Background Heater–cooler devices (HCD) have been implicated in a cardiosurgical contamination scenario causing prosthetic valve endocarditis.

Aim We characterized contamination of new HCDs and assessed the risk of intraoperative microorganism transmission from the HCD to the operating field.

Methods We initially acquired four new FlexTherm and then four new Maquet HCU40 HCDs and assessed occurrence and speed of microbial contamination (including mycobacteria) assessing swab and water samples from the device. In parallel, we collected repeated samples from different sites in the operating room either by swab sticks or by exposing different sample plates to room air. We also reviewed microbiological results from the hospital and compared them to cardiosurgical wound infections and endocarditis cases. Finally, we simulated cardiosurgical conditions and assessed the devices' ability to expel air to the operative field.

Results All new HCDs were clean before first use. Despite authority-mandated decontamination procedures, microbial growth (Fusarium solani, Sphingomonas paucimobilis, Pseudomonas aeruginosa, Mycobacterium chelonae, and gordonae) was identified in all HCDs over time and could not be permanently eliminated. Four of these mircoorganisms were also found in tap water. However, none of the HCD-organisms were found inside the laminar airflow operating area. Importantly, except for P. aeruginosa, none of the HCD organisms were found in patients with surgical wound infections or endocarditis. HCD-expelled air did not rise more than 40 cm above ground.

Conclusion HCDs cannot be expected to remain sterile despite extensive decontamination procedures. However, airborne transmission of microorganisms directly from the HCD to the operating field appears unlikely.

背景 加热器-冷却器装置 (HCD) 与导致人工瓣膜心内膜炎的心脏手术污染情况有关。

目的 我们对新 HCD 的污染进行了表征，并评估了术中微生物从 HCD 传播到手术区域的风险。

方法 我们最初购买了四个新的 FlexTherm，然后购买了四个新的 Maquet HCU40 HCD，并评估了微生物污染（包括分枝杆菌）的发生和速度，评估了设备中的拭子和水样。同时，我们通过拭子棒或将不同的样品板暴露在室内空气中，从手术室的不同地点收集重复样本。我们还回顾了医院的微生物学结果，并将其与心脏外科伤口感染和心内膜炎病例进行了比较。最后，我们模拟了心脏手术条件并评估了设备将空气排出到手术区域的能力。

结果 所有新的 HCD 在首次使用前都是干净的。尽管有权威规定的去污程序，但随着时间的推移，在所有 HCD 中都发现了微生物生长（茄病镰刀菌、少动鞘氨醇单胞菌、铜绿假单胞菌、龟分枝杆菌和戈登氏菌），并且无法永久消除。在自来水中也发现了其中四种微生物。然而，在层流操作区域内没有发现任何 HCD 微生物。重要的是，除铜绿假单胞菌外，在手术伤口感染或心内膜炎患者中均未发现任何 HCD 微生物。HCD 排出的空气没有上升超过地面 40 厘米。

结论 尽管进行了广泛的去污程序，但不能期望 HCD 保持无菌状态。然而，微生物直接从 HCD 到手术区域的空气传播似乎不太可能。