Previously, research studying the effects of forced-air warming on laminar flow operating theaters was limited to contamination…until now.

The use of forced-air warming during orthopedic implant surgery was associated with a 3.8 times increase in deep joint infections as compared to warming patients without forced-air, according to a newly published study.

The study, published in the November issue of the Journal of Bone and Joint Surgery (Br), was conducted by orthopedic surgeons at Northumbria Healthcare Trust in the United Kingdom. Reviewing hip replacement surgeries performed on 1,437 patients over 2.5 years, the study compared the incidence of deep joint infections on patients warmed with 3M’s Bair Hugger® forced-air system with those warmed with the air-free HotDog® system. Patients warmed with the Bair Hugger system suffered deep joint infections at a rate of 3.1%; after discontinuing the use of foced-air warming, the infection rate was 0.8%. Air-free HotDog patient warming was the replacement.

“A 74% percent reduction in implant infections is incredibly significant,” said Dr. Scott Augustine, anesthesiologist and CEO of Augustine Temperature Management, manufacturer of HotDog warming. “Every joint infection is a disaster—both for the patient and the system. The process is horrific: ex-plant the joint, prolonged hospitalization, 6-8 weeks of IV antibiotics and then—assuming no amputation—re-plant the joint. The average cost is around $100,000.”

“Based on this study,” Dr. Augustine said, “discontinuing the use of forced-air warming on orthopedic implant patients could save hundreds of millions in medical costs—and reduce suffering for thousands of patients.” Dr. Augustine is the inventor of both HotDog warming and the Bair Hugger system.

According to the authors of the study, the higher rates of infection were associated with the disruption of operating room ventilation by the forced-air blowers: “Excess heat from FAW [forced air] resulted in the development of hot-air convection currents between the surgeon’s body and the operating table, that transported [contaminated] floor-level air upwards and into the surgical site.”

As a result, the authors concluded: “Air-free warming is, therefore, recommended over forced-air warming for orthopedic procedures.”


McGovern P.D., et al: J. Bone and Joint Surgery Br, Vol. 93-B, Issue 11, pp 1537-44. Nov. 2011.

Note: Augustine Temperature Management provided no funding to support the study. One of the study’s authors, Mark Albrecht, has been an employee of Augustine Biomedical + Design and is currently on a Fellowship from the company, pursuing a masters in statistics at the University of Minnesota. This relationship was revealed in the study by the following: “The author or one or more of the authors have received or will receive benefits for personal or professional use from a commercial party related directly or indirectly to the subject of this article.” Other than this relationship, our company had no financial connection to the study whatsoever.