BACKGROUND: Partial pressure of end-tidal carbon dioxide(PETCO2) has been used to monitor the effectiveness of precordial compression(PC) and regarded as a prognostic value of outcomes in cardiopulmonary resuscitation(CPR). This study was to investigate changes of PETCO2 during CPR in rats with ventricular fi brillation(VF) versus asphyxial cardiac arrest.METHODS: Sixty-two male Sprague-Dawley(SD) rats were randomly divided into an asphyxial group(n=32) and a VF group(n=30). PETCO2 was measured during CPR from a 6-minute period of VF or asphyxial cardiac arrest.RESULTS: The initial values of PETCO2 immediately after PC in the VF group were signifi cantly lower than those in the asphyxial group(12.8±4.87 mmHg vs. 49.2±8.13 mmHg, P=0.000). In the VF group, the values of PETCO2 after 6 minutes of PC were significantly higher in rats with return of spontaneous circulation(ROSC), compared with those in rats without ROSC(16.5±3.07 mmHg vs. 13.2±2.62 mmHg, P=0.004). In the asphyxial group, the values of PETCO2 after 2 minutes of PC in rats with ROSC were signifi cantly higher than those in rats without ROSC(20.8±3.24 mmHg vs. 13.9±1.50 mmHg, P=0.000). Receiver operator characteristic(ROC) curves of PETCO2 showed signifi cant sensitivity and specifi city for predicting ROSC in VF versus asphyxial cardiac arrest.CONCLUSIONS: The initial values of PETCO2 immediately after CPR may be helpful in differentiating the causes of cardiac arrest. Changes of PETCO2 during CPR can predict outcomes of CPR.
目的探讨缺血期亚低温对常温再灌注后心肌细胞的保护作用及其可能机制。方法本实验在中山大学心肺脑复苏研究所完成。取50只SD新生1—2d乳鼠心脏，建立心肌细胞体外模型，利用氧糖剥夺（oxygen and glncose deprivation，OGD）和氧糖恢复（oxygen and glucoserestoration，OGR）模拟缺血一再灌注过程。将细胞随机（随机数字法）分入常温对照组、32℃ OGD-37℃OGR组（低温组）、37℃ OGD—OGR组（常温组），并在OGR0，0．5，1．0，1．5，2．0h分别测定心肌细胞收缩频率和平均收缩速率；在OGR0，2h分别收集细胞进行透射电镜观察超微结构以及线粒体变化，同时采取差速离心法制备心肌细胞线粒体匀浆液，使用Clark氧电极测定上述两个检测时点的线粒体呼吸控制率（respiratory control rate，RCR）。采用SPSSl3．0统计软件分析结果。结果低温组和常温组在OGD1h后都出现收缩频率和收缩速率下降，但是常温组下降更明显（P=0．000）。随着OGR时间延长，两组的收缩参数都呈上升趋势，但低温组在1h后收缩功能接近正常，而常温组在观测时点始终低于对照组和低温组（P=0．000）。心肌细胞超微结果提示，常温组的线粒体肿胀明显，基质密度降低。线粒体RCR测定提示，低温组和常温组在OGR0h都明显降低，但后者损伤效应显著延长，持续到OGR2h。结论单纯缺血期亚低温可以减轻细胞线粒体的损伤，并有助于心肌细胞早期恢复收缩功能。
