Nursing Journal: Forced-Air Warmers May Allow Pathogens to Contact Surgical Wounds

October 10, 2013

   

AORN Journal, noting concerns about infection risk from forced-air warmers, called for multi-center, randomized, controlled trials. Evidence of bacteria in the air-flow paths of forced-air warmers; authors ask manufacturers to consider redesign.

In a continuing-education review article in the October issue of AORN Journal, published by the Association of Operating Room Nurses, the authors examined 192 sources.  Their conclusions included the following:

• “Clinicians should take steps to prevent health care–associated infections from the use of forced-air warmers….”  Such steps include “routinely and meticulously” cleaning the devices.

•  Forced-air warmers may interrupt the flow of filtered air toward the area of the wound and may allow dust particles containing pathogenic organisms to come into contact with the wound.

•  Five separate studies suggested that forced-air warmers could be harboring bacteria or bacteria-containing particles.

Among the research considered by the authors was “Forced-air warming and ultra-clean ventilation do not mix: an investigation of theatre ventilation, patient warming and joint replacement infection in orthopaedics,” by UK orthopedic surgeon PD McGovern et al and published in the Journal of Bone & Joint Surgery.  The research included 1,437 patients undergoing hip or knee replacement.  The “Finding and comments” of the AORN Journal authors included:

“High risk of developing deep infections for subjects warmed with forced-air warming systems (odds ratio, 3.8; P=.024).”

The Paradox of Forced-Air Patient Warming

Studies show that forced-air warming (FAW) reduces soft-tissue surgical infections. How can FAW be linked to increased deep-joint infections?

The paradox is easy to explain: BIOFILM.  A bacterium that lands on a prosthetic implant can secrete a coating of biofilm that protects it from both antibodies and antibiotics. Bacteria in soft-tissue cannot form effective biofilm coatings.

Secretion of biofilm allows a single airborne germ to cause a deep infection of a joint implant (Lidwell, 1983).  When the germ lands on the new implant, it protects itself in a biofilm coating and then sprouts weeks-to-months later as a catastrophic deep joint infection.  The increased airborne contamination from FAW vastly increases the chances of an airborne bacterium landing on the new implant.

In contrast, without biofilm protection, the germs in soft-tissue are susceptible to antibiotics and to an immune system activated by heat.  As a result, the creation of soft-tissue surgical infections require large inoculums of more than 100,000 germs (Elek & Cohen, 1957).

This also explains why soft-tissue surgical infections may not be increased by contaminated FAW air, while blowing even one germ into the surgical site during implant surgery can have significant negative concequences.

Watch this terrific video about bacterial biofilms 

produced by the Arthroplasty Patient Foundation:

Here is another interesting video about bacterial biofilms 

and orthopedic implants produced by the Arthroplasty Patient Foundation: