Clinical evaluation of the change of pressure gradient between mean systemic filling pressure and central venous pressure in fluid responsiveness for septic shock patients

Abstract

Objective To evaluate clinical value of the change of pressure gradient between mean systemic filling pressure (Pmsf) and central venous pressure (CVP) in fluid responsiveness for septic shock patients. Methods A prospective observational study was conducted. Twenty patients with septic shock undergoing mechanical ventilation who admitted to intensive care unit of Nanjing Drum-tower Hospital from January 2017 to September 2017 were enrolled. All patients underwent volume expansion (VE) (300 ml saline for 20 min, rapid intravenous infusion). The patients were divided into fluid responded group (ΔCI≥10%) and fluid unresponded group (ΔCI<10%), according to the change of cardiac output index (ΔCI) after VE. The hemodynamic parameters [heart rate (HR), mean arterial pressure (MAP), central venous pressure (CVP), systemic vascular resistance index (SVRI), intrathoracic blood volume index (ITBVI), extravascularlung water index (EVLWI), stroke volume variation (SVV), Pmsf, Pmsf-CVP, the change of Pmsf (ΔPmsf), Δ(Pmsf-CVP)] before and after VE were recorded. The hemodynamic parameters were compared between two groups. Receiver operating characteristic (ROC) curve was plotted to analyze the value of hemodynamic parameters in fluid responsiveness. Results VE were performed in 26 instances in 20 patients, among which 17 instances were fluid responded. Pmsf and (Pmsf-CVP) before VE in responsive group were significantly lower than those of the non-responsive group [(19.06±3.03) mmHg vs (23.00±5.96) mmHg, (8.29±3.92) mmHg vs (14.78±6.12) mmHg, t=-2.26, -3.30, all P<0.05]. ΔPmsf and Δ(Pmsf-CVP) in responsive group were significantly higher than those of the non-responsive group [10.00(6.00, 14.00) mmHg vs 4.00 (1.00, 9.50)mmHg, 7.00(3.50, 11.50) mmHg vs -1.00(-2.00, 3.00) mmHg, z=-2.57, -2.75, all P<0.05]. ROC curve analysis showed that the area under ROC curve (AUC) of Pmsf before VE, (Pmsf-CVP) before VE, ΔPmsf and Δ(Pmsf-CVP) for evaluating fluid responsiveness was 0.739, 0.810, 0.810 and 0.902 respectively, which was significantly higher than that of ΔCVP (AUC=0.654). The optimal cut-off value of Pmsf before VE for evaluating fluid responsiveness was 21.98 mmHg with a sensitivity of 88.2%, and a specificity of 66.7%. The optimal cut-off value of (Pmsf-CVP) before VE for evaluating fluid responsiveness was 11.48 mmHg with a sensitivity of 88.2%, and a specificity of 77.8%. The optimal cut-off value of ΔPmsf for evaluating fluid responsiveness was 5.5 mmHg with a sensitivity of 82.4%, and a specificity of 66.7%. The optimal cut-off value of Δ(Pmsf-CVP) for evaluating fluid responsiveness was 3.5 mmHg with a sensitivity of 76.5%, and a specificity of 100.0%. Conclusion Pmsf before VE, (Pmsf-CVP) before VE, ΔPmsf and Δ(Pmsf-CVP) can evaluate fluid responsiveness in patients with septic shock and undergoing mechanical ventilation. Δ(Pmsf-CVP) has the highest value among these parameters. Key words: Septic shock; Fluid responsiveness; Mean systemic filling pressure; Change of pressure gradient between mean systemic filling pressure and central venous pressure