Stroke volume variation does not predict fluid responsiveness in patients with septic shock on pressure support ventilation

Abstract

Background: Stroke volume variation (SVV) - as measured by the pulse contour cardiac output (PiCCO®) system - predicts the cardiac output response to a fluid challenge in patients on controlled ventilation. Whether this applies to patients on pressure support ventilation is unknown. Methods: Thirty consecutive patients with septic shock were included. All were on pressure support ventilation, monitored using the PiCCO® system and receiving 500 ml of colloid on clinical indications. Arterial pulse contour SVV and the transpulmonary thermodilution cardiac index were measured before and after fluid challenge. Results: Forty-seven per cent of the patients were defined as fluid responders by an observed increase of > 10% in the cardiac index after fluid. Prior to fluid challenge, the cardiac index was lower in responders compared with non-responders (mean ± SD, 3.0 ± 0.6 vs. 4.0 ± 1.2 l/min/m2, P < 0.01). In contrast, pre-infusion values of SVV were similar between subsequent responders and non-responders (13 ± 5 vs. 16 ± 6%, P = 0.26). The mean areas under the ROC curves were 0.77 (95% confidence interval, 0.60-0.94) and 0.52 (0.30-0.73) for pre-fluid cardiac index and SVV, respectively, indicating a predictive power of only the cardiac index. Conclusions: SVV did not predict the response in cardiac output to fluid challenge in patients with septic shock on pressure support ventilation. © Acta Anaesthesiologica Scandinavica (2006).