Judge tosses lawsuits from 5,000-plus plaintiffs against 3M warming blanket

A $2.6 billion market

The Bair Hugger is the dominant device in what Grand View Research estimates is a $2.6 billion market for patient temperature-management systems. It competes with patient-warming systems made by Medtronic PLC, Smiths Medical PLC, Zoll Medical Corp. and others.

Most of the plaintiffs who eventually sued 3M contracted deep-joint infections following hip or knee replacement procedures, often a year or more after the surgery. Unlike with soft-tissue incisions, which require hundreds of thousands of bacteria to trigger a catastrophic infection, the plaintiffs’ experts said a single bacterium on an artificial implant could lead to serious infection over time because the device has no immune system to prevent a bacterial biofilm from forming.

Prosthetic-joint infections happen in 1% to 2% of all hip- and knee-implant cases, and typically the root cause is never identified. They are serious medical events often requiring operations to replace the infected joints. The two-year mortality rate following a prosthetic-joint infection in a hip or knee is estimated between 4% and 8%, depending on patient characteristics, including age.

The multidistrict litigation against 3M featured more than 2,000 legal filings and hundreds of exhibits to support or discredit allegations contained in more than 5,000 individual lawsuits from plaintiffs across the country, whose claims were consolidated in 3M’s home district, the U.S. District Court for Minnesota. In the only federal case that went to trial, a jury digested two weeks of testimony and then took two hours to rule in favor of 3M on all counts.

At the time, the plaintiffs had vowed to press on, arguing that corporate executives had acted in bad faith regarding the Bair Hugger.

But the plaintiffs never presented evidence showing a specific microbial strain was spread by an individual device used in surgery and led to a patient infection. Instead, they relied on methods like advanced computer modeling and observational studies to prove their point.

FDA-approved device

Several medical societies and independent evidence-based reviews have considered the theoretical infection risks from devices like the Bair Hugger over the years, and none has said there is definitive evidence showing the devices pose more risks than benefits. 3M has said observational studies purporting to show infection risks are flawed and biased.

In 2017, the FDA said that after “a thorough review of available data,” the agency could not identify any consistently reported association between the use of forced air thermal regulating systems such as the Bair Hugger and surgical site infection. “Therefore, the FDA continues to recommend the use of thermoregulating devices [including forced air thermal regulating systems] for surgical procedures when clinically warranted,” the agency said.

3M noted that the federal judge’s decision to dismiss the lawsuits comes about six months after the Minnesota Court of Appeals upheld a state court decision to dismiss 61 similar cases from Minnesota plaintiffs. Two similar cases, filed in state courts in Missouri and Texas, are still pending.