Abstract
Background Heater–Cooler units (HCUs) supply tempered water through blood heat exchangers and
through warming/cooling blankets to control the body temperature of heart surgery
patients. Bacteria which potentially colonize the stored water may escape from the
tank into the environment and are carried by the device's cooling air exhaust into
the sterile field and finally may infect open chest heart surgery patients. Reports
from several countries are connecting the infection of open chest heart surgery patients
to airborne transmitted Mycobacteria chimaera which were found in the water of heater–cooler devices. As a consequence of the vigilance
system for medical products, we investigated the potential release and the possible
transmission of bacteria from the tank water into the sterile operating field.
Materials and Methods In the absence of an evaluation standard for this problem, measurable acceptance
criteria for particle releases and a qualitative method for bacteria transmission
assessment have been deployed. To assess potential bacteria transmission into the
sterile field, tank water of the test devices was inoculated with high concentrations
of Pseudomonas aeruginosa (reference strain ATCC15442) and operated in an operating room with simulated use.
Results The particle release at the tank lids of the Maquet/Getinge HCU 30 and HCU 40 during
the filling of the tubes with water (deaeration) and during the removal of water from
the tubes (emptying) increased slightly, but close to the blank readings for the larger
particles. As expected, the particle release at the cooling air grids was higher than
around the tank openings. Consistent with the particle measurements, no bacteria from
the tank water were found in the sterile field during simulated use of all highly
inoculated machines in an operating room.
Conclusion In summary, we assess the risk of infecting open chest heart surgery patients with
aerosol-transmitted bacteria from water inside the Maquet/Getinge HCU 40, HCU 30 to
be negligible, if handled in accordance with common clinical hygienic precautions.
Keywords
infection - perfusion - practice - guidelines - surgery - complications - instruments
