Utility of stroke volume variation measured using non-invasive bioreactance as a predictor of fluid responsiveness in the prone position

The aim of this prospective study was to evaluate the usefulness of stroke volume variation (SVV) derived from NICOMA (R) to predict fluid responsiveness in the prone position. Forty adult patients undergoing spinal surgery in the prone position were included in this study. We measured SVV from NICOMA (R) (SVVNICOM) and FloTrac (TM)/Vigileo (TM) systems (SVVVigileo), and pulse pressure variation (PPV) using automatic (PPVauto) and manual (PPVmanual) calculations at four time points including supine and prone positions, and before and after fluid loading of 6 ml kg(-1) colloid solution. Fluid responsiveness was defined as an increase in the cardiac index from Vigileo (TM) of >= 12 %. There were 19 responders and 21 non-responders. Prone positioning induced a significant decrease in SVVNICOM, SVVVigileo, PPVauto, and PPVmanual. However, all of these parameters successfully predicted fluid responsiveness in the prone position with area under the receiver-operator characteristic curves for SVVNICOM, SVVVigileo, PPVauto, and PPVmanual of 0.78 [95 % confidence interval (CI) 0.62-0.90, P = 0.0001], 0.79 (95 % CI 0.63-0.90, P = 0.0001), 0.76 (95 % CI 0.6-0.88, P = 0.0006), and 0.84 (95 % CI 0.69-0.94, P < 0.0001), respectively. The optimal cut-off values were 12 % for SVVNICOM, SVVVigileo, and PPVauto, and 10 % for PPVmanual. SVV from NICOMA (R) successfully predicts fluid responsiveness during surgery in the prone position. This totally non-invasive technique for assessing individual functional intravenous volume status would be useful in a wide range of surgeries performed in the prone position.