BACKGROUND Health care itself contributes to climate change. Anesthesia is a "carbon hotspot," yet few data exist to compare anesthetic choices. The authors examined the carbon dioxide equivalent emissions associated with general anesthesia, spinal anesthesia, and combined (general and spinal anesthesia) during a total knee replacement. METHODS A prospective life cycle assessment of 10 patients in each of three groups undergoing knee replacements was conducted in Melbourne, Australia. The authors collected input data for anesthetic items, gases, and drugs, and electricity for patient warming and anesthetic machine. Sevoflurane or propofol was used for general anesthesia. Life cycle assessment software was used to convert inputs to their carbon footprint (in kilogram carbon dioxide equivalent emissions), with modeled international comparisons. RESULTS Twenty-nine patients were studied. The carbon dioxide equivalent emissions for general anesthesia were an average 14.9 (95% CI, 9.7 to 22.5) kg carbon dioxide equivalent emissions; spinal anesthesia, 16.9 (95% CI, 13.2 to 20.5) kg carbon dioxide equivalent; and for combined anesthesia, 18.5 (95% CI, 12.5 to 27.3) kg carbon dioxide equivalent. Major sources of carbon dioxide equivalent emissions across all approaches were as follows: electricity for the patient air warmer (average at least 2.5 kg carbon dioxide equivalent [20% total]), single-use items, 3.6 (general anesthesia), 3.4 (spinal), and 4.3 (combined) kg carbon dioxide equivalent emissions, respectively (approximately 25% total). For the general anesthesia and combined groups, sevoflurane contributed an average 4.7 kg carbon dioxide equivalent (35% total) and 3.1 kg carbon dioxide equivalent (19%), respectively. For spinal and combined, washing and sterilizing reusable items contributed 4.5 kg carbon dioxide equivalent (29% total) and 4.1 kg carbon dioxide equivalent (24%) emissions, respectively. Oxygen use was important to the spinal anesthetic carbon footprint (2.8 kg carbon dioxide equivalent, 18%). Modeling showed that intercountry carbon dioxide equivalent emission variability was less than intragroup variability (minimum/maximum). CONCLUSIONS All anesthetic approaches had similar carbon footprints (desflurane and nitrous oxide were not used for general anesthesia). Rather than spinal being a default low carbon approach, several choices determine the final carbon footprint: using low-flow anesthesia/total intravenous anesthesia, reducing single-use plastics, reducing oxygen flows, and collaborating with engineers to augment energy efficiency/renewable electricity. EDITOR’S PERSPECTIVE

中文翻译：

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全膝关节置换术的一般、区域和联合麻醉的碳足迹。

背景 医疗保健本身会导致气候变化。麻醉是一个“碳热点”，但很少有数据可以比较麻醉选择。作者检查了全膝关节置换术期间与全身麻醉、脊髓麻醉和联合（全身麻醉和脊髓麻醉）相关的二氧化碳当量排放。方法 在澳大利亚墨尔本对三组接受膝关节置换术的每组 10 名患者进行前瞻性生命周期评估。作者收集了麻醉物品、气体和药物的输入数据，以及用于病人加热和麻醉机的电力。七氟醚或丙泊酚用于全身麻醉。生命周期评估软件用于将输入转换为碳足迹（以千克二氧化碳当量排放为单位），与模拟的国际比较。结果 对 29 名患者进行了研究。全身麻醉的二氧化碳当量排放量平均为 14.9 (95% CI, 9.7 to 22.5) kg 二氧化碳当量排放量；脊髓麻醉，16.9 (95% CI, 13.2 to 20.5) kg 二氧化碳当量；对于联合麻醉，18.5 (95% CI, 12.5 to 27.3) kg 二氧化碳当量。所有方法中二氧化碳当量排放的主要来源如下：用于患者暖风机的电力（平均至少 2.5 千克二氧化碳当量 [20% 总量]）、一次性用品、3.6（全身麻醉）、3.4（脊柱) 和 4.3（合并）公斤二氧化碳当量排放量，分别（约 25% 总量）。对于全身麻醉组和联合组，七氟醚平均贡献 4 分。分别为 7 千克二氧化碳当量（总计 35%）和 3.1 千克二氧化碳当量（19%）。对于脊柱和联合，洗涤和消毒可重复使用的物品分别贡献了 4.5 千克二氧化碳当量（总计 29%）和 4.1 千克二氧化碳当量（24%）排放。氧气的使用对脊髓麻醉剂的碳足迹很重要（2.8 kg 二氧化碳当量，18%）。建模表明，国家间二氧化碳当量排放变异性小于组内变异性（最小/最大）。结论 所有麻醉方法都有相似的碳足迹（地氟醚和一氧化二氮不用于全身麻醉）。不同于脊髓是默认的低碳方法，有几种选择决定了最终的碳足迹：使用低流量麻醉/全静脉麻醉，减少一次性塑料，减少氧气流量，并与工程师合作以提高能源效率/可再生电力。编辑的观点