Heater-Cooler Infections: Incidence Most Likely Underreported

HOUSTON -- While the LiveNova/Sorin 3T heater-cooler device for heart surgery has gotten the lion's share of attention over Mycobacterium chimaera infections, every similar device on the market has contamination reported and most have infected patients, researchers reported from FDA data.

Based on all 339 reports to the FDA Medical Device Report database through August 2016, 89% of reports of device contamination or patient infection have involved the Sorin 3T device, Keith Allen, MD, of St. Luke's Hospital in Kansas City, reported at the Society of Thoracic Surgeons meeting. This device accounts for 60% of U.S. market share.

However, all five manufacturers' heater-cooler units commercially available worldwide have had reports of contamination sent to the FDA through the mandatory or voluntary reporting. Four of the five have had patient infections reported; three have had associated deaths.

"We've only begun to scratch the surface, even though it has been going on for 2 years," Allen noted at the special session that opened the scientific program of the meeting. And given the long latency with no screening possible or true surveillance, "the incidence is likely underreported."

The problem first emerged in 2015 with case reports from Europe that were traced back to heater-cooler use, and the FDA sent out a safety alert that year warning of the risk across all heater-cooler devices.

Genetic analysis confirmed that many of the cases originated from source contamination at the Sorin 3T manufacturing plant. Allen noted that Sorin used to test the devices with water at the plant and ship them wet to hospitals around the world.

That's why perhaps the very first cardiothoracic surgery patient treated using a heater-cooler device obtained 3 weeks prior at Pennsylvania's York Hospital -- "ground zero" for M. chimaera heater-cooler infections in the U.S., according to panelist Larry Shears, MD, chief of cardiothoracic surgery there -- was found to be infected 3 years later.

These nontuberculous mycobacteria (ubiquitous in the environment and particularly endemic to plumbing) are slow growing, so patients may not present with problems for up to 5 years after surgery in which they are infected.

But while the Sorin manufacturing plant contamination led to an outbreak that brought these infections to light, Allen noted that the bacteria are everywhere and very hard to decontaminate from any device once a biofilm is formed. "There really is a device class effect that makes all susceptible to both contamination and aerosolization of [nontuberculous mycobacteria]."

"I believe you will see this problem crop up with any device, not just any heater-cooler, but any warming or cooling device that's water based, any potential airflow device that creates condensation," he concluded. "These all have potential for contamination."

"Whereas all devices have been implicated, I do think Sorin is different," said Neil Fishman, MD, an infectious diseases specialist at the University of Pennsylvania in Philadelphia and a past-president of the Society for Healthcare Epidemiology of America. Speaking at the session, he pointed to the large fan on the Sorin 3T compared with one the size of a computer fan on most of the other heater-cooler devices.

Panelist Miguel Sousa Uva, MD, PhD, president of the European Association for Cardio-Thoracic Surgery, also noted one study in which water was contaminated in 77% of Sorin devices and 15% of Maquet devices.

The problem is that contaminated water turns into aerosol released from any small defect and gap, not just through the fan exhaust, he noted.

The longer patients are exposed, the higher the risk, though, noted Fishman. Data presented to FDA showed more than 16-fold risk for patients on cardiopulmonary bypass pump for more than 2 hours and with a total length of heater-cooler exposure of more than 5 hours (counting time when the device was turned on in the room with the patient, even if not actively used).

Treatment requires multiple agents to treat and even then is not very effective, with overall mortality greater than 50% that is attributed to late diagnosis, Fishman added.

Part of the late-diagnosis problem has been that these patients present to their primary care physician long after the surgery, which makes the CDC's recommendation of notifying not just potentially affected patients but also physicians in the area key, Shears noted.

All the panelists agreed on the need to also immediately involve legal counsel in incorporating the risk of these infections into informed consent for cardiothoracic surgery for which the machines will be needed.

"Twelve patients have already filed lawsuits against the facility. None of those 12 patients actually have disease. The lawyers are extremely aggressive. You're going to be dealing with this the same way as MI," Shears said regarding his center.

One protection for centers and operators will be creating competency maintained in records, including documentation of cleaning the device according to the manufacturers' recommendations and of the serial number of the heater-cooler unit used in each surgery, noted panelist Kenneth Shann, CCP, director of perfusion services at Massachusetts General Hospital in Boston and president of the American Society of Extracorporeal Technology.

Comment