Effect of permissive hypercapnia on intraoperative cerebral oxygenation and early postoperative cognitive function in elderly patients undergoing laparoscopic surgery

Yuan Li; Zhang Xiaomin; Liu Na; Shi Junqi; Sun Xiaojie; Li Guoli; Teng Jinliang

doi:10.3760/j.issn.1673-4777.2026.01.014

Abstract：Objective To investigate the effect of hypercapnia ventilation mode on elderly patients undergoing laparoscopic radical resection of colorectal cancer on the basis of goal-directed fluid therapy,and to observe the changes of intraoperative regional cerebral oxygen saturation and postoperative cognitive function.Methods A total of 60 elderly patients scheduled for elective laparoscopic radical resection of colorectal cancer in the First Affiliated Hospital of Hebei North University from July 2023 to June 2024 were selected.They were divided into a control group and an observation group by random number table method,with 30 cases in each group.Both groups received fluid replacement under the guidance of goal-directed fluid therapy.Respiratory parameters were adjusted to maintain intraoperative arterial partial pressure of carbon dioxide(PaCO2)at 35-45 mmHg and pH 7.35-7.45 in the control group,while in the observation group,PaCO2 was maintained at 46-55 mmHg and pH 7.25-7.35.The general data,PaCO2 at different time points[preoperatively(T0),5 min before pneumoperitoneum(T1),20 min after pneumoperitoneum(T2),1 h after pneumoperitoneum(T3),2 h after pneumoperitoneum(T4),and 20 min after the end of pneumoperitoneum(T5)],intraoperative regional cerebral oxygen saturation(rSO2),results of arterial blood gas analysis,cerebral oxygen metabolism indicators,serum cognitive function indicators,and early postoperative cognitive function indicators were compared between the two groups.Results There were no statistically significant differences in general data between the two groups(all P＞0.05).Compared with T0,PaCO2 and rSO2 in the observation group increased,while pH decreased at T2-T5(all P＜0.05).PaCO2 and rSO2 at T2-T4 in the observation group were higher than those in the control group;pH at T2-T5 in the observation group were lower than those in the control group(all P＜0.05).At 1 h after pneumoperitoneum,the internal jugular venous oxygen saturation in the observation group was higher than that in the control group,while the arterial-internal jugular venous oxygen content difference and cerebral oxygen extraction rate were lower than those in the control group(all P＜0.05).The level of brain-derived neurotrophic factor on the first day after surgery in the observation group was higher than that in the control group,and the levels of neuron-specific enolase and homocysteine were lower than those in the control group(all P＜0.05).Compared with the day before surgery,the Mini-Mental State Examination(MMSE)scores of both groups decreased on the first day after surgery;the MMSE score of the observation group on the first day after surgery was higher than that of the control group(all P＜0.05).The incidence of postoperative cognitive dysfunction in the observation group was lower than that in the control group[10.0％(3/30)vs 36.7％(11/30)](P＜0.05).Conclusion On the basis of goal-directed fluid therapy,the application of permissive hypercapnia ventilation mode in elderly patients undergoing laparoscopic radical resection of colorectal cancer can increase cerebral blood flow,elevate rSO2,reduce cerebral oxygen metabolism level,mitigate cognitive function impairment,and contribute to the rapid postoperative recovery of patients.