London's Air Ambulance, Bart's Health NHS Trust, London, UK.
Essex and Herts Air Ambulance Trust, UK.
Anaesthesia. 2017 May;72(5):580-584. doi: 10.1111/anae.13852. Epub 2017 Mar 14.
Pre-oxygenation before tracheal intubation aims to increase safe apnoea duration by denitrogenation of the functional residual capacity of the lungs, and increasing oxygen stores at the onset of apnoea. Pre-oxygenation options in the pre-hospital environment are limited due to oxygen availability and equipment portability. The aim of this study was to evaluate the effectiveness of strategies available in this setting. This was a prospective, randomised, crossover study of 30 healthy volunteers who underwent 3-min periods of pre-oxygenation by tidal volume breathing with a non-rebreather mask, a bag-valve-mask and a portable ventilator. The primary outcome measure was fractional expired oxygen concentration of the first exhaled breath after each technique. The secondary outcome measure was ease of breathing, assessed using a visual analogue scale. The mean (95%CI) fractional expired oxygen concentrations achieved with the non-rebreather mask were 64 (60-68)%, bag-valve-mask 89 (86-92)% and portable ventilator 95 (94-96)%. Pre-oxygenation efficacy with the non-rebreather mask was significantly worse than with either the bag-valve-mask (p < 0.001) or ventilator (p < 0.001). No significant difference in ease of breathing was identified between the bag-valve-mask and ventilator, but both were perceived as being significantly more difficult to breathe through than the non-rebreather mask. We conclude that, in healthy volunteers, the effectiveness of pre-oxygenation by bag-valve-mask and portable ventilator was superior to pre-oxygenation with a non-rebreather mask, although the non-rebreather mask was easier to breathe through than the other pre-oxygenation devices.
气管插管前预充氧旨在通过肺功能残气量的脱氮和在呼吸暂停开始时增加氧气储备来延长安全无通气时间。由于氧气供应和设备便携性，院前环境中的预充氧选择有限。本研究的目的是评估该环境中可用策略的有效性。这是一项前瞻性、随机、交叉研究，纳入了 30 名健康志愿者，他们通过非再呼吸面罩、球囊面罩和便携式呼吸机进行了 3 分钟的潮气量呼吸预充氧。主要结局指标是每种技术后第一次呼气末呼出氧分数。次要结局指标是使用视觉模拟评分评估呼吸的容易程度。非再呼吸面罩的平均（95%CI）呼气末氧分数为 64（60-68）%，球囊面罩为 89（86-92）%，便携式呼吸机为 95（94-96）%。非再呼吸面罩的预充氧效果明显差于球囊面罩（p<0.001）或呼吸机（p<0.001）。球囊面罩和呼吸机之间在呼吸的容易程度上没有显著差异，但两者都被认为比非再呼吸面罩更难以呼吸。我们得出结论，在健康志愿者中，球囊面罩和便携式呼吸机的预充氧效果优于非再呼吸面罩，尽管非再呼吸面罩比其他预充氧设备更容易呼吸。
