Anesthesia administered during surgery causes the body’s core temperature to drop, resulting in hypothermia or a low body temperature. A patient’s temperature might drop as much as 5-7 degrees Celsius, according to research by Duke University School of Medicine. This significant drop in your temperature while undergoing surgery may cause you to feel cold and shiver when you begin to wake up after the procedure. A rewarming period is necessary to regain homeostasis and improve post-surgical outcomes. If a patient’s body temperature is not restored properly, both post-op bleeding and recovery time can increase.

In the late 1980s, 3M created the Bair Hugger Normothermia System, providing a range of patient warming products, including warming blankets, warming gowns, and a non-invasive temperature monitoring system. Normothermia is the body’s normal core temperature, usually between 36 and 38 degrees Celsius. Keeping the body regulated to this status quo during surgery can lower the risk for surgical complications.

The warming blanket draped over surgical patients pre-, during, or post-procedure, has a heater accompanying it that draws in air from the operation room, heats it, and then blows it through the blanket onto the patient’s exposed skin. Without the use of warming products, data collected by one thermal management technologies company showed that 30% to 40% of patients are hypothermic once they reach post-operative status and they’re recovering from the anesthesia.

As a result, Bair Hugger surgical warming blankets became very popular across the U.S., used in nearly 90% of all major surgeries. More than 50,000 Bair Hugger units are currently in use across the country, and more than 300 million surgical patients have been warmed by 3M’s Bair Hugger Normothermia System, per the company’s website. The Bair Hugger warming products can be used with both adult and pediatric patients.

Bair Hugger surgical warming blankets may have very well helped to improve surgical outcomes and even saved some patients’ lives. But the use of these blankets can also potentially cause injuries due to their faulty design and operation.

Operating rooms use Laminar Air Flow Systems to keep filtered air continuously circulating throughout the surgical space. These air flow systems help prevent airborne contaminants from finding their way into an incision, thereby reducing the risk of infection. The Bair Hugger system has the potential to disrupt this air system by allowing some of the warm air emitted from the portable heating machine to cycle below the operating table where it can collect bacteria.

According to thousands of lawsuits, the hot air distributed into the blanket by the Bair Hugger heating device can possibly escape from under the surgical drape below or at the head end of the surgical table. This air then creates airflow currents that flow against the downward airflow of the operating room, according to one lawsuit. The lawsuit goes on to explain that as the escaped warm air rises, “it deposits bacteria from the floor of the surgical room into the surgical site.”

Another way in which the Bair Hugger systems can cause injury is if the devices are not properly sanitized or maintained. If a device is internally contaminated, the bacteria trapped within the device can migrate to the surgical site as the air is circulated through the machine.

Patients most susceptible to these injuries are those with diabetes or immune deficiencies that make healing more challenging. If antibiotics and additional surgeries aren’t effective, your doctor might suggest revision surgeries, joint fusion, or amputation to eradicate the infection. These treatment options can be costly, disfiguring, have long recovery times, and cause extreme emotional and physical pain and suffering.

Nearly 6,000 people have sued 3M over alleged defects present in its Bair Hugger forced air warming devices. These individuals assert they suffered serious infections, sometimes requiring additional surgeries or even amputations. Manufacturers named in the lawsuits include 3M and its former nomenclature Arizant Healthcare. The harmed plaintiffs claim that defendants knew or should have known about the potential risks and failed to intervene to fix the problem or adequately warn consumers. Additionally, they claim that misrepresentations made by the company served to mislead health care providers about the supposed safety of Bair Hugger devices used in surgical procedures.

In one lawsuit, the plaintiff states that some time between 2002 and 2009, the defendants reduced the efficiency of the air filtration of Bair Hugger blowers. This design decision also reduced the device’s safety by contaminating the internal airflow paths of the blowers with pathogens and putting patients at increased risk of infection, according to the lawsuit. The allegations continue, asserting that the defendants became aware of the problem some time around 2009. Since 1987, the FDA has issued at least 14 additional clearances for changes or new versions of the devices.

Since 2013, the U.S. Food and Drug Administration (FDA) has received hundreds of adverse event reports relating to the Bair Hugger system. In 2017, the FDA became aware of infection concerns, but recommended that health care providers continue to use Bair Hair surgical warming blankets or forced air warming or thermal regulating systems “when clinically warranted.” The federal agency stated in a letter dated August 30, 2017, that after a “thorough review of available data” it was “unable to identify a consistently reported association between the use of forced air thermal regulating systems and surgical site infection.”

In 2018, 3M recalled 165,000 Bair Hugger warming blankets due to a design defect. Some blankets failed to fully inflate after the company redesigned the system’s underbody blankets. The manufacturer warned that partial inflation could prevent proper warming. One report to the FDA claimed that a patient suffered hypothermia during surgery due to the blanket failing to fully inflate. However, no recalls have been issued by 3M due to reported infections.

3M continues to advertise its Bair Hugger surgical warming blankets as safe and effective in all surgeries. The manufacturer contends that 170 studies have found forced-air warming to be safe. Meanwhile, the inventor of Bair Hugger products, Dr. Scott Augustine, has urged 3M to recall the devices after claiming those studies are misleading.

An Eighth Circuit Court ruling issued in August 2021, finds 3M once again facing thousands of lawsuits by injured surgical patients. These lawsuits were reinstated by the appeals court after the multidistrict litigation was dismissed in 2019. The U.S. Court of Appeals for the Eighth Circuit said that testimony from the plaintiffs’ experts was wrongly barred as unreliable. 

3M will now have to defend against the many plaintiffs alleging they developed infections from the Bair Hugger devices used during joint replacement surgeries. These harmed individuals allege the forced-air system caused infections in the affected joints, resulting in significant damages.