潮气量设置对部分二氧化碳重复吸入心输出量测定准确性影响的动物实验研究

Effect of tidal volume setting on the accuracy of partial CO_2 rebreathing technique for cardiac output monitoring by animal experiment

目的:探讨机械通气潮气量设置对部分CO2重复吸入心输出量测定准确性的影响,为临床应用提供依据。方法:选用重庆地区健康雄性杂种犬8只,麻醉后气管切开机械通气。接无创心输出量监测仪(美国NICO),应用部分CO2重复吸入法测定心输出量(CORB);同时经右颈内静脉插入肺动脉漂浮导管,以热稀释法测定有创心输出量(COTD)。改变机械通气参数潮气量设置,分别在潮气量12ml/kg、6ml/kg条件下用两种方法同时测定心输出量,两种方法所测心输出量进行自体配对相关性研究。结果:配对t检验示潮气量为12ml/kg时,CORB为5.40 L/min±1.35 L/min,COTD为5.31 L/min±1.42 L/min,CORB和COTD比较,差异无显著性(P>0.05);CORB和COTD的偏差、精确性分别为0.19和1.06,相关系数为0.90,容许范围为-1.78 L/min至+2.14L/min;Vt设置为6ml/kg时CORB为4.21 L/min±1.20L/mln,COTD为5.65 L/min±1.61 L/min,CORB较COTD低,差异有显著性(P<0.05),两者的偏差、精确性分别为-1.68和1.04,相关系数为0.74,容许范围为-3.78 L/min至+1.58L/min。结论:部分二氧化碳重复吸入无创心输出量与热稀释有创心输出量相关性良好,潮气量是影响CORB准确性的因素之一。

Objective To explore the Effect of tidal volume setting on the accuracy of partial CO2 rebreathing technique for cardiac output monitoring in order to provide the evidence of clinical application. Methods Eight healthy anesthetized and ventilated dog were enrolled in this study. Each animal was inserted with Swan - Ganz catheter , and was installed a partial CO2 rebreathing ventilator circuit （Novametrix Medical SysteMs Inc, NICO）. Simultaneous measurement of CORB, and CORD, were performed under two different ventilatory settings：（1） volume controlled ventilation with tidal volume of 12ml/kg（VCV, VT 12ml/kg） ;（2）volume controlled ventilation with tidal volume of 6ml/kg（ VCV, VT 6ml/kg） ; Paired t - test and regression statistics were used to compare the degree of agreement between concurrent measurement of COn, and CORb. Results Paired t - test analysis revealed no significant difference between COW and COTD measurement when VCV at VT 12ml/kg（ P 〉 0. 05 ）. Under this ventilator）, setting, Regression analysis revealed an R value of 0.90 and the bias and limits of agreement were as follows ： 0. 19 and - 1.78L/min - ＋ 2.14L/min; while,there is also a significant correlation was found between CORB and COrn when Vt setting at 6ml/kg： R = 0.74, bias - 1.68, limits of agreement -3.78L/min - ＋ 1.58 L/min, the CORs, technique underestimated cardiac, output compared with COrn technique（P 〈 0. 05）. Conclusion There is a high correlation between CORB, and COrD measurement. Tidal volume is one of the important factor affecting the accuracy of CORB.