Arieli Ran, Arieli Yehuda, Eynan Mirit, Abramovich Amir
Israel Naval Medical Institute, IDF Medical Corps, P.O. Box 8040, 31080 Haifa, Israel.
Mil Med. 2012 Nov;177(11):1426-30. doi: 10.7205/milmed-d-12-00285.
The traditional method used to evaluate escape masks has been to examine the composition of the inspired gas, although arterial carbon dioxide (CO2) and oxygen (O2) would be more relevant physiological parameters. The recent development of reliable, fast-responding transcutaneous CO2 detectors makes it possible to evaluate arterial CO2 and O2 saturation. The CAPS 2000 escape mask was designed to protect the head and respiratory system from chemical or biological attack. The question arises of whether there might be a risk of dangerous hypoxia-hypercapnia in rebreathing from the mask because of leakage of the expired gas from the nose-cup into the hood, although theoretical considerations rule this out. We studied a worst case scenario.
Nine subjects wore the CAPS 2000 for 15 minutes after removal of the inspiratory valves. A mass spectrometer and transcutaneous sensor were used to measure O2 and CO2, arterial O2 saturation, and arterial partial pressure of CO2 (PCO2).
Blood oxygen saturation decreased from an initial value of 98.4% to 96.2% at 2 minutes, subsequently rising and stabilizing at a level similar to control. Subcutaneous PCO2 rose from the control level of 36 to 43 torr after 5 minutes, then decreased to 42 torr and stabilized at that level. Inspired PO2 dropped from 21% to 16% at 3 to 4 minutes, rose to 17% at 8 minutes, and stabilized thereafter. Inspired PCO2 rose to 3% in the first minute and continued to rise to 3.5% at 3 minutes, after which it slowly decreased to 3% and stabilized at that level.
The transcutaneous CO2 detector provided a true indication of the physiological state of the subject, and these parameters are sufficient on their own for the evaluation of breathing masks. CO2 and O2 did not reach dangerous levels with the inspiratory valves removed from the CAPS 2000 mask.
尽管动脉二氧化碳（CO₂）和氧气（O₂）是更相关的生理参数，但过去用于评估逃生面罩的传统方法是检测吸入气体的成分。可靠、快速响应的经皮CO₂探测器的最新发展使得评估动脉CO₂和O₂饱和度成为可能。CAPS 2000逃生面罩旨在保护头部和呼吸系统免受化学或生物攻击。由于呼出气体从鼻罩泄漏到面罩中，从面罩中再呼吸时可能存在危险的低氧血症-高碳酸血症风险，尽管理论上的考虑排除了这种情况。我们研究了一种最坏情况。
九名受试者在取下吸气阀后佩戴CAPS 2000达15分钟。使用质谱仪和经皮传感器测量O₂和CO₂、动脉血氧饱和度以及动脉血二氧化碳分压（PCO₂）。
血氧饱和度从初始值98.4%在2分钟时降至96.2%，随后上升并稳定在与对照组相似的水平。皮下PCO₂在5分钟后从对照水平36升至43托，然后降至42托并稳定在该水平。吸入PO₂在3至4分钟时从21%降至16%，在8分钟时升至17%，此后稳定。吸入PCO₂在第一分钟升至3%，并在3分钟时继续升至3.5%，之后缓慢降至3%并稳定在该水平。
经皮CO₂探测器真实反映了受试者的生理状态，这些参数本身足以用于评估呼吸面罩。从CAPS 2000面罩上取下吸气阀后，CO₂和O₂未达到危险水平。
