Changes of cerebral regional oxygen saturation during pneumoperitoneum and Trendelenburg position under propofol anesthesia: a prospective observational study

BACKGROUND: We evaluated the change of cerebral regional tissue oxygen saturation (rSO(2)) along with the pneumoperitoneum and the Trendelenburg position. We also assessed the relationship between the change of rSO(2) and the changes of mean arterial blood pressure (MAP), heart rate (HR), arterial carbon dioxide tension (PaCO(2)), arterial oxygen tension (PaO(2)), or arterial oxygen saturation (SaO(2)). METHODS: Forty-one adult patients who underwent a robotic assisted endoscopic prostatic surgery under propofol and remifentanil anesthesia were involved in this study. During the surgery, a pneumoperitoneum was established using carbon dioxide. Measurements of rSO(2), MAP, HR, PaCO(2), PaO(2), and SaO(2) were performed before the pneumoperitoneum (baseline), every 5 min after the onset of pneumoperitoneum, before the Trendelenburg position. After the onset of the Trendelenburg position, rSO(2), MAP, HR were recorded at 5, 10, 20, 30, 45, and 60 min, and PaCO(2), PaO(2), and SaO(2) were measured at 10, 30, and 60 min. RESULTS: Before the pneumoperitoneum, left and right rSO(2) were 67.9 ± 6.3% and 68.5 ± 7.0%. Ten minutes after the onset of pneumoperitoneum, significant increase in the rSO(2) was observed (left: 69.6 ± 5.9%, right: 70.6 ± 7.4%). During the Trendelenburg position, the rSO(2) increased initially and peaked at 5 min (left: 72.2 ± 6.5%, right: 73.1 ± 7.6%), then decreased. Multiple regression analysis showed that change of rSO(2) correlated with MAP and PaCO(2). CONCLUSIONS: Pneumoperitoneum and the Trendelenburg position in robotic-assisted endoscopic prostatic surgery did not worsen cerebral oxygenation. Arterial blood pressure is the critical factor in cerebral oxygenation. TRIAL REGISTRATION: Japan Primary Registries Network (JPRN); UMIN-CTR ID; UMIN000026227 (retrospectively registered).