中心静脉-动脉二氧化碳分压差联合颈内静脉扩张指数预测脓毒性休克患者容量反应性

Predictive value of central venous-arterial carbon dioxide tension difference combined with internal jugular vein dilation index for fluid responsiveness in septic shock patients

目的评估容量负荷试验引起的中心静脉-动脉二氧化碳分压差(ΔPcv-aCO_(2))变化联合颈内静脉扩张指数(internal jugular vein dilation index,ΔIJV)能否预测脓毒性休克并行机械通气患者的容量反应性。方法前瞻性纳入2018年1月至2020年1月兰州大学第二医院重症医学科诊断为脓毒性休克并行机械通气的成年患者,所有患者均接受容量负荷试验(30 min内输注500 mL平衡液),记录容量负荷试验前(T0)及容量负荷试验后即刻(T1)相关血流动力学指标,分别于T0及T1同时收集中心静脉及动脉血行血气分析,中心静脉-动脉二氧化碳分压差(Pcv-aCO_(2))=PcvCO_(2)-PaCO_(2),ΔPcv-aCO_(2)=Pcv-aCO_(2)T1-Pcv-aCO_(2)T0。超声测量左心室搏出量(SV)、颈内静脉最大前后径(IJVmax)及最小前后径(IJVmin),计算ΔIJV=(IJVmax-IJVmin)/[(IJVmax+IJVmin)/2]×100%,ΔSV=(SVT1-SVT0)/SVT0×100%,ΔSV≥15%为有容量反应性(R组),ΔSV<15%为无容量反应性(NR组)。组间及组内比较容量负荷试验前后相关指标;ΔPcv-aCO_(2)和ΔIJV与ΔSV的相关性采用Pearson相关分析评价;通过受试者工作特征曲线下面积(AUC)评估ΔPcv-aCO_(2)和ΔIJV对容量反应性的预测价值。结果研究共纳入86例患者,R组47例,NR组39例。R组容量负荷试验前△IJV明显大于NR组,容量负荷试验后Pcv-aCO_(2)下降(ΔPcv-aCO_(2))较NR组更明显(P<0.05)。△SV与容量负荷试验前ΔIJV呈明显正相关(r=0.804,P<0.001),与△Pcv-aCO_(2)呈明显负相关(r=-0.721,P<0.001)。容量负荷试验前ΔIJV预测容量反应性的AUC为0.878[95%可信区间(95%CI)0.789~0.939],ΔIJV>19.0%为预测截断值,敏感度72.3%,特异度94.8%,阳性似然比(LR+)14.1,阴性似然比(LR-)0.3;ΔPcv-aCO_(2)预测容量反应性的AUC为0.801(95%CI 0.701~0.879),容量负荷试验后Pcv-aCO_(2)下降>0.7 mm Hg为预测截断值,敏感度72.3%,特异度92.3%,LR+9.4,LR-0.3;容量负荷试验前ΔIJV联合ΔPcv-aCO_(2)预测容量反应性的AUC为0.932(95%CI 0.856~0.975),明显大于各自的AUC(Z=2.089,P=0.037;Z=2.920,P=0.004),两指标联合后ΔIJV>18.0%和Pcv-aCO_(2)下降>0.4 mm Hg作为预测截断值,敏感度83.0%,特异度97.4%,LR+32.3,LR-0.2。结论ΔPcv-aCO_(2)及ΔIJV均能预测脓毒性休克并行机械通气患者的容量反应性,两指标联合可提高预测价值。

Objective To evaluate whether the changes in central venous-to-arterial carbon dioxide tension difference(ΔPcv-aCO_(2))induced by the fluid challenge combined with internal jugular vein dilation index(ΔIJV)can predict volume responsiveness in the patients with septic shock and mechanical ventilation.Methods Mechanically ventilated adult patients diagnosed with septic shock in the Intensive Care Unit of Lanzhou University Second Hospital from January 2018 to January 2020 were prospectively enrolled,and all the patients received a fluid challenge(500 mL of equilibrium solution infusion within 30 min).Hemodynamic data coupled with ultrasound evaluation of stroke volume(SV),internal jugular vein maximal antero-posterior diameter(IJVmax)and minimal diameter(IJVmin)were collected before fluid challenge(T0)and after fluid challenge(T1).Internal jugular vein dilation index(ΔIJV)and fluid challenge-induced increase in stroke volume(ΔSV)were calculated.ΔIJV=(IJVmax-IJVmin)/[(IJVmax+IJVmin)/2]×100%,ΔSV=(SVT1-SVT0)/SVT0×100%,ΔSV≥15%for volume-responders(R group)andΔSV<15%for non-volume-responders(NR group).Central venous and arterial blood was collected simultaneously at T0 and T1 for blood gas analysis,respectively.Central venous-to-arterial carbon dioxide tension difference(Pcv-aCO_(2))=PcvCO_(2)-PaCO_(2),ΔPcv-aCO_(2)=Pcv-aCO_(2)T1-Pcv-aCO_(2)T0.Parameters before and after the fluid challenge were compared between and within groups.Correlation ofΔPcv-aCO_(2)andΔIJV withΔSV were evaluated by Pearson correlation analysis.The predictive value ofΔPcv-aCO_(2)andΔIJV in volume responsiveness was assessed by comparing the area under the receiver operating characteristic curve(AUC).Results A total of 86 patients were included in the study,47 patients in R group,and 39 patients in NR group.R group presented higherΔIJV before fluid challenge,and higherΔPcv-aCO_(2)after fluid challenge than NR group(P<0.05).The correlation betweenΔSV andΔIJV before fluid challenge was 0.804(P<0.001),and betweenΔSV andΔPcv-aCO_(2)was-0.721(P<0.001).The AUC ofΔIJV before fluid challenge for predicting fluid responsiveness was 0.878(95%CI 0.789-0.939).The best cutoff value forΔIJV was>19.0%with 84.4%sensitivity,94.8%specificity,14.1 positive likelihood ratio(LR+),0.3 negative likelihood ratio(LR-).The AUC forΔPcv-aCO_(2)was 0.801(95%CI 0.701-0.879).The best cutoff value forΔPcv-aCO_(2)was fluid challenge-induced decrease in Pcv-aCO_(2)>0.7 mm Hg with 72.3%sensitivity,92.3%specificity,9.4 LR+,0.3 LR-.The AUC forΔIJV before fluid challenge combined withΔPcv-aCO_(2)was 0.932(95%CI 0.856-0.975),which was significantly greater than that ofΔIJV(Z=2.089,P=0.037)orΔPcv-aCO_(2)(Z=2.920,P=0.004)alone.ΔIJV>18.0%and Pcv-aCO_(2)decrease>0.4 mm Hg were used as predictive cutoff values after the combination of two indicators with 83.0%sensitivity,97.4%specificity,32.3 LR+,0.2 LR-.Conclusions BothΔPcv-aCO_(2)andΔIJV can predict volume responsiveness in mechanically ventilated patients with septic shock,and the combination of the two indices improves their predictive value.