Bair Hugger Complications

Bair Hugger warming system complications reported to the Food and Drug Administration from 2018 to 2019 include rare instances of skin rashes, burns and hypothermia. Thousands of patients who used Bair Hugger blankets also reported serious infections, including methicillin-resistant Staphylococcus aureus (MRSA). Some studies suggest the forced air used by the blankets stirs up airborne particles which may lead to infection.

Last Modified: September 5, 2023
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More than 5,000 patients have sued 3M, the manufacturer of Bair Hugger, alleging the device was responsible for infections they experienced from surgery. Many surgeries involved implants, including knee, hip and other joint replacements, which have a higher risk for contamination than other surgeries.

3M has denied the blankets can cause infections.

“The Bair Hugger warming system is safe and effective. Dozens of scientific studies show that forced-air warming devices effectively warm patients before, during and after surgery and can reduce the risk of surgical site infections,” the company said in a fact sheet about infection allegations.

However, an April 11, 2022 appeals court document filed by 3M’s lawyers in the the Supreme Court of the United States said that, “3M admits that
Bair Hugger is ‘not sterile,’ and does not dispute that the device harbors and grows bacteria.” The documents also cites evidence showing a study found “nearly a 400% increased risk of infection
among those patients who were warmed by Bair
Hugger,” though the authors admitted the study did not establish causation.

MRSA: An Antibiotic-Resistant 'Superbug'

Closeup 3D rendering of staphylococcus aureus, a serious infection linked to Bair Hugger devices
The risk of infection from staphylococcus aureus increases if the person carrying it has surgery

MRSA is a strain of common bacteria that has grown resistant to antibiotics. Drug-resistant bacteria are sometimes called “superbugs” because they are so hard to treat with routine medicines.

Staphylococcus aureus is a common bacteria that usually goes unnoticed. About 2 in 10 people always carry it in their body. Another 6 in 10 people will carry it in their bodies from time to time. Healthy people have a small risk of infection from the bacteria, but that risk increases if a person carrying the bacteria has surgery.

MRSA is much more serious because it cannot be easily treated with antibiotics.

  • Being hospitalized
  • Having a medical device implanted or used inside the body
  • Living in a long-term care facility
  • Living in crowded or unsanitary conditions
  • Taking part in contact sports

Doctors may be able to drain the infection without the use of drugs if it is caught early enough. While MRSA is resistant to most antibiotics, there are some drugs that can still be effective. But the Centers for Disease Control and Prevention (CDC) recommends that doctors first use lab tests to find out exactly what strain of MSRA the patient has. This allows doctors to select the most effective antibiotic to treat it.

Complications from MRSA Infections

Complications from MRSA infections can be life-threatening and may overcome patients quickly. The only way to know if MRSA is responsible for an infection is through laboratory tests. It is important for people who think they may be infected to talk with their doctor as soon as possible.

MRSA can cause difficult-to-treat and sometimes fatal conditions, including sepsis, pneumonia and skin infections that can spread deep into the body.


Sepsis is a medical emergency requiring immediate medical attention. It is the body’s own, life-threatening response to an infection. Sepsis can cause tissue damage, organ failure and even death. The CDC lists Staphylococcus aureus as one of the most frequently identified forms of bacteria responsible for sepsis.

  • Clammy or sweaty skin
  • Confusion or disorientation
  • Extreme pain or discomfort
  • Fast heart rate
  • Fever or chills
  • Shortness of breath


Several different kinds of bacteria, viruses and fungi can cause pneumonia, but cases caused by MRSA can advance quickly and can be deadly. It can be extremely hard to treat MRSA pneumonia, and up to 7 in 10 people who develop it die. The risk of severe cases of pneumonia may even remain if doctors are able to stop the MRSA infection.

Not all pneumonia is due to MRSA, but people who have had surgery or have been hospitalized should pay close attention to possible bacterial pneumonia symptoms.

  • Chest pains, especially when coughing or breathing
  • Chills
  • Cough (with yellow, green or bloody mucus)
  • Fever


MRSA skin infections can be painful. They can quickly lead to deep abscesses requiring surgery to drain. Left untreated, they can spread from the skin to bones, joints and into the bloodstream.

Once in the blood, MRSA infections can spread to the lungs and heart, where it can disrupt heart valves.

  • Fever accompanying a skin infection
  • Pimples, cuts or other skin irregularities fill with fluids
  • Red, swollen or painful area on the skin
  • Skin is warm to the touch

Patients or caretakers who think an infection may be due to MRSA should cover it with a bandage, wash their hands thoroughly with soap and water and call their doctor.

Can Warming Blankets Increase Infection Risk?

Bair Hugger’s maker, 3M Company, claims that the devices are safe. It says surgeons have used them in millions of surgeries without problems. But thousands of Bair Hugger lawsuits claim the devices caused patients’ infections.

Studies have looked at how forced-air warming (FAW) devices affect air currents. Researchers looked at their potential to move small particles around operating rooms. Some studies found changes in air currents. Lawsuits claim this can carry contaminates into open incisions.

Bair Hugger Infection Risk Studies
  • 2011: Deep-Joint Infection
    A 2011 study published in The Journal of Bone and Joint Surgery simulated hip replacement and lumbar spinal procedures using both forced-air warming and conductive fabric warming, with a mannequin as a patient. In 2011, researchers compared forced-air warming, used in the Bair Hugger device, to an alternative-warming device that did not use forced air. They simulated a hip-replacement surgery and found that the forced-air device generated air currents that “mobilized floor air into the surgical site area.”

    “Air-free warming is, therefore, recommended over forced-air warming for orthopedic procedures,” the researchers concluded.
  • 2011: Convection
    Other researchers in 2011 conducted a similar study that was also reported in The Journal of Bone and Joint Surgery. They released neutrally buoyant detergent bubbles in a simulated surgery and tracked whether the bubbles moved to the simulated incision. When forced-air warming was used, they found “a significant mean increase” in the number of particles over the surgical site. They found forced-air warming sent more than 275 times as many bubbles over the simulated incision.
  • 2012: Increased Air Temperature
    A 2012 study in the UK journal Anaesthesia found similar results, but cautioned that the simulations were not perfect. Researchers pointed out that it was difficult to recreate the airflow generated or affected by multiple health care professionals working in an operating room. They also said that airflow should be one of several factors taken into account in determining what type of heating device to choose for a procedure. Waste heat created convection currents that created turbulence over the patient that could draw damaging particles from below the operating table to the surgical site.
  • 2013: Visualizing Forced-Air Warming
    A 2013 study published in The Bone & Joint Journal found that waste heat from forced-air warming blankets such as the Bair Hugger, “can increase the temperature and concentration of airborne particles” around patients in operating rooms, increasing the chance of infection. Researchers in the study also simulated knee-replacement surgeries. They compared simulations using a forced-air warming blanket, to those using a warming device that did not use forced-air. They found that air "turbulence over the patient" containing 2 million airborne particles per cubic meter in the forced-air simulation. That compared to just 1,000 particles from alternative warming methods. Researchers said their study did not show an increased infection risk. But they said certain types of operating room set-ups “can significantly disrupt” airflow. They warned that this could “draw particles from the potentially contaminated area below the sterile surgical field.”
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Critics say that these studies have flaws that make them inconclusive or unreliable. They say that the studies show no proof that FAW systems increase infection risk. 3M says that no study has ever established any link between Bair Huggers and infection risk.

Redesign, Temperature Problems Trigger Bair Hugger Recall

In January 2018, 3M recalled more than 165,000 Bair Hugger underbody blankets. The recall notice blamed a design change for preventing some devices from fully inflating.

“If blankets are only partially inflated during use in surgery, the potential exists for incomplete warming therapy to be given to a patient,” 3M said in a Field Safety Notice.

The FDA received a report shortly before the recall. It said that one of the blankets failed to fully inflate during surgery. A patient suffered hypothermia. Doctors moved the patient to the intensive care unit until the patient’s body temperature returned to normal.

3M Defends Bair Huggers

Minnesota-based 3M purchased the company that makes Bair Hugger in 2010 for $810 million and has defended its product against claims that the devices can increase infection risks.

Some of the most serious criticism of the devices comes from Bair Hugger’s inventor, Dr. Scott Augustine. Augustine now manufactures a competing device, the Hot Dog, which does not use forced-air warming. He claims his new product is safer than the Bair Hugger he invented in 1987.

In response to Augustine’s claims, multiple studies and increasing numbers of lawsuits, 3M launched a campaign to prove Bair Huggers were safe. 3M said Augustine’s claims are alarmist and based on faulty studies and offers as evidence the results of more than 170 studies and more than 60 randomized clinical trials that show the system’s benefits, efficacy and safety.

In 2016, 3M published a pamphlet entitled Let’s Spread Good Science in which it maintained that an independent review of literature about FAW systems by ECRI Institute, an independent organization, found “insufficient evidence to establish that the use of FAW systems leads to an increase in SSIs (surgical site infections) compared to other warming methods,” and claimed that studies to the contrary used flawed methodologies.

“There is no evidence that forced-air warming increases the risk of infection,” 3M attorney Christiana Jacxsens told Outpatient Surgery Magazine in 2015. “In its entire history, not one hospital, doctor or medical provider has reported a single confirmed incidence of infection believed to be caused by the Bair Hugger device.”

Dr. Javad Parvizi, professor of orthopedic surgery at Thomas Jefferson University’s Rothman Institute, analyzed the evidence presented that FAW increased infections. He said, “There is no scientific proof that the use of forced-air warming blankets leads to an increase in surgical site infection regardless of the type of surgical procedure and the type of operating room.”

FDA 'Actively Monitoring' Bair Hugger Concerns

In August 2017, the U.S. Food and Drug Administration sent a letter to health care providers about FAW devices. The FDA said it was aware that people may avoid the devices due to concerns over possible infection risks. The letter pointed out that warming devices had a successful record. It credited the devices for less bleeding, faster recoveries and decreased infection risk.

The agency said it “continued to recommend” use of FAW devices such as Bair Hugger. The letter said the FDA analyzed data, research and medical guidelines before coming to its decision.

“The FDA will continue to actively monitor this situation and will update this communication if significant new information becomes available,” the letter concluded.

Please seek the advice of a medical professional before making health care decisions.