

The clinical concern, according to the article, is that the convection currents created by Bair Hugger will mobilize contaminants and/or impede the ventilation systems’ ability to clear contaminants from the surgical site.  The concerns, they stated, “are most relevant for smaller airborne particles…such as free-floating bacteria and skin cell fragments.”

The study compared the impact of Bair Hugger warming with air-free HotDog conductive fabric warming.  No convective currents were detected when HotDog warming was applied.  In explanation, the scientists stated:

 “Because conductive blankets (like HotDog) are localized in their application, they tend to have higher thermal efficiencies and contribute less excess heat to the environment than forced air.”

In contrast, Bair Hugger “was found to have a significant disruptive impact on clean airflow patterns over the surgical site….”

AANA Journal: 96% of Bair Hugger Blowers Contaminated

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.”