体外膜肺的动物实验研究

An experimental study on extracorpreal membrane oxygenation

目的观察膜肺（ＥＣＭＯ）体外吸收氧及排出二氧化碳的效果。方法绵羊１１只，戊巴比妥钠麻醉后，气管切开、插管，与呼吸机相连。右颈内静脉及右颈总动脉内放置导管。血从右颈内静脉引出，经过膜氧合器气体交换后，从右颈总动脉回输体内。实验依次分４个阶段：（１）ＥＣＭＯ前机械通气；（２）ＥＣＭＯ与机械通气并用（小流量阶段）；（３）仅用ＥＣＭＯ（大流量阶段）；（４）ＥＣＭＯ后机械通气。取羊股动脉血及膜氧合器前后的血标本进行血气分析。结果用ＥＣＭＯ前动脉血气分析的均值为：ｐＨ值７．５０、动脉血二氧化碳分压（ＰａＣＯ２）５．２９ｋＰａ（１ｋＰａ＝７．５ｍｍＨｇ）、氧分压（ＰａＯ２）１８．４、ＰａＯ２／吸入氧浓度（ＦｉＯ２）比值为３３８，ＥＣＭＯ小流量、大流量及ＥＣＭＯ停止后各阶段的ｐＨ值、ＰａＯ２及ＰａＯ２／ＦｉＯ２比值与ＥＣＭＯ前相比，差异无显著意义（Ｐ＞０．０５），ＥＣＭＯ过程中ＰａＣＯ２较低，差异有非常显著意义（Ｐ＜０．０１）。血液通过膜氧合器后，ｐＨ值、ＰＯ２值明显升高（Ｐ＜０．０１），ＰＣＯ２明显降低（Ｐ＜０．０１）。结论ＥＣＭＯ体外可吸收足够的氧，有效排出ＣＯ２，维持血ｐＨ值稳定。

Objective To evaluate the effect of ECMO bypass on the improvement of gas exchange in eleven sheep. Methods Standard procedures for veno arterial ECMO were used in all animals. Blood was typically siphoned from the right jugular venous cannula and returned to animal by the right common carotid cannula after being oxygenated. Procedures were divided into four phases: (1)pre ECMO; (2)during ECMO(50 ml·kg -1 ·min -1 )with required mechanical ventilation; (3) during ECMO(80～100 ml·kg -1 ·min -1 ) with minimal ventilatory support; (4) post ECMO. Blood gas analysis was made for blood samples taken from femoral artery at each of the four phases, and from pre oxygenator and post oxygenator of ECMO bypass during ECMO phases.Results At pre ECMO, the pH, PaO 2, PaCO 2 and PaO 2/FiO 2 of arterial blood were 7.50, 18.4 kPa, 5.29 kPa and 338, respectively. The above parameters did not change at the phases both during ECMO and post ECMO, except that PaCO 2 reduced markedly druing ECMO ( P <0.01). After oxygenation on ECMO bypass, the PO 2 of blood taken from post oxygenator increased by more than three times ( P <0.01), while PCO 2 remarkably decreased ( P < 0.01). Conclusion During ECMO, oxygen is efficiently taken in, carbon dioxide given up and normal blood pH maintained stable.