Utility of Dynamic Variables Measured by Calibrated Pulse Contour Analysis of Oesophageal Doppler Monitor for Predicting Fluid Responsiveness During Robot-Assisted Laparoscopic Prostatectomy

Robot-assisted laparoscopic prostatectomy (RALP) is widely performed due to its many advantages, including a reduced need for blood transfusion and fewer surgical complications compared with conventional open prostatectomy. As this approach is also recommended in elderly patients with serious comorbidities, optimal fluid therapy guidance during this procedure is important.

Dynamic variables such as pulse pressure variation (PPV) and stroke volume variation (SVV) are used to predict and guide fluid therapy during controlled ventilation. These variables arise from heart-lung interactions during positive pressure ventilation, which influence left ventricular stroke volume (SV). RALP requires carbon dioxide insufflation and the steep Trendelenburg position to optimise surgical conditions, and can reduce cardiac output and respiratory compliance. Accordingly, the usefulness of PPV and SVV, which are affected by changes in intrathoracic pressure, in predicting fluid responsiveness during laparoscopic surgery under these conditions may be questioned. A recent study established that PPV and SVV derived by uncalibrated pulse contour analysis had a relatively poor capacity to predict fluid responsiveness during laparoscopy on dynamic preload indices. In contrast, another study SVV measured by oesophageal Doppler monitor (ODM) could predict fluid responsiveness during laparoscopic surgery.

The CardioQ-ODM+ combines the proven ODM Doppler measurement of blood flow with pulse contour analysis, which is quickly and easily calibrated from the Doppler signal. We hypothesized that PPV and SVV measured by calibrated pulse contour analysis would be a good indicator of fluid responsiveness during laparoscopy with pneumoperitoneum.

The primary objective of this study was to demonstrate that PPV and SVV measured by calibrated pulse contour analysis of CardioQ-ODM+ can accurately predict fluid responsiveness during RALP, which involves both pneumoperitoneum and the Trendelenburg position. Investigators also assessed the capacity of other dynamic variables (SPV [systolic pressure variation], and SVV determined by ODM Doppler flow, dynamic elastance [PPV/SVV] and corrected flow time [FTc]) to predict fluid responsiveness during RALP.