Abstract
The authors of this article have written an informative and concise study evaluating the effect of steep-head down tilt and pneumoperitoneum during robot-assisted laparoscopic radical prostatectomy using newer technology to evaluate cerebral blood volume. The near infrared time-resolved spectroscopy device has been well studied and established in other fields and the authors have detailed how this methodology was superior to others concerning accuracy and reproducibility.
The relationship between cerebral blood volume and intracranial pressure is based on the inelastic nature of the cranial compartment and first described by the Monro–Kellie doctrine, 1 but whether there is increased blood volume and/or pressure during robot-assisted laparoscopic prostatectomy remains controversial. This is one of the first studies to evaluate the time course of cerebral blood volume during robot-assisted laparoscopic prostatectomy and with the addition of cerebral oxygen saturation using new near infrared time-resolved spectroscopy.
Their findings suggest that there is a compensatory mechanism that restores cerebral blood volume during the end time points and it would have been interesting to evaluate other parameters such as the intracranial pressure, cerebral perfusion pressure, or cerebral blood flow during these cases to give a more complete picture. Including these factors would shed light on the complex dynamic/relationship these variables have with each other and elucidate a possible compensatory mechanism to restoring cerebral blood volume.
Otherwise this was an interesting study that appreciates and controls for the effect of anesthesia, patient positioning, angle of Trendelenburg, and the effect of pneumoperitoneum. We congratulate the authors for their work. This study represents a fundamental area of research in endourology, and more studies similar to this one will certainly help in clarifying the intricacies of robotic urologic surgery, hemodynamics, and patient safety.