Abstract
Background: Pulse pressure variation (PPV) and stroke volume variation (SVV) induced by mechanical ventilation are widely used as predictors of fluid responsiveness. However, the reliability of these dynamic preload indices is controversial under pneumoperitoneum. In addition, the usefulness of these indices is being called into question with the increasing adoption of lung-protective ventilation using low tidal volume (VT) in surgical patients. We investigated whether increasing tidal volume (VT) from 6 to 8 ml/kg can improve the predictive power of PPV and SVV during pneurmoperitoneum. Methods: We performed a prospective observational study in patients undergoing robot-assisted laparoscopic surgery in the Trendelenburg position under lung-protective ventilation. PPV, SVV, and the stroke volume index (SVI) were measured at a VT of 6 mL/kg and 3 minutes after increasing the VT to 8 mL/kg. The VT was reduced to 6 mL/kg, and measurements were performed before and 5 minutes after volume expansion (infusing 6% hydroxyethyl starch 6 ml/kg over 10 minutes). Fluid responsiveness was defined as ≥ 15% increase in the SVI. Results: Twenty-four of the 38 patients enrolled in the study were responders. In the receiver operating characteristic curve analysis, the augmented PPV and SVV associated with a temporary increase in VT from 6 to 8 ml/kg improved the predictability of fluid responsiveness, with area under the curve (AUC) values of 0.85 (95% confidence interval (CI), 0.70–0.95, P < 0.0001) and 0.77 (95% CI 0.61–0.89, P = 0.0003), compared to PPV and SVV values (as measured by VT) of 6 ml/kg. The absolute change in PPV and SVV values obtained by transiently increasing VT also predicted fluid responsiveness, with AUC values of 0.95 (95% CI 0.83–0.99, P < 0.0001) and 0.76 (95% CI 0.60–0.89, P = 0.0006). Conclusions: Augmented PPV and SVV values, and absolute changes therein obtained by increasing VT from 6 to 8 ml/kg, predicted fluid responsiveness with high sensitivity and specificity in our surgical population.
Hemodynamic, renal and hormonal effects of lung protective ventilation during robot-assisted radical prostatectomy, analysis of secondary outcomes from a randomized controlled trial
