体外循环围术期心脏迷走神经活动与心排量和呼气末CO_2关系

Relationship of Cardiac Vagus Activity on cardiac Output and End-tidal CO2 Tension Occurring Perioperatively with Cardiopulmonary Bypass

本研究旨在探讨体外循环围术期心脏迷走神经活动的变化对心排量（ＣＯ）和呼气末ＣＯ_２（ＥＴＣＯ_２）的影响，以及三者之间的相互关系；并进一步阐明迷走神经拮抗剂—东茛菪碱的心肌保护作用。实验用纯种、同龄猪１０头，随机分为对照（ｎ＝５）和治疗组（ｎ＝５）。常规建立体外循环。主动脉阻断时，对照组灌注仁济医院配方停跳液，治疗组加用东茛菪碱（２０μｇ／ｋｇ）。分别于主动脉阻断前（Ｎ）、心脏复跳即刻（Ｏ）、再转流３０分钟（Ｒ）测定ＣＯ和ＥＴＣＯ_２，并取心大静脉血测定乙酰胆碱（Ａｃｈ）。结果发现：（１）Ａｃｈ在再灌注期释放明显增多，东茛菪碱能有效地减少其释放，阻断其作用；（２）东茛菪碱保护心功能的作用优于常规心肌保护组；（３）ＥＴＣＯ_２呈现与ＣＯ相似的变化，说明东茛菪碱有效地减少了肺内分流；（４）在减少肺内分流的情况下，ＥＴＣＯ_２可作为ＣＯ的间接观察指标。结论：东茛菪碱可有效阻断再灌注期乙酰胆碱的释放，起到保护心肌的作用。

The study was designed to elucidate the influence of cardiac vagus activity on cardiac output(CO) and end-tidal CO_2 tension(ETCO_2)and their interrelationship during openheart surgery under cardio-pulmonary beypass (CPB).Accordingly,the protective effect of vagus antagonist Scopolamine for myocardial preservation could be further evaluated.Ten pigs of same age were divided into two groups:Control group (C,n=5) and Scopolamine treated group (S,n= 5).Swan-Ganz catheters were introduced into internal jugular vein for cardiac output and Nellcor CO_2 Monitor for ETCO_2.After endotracheal intubation CPB was established. Following aortic occlusion Ren Ji cardioplegic solution was administered in Control group while Scopolamine was added into RJ solution (20μg/kg) for Scopolamine group,CO and ETCO_2were determined at N (prebypass),A(after resumption of heart beat),R(termination of bypass) and acetylcholine (Ach)was also determined in the blood sample from coronary sinus.The result showed that (1) at A and R Ach increased remarkably in Control group as compared to S group(P<0.004);(2)In both group CO was found reduced(P<0.01).However at R there was significant elevation in S group as compared to C group(P<0.05);(3) Alteration of ETCO_2 showed similar trend as CO:(4)At A and R changes of Ach were negatively correlated to ETCO_2and CO(P<0.0002),while ETCO_2 and CO showed positive correlation(P<0.0001).Hence our experiment indicated that(1)there was increased release of Ach during reperfusion and Scopolamine effectively inhibited the release of Ach and its influence;(2)Scopolamine provided much better protection than conventional cardioplegia;(3)ETCO_2 showed similar change in CO indicating diminished intrapulmonary A-V shunt by Scopolamine;(4)ETCO_2 can be considered as an indirect parameter for cardiac output under the situation of diminished intrapulmonary A-V shunt.