The Clinical Research Of End-tidal Carbon Dioxide Partial Pressure Combined Passive Leg Raising Test In Volume Responsiveness Assessment On Shocked Patients Post Cardiac Operation

Background:It is vital to improve cardiac output and tissure perfusion in resuscitation with fluid in shocked patients.Overload of fluid for critically ill patients might lead to hear failure,pulmonary edema and increased mortality.Good effectiveness of fluid resuscitation is based on favorable volume responsiveness.Studies have demonstrated that only approximately 50%of hemodynamically unstable patients in the intensive care unit（ICU）respond to a fluid challenge.Instability of hemodynamics and complexity of cardiovascular function often appears in patients of post cardiac operation.Timely and accurate assessments of volume responsiveness are especially important to these patients.Passive leg raising（PLR）is a reversible maneuver that minics rapid fluid loading and increases cardiac preload.A rapid measurement of cardiac index（CI）is to meet the transient effect of increasing CI induced by PLR.Nowadays,dierect measurements of CI are limited in clinical settings.Convenient and reliable means for evaluating volume responsiveness are requied.Recent research hints at home and abroad that there is a close positive correlation with a value of end-tidal carbon dioxide partial pressure change（APetCO₂）and an increase in CI（ACI）in ventilated patients with stable ventilation and metabolism.Objective:To assess whether PetCO₂ combined PLR test could be used to predict volume responsiveness in shocked patients post cardiac operation.Methods:A prospective observational study of self-before and after mating was conducted.The shocked patients post cardiac operation undergoing complete mechanical ventilation admitted to Department of Critical Care Medicine of First Affiliated Hospital of College of Medicine,Zhejiang University from June 2014 to October 2015 were enrolled.PetCO₂ and hemodynamic parameters including stroke volume variation（SVV）,CI,mean arterial pressure（MAP）monitored by a pulse indicator continuous cardiac output（PiCCO）were determined before and after PLR and volume expansion（VE）.Volume responsiveness was defined asACI of 15%or greater after volume expansion,namely response group（ACI>15%）and non-response group（ACI<15%）.The value of PLR-induced PetC02 change（APetCO₂ PLR）to predict volume responsiveness was evaluated by receiver operating characteristic curves（ROC）.Results:Of the 41 patients enrolled,21 had volume responsiveness（response group）,and 20 had no responsiveness（non-response group）.After PLR,CI and PetCO₂ were both significantly increased in the response group compared with non-response group[ACI:（13.5±4.6）%vs.（3.6±3.5）%,APetC02:（7.4±3.4）%vs.（2.8±2.5）%,both P<0.05].After PLR,APetCO₂PLR and baseline SVV were positively correlated with PLR-induced CI change（ACI PLR）（r1 =0.50,r2 =0.38,both P<0.05）.VE-induced PetCO₂ change（APetCO₂ vE）,baseline SVV and ACI PLR were positively correlated with VE-induced CI（ACIVE）（r1=0.58,r2=0.56 and r3=0.84,all P<0.05）.The area under ROC curve（AUC）ofAPetCO₂ PLR was 0.875±0.054[95%confidence interval（95%CI）=0.769-0.981,P<0.05].APetCO₂ PLR≥5.8%predicted volume responsiveness with sensitivity of 76.2%and specificity of 90.0%.AUC of ACI PLR was 0.933±0.036（95%CI=0.862-1.000,P<0.05）.ACI PLR>10.4%predicted volume responsiveness with sensitivity of 81.0%and specificity of 90.0%.AUC of baseline SVV was 0.831 ±0.066（95%CI=0.702-0.960,P<0.05）.Baseline SVV>12.5%predicted volume responsiveness with sensitivity of 85.7%and specificity of 75.0%.Conclusions:The change of PetCO₂ induced by passive leg raising is a convenient,reliable and non-invasive indicator to predict volume responsiveness in shocked patients post cardiac operation with mechanical ventilation.