Effect Of Different Arterial Carbon Dioxide On Optic Nerve Sheath Diameter And Respiratory Mechanics In Patients Undergoing Retroperitoneal Approach Laparoscopic Surgey With Total Intravenous Anesthesia

Objective:To study the effect of different arterial carbon dioxide on optic nerve sheath diameter（ONSD）and respiratory mechanics in patients undergoing retroperitoneal approach laparoscopic surgey with total intravenous anesthesia.Methods:ninety patients scheduled for elective retroperitoneal approach laparoscopic surgery in lateral clasp-knife position under general anesthesia from October 2020 to September 2022 were randomly divided into 2 groups,fourty-five patients in each group,normal arterial carbon dioxide（group A）and high arterial carbon dioxide group（group B）.Mean airway pressure,lung compliance and end-expiratory carbon dioxide（EtCO₂）were recorded at T0（5mins after endotracheal intubation）,T1（5 mins after lateral clasp knife position）,T2（10 mins after pneumoperitoneum）,T3（30 mins after pneumoperitoneum）,T4（50 mins after pneumoperitoneum）and T5（5mins before the end of surgery）.ONSD,mean arterial pressure,heart rate,Pplat,Ppeak,arterial blood pH,arterial partial pressure of oxygen（Pa O₂）,arterial blood partial pressure of carbon dioxide（Pa CO₂）should be recorded and Cstat,Cdyn,medical power,Vd/Vt should be caculated at T0（5mins after endotracheal intubation）,T1,T2,T3,T4 and T5,（5mins before the end of surgery）.Occurance of delirium,nausea and vomiting,eye discomforts,postoperative respiratory failure were recorded.Results:ONSD of both groups were higher than T0 at T1、T2、T3、T4 and T5（all P<0.05）,but two groups has no significant differences.Medical power and dead space fraction（Vd/Vt）in group B at T1、T2、T3、T4 were lower than group A（P<0.05）.Lung compliance（Cdyn,Cstat）and heart rate in group B at T1,T2,T3,T4 were higher than group A（P<0.05）.Ppeak and Pplat in both groups were higher than T0at T1、T2、T3、T4、T5,but there were no significant difference in both groups.Mean arterial pressure of both groups has no significant difference than T0 at T1、T2、T3、T4.There was no significant difference in other indexes（P>0.05）.And there were 2cases of nausea and vomiting in the control group and 1 case of nausea and vomiting in the group B.No delirium,eye discomforts and postoperative respiratory failure occurred in the two groups.Conclusion:Permissible hypercarbonic acid method is suitable for posterior laparoscopic surgery,has no significant effect on intracranial pressure,and can reduce mechanical work and dead space fraction,compared with normal carbonitrigosis group can protect lung function,and does not increase postoperative patients’delirium,nausea and vomit,respiratory failure and other risks,can be safely used in the posterior laparoscopic surgery process.