In its Guide to the Elimination of Orthopedic Surgical Site Infections, the Association of Professionals in Infection Control and Epidemiology (APIC) states, “If airflow is interrupted, rapid air turbulence can stir settled particles, enabling them to become airborne thus increasing the risk for wound contamination.” By applying recent research to APIC’s Guidance, found that forced-air warming systems violate APIC’s Guidance “by drawing potentially contaminated particles from below the operating table into the surgical site.”   

Minneapolis, MN July 25, 2013
According to the Association of Professionals in Infection Control (APIC), the maintenance of uninterrupted, downward airflow during orthopedic surgery is “vitally important.” Several recent articles published in top peer-reviewed medical journals, however, confirm that forced-air patient warming, such as 3M’s Bair Hugger, produces rising, turbulent convection currents that can mobilize floor-level contaminants.

The printing and distribution of APIC’s Guide was sponsored by 3M.  APIC, of course, neither endorses nor is affiliated with this press release.

“The APIC guidance,” says Dr. Scott Augustine, inventor of Bair Hugger, “ summarizes the reason that researchers have questioned the safety of forced-air patient warming (“FAW”) in orthopedic implant and other ultra-clean surgeries.  I believe the research is conclusive—the largest study involved a retrospective analysis of 1,437 hip or knee replacements. It showed a 74.6% decrease in deep joint infection when FAW was discontinued and replaced with air-free warming.”  

The study, conducted by British orthopedic surgeon P.D. McGovern et al., concluded that the “excess heat from forced-air warming resulted in the development of hot-air convection currents between the surgeon’s body and the operating table that transported floor-level air upwards and into the surgical site.”

APIC specifically mentions the risks to orthopedic infection when airflow is compromised: “If airflow is interrupted, rapid air turbulence can stir settled particles, enabling them to become airborne thus increasing the risk for wound contamination.”

“The risk identified by APIC,” Dr. Augustine stated, “is especially severe during orthopedic implant surgery because bacteria that land on artificial knees or hips produce a biofilm that makes them impervious both to antibiotics and to antibodies. While it creates significant risk in orthopedics, forced-air warming may still be safe in soft-tissue surgeries.”

Four other peer-reviewed articles have established that the 1000+ watts of rising heat produced by FAW blowers mobilize contamination from the floor of the operating room and deposit it in the sterile surgical field. The most recent study, by Legg et al. and published in the Bone & Joint Journal, showed a 217,000% increase in contamination over the wound site when FAW was used.

Legg stated: “…forced-air warming…can significantly disrupt unidirectional air flow and draw particles from the potentially contaminated area below the sterile field. This is a concern.”
Other studies measured the convection currents created by FAW blowers and the impact on hospital ventilation, concluding that even laminar flow ventilation is disrupted.

In the April 2013 issue of Health Devices, ECRI reviewed the published research related to the risks of FAW and chose not to recommend that FAW be banned in all ultra-clean surgeries. Under the headline “FORCED-AIR WARMING MAY DISTURB AIR PATTERNS IN THE OPERATING ROOM,” however, ECRI did conclude that the use of FAW in orthopedic surgery was “particularly worrisome” and “especially concerning.”

“By stressing the importance of clean, non-turblulent air in the operating room,” concluded Dr. Augustine, “APIC has definitely promoted patient safety. APIC does not warn against using FAW in orthopedic surgery, but this new research was not available when the APIC guide was written. As more research in this area becomes available, I expect the issue will be reconsidered.”

A full version of APIC’s Guide to the Elimination of Orthopedic Surgical Site Infections may be seen here.

About exists for the purpose of communicating with healthcare providers, infection control specialists, insurers, risk managers, and other interested parties regarding the risk and consequences of surgical site infections. is underwritten by Augustine Temperature Management and other healthcare-related organizations.

About the Association for Professionals in Infection Control and Epidemiology (APIC) Guide to Elimination of Orthopedic Surgical Site Infections (from APIC website):
Practical tools, strategies, and resources for infection preventionists, care providers, surgical staff and quality improvement teams; developed with the Association of periOperative Registered Nurses (AORN).

Citations To Studies Regarding The Safety Of Forced-Air Warming:

  1. Albrecht M, Leaper D et al. Forced-air warming blowers: An evaluation of filtration adequacy and airborne contamination emissions in the operating room. Am J Infect Control 2011;39:321-8.
  2. Belani et al. Patient warming excess heat: The effects on orthopedic operating room ventilation performance. Anesthesia & Analgesia August 2013 vol. 117 no. 2 406-411
  3. Dasari et al. Effect of forced air warming on the performance of operating theatre laminar flow ventilation. Anaesthesia 2012;67:244-249.
  4. Leaper D et al. Forced-air warming: a source of airborne contamination in the operating room? Orthopedic Rev. 2009;1(2):e28.
  5. Legg, et al. Do forced-air patient-warming devices disrupt unidirectional downward airflow? Journal of Bone and Joint Surgery Br. 2012;94-B:244-256.
  6. Legg, A.J. and Hamer, A.J. Forced-air patient warming blankets disrupt unidirectional airflow. Bone and Joint Journal, March 2013 vol. 95-B no. 3 407-410
  7. McGovern et al. Forced-air warming and ultra-clean ventilation do not mix. J Bone and Joint Surg-Br. 2011;93(11):1537-1544.