上腔静脉血二氧化碳分压乳酸与动脉净差值氧利用率在早期重型颅脑损伤患者中的变化及意义

Change and significance of arteriovenous difference of lactic acid and carbon dioxide, oxygen utilization coefficient in the superior vena cava at the early stage of severe brain injury

目的观察上腔静脉血氧利用率（O2UCsv）、上腔静脉血与动脉血二氧化碳分压净差值（VAPsvCO2）、上腔静脉与动脉血乳酸净差值（VAsvLa）在早期重型颅脑损伤患者中的变化及评价它们反映全脑氧代谢改变的意义。方法比较VAPsvCO2、VAsvLa、O2UCsv与颈静脉血各值间及病情轻重间的差异。结果重型组VAPsvCO2、VAsvLa、O2UCsv与颈内静脉血比较差异无统计学意义（均P〉0．05）；轻中型颅脑损伤患者VAPsvCO2、VAsvLa与颈内静脉血比较差异无统计学意义（均P〉0．05），O2UCsv与颈内静脉血比较差异有统计学意义（P〈0．05）。VAsvLa在重型组中为负值，轻中型组为正值，两组比较差异有统计学意义（P〈0．05）。VAPsvCO2在重型、轻中型组中均为正值，轻中型组差值较重型组大（P〈0．05）；O2UCsv重型组较轻中型组数值小（P〈0．05）。结论重型颅脑损伤患者呈低O2UCsv、低VAPsvCO2、负VAsvLa，均与颈内静脉血中各值呈正相关，是早期颅脑损伤病情极重的标志。上腔静脉血血气、乳酸监测对全脑氧代谢监测有临床价值。

Objective To observe the change of oxygen utilization coefficient （O2 UC ） of superior vena cava（sv） and arteriovenous difference of lactic acid （VAsvLa） and carbon dioxide （VAPCO2sv） in the superior vena cava at the early stage of severe brain injury, and to evaluate their significance in reflecting the oxygen metabolic changes of the whole brain. Method To compare the O2 UC, VAPCO2 and VALa in superior vena cava with those in internal jugular vein and in mild - moderate and severe brain injury. Result No difference was observed between VAPCO2 sv, VAsvLa, O2 UCsv of patients with severe brain injury and those of internal jugular vein（all P 〉 0.05）. No significant difference existed between VAPCO2 sv and VAsvLa of patients with mild -to- moderate brain injury and those of internal jugular vein（both P 〉 0.05）. The O2UCsv was significantly different from oxygen utilization coefficient in internal jugular vein （P 〈 0. 05）. VAsvLa was negative in the patients with severe brain injury, while VAsvLa was positive in the patients with mild - to - moderate brain injury. The differences between the two groups were obvious （P 〈 0. 05 ）. VAPCOEsV in patients with both severe and mild - to - moderate brain injury was positive. The net value of difference in mild-to-moderate brain injury was greater than that of severe brain injury（P 〈0.05）. O2UCsv in mild - to - moderate brain injury was greater than that of severe brain injury （ P 〈 0.05 ）. Conclusion Patients with severe brain injury show low O2UCsv, low VAPCO2sv and negative VAsvLa, which are all positively correlated with those of internal jugular vein, and is an indication of serious condition of brain injury at the early stage. Blood -gas and lactic acid monitoring of superior vena cava is an alternative approach in cerebral oxygen metabolism monitoring with clinical value.