Horn Danielle B, Nguyen Ken D, Maga Joni M, Epstein Richard H
Pain Medicine, Jackson Memorial Hospital, Miami, USA.
Medical Education, University of Miami Miller School of Medicine, Miami, USA.
Cureus. 2025 Aug 28;17(8):e91195. doi: 10.7759/cureus.91195. eCollection 2025 Aug.
Background The anesthesiology standard of care requires limiting oxygen (O) concentration to less than or equal to 30% during monitored anesthetic care for upper chest and head and neck surgery to reduce the fire risk. While Venturi devices are used to regulate O concentration, they generate high flow rates, which may increase O concentration near the face mask. Even small increases of O concentration greater than room air significantly increase combustibility, highlighting the need for careful O delivery strategies. Methods A face mask was attached to a full-body patient simulator. The mask was connected to 1) the breathing circuit via a 15-mm tracheal tube adapter using the anesthesia machine's O blender set at 30%, or 2) the auxiliary O port using a 31% Venturi device. Surgical drapes were placed on intravenous poles ("ether screen") to separate the anesthesia and surgical side. Inflow O flow was 6 L/min for both groups, with the Venturi delivering ≈52 L/min. After room air calibration, ambient O concentrations were measured at three sites on the anesthesia side and three on the surgical side of the drape at no flow and then 15, 30, and 60 minutes after O flow initiation. Experiments were repeated three times. Results The pooled differences in the O concentration increases between the two devices were 0.80% (95% CI 0.53 to 1.07, P<.001) on the surgical side and 2.22% (95% CI 2.02 to 2.42, P<.001) on the anesthesia side of the ether screen. At 60 minutes, the mean (SD) concentrations in the Venturi group were 22.99% (0.31%) on the anesthesia side and 21.72% (0.90%) on the surgical side. Corresponding values in the anesthesia circuit group were 21.07% (0.12%) and 21.00% (0.11%). Conclusions A 31% Venturi device resulted in clinically relevant increases in ambient O concentrations on both sides of the ether screen compared to using the anesthesia machine O blender set at 30%. The differences are substantive because each 1% increase in the ambient O concentration increases the combustion rate of cotton by 15%. The use of a Venturi device to regulate O concentrations in the presence of an ignition source during head and neck surgery is not recommended. We advocate for anesthesia machine manufacturers to provide an integrated O blender for the auxiliary gas outlet of all their products as a fire safety measure.
麻醉护理的标准要求，在上胸部以及头颈部手术的麻醉监测护理过程中，将氧气（O）浓度限制在小于或等于30%，以降低火灾风险。虽然文丘里装置用于调节O浓度，但它们会产生高流速，这可能会增加面罩附近的O浓度。即使O浓度比室内空气略有增加也会显著提高可燃性，这突出了谨慎的O输送策略的必要性。方法：将一个面罩连接到一个全身患者模拟器上。该面罩通过一个15毫米气管导管转接器连接到1）使用设置为30%的麻醉机O混合器的呼吸回路，或2）使用31%文丘里装置的辅助O端口。手术单放置在静脉输液杆上（“乙醚屏障”）以分隔麻醉侧和手术侧。两组的O流入流量均为6升/分钟，文丘里装置输送约52升/分钟。在进行室内空气校准后，在无流量时以及开始O流量后15、30和60分钟，在手术单麻醉侧的三个位置和手术侧的三个位置测量环境O浓度。实验重复三次。结果：在乙醚屏障的手术侧，两种装置之间O浓度增加的合并差异为0.80%（95%CI 0.53至1.07，P<0.001），在麻醉侧为2.22%（95%CI 2.02至2.42，P<0.001）。在60分钟时，文丘里组在麻醉侧的平均（标准差）浓度为22.99%（0.31%），在手术侧为21.72%（0.90%）。麻醉回路组的相应值为21.07%（0.12%）和21.00%（0.11%）。结论：与使用设置为30%的麻醉机O混合器相比，31%的文丘里装置导致乙醚屏障两侧的环境O浓度出现临床相关的增加。这些差异很显著，因为环境O浓度每增加1%，棉花的燃烧速率就会增加15%。不建议在头颈部手术中有火源存在的情况下使用文丘里装置来调节O浓度。我们主张麻醉机制造商为其所有产品的辅助气体出口提供一个集成的O混合器作为消防安全措施。
