分钟通气量对NICO心输出量测定的影响

Effect of Minute Ventilation Setting on the Novametrix Medical Systems Inc(NICO) for Cardiac Output Monitoring by Experiment

目的探讨机械通气的分钟通气量对无创心输出量监测仪(NICO)心输出量测定准确性的影响,为重症监护病房(ICU)更好地应用此监测仪提供依据。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NICO,应用部分CO2重复吸入法测定无创心输出量(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)。改变机械通气参数设置,分别在分钟通气量12.0L/min、6.0L/min条件下用两种方法同时测定心输出量,并对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:分钟通气量为12.0L/min时,CORB为(5.38±1.65)L/min,COTD为(5.31±1.62)L/min,CORB和COTD比较,差异无统计学意义(P>0.05);CORB和COTD的偏差、精确性分别为0.19和1.07,相关系数为对0.89,容许范围为(-1.76^+2.24)L/min;分钟通气量设置为6.0L/min时,CORB为(4.32±1.23)L/min,COTD为(5.48±1.51)L/min,CORB较COTD低,差异有统计学意义(P<0.05),两者的偏差、精确性分别为-1.78和1.14,相关系数为0.75,容许范围为(-3.76^+1.56)L/min。结论应用NICO测定的无创心输出量与经典热稀释法测定的有创心输出量相关性良好,但分钟通气量对前者心输出量测定具一定影响,较小分钟通气量控制通气时,CORB和COTD相关性降低。

Objective To explore the effect of minute ventilation setting on the Novametrix Medical Systems Inc（NICO） for cardiac output monitoring in order to provide the evidence of clinical application in ICU.Methods Eight healthy anesthetized and ventilated dogs 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 COTD were performed under two different ventilator settings： ① volume controlled ventilation with minute ventilation of 12.0L/min（VCV,VT 6mL/kg,RR20breaths/min）;② volume controlled ventilation with minute ventilation of 6.0L/min（VCV,VT 6mL/kg,RR10breaths/min）;Paired t-test and regression statistics were used to compare the degree of agreement between concurrent measurement of COTD and CORB.Results Paired t-test analysis revealed no significant difference between CORB and COTD measurement when VCV at VE12.0L/min（P0.05）.Under this ventilator setting,Regression analysis revealed an Rvalue of 0.89 and the bias and limits of agreement were as follows： 0.19 and-1.76~＋2.24L/min;while,there is also a significant correlation was found between CORB and COTD when VE setting at 6.0L/Min：R=0.75,bias-1.78,limits of agreement-3.76~＋1.56 L/min,the CORB technique underestimated cardiac output compared with COTD technique（P0.05）.Conclusion There is a high correlation between CORB and COTD measurement.Minute ventilation is the dominant factor affecting the accuracy of CORB.