Effect Of Dexmedetomidine On The Optic Nerve Sheath Diameter In Patients Undergoing Robot-assisted Laparoscopic Radical Prostatectomy

Objective:In recent years,the incidence of prostate cancer in China has increased significantly.Robot-assisted laparoscopic radical prostatectomy?RALP?is an effective surgical method for the treatment of prostate cancer.In surgery,carbon dioxide pneumoperitoneum and head down bed rest?HDBR?are required to obtain sufficient operating view,both of which can cause increased intracranial pressure.Increased intracranial pressure will cause decreased cerebral perfusion pressure,leading to cerebral ischemia and impaired cerebral circulation.The optic nerve sheath diameter has a certain correlation with the increased intracranial pressure.Ultrasound in monitoring change of the optic nerve sheath diameter?ONSD?is a non-invasive and reliable assessment method for assessing cranial hypertension.Dexmedetomidine can be used to decrease intracranial pressure by decreasing cerebral blood flow and cerebral blood volume,as well as increasing cerebral vasoconstriction.By observing the effect of constant pumped infusion of dexmedetomidine on the optic nerve sheath diameter of patients,we can understand the changes of intracranial pressure in patients.This can provide more valuable references for monitoring and controlling intracranial pressure during RALP in order to prevent continuous increasing intracranial pressure.Methods:In this clinical randomized controlled trial,sixty patients underwent elective robot-assisted laparoscopic radical prostatectomy were selected.They were divided into treatment group and control group.Continuous intravenous injection of dexmedetomidine?0.5ug/kg/h?can be detected in the treatment group since the beginning of anesthesia induction.Meanwhile patients of the control group were treated with constant pumped infusion of 0.9%saline.Keeping a record of patients'changes of point MAP,HR,SpO₂,BIS,CVP,ETCO₂,bilateral ONSD at T0?before anesthesia induction?,T1?10 minutes after tracheal intubation?,T2?30 minutes after head down bed rest?HDBR?combined with carbon dioxide?,T3?90 minutes after head down bed rest?HDBR?combined with carbon dioxide?,T4?150 minutes after head down bed rest?HDBR?combined with carbon dioxide?,T5?Resuming dorsal position after closing the carbon dioxide pneumoperitoneum?.Results:1.In both groups,there was no significant difference in age,BMI,underlying diseases history and Gleason score?P>0.05?.Also,there was no significant difference in blood loss,fluid resuscitation,operation time and anesthesia time?P>0.05?.2.There were significant differences in point ONSD at different measurement time.There were significant differences in point ONSD between the treatment group and the control group at T2,T3,T4,T5?P<0.05?.Compared with T0,there were increases in point ONSD at T2,T3,T4,T5?P<0.05?in both groups.3.There were differences in point HR between the treatment group and the control group at different measurement time.There were significant differences in point HR between the treatment group and the control group at T2,T3?P<0.05?.Compared with T0,there were decreases in point HR at T1,T2,T3,T4,T5?P<0.05?.HR continued to decrease after T0,and gradually increased after T4.4.There was no difference in point MAP between the treatment group and the control group at different measurement time.Compared with T0,there was no difference in point MAP at T1,T2,T3,T4,T5?P>0.05?.MAP was kept within±20%?pre-operation?during the surgery.5.There was no difference in point CVP between the treatment group and the control group at different measurement time.Compared with T0,there were significant increases in point CVP of at T3,T4 in both groups?P<0.05?.CVP continued to increase after T1,peaked at T3,and then gradually decreased after T4.6.There was no difference in point ETCO₂ between the treatment group and the control group at different measurement time.Compared with T1,there was no difference in point ETCO₂ at T2,T3,T4,T5?P>0.05?.ETCO₂ continued to increase after T1 and gradually decreased after T4.7.Age was negatively correlated with the width extent of ONSD at T2?r=-0.48,P=0.02?.BMI,HR,CVP,and ETCO₂ were independent of the width extent of ONSD at T2.Conclusion:1.Constant pumped infusion of dexmedetomidine can alleviate the increase in intracranial pressure during RALP.2.The changes of intracranial pressure was assessed by non-invasive ultrasound measuring ONSD.3.Therefore,intracranial pressure should be carefully monitored and controlled to prevent its continuous increases during RALP.