The Changes Of Arterial Carbon Dioxide Pressure（PaCO₂） During Passive Leg Raising（PLR） Predict Fluid Responsiveness In Circulatory Failure Patients

Objective: To investigate whether the changes of arterial carbon dioxidepressure(PaCO2) during passive leg raising(PLR) predict fluid responsiveness incirculatory failure patients.Methods:32patients with circulatory failure were enrolled in the study.Hemodynamic changes were determined by Pulse Indicator Continuous CardiacOutput(PiCCO) during a four-minute PLR(4-min PLR). Cardiac index(CI) combinedwith PaCO2before and after one minute of PLR were recorded respectively. Fluidchallenge was conducted by500ml equilibrium liquid within one hour after PLR, CIvalues were recorded before and after the infusion. The correlation betweenPLR-induced CI change(ΔCIPLR) and PaCO2(ΔPaCO2-PLR) was analyzed. Fluidresponsiveness was defined as an increase in CI(ΔCI) of15％or greater after volumeexpansion. The value of ΔPaCO2-PLRto predict fluid responsiveness was evaluated byreceiver operating characteristic(ROC) curves．Results: All the32patients completed the trial. After PLR，CI and PaCO2were bothsignificantly increased. ΔCIPLRand ΔPaCO2-PLRwere strongly correlated(r=0.64,P<0.05). An increase of≥5％in ΔPaCO2-PLRwas a high diagnostic valure to predictefluid responsiveness with a sensitivity of82.1%, specificity of100%, positivepredictive value of100%and negative predictive value of44.4%, and the area underROC curve of ΔPaCO2-PLRwas0.90(95％CI0.79-1.0，P<0.05).Conclusion: The change of arterial carbon dioxide partial pressure induced bypassive leg raising is a easy way to predict fluid responsiveness in circulatory failurepatients.