Comparison of the carotid corrected flow time and tidal volume challenge for assessing fluid responsiveness in robot-assisted laparoscopic surgery

Purpose We aimed to evaluate the ability of carotid corrected flow time assessed by ultrasound to predict fluid responsiveness in patients undergoing robot-assisted laparoscopic gynecological surgery in the modified head-down lithotomy position. Methods This prospective single-center study conducted at the Chongqing University Cancer Hospital included patients undergoing robot-assisted laparoscopic surgery in the modified head-down lithotomy position. Carotid doppler parameters and hemodynamic data, including corrected flow time, pulse pressure variation (PPV), stroke volume variation, and stroke volume index at a tidal volume of 6 mL/kg predicted body weight and after increasing the tidal volume to 8 mL/kg predicted body weight (tidal volume challenge), respectively, were measured. Fluid responsiveness was defined as a stroke volume index ≥10% increase after volume expansion. Results Among the 52 patients included, 26 were classified as fluid responders and 26 as non-responders based on the stroke volume index. The area under the receiver operating characteristic curve values measured to predict the fluid responsiveness to corrected flow time and changes in PPV (ΔPPV 6–8 ) after tidal volume challenge were 0.82 [95% confidence interval (CI): 0.705–0.937; P < 0.0001] and 0.85 (95% CI: 0.740–0.956; P < 0.0001), respectively. Both values were higher than those for PPV at a tidal volume of 8 mL/kg (0.79, 95% CI: 0.674–0.911; P = 0003). The optimal cut-off values for corrected flow time and ΔPPV 6–8 were 356.5 ms and >1%, respectively. Conclusion The change in PPV after tidal volume challenge and corrected flow time reliably predicted fluid responsiveness in patients undergoing robot-assisted laparoscopic gynecological surgery in the modified head-down lithotomy position. Trial registration Chinese Clinical Trial Register (CHiCTR2200060573)