RESUMEN
BACKGROUND: Robotic assisted prostatic surgery is frequently used because of its reduced side-effects compared with conventional surgery. During surgery, an extreme Trendelenburg position and CO2 pneumoperitoneum are necessary, which may lead to cerebral oedema, can potentially reduce brain perfusion and therefore could impair cerebral oxygenation. Cerebral oxygen saturation can be measured non-invasively using near-infrared spectroscopy (NIRS). OBJECTIVE: The hypothesis of the present study was that steep Trendelenburg positioning during robotic assisted prostatic surgery impairs cerebral oxygen saturation measured using two different NIRS monitors. DESIGN: Clinical observational study. SETTING: Primary care university hospital, study period from March 2012 to February 2013. PATIENTS: A total of 29 patients scheduled for robotic assisted prostatic surgery in a steep Trendelenburg position. INTERVENTIONS: Cerebral oxygen saturation was measured throughout anaesthesia using the INVOS sensor (a trend monitor using two infrared wavelengths) for one hemisphere and the FORE-SIGHT sensor (a monitor using four wavelengths of laser light to calculate absolute oxygen saturation) for the other hemisphere in an alternate randomisation. MAIN OUTCOME MEASURE: Changes in cerebral oxygenation of more than 5% during surgery in the Trendelenburg position. RESULTS: The median duration of Trendelenburg positioning was 190 (interquartile range 130 to 230) min. Cerebral oxygen saturation decreased with INVOS from 74 ± 5% at baseline to a lowest value of 70 ± 4% with a slope of -0.0129 min(-1) (P < 0.01) and with FORE-SIGHT from 72 ± 5% at baseline to a nadir of 70 ± 3% with a slope of -0.008 min(-1) (P < 0.01). Comparing INVOS with FORE-SIGHT, there was a good association, with a slope of 0.86 ± 0.04 (P < 0.01). CONCLUSION: Both monitors showed a clinically irrelevant decrease in cerebral oxygen saturation of less than 5% over 4 h in a steep Trendelenburg position combined with CO2 pneumoperitoneum in patients undergoing robotic assisted prostatic surgery. This extreme positioning seems to be acceptable with regard to cerebral oxygenation. TRIAL REGISTRATION: clinicaltrials.gov Identifier: ID NCT01275898.