心肺复苏不同时间点液体反应性及其对自主循环恢复影响的研究

Fluid response in the process of cardiopulmonary resuscitation and its impact on the return of spontaneous circulation

目的研究心脏骤停(CA)中不同时间点实验动物液体反应性及其对自主循环恢复(ROSC)的影响.方法清洁级健康小型长白猪20只,按照随机数字表法分为液体负荷试验组(fluid test,FT组)和对照组(resuscitation only,RO组).按实验常规置管监测主动脉压力(AoP)、中心静脉压力(CVP)及左侧颈动脉血流.电刺激法诱导心室纤维颤动(室颤),无血流时间5 min后给予胸外按压和通气;FT组实验动物按压5 min后经右侧颈内静脉快速输注生理盐水200 mL,此后每按压5 min快速给予液体负荷200 mL,共4次(共计生理盐水800 mL);RO组实验动物除不给予液体负荷外,其余处理与FT组相同,复苏时间20 min.复苏开始后在4个观测时间点(5、10、15、20 min)记录相关血流动力学及血气参数,判断不同时间点液体反应性.20 min后给予电复律,比较两组实验动物ROSC情况.结果FT组复苏5、10 min时存在液体反应性,15、20 min(累积液体量600和800 mL)时无液体反应性.FT组液体负荷800 mL后与RO组比较ROSC率差异无统计学意义(P>0.05).与RO组比较给予液体负荷400 mL后显著增加实验动物冠状动脉灌注压力(CPP,cm H2O:36.2±5.1 vs.28.8±6.3,P<0.01),但继续给予液体负荷试验(15 min累积液体600 mL,20 min累积液体800 mL)CPP不再增加.右心房压力-颈动脉血流速(P-F)曲线显示液体400 mL有最佳的压力-流速曲线关系.颈动脉最大血流速、血气分析[氧合指数(PaO2/FiO2)]FT组在复苏过程中均显著高于RO组,中心静脉血氧饱和度(SvO2)复苏开始10 min(液体400 mL)至复苏结束(液体800 mL)显著高于RO组,与RO组比较,FT组动静脉二氧化碳分压差(CO2-CaP)随液体输注而降低,但液体输注800 mL后两组间差异无统计学意义(37.0±2.1 vs.32.0±5.5,P=0.25).结论心肺复苏(CPR)中的液体反应性随着复苏时间的变化有所不同.适当前负荷可显著增加按压射血,但过量液体负荷可能有害,前负荷-按压质量偶联的最佳匹配关系仍需要进一步的研究来明确.

Objective To evaluate the fluid response and the ffcts of fluid on the return of spontaneous eirculation(ROSC)among cardiac arrest animal models.Method Twenty healthy landrace pigs of clean grade were divided into 2 groups:the tluid test(FT)group and resuscitation only(RO)group.Aortic pressure(CVP),central venous pressure,the blood flow of the left cervical arltery were recorded.Ventricular fibrillation was induced by electrical stimulation,chest compression and ventilation were then performed after 5 min no-flow time.For FT group,200 mL normal saline(NS)was administered through right internal jugular vein every 5 min after the start of CPR,with a total amount of 800 mL.For RO group,the same managements were given except the intravenous fluid,continuous compression lasted for 20 min,then intravenous epinephrine and deflibillation was performed.Hemodynamie parameters and blood gas analysis were recorded and analyzed depending on different time points of CPR(5,10,15,and 20 min).The primary outcome was the fluid response at different time points of CPR in the FT group,the secondary outcome was ROSC between groups.Results Fluid response was observed at 5 min and 10 min after compression,but didn't exist at the time point of 15 min and 20 min(accumulative fluid administered 600 mL and 800 mL).Compared with the RO group,FT group after the administration of 800 mL normal saline did not have a signifcant difference in the rate of ROSC.However,after the administration of 400 mL normal saline,significant increase of coronary perfusion pressure(CPP,cm H2O:36.2±5.1 vs.28.8±6.3,P<0.01)was observed.However,further fluid response tests(15 min,accumulated normal saline volume 600 mL,20 min accumulated normal saline volume 800 mL)did not significantly increase CPP.The right atrium-flow curve showed that 400 mL normal saline had the best pressure-flow relation.Maximum cervical blood flow,PaO2/FiO2 were significantly higher in the FT group than in RO group during the 20-min CPR;Oxygen saturation of central venous(SvO2)was higher from 10 min of CPR to the end of resuscitation in the FT group.CO2-gap was lower at the first 15-min CPR,but no significantly diferent at the end of 20-min CPR(accumulative 800 mL normal saline)in the FT group compared with RO group(37.0±2.1 vs.32.0±5.5,P=0.25).Conclusion Fluid response varied at different time points of CPR.Preload may increase CPP as well as blood flow during CPR with the right amount of volume,whereas more fluid may be harmful.Optimal inherent relationship of preload and quality of compression may need further research in the future.