瓣膜置换术患者不同呼吸状态下PetCO_2与PaCO_2关系研究

A comparative study of PaCO_2 and PetCO_2 under different respiration patterns during artificial valve replacement

目的 :研究瓣膜置换术患者由自主呼吸转变为机械通气后动脉血 CO2 分压 (Pa CO2 )与呼气末 CO2 分压 (Pet CO2 )关系的变化。 方法 :选择 2 2例心功能 级瓣膜置换术患者 ,观察全身麻醉前、后 Pa CO2 、Pet CO2 、心排血量 (CO)、平均动脉压(MAP)、平均肺动脉压 (PAP)、中心静脉压 (CVP)、肺动脉楔压 (PAWP)、外周血管阻力 (SVR)、肺血管阻力 (PVR)、肺泡死腔/潮气量 (VD/ VT,alv)的变化。 结果 :与麻醉诱导前的自主呼吸相比 ,机械通气后 Pa CO2 - Pet CO2 差值、CVP、VD/ VT,alv比值显著升高 (P<0 .0 1) ,Pet CO2 、CO、PAP、PAWP和 MAP均显著下降 (P<0 .0 1和 P<0 .0 5 ) ,而 Pa CO2 、SVR、PVR、碱剩余 (BE)均无明显改变。自主呼吸下 Pet CO2 、CO与 VD/ VT,alv的相关性较差 ,而机械通气时 Pet CO2 与 CO呈明显正相关 (P<0 .0 5 ) ,Pet CO2 、CO与 VD/ VT,alv比值则呈明显的负相关。 结论 :Pa CO2 与 Pet CO2 的关系随呼吸方式的变化而不同 ,自主呼吸时两者相关性良好 ,而控制呼吸时两者相关性较差。机械通气时 Pet CO2 与 CO明显相关 ,可通过改善循环功能而提高通气效率。Pet CO2 在循环状况不稳定时难以反映 Pa CO2 ,应行动脉血气分析来判断 Pa CO2 。

Objective:To investigate the relationship between PaCO 2 and PetCO 2 while the respiration pattern changed from spontaneous to mechanical ventilation during artificial valve replacement. Methods:The changes of PaCO 2,PetCO 2,CO,MAP,PAP,CVP,PAWP,SVR,PVR and V D/V T,alv from spontaneous respiration to mechanical ventilation were observed pre and post general anesthesia in 22 patients undergoing artificial valve replacement. Results:Compared with spontaneous respiration before general anesthesia induction, the differences between PaCO 2 and PetCO 2,CVP,V D/V T,alv ratio were significantly increased( P <0.01), PetCO 2,CO,PAP,PAWP and MAP were markedly decreased( P <0.01 and P < 0.05), and no obvious changes in PaCO 2,SVR,PVR and BE were found after mechanical ventilation. PetCO 2 and CO didn't correlate with V D/V T,alv under spontaneous respiration, but PetCO 2 correlated positively with CO ( P <0.05), PetCO 2 and CO correlated negatively with V D/V T,alv under mechanical ventilation. Conclusion:The correlativity between PaCO 2 and PetCO 2 changes under different respiration pattern. They have good relativity under spontaneous respiration, but the relativity get worse under mechanical ventilation. PetCO 2 and CO have good relativity under mechanical ventilation. Respiratory efficiency can be increased by modification of circulatory function. Under unsteady hemodynamics, PetCO 2 can't reflect PaCO 2 accurately, the latter should be checked by blood gas analysis.