Surgical site infection (SSI) in the form of postoperative deep sternal wound infection (DSWI) after cardiac surgery is a rare, but potentially fatal, complication. In addressing this, the focus is on preventive measures, as most risk factors for SSI are not controllable. Therefore, operating rooms are equipped with heating, ventilation and air conditioning (HVAC) systems to prevent airborne contamination of the wound, either through turbulent mixed air flow (TMA) or unidirectional air flow (UDAF). To investigate if the risk for SSI after cardiac surgery was decreased after changing from TMA to UDAF. This observational retrospective single-centre cohort study collected data from 1288 patients who underwent open heart surgery over 2 years. During the two study periods, institutional SSI preventive measures remained the same, with the exception of the type of HVAC system that was used. Using multi-variable logistic regression analysis that considered confounding factors (diabetes, obesity, duration of surgery, and re-operation), the hypothesis that TMA is an independent risk factor for SSI was rejected (odds ratio 0.9, 95% confidence interval 0.4–1.8; >0.05). It was not possible to demonstrate the preventive effect of UDAF on the incidence of SSI in patients undergoing open heart surgery when compared with TMA. Based on these results, the use of UDAF in open heart surgery should be weighed against its low cost-effectiveness and negative environmental impact due to high electricity consumption. Reducing energy overuse by utilizing TMA for cardiac surgery can diminish the carbon footprint of operating rooms, and their contribution to climate-related health hazards.

中文翻译：

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单向气流通气对心脏手术手术部位感染的影响：环境影响是选择湍流混合气流的一个因素


心脏手术后以术后深部胸骨伤口感染 (DSWI) 形式出现的手术部位感染 (SSI) 是一种罕见但可能致命的并发症。在解决这个问题时，重点是预防措施，因为 SSI 的大多数风险因素都是不可控的。因此，手术室配备了供暖、通风和空调 (HVAC) 系统，以防止通过湍流混合气流 (TMA) 或单向气流 (UDAF) 对伤口造成空气污染。调查从 TMA 改为 UDAF 后心脏手术后 SSI 的风险是否降低。这项观察性回顾性单中心队列研究收集了 1288 名接受心脏直视手术超过 2 年的患者的数据。在两个研究期间，机构 SSI 预防措施保持不变，但所使用的 HVAC 系统类型不同。使用考虑了混杂因素（糖尿病、肥胖、手术持续时间和再次手术）的多变量逻辑回归分析，拒绝了 TMA 是 SSI 独立危险因素的假设（比值比 0.9，95% 置信区间 0.4– 1.8；>0.05)。与 TMA 相比，无法证明 UDAF 对接受心脏直视手术的患者 SSI 发生率具有预防作用。根据这些结果，在心脏直视手术中使用 UDAF 时，应权衡其成本效益低以及高耗电量对环境造成的负面影响。通过利用 TMA 进行心脏手术来减少能源过度使用，可以减少手术室的碳足迹及其对气候相关健康危害的影响。