反复室颤及除颤对猪酸碱平衡及电解质的影响

Effect of repeated episodes of ventricular fibrillation and defibrillation on arterial acid-base and electrolytes changes in a swine model

目的通过猪心室颤动(ventricular fi brillation,VF)模型,研究反复室颤及除颤对猪酸碱平衡及电解质的影响。方法16头北京长白猪,体重(32±2.5)kg,麻醉后经左股静脉放置临时起搏电极直至右心室,连接医用程控刺激仪,制备VF模型。左股动脉置入动脉导管,连接PiCCO监护仪测量平均动脉压及心输出量,并抽取动脉血。随机数字法将动物分为手动除颤或自动体外除颤组,每组8只。手动除颤组诱发VF 15 s后除颤,首次选择除颤仪推荐的150 J,如果失败给予2 min心肺复苏,之后选择能量200 J。自动体外除颤组按语音提示操作除颤。除颤成功后实验动物稳定30 min,然后再诱发下次VF,以上过程反复进行5次。每次自主循环恢复30 min后进行动脉血气、心肌酶学检测,同时进行血流动力学测定。结果所有动物均成功诱发5次VF,并除颤成功。两组动物在反复致颤、除颤后心率和平均动脉压未见显著变化,心输出量与基础状态相比出现下降趋势,但下降幅度差异无统计学意义(P均>0.05)。两组动物在各测量时间点的动脉血pH值、HCO3-、血钠、乳酸与各自基础状态比较差异均无统计学意义(P均>0.05),但两组动物血钾随时间变化出现降低,与各自基础状态相比,差异有统计学意义(P均<0.05)。两组动物静脉血肌红蛋白、肌酸激酶同工酶-MB及心肌肌钙蛋白I与各自基础状态相比及各自组间同时间点相比差异均无统计学意义(P均>0.05)。结论反复室颤及除颤对猪酸碱平衡无明显影响,对血钾有显著降低作用;手动除颤和自动体外除颤对猪除颤效果、血流动力学及心肌损伤方面差异无统计学意义。

Objectives To investigate changes in arterial acid-base and electrolytes after repeated episodes of ventricular fi brillation(VF)and defi brillation in a swine model.Methods Sixteen Peking white swine,weighting(32±2.5)kg,were placed with temporary pacemaker electrodes via the left femoral vein into the right ventricle after anesthesia.Then VF was electrically induced by using a programmed electrical stimulation instrument.An arterial cannula was inserted into the left femoral artery to measure mean arterial blood pressure and cardiac output using a PiCCO monitor,with blood samples collected.The pigs were randomly divided into two group:the manual defi brillation group(MD,n=8)and the automated external defi brillation group(AED,n=8).The fi rst defi brillation was attempted with the manufacturer’s dose(150 J)for 15 s after the successful induction of VF in the MD group.If spontaneous circulation was not recovered,2-min chest compression and subsequent defi brillation(200 J)were attempted.For the AED group,the defibrillation was delivered following voice prompts of the AED.After the return of spontaneous circulation,the pig was allowed to stabilize for 30 min,followed by the induction of the next episode of VF.The above process was repeated fi ve times.Arterial blood gas,cardiac biomarkers,and hemodynamic variables were measured at 30 min after the return of spontaneous circulation.Results All pigs were successfully induced VF fi ve times and defi brillated successfully.There were no signifi cant changes in heart rate and mean arterial blood pressure between the two groups after repeated episodes of VF and defibrillation.Compared with baseline measurements,cardiac output tended to decrease after repeated episodes of VF and defi brillation but was not statistically signifi cant(all P>0.05).There were no signifi cant differences in arterial pH,HCO3-,sodium,and lactic acid in the two groups between each measurement time point and baseline values after repeated VF(all P>0.05),but potassium levels in the two groups decreased with time,and the difference was statistically significant compared with the baseline measurement(all P<0.05).There were no signifi cant differences in myoglobin,creatine kinase isoenzyme-MB,and cardiac troponin I for the two groups compared with baseline values after repeated episodes of VF and defibrillation or various episodes of VF between the two groups(all P>0.05).Conclusions Repeated episodes of VF and defi brillation have no signifi cant effect on pH balance,but signifi cantly decrease blood potassium.Clinical approaches(MD vs.AED)do not affect defi brillation effect,with no signifi cant differences in hemodynamic variables and myocardial injuries.