The Heater Cooler Conundrum: Has the Sky Fallen?

“If anyone has a chart or list/table that compares all of the current Heater Coolers, that would go a long way to helping institutions make informed choices as to selecting systems that have the smallest potential footprint regarding impact on laminar flow in the OR, as well as the least amount of potential pt. exposure to these pathogens.”

Editor’s Note:

I’m sure all of us are equally concerned regarding the surge of FDA reports and studies discussing the dissemination of mycobacterium chimaera, a slow-growing mycobacteria, that is aerosolized by Heater-Coolers during the conduct of open heart surgery and cardiopulmonary bypass.

While one or two manufacturers have been identified regarding their particular Heater Coolers, the jury is still not out as to the across-the-board implications for the other models out there.

Some institutional adjustments have gone as far as to extend the water lines and placing the HC outside of the OR suite, with another clinician operating the device controls. The theoretical 5 meter barrier limit (length of water lines)? Is it an issue? And how are institutions or perfusionists bypassing (no pun) it?

If anyone has a chart or list/table that compares all of the current Heater Coolers, that would go a long way to helping institutions make informed choices as to selecting systems that have the smallest potential footprint regarding impact on laminar flow in the OR, as well as the least amount of potential pt. exposure to these pathogens.

Plz feel free to render advice on how you are dealing with these issues, and share your ideas or suggestions on how to mitigate the impact.

Thanks 🙂

Frank

What exactly is going on here?

Click image above to view source article

Heater-cooler design:
The designs of most heater-cooler devices are similar since they contain between one and three large tanks filled with water that are either heated or cooled for delivery to the device’s heat exchanger(s) or to blankets. While the heater-cooler device is running, the water in these tanks is agitated during normal circulation through the circuits.Some heater-cooler devices contain air filters and water filters; others do not. Water filters (0.2 micron) should be able to remove most NTM from tap water that is used in filling/refilling, topping off, rinsing, making ice and cleaning the heater cooler units. Air filters located on some units are not efficient enough to capture NTM bacteria. An air filter that has the capability to capture NTM bacteria may alter device safety or performance and would therefore need to be evaluated by each manufacturer as a possible mitigation technique before implementation.Fans are found on most units and are usually used to cool the unit and/or aid in the cooling efficiency of a compressor. These fans may facilitate the movement of aerosolized NTM from the inside of the unit into the operating room, and possibly into the sterile surgical field.

Laminar flow disruption:
Laminar air flow refers to an engineering control within the operating room environment that intends to provide protection by reducing the risk of airborne exposure to bacteria or other contamination during surgery. One study, utilizing a single heater-cooler unit, suggests that the device’s exhaust fan, depending on the distance and direction of the exhaust, may disrupt the protective nature of the laminar air flow above the patient. The authors of this study hypothesized that NTM that is airborne may then be carried into the surgical field.

Getting to the True Scope of the Issue

Kudos to the Authors as well as Specialty Care– for writing and sponsoring this excellent article! The full article is in PDF format, can be viewed and downloaded by clicking HERE.

Reality Check

Impact and Notes: (Not to diminish the seriousness of the situation, but rather to put it into a rational perspective.)

Nosocomial infections are a recognized risk in any operating room theater.
These organisms in a lot of places in the operating room as well your home environment- HVAC systems (Heating and Cooling)
Absolutely countless patients as well as clinicians are and have been exposed to these organisms since inception of not only open heart bypass, but the myriad of other operations that require similar devices etc-
Excessive device cleaning, does not necessarily eliminate the microorganism.
Class action law suits and litigation are far more opportunistic and beginning to pop up.

Background: Non-Tuberculous Mycobacteria (NTM)

Common water-borne environmental contaminant
FDA has recognized that “NTM organisms are widespread in nature and
can be found in soil and water, including tap water sources. They are
typically not harmful, but in rare cases may cause infections in very ill
patients and/or in individuals with compromised immune systems.”
NTM presence can result in post-surgical infection only if directly
transmitted to the patient
Rare transmission by aerosolization only recently appreciated
NTM post-surgical infection appears to be exceedingly uncommon.
- For example, in an October 2015 publication, Public Health England stated:
  “This new risk is extremely small. Approximately 1 in 10,000 patients having this type of surgery might be affected. This level of risk is so small that surgery
  should not be delayed, as the risks of delaying surgery are greater than proceeding.”
- “This risk identified above is extremely small compared to the background risk of infection recognized following this type of surgery.”

FDA Recommendations:

Recommendations for Health Care Facilities and Staff
In addition to following standard precautions, the FDA recommends that facilities and staff using heater-cooler devices consider implementing the following measures to reduce risk to patients:

Strictly adhere to the cleaning and disinfection instructions provided in the manufacturer’s device labeling. Ensure you have the most current version of the manufacturers’ instructions for use readily available to promote adherence.
Do not use tap water to rinse, fill, refill or top-off water tanks since this may introduce NTM organisms. Use only sterile water or water that has been passed through a filter of less than or equal to 0.22 microns. When making ice needed for patient cooling during surgical procedures use only sterile water or water that has been passed through a filter of less than or equal to 0.22 microns. Deionized water and sterile water created through reverse osmosis is not recommended because it may promote corrosion of the metal components of the system.
Direct the heater-cooler’s vent exhaust away from the surgical field to mitigate the risk of aerosolizing heater-cooler tank water into the sterile field and exposing the patient.
Establish regular cleaning, disinfection and maintenance schedules for heater-cooler devices according to the manufacturers’ instructions to minimize the risk of bacterial growth and subsequent patient infection.
Develop and follow a comprehensive quality control program for maintenance, cleaning, and disinfection of heater-cooler devices. Your program may include written procedures for monitoring adherence to the program and documenting set up, cleaning, and disinfection processes before and after use.
Immediately remove from service heater-cooler devices that show discoloration or cloudiness in the fluid lines/circuits, which may indicate bacterial growth. Consult your hospital infection control officials to perform the appropriate follow up measures and report events of device contamination to the manufacturer.
Consider performing environmental, air, and water sampling and monitoring if heater-cooler contamination is suspected. Environmental monitoring requires specialized expertise and equipment to collect and process samples, which may not be feasible in all facilities.
Health care facilities should follow their internal procedures for notifying and culturing patients if they suspect infection associated with heater-cooler devices.
Submit a report to the manufacturer and to the FDA via MedWatch if you suspect heater-cooler devices have led to patient infections.