21 - Cardiac heater coolers

Abstract

The microbial risks of using medical equipment aren’t always transparent. Following years of using cardiac heater coolers for heart bypass surgery, a number of clinicians in Switzerland identified that there was a link between infections postsurgery and the heater coolers being in the operating theater. The heater coolers contain tanks of water that are used to regulate the temperature of the patient during surgery. As the heater cooler was being used, the water was agitated and small gaps that had appeared in the otherwise sealed tanks resulted in bacteria being dispersed across the operating theater and infecting the patients during heart bypass operations. Very few people would have made the link between the infections and the heater coolers, particularly 2years postsurgery. Yet the team in Switzerland managed to put together the pieces of the jigsaw. Mycobacteria chimaera, a nontuberculous mycobacteria, is a slow-growing organism that was able to survive in the water tank biofilms, was dispersed as an aerosol, and grew in the patient so slowly, often with 2years passing before the intention was apparent. While the manufacturers were quick to point out that the hospitals were not following the disinfection guidelines, it became apparent, through molecular diagnosis, that the exact same strain that was causing the infection was to be found in the manufacturer’s production plant. However, hospitals must continue to microbiologically assess the water in their heater coolers and to follow the manufacturer’s disinfection regimens to ensure that the heater coolers do not represent a microbiological risk to patients.