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目的评价中心静脉-动脉二氧化碳分压差/动脉-中心静脉氧含量差比值[P(cv-a)CO_2/C(a-cv)O_2]对脓毒性休克患者液体复苏后氧代谢变化的预测价值。方法采用前瞻性观察研究方法,纳入2013年11月至2014年4月南京大学医学院附属鼓楼医院重症医学科收治的脓毒性休克患者。所有患者均给予容量负荷试验(生理盐水300 ml于20 min内经静脉快速滴注)。根据液体复苏前后心排指数的变化(ΔCI),分为液体有反应组(ΔCI≥10%)和无反应组(ΔCI<10%)。在液体有反应组,根据液体复苏前后氧耗的变化(ΔVO_2)分为ΔVO_2≥10%和ΔVO_2<10%两个亚组。采用脉搏指示连续心排出量(PICCO)监测患者的心排指数(CI),并通过血气分析测定患者血红蛋白水平、动脉血二氧化碳(Pa CO_2)、动脉血氧分压(Pa O_2)、动脉血氧饱和度(Sa O_2)、动脉血乳酸、中心静脉血二氧化碳(Pcv CO_2)、中心静脉血氧分压(Pcv O_2)、中心静脉血氧饱和度(Scv O_2),并计算P(cv-a)CO_2/C(a-cv)O_2和氧耗(VO_2)。比较两组患者液体复苏前后的P(cv-a)CO_2/C(a-cv)O_2指标差异。结果纳入18例脓毒性休克患者,共实施液体复苏23次,其中液体有反应性17例次,无反应性6例次。液体有反应组和无反应组比较,复苏前P(cv-a)CO_2/C(a-cv)O_2、动脉血乳酸、Scv O_2均无显著差异[P(cv-a)CO_2/C(a-cv)O_2(mm Hg/ml):2.05±0.75 vs.1.58±0.67;乳酸(mmol/L):3.78±2.50 vs.3.26±2.42;Scv O_2(%):73.71±9.64 vs.70.30±12.01,均P>0.05)。液体有反应组中,有10例次ΔVO_2≥10%,7例次ΔVO_2<10%,ΔVO_2≥10%亚组复苏前P(cv-a)CO_2/C(a-cv)O_2(mm Hg/ml)显著高于ΔVO_2<10%亚组(2.43±0.73 vs.1.51±0.37,P<0.01),动脉血乳酸(mmol/L)亦显著高于ΔVO_2<10%亚组(4.53±2.52 vs.1.46±0.82,P<0.01),Scv O_2(%)无显著变化(70.79±9.15 vs.72.13±13.42,P>0.05)。P(cv-a)CO_2/C(a-cv)O_2、乳酸和Scv O_2预测复苏后ΔVO_2≥10%的受试者工作特征曲线下面积(AUC)分别为0.843、0.921、0.529。以P(cv-a)CO_2/C(a-cv)O_2≥1.885 mm Hg/ml预测液体复苏后ΔVO_2≥10%的敏感性为70%,特异性为86%。结论对于有液体反应性的脓毒性休克患者,P(cv-a)CO_2/C(a-cv)O_2可用于预测液体复苏后氧代谢的变化,是一项指导液体复苏的有效指标。
Objective To evaluate the predictive value of central venous-arterial partial pressure of carbon dioxide / arterial-central venous oxygen difference [P (cv-a) CO_2 / C (a-cv) O_2] on the changes of oxygen metabolism after fluid resuscitation in septic shock patients . Methods A prospective observational study was included in the septic shock patients admitted to the Department of Critical Care Medicine, Drum Tower Hospital, Nanjing University School of Medicine from November 2013 to April 2014. All patients were given a volume load test (saline 300 ml rapid intravenous infusion within 20 min). According to the change of cardiac index (ΔCI) before and after liquid resuscitation, there were two groups: liquid reaction group (ΔCI≥10%) and non-reaction group (ΔCI <10%). In the response group, the changes of oxygen consumption (ΔVO_2) before and after liquid resuscitation were divided into two subgroups: ΔVO_2≥10% and ΔVO_2 <10%. The patient’s cardiac index (CI) was monitored by PICCO. Hemoglobin level, PaCO 2, Pa O 2, arterial oxygenation (Sav_2), arterial blood lactate, Pcv CO_2, Pcv O_2 and Scv O_2 were calculated, and P (cv-a) CO_2 / C (a-cv) O_2 and oxygen consumption (VO_2). The difference of P (cv-a) CO 2 / C (a-cv) O 2 before and after liquid resuscitation was compared between the two groups. Results A total of 18 patients with septic shock were enrolled in this study. Liquid resuscitation was performed 23 times, of which 17 cases were reactive and 6 cases were nonreactive. There were no significant differences in P (cv-a) CO_2 / C (a-cv) O_2, arterial blood lactate and Scv O_2 before and after resuscitation -cv) O 2 (mm Hg / ml): 2.05 ± 0.75 vs.1.58 ± 0.67; Lactic acid (mmol / L): 3.78 ± 2.50 vs.3.26 ± 2.42; Scv O 2 (%): 73.71 ± 9.64 vs. 70.30 ± 12.01 , All P> 0.05). There were 10 cases of ΔVO_2≥10%, 7 cases of ΔVO_2 <10%, and ΔVO_2≥10% of the responders before liquid resuscitation. The levels of cv-a CO_2 / C (a-cv) O_2 (mm Hg / ml) was significantly higher than that of ΔVO_2 <10% (2.43 ± 0.73 vs.1.51 ± 0.37, P <0.01), arterial blood lactate (mmol / L) was significantly higher than that of ΔVO_2 <10% (4.53 ± 2.52 vs. 1.46 ± 0.82, P <0.01). There was no significant change in Scv O 2 (%) (70.79 ± 9.15 vs.72.13 ± 13.42, P> 0.05). The area under the working characteristic curve of subjects with ΔVO_2≥10% predicted by P (cv-a) CO_2 / C (a-cv) O_2, lactic acid and Scv O_2 were 0.843,0.921 and 0.529, respectively. The predictive value of ΔVO_2≥10% after liquid resuscitation with P (cv-a) CO_2 / C (a-cv) O_2≥1.885 mm Hg / ml was 70% and the specificity was 86%. Conclusions P (cv-a) CO 2 / C (a-cv) O 2 can be used to predict the changes of oxygen metabolism after fluid resuscitation in patients with fluid-reactive septic shock. It is an effective indicator of fluid resuscitation.