Manual facemask ventilation, a core component of elective and emergency airway management, is classified as an aerosol-generating procedure. This designation is based on one epidemiological study suggesting an association between facemask ventilation and transmission during the SARS-CoV-1 outbreak in 2003. There is no direct evidence to indicate whether facemask ventilation is a high-risk procedure for aerosol generation. We conducted aerosol monitoring during routine facemask ventilation and facemask ventilation with an intentionally generated leak in anaesthetised patients. Recordings were made in ultraclean operating theatres and compared against the aerosol generated by tidal breathing and cough manoeuvres. Respiratory aerosol from tidal breathing in 11 patients was reliably detected above the very low background particle concentrations with median [IQR (range)] particle counts of 191 (77–486 [4–1313]) and 2 (1–5 [0–13]) particles.l^-1, respectively, p = 0.002. The median (IQR [range]) aerosol concentration detected during facemask ventilation without a leak (3 (0–9 [0–43]) particles.l^-1) and with an intentional leak (11 (7–26 [1–62]) particles.l^-1) was 64-fold (p = 0.001) and 17-fold (p = 0.002) lower than that of tidal breathing, respectively. Median (IQR [range]) peak particle concentration during facemask ventilation both without a leak (60 (0–60 [0–120]) particles.l^-1) and with a leak (120 (60–180 [60–480]) particles.l^-1) were 20-fold (p = 0.002) and 10-fold (0.001) lower than a cough (1260 (800–3242 [100–3682]) particles.l^-1), respectively. This study demonstrates that facemask ventilation, even when performed with an intentional leak, does not generate high levels of bioaerosol. On the basis of this evidence, we argue facemask ventilation should not be considered an aerosol-generating procedure.

中文翻译：

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手动面罩通气过程中气溶胶产生的定量评估


手动面罩通气是选择性和紧急气道管理的核心组成部分，被归类为气溶胶产生程序。这一指定基于一项流行病学研究，该研究表明 2003 年 SARS-CoV-1 爆发期间口罩通气与传播之间存在关联。没有直接证据表明口罩通气是否是产生气溶胶的高风险程序。我们在常规面罩通气和麻醉患者故意产生泄漏的面罩通气期间进行了气溶胶监测。记录是在超净手术室中进行的，并与潮式呼吸和咳嗽动作产生的气溶胶进行比较。可靠地检测到 11 名患者潮式呼吸产生的呼吸气溶胶高于非常低的背景颗粒浓度，中位 [IQR（范围）] 颗粒计数为 191 (77–486 [4–1313]) 和 2 (1–5 [0–13]) ]) 粒子.l ^-1 ，分别为 p = 0.002。面罩通气期间检测到的气溶胶浓度中位数（IQR [范围]），无泄漏 (3 (0–9 [0–43]) 个颗粒.l ^-1 ) 和故意泄漏 (11 (7–26 [1–62]) ]) 粒子.l ^-1 ) 分别比潮汐呼吸低 64 倍 (p = 0.001) 和 17 倍 (p = 0.002)。面罩通气期间，无泄漏 (60 (0–60 [0–120]) 颗粒.l ^-1 ) 和有泄漏 (120 (60–180 [60–480]) 颗粒物时的中位值（IQR [范围]）峰值颗粒浓度) 颗粒.l ^-1 ) 分别比咳嗽 (1260 (800–3242 [100–3682]) 颗粒.l ^-1 ) 低 20 倍 (p = 0.002) 和 10 倍 (0.001)。 这项研究表明，面罩通气，即使在有意泄漏的情况下，也不会产生高水平的生物气溶胶。根据这一证据，我们认为面罩通气不应被视为产生气溶胶的程序。