Original Effect of dexmedetomidine on intracranial pressure in patients undergoing gynecological laparoscopic surgery in Trendelenburg position through ultrasonographic measurement of optic nerve sheath diameter

Objective: To evaluate the effect of dexmedetomidine on intracranial pressure (ICP) in patients undergoing gynecological laparoscopic surgery in Trendelenburg position through ultrasonographic measurement of optic nerve sheath diameter (ONSD). Methods: Ninety patients underwent total laparoscopic hysterectomy were selected as research subjects in this prospective study. These patients were divided into a dexmedetomidine group (n=45) and a control group (n=45) using a random number table. The dexmedetomidine group was pumped with 0.5 mu g/kg dex-medetomidine (20041731, Yangtze River Pharmaceutical Group, China) 10 min before the anesthesia induction, followed by a continuous pump of 0.5 mu g/(kg.h) until the end of the surgery, and the control group was pumped with 0.5 mu g/(kg.h) 0.9% sodium chloride solution. Patients in both groups were assisted with mechanical ventilator after endotracheal intubation by rapid induction. Intraoperatively, the pneumoperitoneum pressure was maintained at 14 mmHg, and the bispectral index was maintained at 40 to 60. We recorded ONSD measured with ultrasonography in both groups at 5 min before induction of anesthesia in supine position (T1), 5 min after CO2 pneumoperitoneum in Trendelenburg position (T2), 30 min after CO2 pneumoperitoneum in Trendelenburg position (T3), 60 min after CO2 pneumoperitoneum in Trendelenburg position (T4) and 5 min after the close of pneumoperitoneum in supine position (T5). The cerebral oxygen metabolism indicators of the two groups at different time periods were compared, including jugular venous oxygen saturation (SjvO2), arterial content and arterial-to-internal jugular difference (Da-jvO2), cerebral oxygen extraction rate (CERO2). Heart rate (HR) and mean arterial pressure (MAP) were also recorded at T1-T5. Besides, American Society of Anesthesiologists (ASA) grade, time of endotracheal extubation, recovery time for orientation and postoperative adverse reactions were recorded in each group. Results: There were signifi-cant differences in ONSD at T2 ((4.77 +/- 0.14) mm vs. (4.98 +/- 0.13) mm), T3 ((5.19 +/- 0.15) mm vs. (5.53 +/- 0.14) mm), T4 ((5.10 &+/- 0.11) mm vs. (5.27 +/- 0.13) mm) and T5 ((4.71 & PLUSMN;0.12) mm vs. (4.4 +/- 0.16) mm) between the two groups (all P < 0.05), and obvious differences were also found within groups when comparing the ONSD at T2-T5 to that at T1 (P < 0.05). There were also significant differences in SjvO2, Da-jvO(2) and CERO2 between the control group and the dexmedetomidine group at T2-T5 (all P < 0.05), and obvious differences were found within groups when comparing the indices at T2-T5 to those at T1 (P < 0.05). The incidences of postoperative dizziness (20.00%), nausea and vomit-ing (17.78%), and headache (13.33%) in the dexmedetomidine group and were significantly lower than those in the control group (55.56%, 48.89% and 42.22%, respectively; all P < 0.05). At T2-T5, dexmedetomidine group had lower HR than control group (P < 0.05), while no differences were found in MAP between the two groups (P > 0.05). There were also no differences in ASA grade, time of endotracheal extubation, and recovery time for orientation between the two groups (both P > 0.05). Conclusion: Dexmedetomidine can effectively decrease the occurence of increased ICP in patients undergoing gynecological laparoscopic surgery in Trendelenburg position, improve brain oxygen me-tabolism, and reduce the incidences of postoperative dizziness, nausea and vomiting as well as headache (China Clinical Trials Registration Center, registration number: ChiCTR2100052046, https://www.chictr.org.cn).