Heater-cooler devices are often necessary for use during surgeries to warm or cool patients as part of their care. They are especially important tools for surgeries involving the heart and lungs (cardiothoracic surgeries). Heater-cooler devices, as shown below in Figure 1¹, include tanks that provide temperature-controlled water to external heat exchangers or to warming/cooling blankets through closed water circuits.

Figure 1: Schematic representation of heater–cooler circuits tested for transmission of Mycobacterium chimaera during cardiac surgery despite an ultraclean air ventilation system. Blue arrows indicate cold water flow, and red arrows indicate hot water flow and patient blood flow.

As indicated above in Figure 1, the:

• Blue arrows identify the cardioplegia circuit and show cardioplegia solution entering the “heart lung machine.” Cardioplegia is used to stop the heart during surgery.
• Rectangles with zigzag lines are heat exchange coils. They separate heater-cooler fluid flow from patient fluid or blood flow.
• Red arrows identify the patient blood circuit and show hot water flow and patient blood flow.

Additionally, the water in the heater-cooler device is isolated from the patient, cardioplegia solution and blood circuits.

Heater-cooler devices are Class II devices that can be cleared under one of the following cardiovascular classification regulations:

• 870.4250 Cardiopulmonary Bypass (CPB) Temperature Controller
• 870.5900 Thermal Regulating System

The CPB Temperature Controller is intended to supply temperature-controlled water to heat exchangers associated with devices (for example, blood oxygenators) intended to keep circulating blood and organs at a specific temperature best suited to the type of surgery being performed. Thermal Regulating Systems are generally cleared for use with warming/cooling blankets. Although heater-cooler devices fall under the cardiovascular classification regulations, they may be used during a variety of medical procedures.

These web pages:

• Contain information and resources for patients
• Clarify the FDA’s recommendations to health care providers and staff at health care facilities to help minimize patient risks of infections associated with all heater-cooler devices
• Include resources² that may help in assessing and mitigating risks to patients.

¹ Sommerstein R, Rüegg C, Kohler P, Bloemberg G, Kuster SP, Sax H. Transmission of Mycobacterium chimaera from Heater–Cooler Units during Cardiac Surgery despite an Ultraclean Air Ventilation System. Emerg Infect Dis. 2016 June;22(6):1008-13. http://wwwnc.cdc.gov/eid/article/22/6/16-0045_article

² Weeks, J. W., Segars, K., & Guha, S. (2020). The Research Gap in Non-tuberculous Mycobacterium (NTM) and Reusable Medical Devices. Frontiers in public health, 8, 399. https://doi.org/10.3389/fpubh.2020.00399