混合静脉血氧饱和度和静脉-动脉血二氧化碳分压差在体外循环心脏术后氧代谢监测及治疗中的价值

Values of mixed venous oxygen saturation and difference of mixed venous-arterial partial pressure of carbon dioxide in monitoring of oxygen metabolism and treatment after open-heart operation

目的探讨以混合静脉血氧饱和度（SvO2）和混合静脉-动脉血二氧化碳分压差（Pv-aCO2）为早期目标导向治疗（EGDT）靶点在体外循环心脏术后氧代谢监测及治疗中的价值。方法采用前瞻性研究方法，选择2011年12月至2014年3月在成都市第三人民医院择期行体外循环心脏手术并行肺动脉漂浮导管监测，且满足术后转入重症监护病房（ICU）时SvO2＜0.65、血乳酸＞2 mmol/L的成人患者。患者转入ICU后以SvO2≥0.65且Pv-aCO2＜6 mmHg（1 mmHg＝0.133 kPa）为靶点，立即给予EGDT治疗。根据转入ICU 6 h的SvO2及Pv-aCO2水平将患者分为A组（SvO2≥0.65且Pv-aCO2＜6 mmHg）、B组（SvO2≥0.65且Pv-aCO2≥6 mmHg）、C组（SvO2＜0.65），观察3组病情变化及预后差异。结果共入选103例患者，A组44例，B组31例，C组28例。A组转入ICU后6、24、48、72 h（T6、T24、T48、T72）急性生理学与慢性健康状况评分系统Ⅱ（APACHEⅡ）评分（分）均显著低于B组和C组（T6：11.4±5.8比13.9±5.4、13.7±6.4，T24：8.8±3.7比10.8±4.8、11.8±5.4， T48：8.7±4.1比9.6±4.2、10.2±5.1，T72：7.5±3.4比8.6±2.9、9.2±4.2，均P＜0.05）；序贯器官衰竭评分（SOFA，分）也呈同样趋势（T6：6.5±4.3比8.0±3.8、9.1±4.5，T24：6.6±3.6比8.6±3.9、8.5±3.3，T48：5.2±3.4比7.0±3.6、7.6±5.1，T72：4.6±2.4比5.8±2.5、6.8±3.5，均P＜0.05）；A组、B组T6、T24、T48、T72血乳酸（mmol/L）均明显低于C组（T6：1.60±0.95、2.20±1.02比2.55±1.39，T24：2.26±1.26、2.70±1.36比3.34±2.36，T48：2.01±1.15、2.17±1.51比2.42±1.63，T72：1.62±1.14、1.64±0.75比2.11±1.29，均P＜0.05）。A组、B组术后机械通气时间（d）较C组显著缩短（2.8±2.0、3.6±2.3比5.0±3.1，均P＜0.05）；A组术后ICU住院时间（d）较C组显著缩短（4.6±2.5比6.5±3.7，P＜0.05）。3组间术后7 d病死率差异具有统计学意义，与A组（2.3%）比较，B组（22.6%）的优势比（OR）为12.5（P＜0.05），C组（25.0%）的OR为14.3（P＜0.05）。3组间术后并发症发生率及术后28 d病死率比较差异均无统计学意义。Pv-aCO2与心排血指数（CI）呈显著负相关（r＝-0.685，P＝0.000），而Pv-aCO2与血乳酸水平无相关性（r＝0.187，P＝0.080）。结论以SvO2≥0.65且Pv-aCO2＜6 mmHg为EGDT靶点可改善体外循环心脏术后患者病情严重程度及组织缺氧程度，缩短机械通气时间及ICU住院时间，并可降低7 d病死率。

Objective To explore the clinic values of early goal directed treatment （EGDT）with the target of mixed venous oxygen saturation （SvO2）and difference of mixed venous-arterial partial pressure of carbon dioxide （Pv-aCO2） in monitoring of oxygen metabolism and treatment for patients post open-heart operation. Methods A prospective study was conducted. The adult patients admitted to Third People＆#39;s Hospital of Chengdu from December 2011 to March 2014 with SvO2〈0.65 and blood lactic acid〉2 mmol/L when admitted in intensive care unit（ICU）were selected on whom elective open-heart operation and pulmonary artery catheter examination were done. All patients received EGDT with the target of SvO2≥0.65 and Pv-aCO2〈6 mmHg （1 mmHg=0.133 kPa）and were divided into three groups by the values of SvO2 and Pv-aCO2 at 6-hour after ICU admission：A group with SvO2≥0.65 and Pv-aCO2〈6 mmHg,B group with SvO2≥0.65 and Pv-aCO2≥6 mmHg,and C group with SvO2〈0.65. Then the changes and prognosis of the patients in different groups were observed. Results 103 cases were included,44 in A group,31 in B group and 28 in C group. The acute physiology and chronic health evaluationⅡ （APACHEⅡ）score in group A were significantly lower than that in group B or C at 6,24,48 and 72 hours （T6,T24,T48,T72）of ICU admission （T6：11.4±5.8 vs. 13.9±5.4,13.7±6.4;T24：8.8±3.7 vs. 10.8±4.8,11.8±5.4;T48：8.7±4.1 vs. 9.6 ±4.2,10.2 ±5.1;T72：7.5 ±3.4 vs. 8.6 ±2.9,9.2 ±4.2,all P〈0.05）,and the sequential organ failure assessment （SOFA）showed the same tendency （T6：6.5±4.3 vs. 8.0±3.8,9.1±4.5;T24：6.6±3.6 vs. 8.6±3.9, 8.5±3.3;T48：5.2±3.4 vs. 7.0±3.6,7.6±5.1;T72：4.6±2.4 vs. 5.8±2.5,6.8±3.5,all P〈0.05）. The values of blood lactic acid （mmol/L）in group A and B were significant lower than that in group C at T6,T24,T48 and T72 （T6：1.60 ±0.95,2.20 ±1.02 vs. 2.55 ±1.39;T24：2.26 ±1.26,2.70 ±1.36 vs. 3.34 ±2.36;T48：2.01 ±1.15, 2.17 ±1.51 vs. 2.42 ±1.63;T72：1.62 ±1.14,1.64 ±0.75 vs. 2.11 ±1.29,all P〈0.05）. The time of machine ventilation（days）in group A or B was significantly shorter than that in group C（2.8±2.0,3.6±2.3 vs. 5.0±3.1,both P〈0.05）. ICU day （days）in group A was significant shorter than that in group C （4.6±2.5 vs. 6.5±3.7,P〈0.05）. The 7-day mortalities after operation in three groups were significantly different. Compared with group A （2.3%）,the odds ratio （OR）in group B （22.6%）was 12.5 （P〈0.05）,group C （25.0%）14.3 （P〈0.05）. The morbidity and 28-day mortality in three groups were not significantly different. Pv-aCO2 negatively correlated with cardiac index（CI, r=-0.685,P=0.000）,but not correlated with blood lactic acid（r=0.187,P=0.080）. Conclusions EGDT with the target of SvO2≥0.65 and Pv-aCO2〈6 mmHg improved the general condition and tissue hypoxia,shortened the time of machine ventilation and duration of hospitalization in ICU,and decrease the 7-day mortality.