Mannitol improves cerebral oxygen content and postoperative recovery after prolonged retroperitoneal laparoscopy

Background Prolonged pneumoperitoneum has cerebral adverse effects that may delay recovery and cause postoperative cognitive changes. The purpose of this study was to investigate the effect of mannitol infusion after pneumoperitoneum initiation on cerebral oxygen balance and quality of postoperative recovery in patients undergoing prolonged retroperitoneal laparoscopy. Methods Forty patients scheduled for retroperitoneal laparoscopic radical excision of prostatic carcinoma were randomly divided into two groups ( n = 20, each) to receive either 0.5 g/kg of 20% mannitol 150 min after the initiation of pneumoperitoneum or an equal volume of 0.9% normal saline. After surgery, time to extubation and recovery time were recorded. The Observer’s Assessment of Alertness/Sedation (OAA/S) scale was used to assess the quality of recovery. The Mini-Mental State Exam (MMSE) was given to test cognitive function preoperatively and at 1, 2, and 3 h after extubation. Blood samples from the jugular bulb and the radial artery were collected for blood gas analysis before CO 2 insufflation and at 10, 60, and 180 min after insufflation. Results In the control group (without mannitol), the difference between arterial and venous oxygen content (C a O 2 –C v O 2 ) before insufflation (6.21 ± 2.58 mL/dL) was significantly greater than it was 3 h after insufflation (2.63 ± 1.29 mL/dL; p