Institute of Mountain Emergency Medicine, Eurac Research, Bolzano, Italy.
Corpo Nazionale Soccorso Alpino e Speleologico, Milano, Italy.
JAMA Netw Open. 2023 May 1;6(5):e2313376. doi: 10.1001/jamanetworkopen.2023.13376.
Approximately 70% of individuals critically buried in avalanche debris die within 35 minutes as a result of asphyxial cardiac arrest. An artificial air-pocket device (AAPD) that separates inhaled air from exhaled air may delay the onset of severe hypoxemia and eventual asphyxia during snow burial.
To investigate the efficacy of a new AAPD during snow burial in a supine position.
DESIGN, SETTING, AND PARTICIPANTS: This comparative effectiveness trial was performed in winter 2016 with data analysis in November 2016 and November 2022. Each trial used a simulated critical avalanche burial scenario, in which a trough was dug in a snow pile and an additional air pocket of 0.5 L volume was punched into the lateral wall for each control trial. All participants were buried in a supine position. Trials could be voluntarily terminated at any time, with a maximum length of 60 minutes; trials were automatically terminated if the participant's peripheral oxygen saturation (Spo2) dropped to less than 84%.
Each participant conducted 2 trials, one in which they breathed into the AAPD (intervention trial) and the other in which they breathed into the prepared air pocket (control trial).
Measurements included Spo2, cerebral oxygenation, ventilatory parameters, respiratory gas concentrations, and visual-analogue scales. Kaplan-Meier survival curves and rank test for matched survival data were used to analyze the total burial time in each trial.
A total of 13 volunteers (9 men; mean [SD] age, 33 [8] years) were exposed to the intervention and control trials. Intervention trials were terminated less often (2 of 13 trials) as a result of hypoxemia than control trials (11 of 12 trials). Similarly, survival curves showed a longer duration of burial in the intervention compared with the control trials for the time to reach an Spo2 less than 84% (rank test for matched survival data: P = .003). The intervention trials, compared with the control trials, also had slower rates of decrease in fraction of inspired oxygen (mean [SD] rate, -0.8 [0.4] %/min vs -2.2 [1.2] %/min) and of increase in fraction of inspired carbon dioxide (mean [SD] rate, 0.5 [0.3] %/min vs 1.4 [0.6] %/min) and expired ventilation per minute (mean [SD] rate, 0.5 [1.0] L/min2 vs 3.9 [2.6] L/min2).
This comparative effectiveness trial found that the new AAPD was associated with delaying the development of hypoxemia and hypercapnia in supine participants in a critical burial scenario. Use of the AAPD may allow a longer burial time before asphyxial cardiac arrest, which might allow longer times for successful rescue by companions or by prehospital emergency medical services.
大约 70%的人在雪崩掩埋中因窒息性心脏骤停而在 35 分钟内死亡。人工气袋装置（AAPD）可将吸入的空气与呼出的空气隔开，在雪埋时可能会延迟严重低氧血症和最终窒息的发生。
研究一种新的 AAPD 在仰卧位雪埋中的效果。
设计、地点和参与者：这项比较有效性试验于 2016 年冬季进行，数据分析于 2016 年 11 月和 2022 年 11 月进行。每次试验都使用了一个模拟的严重雪崩掩埋场景，在这个场景中，在雪堆中挖出一个槽，每个对照试验在侧壁上打入一个 0.5 升的额外气袋。所有参与者均仰卧位埋入。试验可随时自愿终止，最长时间为 60 分钟；如果参与者的外周血氧饱和度（Spo2）降至 84%以下，试验将自动终止。
每个参与者进行 2 次试验，一次是用 AAPD 呼吸（干预试验），另一次是用准备好的气袋呼吸（对照试验）。
测量包括 Spo2、脑氧合、通气参数、呼吸气体浓度和视觉模拟量表。采用 Kaplan-Meier 生存曲线和匹配生存数据秩检验分析每个试验的总埋置时间。
共有 13 名志愿者（9 名男性；平均[标准差]年龄，33[8]岁）暴露于干预和对照试验中。由于低氧血症，干预试验终止的频率低于对照试验（13 次试验中有 2 次）。同样，生存曲线显示，与对照试验相比，干预试验的埋置时间更长，达到 Spo2 低于 84%的时间（匹配生存数据秩检验：P=0.003）。与对照试验相比，干预试验的吸入氧分数下降速度较慢（平均[标准差]速度，-0.8[0.4]%/min 与-2.2[1.2]%/min），吸入二氧化碳分数增加速度较慢（平均[标准差]速度，0.5[0.3]%/min 与 1.4[0.6]%/min），每分钟呼气量增加速度较慢（平均[标准差]速度，0.5[1.0]L/min2 与 3.9[2.6]L/min2）。
这项比较有效性试验发现，新的 AAPD 与在关键掩埋场景中仰卧参与者的低氧血症和高碳酸血症的发展延迟有关。使用 AAPD 可能会在窒息性心脏骤停前允许更长的埋置时间，这可能为同伴或院前急救医疗服务成功救援提供更长的时间。
