Safety Concerns Raised Regarding Surgical Warming Blankets

A product designed to prevent hypothermia during and after surgery is currently under scrutiny for potential safety hazards, especially when used for hip and knee implant surgeries. Surgical warming blankets, also known as forced-air warming (FAW) blankets, are used to filter and heat air which is then forced beneath a disposable blanket covering all or part of a patient’s body. The blankets are designed to help maintain body temperature and avoid hypothermia. Bair Hugger, manufactured by 3M and Arizant, is a type of FAW system that has been widely used in orthopedic surgeries since the mid-2000s. Unfortunately, Bair Hugger is the subject of several claims which allege that the product caused contamination in the operating room, reportedly leading to serious post-surgical infections with prolonged consequences.

The primary alleged concern associated with the design of FAW blankets is that they can cause heightened bacteria growth and risk of infection, particularly given the disruption of ventilated airflow in the operating room. Operating rooms have specific airflow controls that are designed to expel airborne pathogens and prevent them from reaching the patient. Ventilated air is pushed down from the ceiling toward the operation site and then outward toward the edges of the room. The air currents then flow back up toward the ceiling where they are again ventilated. This airflow creates a curtain of ventilated air around the operation site that helps prevent contaminated air from reaching the patient. The forced air from these warming blankets has been shown in several studies to disrupt the room’s airflow and therefore risk patient contamination.

Although the warm air being forced under the blanket is ventilated, the warm air escapes from under the blanket and flows toward the floor. Studies have shown that this released air creates turbulence in the operation room’s airflow system, causing the contaminated warm air, or “waste heat”, to flow back toward the patient rather than outward and toward the ceiling. When the waste heat is directed toward the patient, the presence of contaminated particles and increased temperature causes bacteria to accumulate that can cause infection.

The greatest concern for infection is with hip and knee implant and replacement surgeries, which by nature involve a high degree of risk for contamination. Post-surgical bacterial infections can lead to more serious, life-threatening complications, and often result in numerous, even redundant, surgeries and prolonged medical treatment. Orthopedic complications specifically impact the future mobility of patients as well.

Lawsuits against the Bair Hugger FAW systems claim that the manufacturers have failed to warn physicians of the potential harms the blankets can cause and that they misleadingly market the blankets as safe to use during surgeries. Many physicians, and even the original inventor of the Bair Hugger FAW system, have called for a halt in the use of these blankets, at least until further studies have been performed or the alleged defects are remedied. Despite these claims, to date there have been no perceivable efforts to modify the defective design of the blankets or widespread prevention of their use in hospitals.

If you or a family member has questions about a defective product, or negligence in the design or manufacture of a surgical warming blanket or other medical device, contact the law office of Swartz & Swartz, P.C. by email at, or call (617) 742-1900 in the Boston area, or toll-free at 1-800-545-3732 in greater Massachusetts, New England, or other states across the U.S.

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