Bair Hugger: The Answer Is Blowing in the Wind

Chilton, WIRosie Bartel is a woman from Chilton, Wisconsin, who went in for a routine knee replacement some years ago. However, Bartel got more than she bargained for and came away from the hospital with more than a new knee. She also left with a MRSA infection that would result in 27 additional surgeries and eventually cost Bartel her right leg, amputated just below the hip. She blames the use of a Bair Hugger forced-air patient warming system during her surgery, eventually filing a Bair Hugger lawsuit.



In her Bair Hugger lawsuit, Bartel noted that the MRSA infection cost her more than her leg: she also lost her job and eventually her home. Bartel has now become an advocate against the forced-air surgical warming systems that were employed during no fewer than 22 million surgical procedures in 2012 alone.

Keeping patients warm during surgery is a relatively new adoption in the history of surgical procedure. While keeping the operating theater cool benefits surgeons and support staff, helping them to stay alert and avoid overheating, it was also thought that keeping the body cool was also beneficial - especially in terms of heart rate and blood pressure during the procedure.

However, this thinking began to change in the 1980s, with active experiments in the use of heated surgical blankets occurring throughout the decade. The Baltimore Sun (04/09/97) carried reports of a study that touted the benefits of keeping a patient warm through all types of surgery, and not just joint replacements: surgery for pancreatic, liver and lung cancer and procedures to correct clogged arteries of the neck and leg. The study excluded heart bypass surgery, in which a lowered body temperature is known to benefit patients.

“There is a reason why people live at 98.6 degrees,” said Dr. Steven M. Frank, lead author of the study that appeared in the April 9, 1997 edition of JAMA (then known as the Journal of the American Medical Association). “We’ve been focusing on heart rate and blood pressure for 100 years but only recently on body temperature.”

The Bair Hugger secured FDA approval and first appeared in 1988

The Bair Hugger warming blanket, one of the earliest devices, was approved by the US Food and Drug Administration (FDA) in 1988 and was put into widespread use. A blanket dotted with a myriad of tiny holes connects to a forced-air heating unit that rests on the floor near the operating table. The unit carries heat via forced air to the blanket, with the warm air transferred to the patient through the blanket. While the heat and air unit remained a constant, the actual blanket that is in contact with the patient during surgery is single-use.

Over the years, however, infections were becoming a problem, and especially for invasive joint replacement surgery where the introduction of a single germ could have devastating consequences.

Some suspicion soon began to surface that heated air produced by the floor-situated Bair Hugger was compromising the carefully controlled ventilation system common to operating theaters that help to maintain the sterile environment.

One report, released in November of last year and published in Volume 88, edition 3 of the Journal of Hospital Infection released to print in November 2014 and posted online August 26 of last year, referenced 10 peer-reviewed, published studies that suggested use of forced-air warming systems such as the Bair Hugger could possibly introduce contamination to the operating field.

In various demonstrations and experiments, it appears that the introduction of heat is potentially problematic. Even when the blower on the Bair Hugger is engaged, the air exchange in tandem with the sterile and filtered Laminar ventilation that flows from above the operating field and pushes downward does not impede the performance of the Laminar airflow, which sees cooled air continue to abide by the laws of physics and fall - and remain - at the floor below.

The problem appears to occur when heat from the floor-situated blower is engaged. Introducing heat causes potentially contaminated air from the floor to rise in the room. Various demonstrations with smoke and/or bubbles and a laser light source appear to bear this out. The warm air rises and collects above the operating field, before it cools and descends into the operating field, bringing any contaminants it originally brought from the floor, down with it.

More research needed

Research proponents are quick to point out that more studies need to be done. There is no data that suggests causation beyond mere association. Still, “We conclude that [forced-air warming of FAW] does contaminate ultra-clean air ventilation; however, there appears to be no definite link to an increased risk of [surgical site infection] based on current research,” the researchers noted. “Nevertheless, whereas this remains unproven, we recommend that surgeons should at least consider alternative patient-warming systems in areas where contamination of the operative field may be critical.”

It should be noted that the co-founder of the Bair Hugger and an early proponent of patient warming is no longer associated with the Bair Hugger FAW device and is speaking out against its continued use, citing in the New York Times the potential for surgical site infection and contamination. Dr. Scott Augustine, an anesthesiologist, is now touting a warming blanket that does not rely on forced air.

The Bair Hugger is marketed by Arizant Healthcare Inc. (Arizant) - originally known as Augustine Medical according to the New York Times (12/24/10), which was purchased by 3M in 2010 for $810 million. Dr. Augustine now operates as Augustine Temperature Management and markets his HotDog Patient Warming blanket as an improvement over the Bair Hugger without the risk of contamination to the operating field.

Proponents of the Bair Hugger say the allegations of potential contamination have not been proven. However, authors of the report note “there has been significant debate about the safety of FAW, and no studies have shown a reduction in SSI by the use of intraoperative FAW except in elective colorectal surgery. In implant surgery even minor contamination of the operative field could be catastrophic, and concerns about this focus on two areas: disruption of clean air through thermal eddies, and direct contamination of air that blows from the use of FAW blowers.”

For her part, Rosie Bartel advises patients facing surgery to ask if FAW is used in the operating theater and - if so - to ask for a non-FAW source of patient warming, or choose another hospital that employs non-FAW. The potential for a catastrophic infection she says in her video blog is just too great.