Changes Of Central Venous Oxygen Saturation Define Fluid Responsiveness In Patients With Septic Shock

Purpose:Although dynamic parameters such as pulse pressure variation, stroke volume variationand so on have been suggested as indicators of fluid responsiveness, some prerequisitesprecludethe widespread use of these dynamic parameters in most clinical settings. In septic shock patients, the relationship between the changes of cardiacindex and the changes of central venous oxygen saturation is unknown. We hypothesized that the changes of central venous oxygen saturationcorrelated with the changes of cardiacindex in septic shock patients receiving fluid challenge, thus allowing the changes of central venous oxygen saturation to define fluid responsiveness.Methods:In this prospective observational study,septic shock patients with invasive cardiac output monitoring were included. Fluid challenges were carried out by infusing 500 ml of normal saline or 4% gelatin. Cardiac indexeswere measured before and after fluid challenges using thermodilution method by averaging three values of measurements. Central venous oxygen saturationswere also measured before and after fluid challenges.The changes of cardiac index and the changes of central venous oxygen saturation were analyzed using Pearson correlation.Fluid responsiveness was defined as an increase in cardiac index ≥10% in patients with sinus rhythm or an increase in cardiac index ≥15% in patients with atrial fibrillation or premature ventricular contractions. Receiver operating characteristics curveanalysis was used to classify fluid responders and nonresponders and area under receiver operating characteristics curve was calculated.Results:Thirty-four septic shock patients were included in this study, with 25 male patients. Their mean acute physiology and chronic health evaluationll score was 26.18 patients (53%) were responders to fluid challenge. In the responders, cardiac indexes increased from 3.1 ± 1.0 to 4.1 ± 1.0 1/min/m2(p< 0.001)and central venous oxygen saturationsincreasedfrom 72.8 ± 11.2 to 81.4 ± 9.6%(p< 0.001) after fluid challenge. In the nonresponders, neither cardiac indexes nor central venous oxygen saturationschanged (3.7 ± 1.4 vs.3.7 ± 1.41/min/m2, p= 0.821 and 73.7 ±1 10.8 vs.74.1 ±11.3%, p=0.649, respectively) after fluid challenge. The correlation between the changes of central venous oxygen saturation and the changes of cardiac index was significant (r= 0.7239, p< 0.001). The area under receiver operating characteristics curve of the changes of central venous oxygen saturation to predict fluid responsiveness was 0.93 (95% confidence interva10.85-1.00). Athreshold value of 5.2% of the changes of central venous oxygen saturation allowed the discrimination between responders and nonresponders with a sensitivity of 0.83 (95%confidence interval 0.59-0.96) and a specificity of 0.94 (95%confidence interval 0.70-1.00).Conclusions:The changes of central venous oxygen saturation correlate with the changes of cardiac index, and the changes of central venous oxygen saturationpredict fluid responsiveness in septic shock patients.However, further validation is mandatory before any recommendation can be made.Introduction; Fluid resuscitation is crucial in managing hemodynamically unstable patients. The last decade witnessed the use of pulse pressure variation(PPV) to predict fluid responsiveness. However,as far as we know,no systematic review and meta-analysis has been carried out evaluate the value of PPV in predicti打g fluid巧sponsiven的s specifically upon patients admitted into intensive care units.METHODS: We searched MEDLINE and EMBASE and included clinical trials that evaluated the association between PPV and fluid responsiveness after fluid challenge m瓜echanically ventilated patients in intensive care units. Data were synthesized using an exact biomial rendition of the bivariate mixed-effects regression model modi行ed for synthesis of diagnostic test data.Result: Twenty-two studies with 807 mechanically ventilated patients with ddal volume〉8 mllcg and without spontaneous breathing and cardiac arrhythmia were included,and465 were responders(58%). The pooled sensitivity was 0.88(95% confidence interval(CI),0.81-0.92) and pooled specificity was 0.89(95% Cl G.84-0.92). A summary receiver operating characteristic cxirve yielded an area under the curve of 0.94(95% Cl 0.91-0.95).A signi巧cant threshold effect was identi巧ed.Conclusions: PPV predicts fluid responsiveness accurately in mechanically ventilated patie打ts wi化 relative large lidal volume and without spontaneous breathing and cardiac arrhythmia.