A widely used patient warming system from 3M Co. takes center stage in a federal trial scheduled to begin Monday in Minneapolis that could affect thousands of patients who came down with serious joint infections after surgery.

South Carolina retiree Louis Gareis, 76, says that 3M’s Bair Hugger warming device most likely caused a serious infection in his artificial hip joint by depositing bacteria-laden particles in his surgical wound in 2010. It forced him to have a second surgery two years later to replace the infected implant.

Maplewood-based 3M denies that its device caused Gareis’ injury and argues that no legitimate science shows his theory of the infection is credible.

Expected to last about three weeks, the trial before U.S. District Judge Joan Ericksen has been designated a “bellwether” case, the first of more than 4,000 individual lawsuits pending against 3M to go to a jury.

Bellwether trials are commonly used to test arguments in a small number of cases to help determine whether to litigate, settle or drop other lawsuits with similar allegations. That means the Gareis case may affect the thousands of other pending Bair Hugger cases.

“It’s essentially a test case,” said Russell Jones, chairman of litigation at the Polsinelli law firm, which is not involved in the Bair Hugger dispute. “Certainly it is a judge’s hope that the bellwether will create a path to resolution for some, if not all, of the other cases.”

The Bair Hugger is a Minnesota-invented medical device used in more than 80 percent of U.S. hospitals during surgery to maintain the patient’s normal body temperature before, during and after a surgery.

The system comes in many different models, but in general it includes a disposable “blanket” that looks somewhat like an inflatable float used in pools. The blanket fills up with warm air pumped through a hose from a warming unit that sits on the floor of the operating room.

Maintaining normal body temperature during an operation can reduce bleeding, speed up recovery and cut the risk of post-surgical infections, according to the Food and Drug Administration. Other companies make similar patient-warming devices, including Michigan-based Stryker.

“After a thorough review of available data, the FDA has been unable to identify a consistently reported association between the use of forced air thermal regulating systems and surgical site infection,” the FDA said in an August 2017 safety letter. “The FDA continues to recommend the use of thermoregulating devices (including forced air thermal regulating systems) for surgical procedures when clinically warranted.”

Inventor weighs in

However, the inventor of the Bair Hugger, Dr. Scott Augustine, says the device can cause infections — and he claims he warned 3M of that before the company acquired the device. 3M paid $810 million to acquire the Bair Hugger’s manufacturer, Arizant, in 2010.

The plaintiffs suing 3M, including Gareis, have adopted Augustine’s theory of how the Bair Hugger can move contaminants into orthopedic surgical sites. They say the theory is supported by scientific experiments and the laws of nature.

Hot air rises. Experts hired by the plaintiffs say sophisticated computer modeling proves that Bair Hugger’s warming unit creates excess heat, leading to convection currents in the operating room that are strong enough to lift microscopic particles that contain small pathogens from the floor and into the air around the patient, including directly above the open wound.

And because artificial joints are susceptible to infection, a single bacterium can land on an implant and form a protective “biofilm” that builds into a serious infection over time, plaintiffs’ attorneys have said in court and legal filings.

Augustine is not an official party to the case, but his name is evoked regularly in pretrial motions and exhibits. 3M has said in court filings that the studies offered by plaintiffs that appear to show the infection risks tied to forced-air warming have ties to Augustine, whose new company, Augustine Temperature Management, sells a competing patient-warming device that doesn’t use forced air, called the HotDog.

Gareis initially claimed that 3M sold the Bair Hugger despite knowing of the risks of infection. However, Ericksen ruled last month that the available scientific and medical data would not have alerted a reasonable manufacturer that the Bair Hugger could cause deep-joint infections at the time Gareis had his hip replacements. That decision swept aside a host of allegations accusing 3M of intentionally or negligently causing harm with its device.

Of the 15 allegations against 3M in Gareis’ original suit, Ericksen’s rulings have winnowed the case down to just one: strict liability for the defective design and manufacture of the Bair Hugger. “Strict liability” means a person or entity can be held liable even if they weren’t negligent or didn’t act with intent to harm.

“The jury is going to be able to decide whether there is a design defect that makes the product unreasonably dangerous,” Ericksen said during a May 4 pretrial hearing.