亚低温改善肾上腺素在心肺复苏早期心功能及微循环障碍中的作用

The effect of mild hypothermia on the myocardial and microcirculatory dysfunction induced by epinephrine during early post-resuscitation

目的探讨亚低温治疗对肾上腺素在大鼠心复苏后早期心功能及微循环障碍的影响。方法40只雄性SD大鼠,建立心脏骤停/心肺复苏(CA/CPR)模型,随机(随机数字法)分成四组(n=10):常温对照组(N),常温肾上腺素组(N+E)、低温对照组(H)、低温肾上腺素组(H+E)。起搏开始后5 min立即开始胸外心脏按压及机械通气,低温组迅速降温至(33±0.5)℃并维持,按压1 min时经股静脉注射肾上腺素0.02 mg/kg或生理盐水,观察自主循环恢复情况。在复苏后1、2、3、4 h各时间点,分别使用心脏超声监测心功能,应用侧流暗视野成像(sidestream dark field imaging,SDF)技术测定大鼠舌下微循环灌注指标:总灌注血管密度(total vessel density,TVD)、灌注血管密度(perfused vessel density,PVD)、灌注血管比例(proportion of perfused vessels,PPV)、微血管血流指数(microvascular flow index,MFI)。监测各时间点血乳酸变化。结果各组大鼠自主循环恢复情况为:N+E组9/10,H+E组10/10,H组4/10,N组1/10。自主循环恢复后,大鼠心脏射血分数(ejection fraction,EF)、心输出量(cardiac output,CO)和舌下微循环指标MFI、PPV、TVD、PVD较前均显著下降(P<0.05)。H+E组EF、CO和微循环指标评分明显高于N+E组及H组(P<0.05)。H+E组复苏后4 h血浆乳酸含量低于N+E组及H组(P<0.05)。结论肾上腺素和亚低温均能提高心脏骤停大鼠自主循环恢复成功率,但给予亚低温干预后,可明显改善肾上腺素复苏后早期心功能和微循环障碍。

Objective To investigate the effect of mild hypothermia on the myocardial and microcirculation dysfunction induced by epinephrine during early post-resuscitation in a rat model of cardiac arrest and cardiopulmonary resuscitation(CPR).Methods Transesophageal cardiac pacing was performed in order to elicit cardiac arrest for 5 min in SD male rats.Totally 40 rats were randomly(random number)divided into 4 groups(n=10):normothermic control group(N),normothermic epinephrine group(N+E),hypothermic control group(H),and hypothermic epinephrine group(H+E).Chest compression was then initiated.Epinephrine(0.02 mg/kg)or saline was administrated at 1 min during CPR.Restoration of spontaneous circulation(ROSC)was recorded,and the rates of ROSC were observed.Myocardial and microcirculatory function were observed at 1,2,3,and 4 h during early post-resuscitation.Serum lactate level was assessed at baseline and ROSC 4 h.Results The ROSC rates were 10/10 in the H+E group,9/10 in the N+E group,4/10 in the H group,and 1/10 in the N group,respectively.Ejection fraction(EF)and cardiac output(CO)in the H+E group were significantly higher than that of other groups(P<0.05).Total vessel density,perfused vessel density,proportion of perfused vessels,and microvascular flow index in the H+E group were also significantly higher than those of other groups during early post-resuscitation.The serum lactate level in the H+E group was significantly lower than that in the N+E and H groups..Conclusions Both epinephrine and mild hypothermia can improve the success rate of resuscitation.However,mild hypothermia can improve the epinephrine induced myocardial and microcirculatory dysfunction during postresuscitation in the rat cardiac arrest.