Kerem D, Daskalovic Y I, Arieli R, Shupak A
Israeli Naval Medical Institute, Haifa, Israel.
Undersea Hyperb Med. 1995 Dec;22(4):339-46.
We evaluated CO2 retention in 24 Navy construction divers breathing air at 1 atm abs (101.3 kPa) and 40% O2 (40/60) nitrox at 4 atm abs (Po2 of 162.1 kPa) inside a pressure chamber. The divers sat immersed to the sternal notch and exercised against pneumatically loaded pedals at a Vo2 of approximately 1.3 liter/min. The mean end-tidal CO2 tension (PET(CO2)2) at 1 atm abs (45.7 +/- 5.0 SD torr) was significantly higher than that of non-divers and diving trainees (40 +/- 5.0) but did not increase significantly at depth (47.1 +/- 6.3). The ranking of CO2 retention was not maintained at depth. Unpredictable upward and downward shifts of up to 10 torr occurred in some divers. The PET(CO2) of six of the divers at pressure was greater than 50 torr, which based on animal studies markedly increases the risk of central nervous system oxygen toxicity. We translated their values into individual depth limits with 40/60 nitrox: three with 50 < PET(CO2) < 55 torr were forbidden to dive beyond 25 m and three with values > 55 torr were restricted to 20 m. We propose that whenever possible, PET(CO2) during exercise at pressure be measured in potential nitrox users and that the above PO2 limits be enforced on moderate and extreme CO2 retainers, respectively.
我们在压力舱内评估了24名海军建筑潜水员在1个绝对大气压（101.3 kPa）下呼吸空气以及在4个绝对大气压（氧分压为162.1 kPa）下呼吸40%氧气（40/60）的氮氧混合气时的二氧化碳潴留情况。潜水员坐在水中，使胸骨上切迹浸入水中，并以约1.3升/分钟的耗氧量蹬踩气动加载踏板进行运动。在1个绝对大气压下，平均呼气末二氧化碳分压（PET(CO2)）为45.7±5.0标准差托，显著高于非潜水员和潜水学员（40±5.0），但在深度增加时并未显著升高（47.1±6.3）。在深度增加时，二氧化碳潴留的排名并未保持。一些潜水员出现了高达10托的不可预测的上下波动。6名潜水员在压力下的PET(CO2)大于50托，根据动物研究，这显著增加了中枢神经系统氧中毒的风险。我们将他们的值转换为使用40/60氮氧混合气时的个人深度限制：3名PET(CO2)在50＜PET(CO2)＜55托之间的潜水员被禁止在超过25米的深度潜水，3名PET(CO2)值大于55托的潜水员被限制在20米深度。我们建议，只要有可能，应对潜在的氮氧混合气使用者在压力下运动时的PET(CO2)进行测量，并分别对中度和重度二氧化碳潴留者执行上述氧分压限制。
