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.