By Gary Evans, AHC Media, Senior Staff Writer
The CDC is alerting hospitals that hundreds of thousands of open-heart surgery patients may be at risk of slow-growing infections caused by heater-cooler devices that were intrinsically contaminated during production.
“New information indicates that these [Stöckert 3T] devices, manufactured by LivaNova PLC (formerly Sorin Group Deutschland GmbH), were likely contaminated … during manufacturing,” the CDC stated in an Oct. 13, 2016 health advisory.1 “Hospitals should advise potentially exposed patients to seek medical care if they are experiencing symptoms such as night sweats, muscle aches, unexplained weight loss, fatigue, or unexplained fever.”
The patients may have been exposed to Nontuberculous Mycobacterium chimaera (NTM), a rarely pathogenic bacteria that is capable of causing life-threatening infections in this particular situation. Hospitals should “consider” notifying patients in writing about the risk going as far back as 2012, the CDC recommended. (See Q&A on notifying patients, in this issue.)
“Almost a quarter of a million patients a year are undergoing surgeries that require use of this [heater-cooler] device,” says Joseph Perz, PhD, an epidemiologist in the CDC’s Division of Healthcare Quality Promotion. “The information we have seen is that Soren units account for about 60% of [U.S.] market share. This device has been on the market for a number of years so it is a large number of patients.”
An advisory by the FDA issued the same day says, “The 3T devices manufactured at this facility were distributed worldwide. In response to the M. chimaera findings in August 2014, the manufacturer added cleaning and disinfection procedures to the production line in September 2014. Samples taken at the same manufacturing facility, by the German regulatory authorities in July 2015, did not show M. chimaera, potentially indicating the contamination at the manufacturing facility had been resolved.”
Risk Hard to Rule Out
However, the FDA is aware of some 3T devices manufactured after September 2014 which have tested positive for M. chimaera. “It has not been confirmed whether these devices were contaminated at the manufacturing facility or became contaminated at the user facility,” the FDA states. “To date, the FDA is not aware of M. chimaera patient infections associated with 3T devices that were manufactured after September 2014.”
Thus, infection preventionists should not consider the risk eliminated even if the devices were purchased after 2014.
“A question that we are getting is does it make a difference if you acquired a new machine after the end of 2014,” Perz says. “The FDA has used that [date of demarcation] to help facilities to prioritize which machines to keep in service, but again there is not enough evidence to say that the risk is eliminated after that date.”
As previously reported in Hospital Infection Control & Prevention, heater-cooler devices are used during cardiac surgical procedures to warm and cool a patient’s blood during cardiopulmonary bypass. The units have a closed-circuit system to circulate water, but can create an aerosol that is vented into the immediate environs by an exhaust fan. The NTM collects in water and biofilms, from where it can be aerosolized over the operating field and the open chest of the patient.
The clinical and infection prevention issues are daunting. The infections may take months to years to emerge, meaning cases are likely to be missed unless an astute clinician traces infection back to heart surgery. Moreover, the NTM infections may be antibiotic resistant and the devices can be difficult to disinfect and continue using with confidence that a patient will not be exposed. The threat has been underscored by outbreaks in Europe and last year in Pennsylvania and Iowa. The CDC reports 29 confirmed cases in the U.S., but given the litany of problems identifying cases there are probably more cases that have gone undetected.
The CDC estimates that in hospitals where at least one infection has been identified, the risk of infection was between about 1 in 100 and 1 in 1,000 patients. Patients who have had a prosthetic device or material implanted appear to be a higher risk of NTM infections. Patients with NTM infections following cardiac surgery may present with a variety of clinical conditions including endocarditis, surgical site infection, hepatitis, and kidney problems, the CDC reports. The CDC recommends that hospitals performing open-chest cardiac surgery should immediately assess their use of heater-cooler devices and determine whether they are currently using -- or have previously used -- 3T devices. Facilities should ensure that they are implementing current FDA recommendations to minimize patient risk to infections associated with heater-cooler devices.
Informed consent is on the table, as the CDC stresses that it is “imperative” that patients and providers are apprised of the risk of infection.
“Informed consent is something we are asking hospitals to consider going forward,” Perz says. “There is also some information that having a prosthetic device implanted as part of the surgery may increase the risk. That is something that can be discussed with patients. When you think about managing the retrospective risk, we are not in favor of only limiting patient communication to those who had the 3T exposure and an implant. We don’t think there is enough information there. Our advice is unless you have completely removed that exhaust consider notifying a broader [number of] patients.”
Hospitals should notify cardiothoracic surgeons, cardiologists, infectious disease physicians and other clinicians about the risk of infection associated with 3T heater-cooler devices. In addition, hospitals should review their facility’s microbiology laboratory database and records of surgical procedures for any positive NTM cultures in surgery patients that might indicate a possible case, the CDC recommends.
It should be noted that risk of infection is relatively low and cardiac procedures can be lifesaving so there is no recommendation at this time to pull the plug on all heater-cooler devices. However, continued use of the devices should be done according to the latest manufacturer’s recommendations, including maintenance and proper positioning of devices to minimize the risk of patient exposure, the CDC advises.
For its part, the FDA recommends that facilities that use the 3T devices “should immediately remove from service any heater-cooler devices, accessories, tubing, and connectors that have tested positive for M. chimaera or have been associated with known M. chimaera patient infections at your facility.”
Hospitals using 3T devices manufactured prior to September 2014, should “strongly consider transitioning away from the use of these devices for open-chest cardiac surgery until the manufacturer has implemented strategies for these devices to mitigate the risks of patient infection. Use of these devices should be limited to emergency and/or life-threatening situations if no other heater cooler devices are available,” the FDA recommends.
“We are looking at both short- and long-term solutions,” Perz says. “Longer-term solutions include making sure that other models on the market are in fact safe and can they be made safer? Are there ways to mitigate the effect specifically around the Soren 3T? I think we are all waiting eagerly for more clear guidance on that.”
“CDC is asking hospitals to formulate plans to reach patients directly,” Perz says. “Patient communication is really important but I would say equally important is communicating with medical providers, to make sure this risk is on their differential. They understand when evaluating a patient to be thinking about open heart surgery as an exposure and to take the right steps. Because the diagnosis is not straightforward -- even if it is on your mind you have to make sure that you are ordering the right tests and so on.”
Similarly, finding the units difficult or impossible to safely decontaminate, hospitals in the Netherlands and some in the U.S. have physically removed the heating-cooling units from the OR, running the tubing to the patient through a wall that prevents aerosolization from the device fan to enter the sterile field. That’s what the University of Iowa did after identifying three patients with M. chimaera infections.
“We wanted to be able to tell our patients that we eliminated this risk, and we felt the only way to do that was to remove heater-cooler devices from our operating rooms,” Daniel Diekema, MD, chief of infectious diseases at the University of Iowa, noted at an FDA meeting earlier this year. “Our OR air, like in many institutions, I assume, is continuously monitored for positive pressure and air exchanges, and we confirmed that even with a heater-cooler unit running with this portal open to accommodate the tubing, it did not impact the airflow and the positive pressure in our operating rooms. We have had no complaints from our perfusionists about this. They have been pleased with the solution. I readily admit and understand that the OR layout in many institutions does not allow for this to be done as easily as we were able to do it.”
Better engineering solutions are needed long-term, he says.
“We know now that we have a bioaerosol generator that’s in a critical area of the hospital. It’s unacceptable, and we have to figure out an engineering solution for that, whether it involves filtration, whether it involves UV, whether it involves a careful evaluation of the differences in design … I think all of these things need to be considered as a more permanent engineering solution is designed.”
While the solution seems to be working for Iowa, the CDC does not have the data to recommend widespread adoption of this method of mitigating the problem, Perz says.
“Device management really falls primarily to the FDA,” he says. “So while we have a role as far as facilitating discussion and helping identify options CDC can’t make a blanket recommendation for hospitals to move [the devices] out of the room. There can be unintended consequences. For facilities like the University of Iowa to talk about this publicly -- that they have been able to manage it -- that is a good thing. You basically have removed the potential exposure for your patient population. There may be other ways of capturing that exhaust and we hope to get more concrete advice on that.”
Clinicians should also be aware that periodic testing of heater-cooler devices to identify units contaminated with M. chimaera is not recommended at this time because the results can be confounded by sample collection challenges, a long culture time, and a high rate of false-negative tests, the FDA advises.
Similarly, if M. chimaera infections develop they can be difficult to detect and to treat. Chuck Daley, MD, Chief of the Division of Mycobacterial and Respiratory Infections at National Jewish Health in Denver, CO, outlined the troubling aspects of the cases at the FDA meeting on June 3, 2016.
“This delay [in infection onset] that we keep hearing about is remarkable, with a time to presentation being a median of 21 months,” he says. “This is not something that clinicians know about. We have to educate them and make them understand that this syndrome actually exists. The other thing that they’re not expecting to see are infections of the prosthetic valves due to a mycobacteria or vascular graft infections. … If we have delays in diagnosis, that means delays in therapy. Delays in therapy mean worse treatment outcomes.”
Adding another level of difficulty, the NTM can be resistant to the macrolide antibiotics that may be used for such infections, Daley says. Moreover, trying to head off the problem by giving prophylactic regimens of macrolides before a procedure may select out drug-resistant bacteria. “When I hear discussion about prophylactic regimens and giving macrolides -- well, if you do that and it fails and the patient now has macrolide resistance. You have doomed the patient,” Daley says. “So I’m very concerned about this idea of preventive therapy. … The bottom line is that I think that if we cannot find earlier diagnosis, basically earlier case finding, we do not have much hope in curing many of these patients. If we found them earlier, perhaps we could intervene and do surgery again, remove the infected graft. But at the time that they’re being found, they’re often so sick it is very difficult to do that.”
- CDC. Health Alert Network. CDC Advises Hospitals to Alert Patients at Risk from Contaminated Heater-Cooler Devices Used during Cardiac Surgery. Oct. 13, 2016. https://emergency.cdc.gov/han/han00397.asp