The role of stroke volume variation in predicting the volume responsiveness of patients with severe sepsis and septic shock

Abstract

Objective To assess the role of stroke volume variation (SVV) in predicting the volume responsiveness of mechanically ventilated patients with severe sepsis and septic shock. Method A total of 28 mechanically ventilated patients with severe sepsis and septic shock were admitted from January 2009 to March 2010. Every patient was treated with volume loading test. Cardiac index (CI), stroke volume index (SVI), systemic vascular resistance (SVR) and SVV were measured non-invasively by Ultrasonic Cardiac Output Monitor (USCOM) device.Patients with an increase in CI ＞ 12% and ＜ 12% after volume loading test were classified as responders and nonresponders, respectively. The comparisons between these two sorts of patients were assessed by using two sample Student' s t -test, and comparisons between changes before and after volume loading test were assessed by using a paired Student's t -test. The roles of SVV, central venous pressure (CVP) and the changes of CVP (△CVP) after fluid administration in predicting volume responsiveness were evaluated by receiver operating characteristic (ROC) curves. Results Before volume loading test, the SVV was higher in responders in comparison with non-responders [(18.2 ± 4.7)% vs. (12.7 ± 4.2)%, P = 0.003] and the CVP was not significantly different between two groups [(10.2±4.0) cmH2O vs. (10.8±4.8) cmH2O, P ＞0.05]. After volume loading test,the CVP was lower in responders [(2.9 ± 3.1 ) cmH2O vs. (5.3 ± 2.7) cmH2O, P = 0.003]. The areas under the ROC curves (AUC) were 0.836 (95% CI:0.680 ～ 0.992,P = 0.003),0.549 (95% CI:0.329 ～ 0.768,P = 0.662)and 0.762 (95% CI:0.570 ～ 0.953,P = 0.019)for SVV, CVP and △CVP, respectively. The 15.5% of SVV value had the 84.6% of sensitivity and 80% of specificity for prediction of volume responsiveness. Conclusions SVV can serve as a valid indicator of predicting volume responsiveness in mechanically ventilated patients with severe sepsis and septic shock and it is more reliable than conventional indicators such as CVP and/△CVP. Key words: Stroke volume variation; Severe sepsis and septic shock; Volume responsiveness; Central venous pressure; Volume challenge; Hemodynamic; Mechanical ventilation; Cardiac index