A Study Of The Value Of Optic Nerve Sheath Diameter And Cerebral Oxygen Saturation In Predicting Postoperative Nausea And Vomiting In Patients Undergoing Prone Spinal Surgery

Objective:To explore the effects of optic nerve sheath diameter（ONSD）and local cerebral oxygen saturation（rScO₂）in prone surgery,indirectly understand changes in intracranial pressure（ICP）,and evaluate the association of ONSD and rScO₂ with postoperative nausea and vomiting,In addition,the risk factors for early postoperative naus-ea and vomiting were identified,which provided new ideas for the prevention of postoperative nausea and vomiting in patients with prone surgery during the perioperative period.Methods:210 patients undergoing elective spine surgery from January 2021 to Janua-ry 2022 at Chifeng Hospital were selected,with ASA classification Ⅰ-Ⅱ,age>18 yea-rs,Apfel adult PONV riskiness score≥2,no anaemia,and no ophthalmic or craniocerebrovascular disease.Patients were routinely monitored after admission.All patients were put under general anaesthesia by total intravenous tracheal intubation,with intermittent intraoperative sedation of inotropes to maintain the appropriate depth of anaesthesia and to keep MAP within 20%of the preoperative basal value.Intraoperatively,rScO₂ values were collected from the time of admission to the end of anaesthesia for 30 min using an EGOS-600A NIR spectroscopic non-destructive monitor.The ONSD values in both eyes were measured using ultrasound at 5 min before induction of anaesthesia（T0）,immediately after the change from supine to prone position（T1）,30 min after prone position（T2）,60 min after prone position（T3）,immediately after the change from prone to supine position（T4）and 30 min after supine position（T5）.To avoid bias in intraoperative anaesthetic management by the anaesthetist due to rScO₂ and ONSD values,the anaesthetist was not involved in the pilot study.Postoperative analgesia was provided using a 48h patient intravenous self-administered analgesia pump.Patients were visited at 24 hours postoperatively and the occurrence of nausea and vomiting was recorded.PONV-positive and PONV-negative groups were divided into two groups according to the follow-up results,and the changes in ONSD and rScO₂values and their correlation with PONV were statistically analysed in both groups.Results:1.Statistical data of all patients:general information including age,body mass index,gender ratio,Apfel score,duration of anaesthesia,duration of prone position with no statistically significant differences.2.Comparison of hemodynamic parameters HR and MAP at different time points,T0>T1,T2,T3,T4,with statistically significant differences（P<0.05）,and T0 and T5 moments,with no statistically significant differences（P>0.05）.3.Comparing ONSD at different time points,the difference between T0 and T1 was not statistically significant（P>0.05）,while the difference between T2 and T5 was statistically significant（P<0.05）for ONSD values T1<T2<T3<T4 and T5<T4.4.Comparison of rScO₂ at different time points,compared with T0,rScO₂values were significantly higher at T1,T1>T2,T3,T4,T5>T0,the difference was statistically significant（P<0.05）,T5 compared with T0,the difference was not statistically significant（P>0.05）.5.PONV-positive group compared with PONV-negative group patient characteristics,ONSD values were more significantly elevated in the PONV-positive group（P<0.001）.6.Correlation analysis between ONSD values and rScO₂ values,there was no correlation between the two（P>0.05）.7.Using the occurrence of PONV as the diagnostic criterion and ONSD and rScO₂as the test variables,ROC curve analysis showed that ONSD 5.82mm could be used as the threshold value to predict PONV.Conclusion:1.The optic nerve sheath diameter values gradually increase with prolonged prone position and the cerebral oxygen saturation increases.2.ONSD 5.82mm in prone spine surgery patients is predictive of the risk of early postoperative nausea and vomiting...