Figure 2. Video image captures showing effect of heater–cooler unit orientation on smoke dispersal in a cardiac surgery room and transmission of Mycobacterium chimaera during cardiac surgery despite an ultraclean air ventilation system. The device was switched on and began to ventilate 10 s after the start of the video. Frames on the left show an overview including unit placement. Frames on the right provide a lateral view of the operating field under the laminar airflow. Simultaneously recorded videos in the upper 2 frames show the first scenario, in which the main ventilation exhaust was directed away from the operating field. Simultaneously recorded videos in the lower 2 frames show the second scenario, in which the main ventilation exhaust was directed toward the operating field.