The Effects Of One-lung Ventilation On Cerebral Oxygen Metabolism And Postoperative Cognitive Function

Part 1 Effects of one-lung ventilation on cerebral oxygen metabolism and cognitive function in elderly ratsObjective To evaluate the effects of one lung ventilation(OLV)on cerebral oxygen metabolism and cognitive function in elderly rats.Methods 90 male SD rats,aged more than 18 months and weighing 400-450 g,were randomly divided into 3 groups with 30 of each:control group(group C),two lung ventilation group(group T)and one lung ventilation group(group O).After induction of propofol,two lung ventilation were given for 5 min after intubation followed by one lung ventilation for 90min and lung inflate for 30min for group O,while only two lung ventilation for 120 min for group T and spontaneous breathing for group C.Continuous intravenous propofol were given to group T and O.9 rats of each group were chosen randomly to capture blood samples from left carotid artery and right internal jugular vein at the time of the beginning(To),30 min(T1),60 min(T2),90 min(T3)of one lung ventilation and 30 min after lung inflate(T4)for blood gas analysis to calculate arteriovenous blood O2 content different(Da-jvO2)and cerebral O2 extraction rate(CERO2).The remaining rats in each group were given Morris water maze(MWM)orientation cruise training 5 days before operation,respectively,at 1d,3d,7d after operation,the water maze experiment were determined.The rats were sacrificed and the levels of Gama-aminobutyric acid(GABA)and glutamate(Glu)in hippocampus were measured by ELISA soon after finishing MWM.Results1.MWM resultsAfter 5 days train,both the escape latency and the swimming distance were gradually shorted(p<0.05),while the swimming speed did not change significantly(p>0.05).Postoperative space exploration experiment,Compared with group T,the escape latency was significantly increased(p<0.05)and the time of the target quadrant was significantly decreased(p<0.05)at 1,3,7d after operation in group O,while the number of crossing the plat and the speed did not changed significantly(p>0.05).There were no statistical differences in the results of each group(p>0.05).2.Cerebral oxygen metabolism resultsCompared with group T,both the Da-jvo2 and CERO2 were significantly increased in group o at T1-4(p<0.05).There were no statistical differences in the results of group C and T(p>0.05).3.The level of GABA and Glu in rat hippocampusCompared with group T,the level of GABA in rat hippocampus was significantly decreased in group O at 1d after operation(p<0.05),but no statistical differences at 3,7d(p>0.05).Compared with group T,the level of Glu in rat hippocampus was significantly increased in group O at 1,3d after operation(p<0.05),but no statistical differences at 7d(p>0.05).Conclusions One lung ventilation may increase the cerebral oxygen metabolism and the incidence of cognitive dysfuction in elderly rats,this results may partly related to the decreased of GABA and increase of Glu in rats hippocampus.Part 2:Effects of CPAP on cerebral oxygen metabolism and postoperative cognitive function in elderly patients undergoing thoracic surgery with one lung ventilation.Objective To evaluate the effects of(continuous positive air pressure)CPAP on cerebral oxygen metabolism and postoperative cognitive function in elderly patients undergoing thoracic surgery with one lung ventilation(OLV).Methods Sixty patients,ASA I-II,aged above 60 yrs and,weighing 40-74 kg,scheduled for elective pulmonary tumorectomy were randomly divided into 2 groups:control group(group C,n=29)and CPAP group(group CPAP,n=31).After induction of anesthesia,the patients were intubated with the double-lumen tube.Correct position of the tube was verified with the fiberoptic bronchoscope.Oxygen saturation of cerebral tissue(ScO2)was monitored during the procedure.The group CPAP:continuous pressure of 5cmH20 and 100%concentration of oxygen was given to the non-ventilated lung.The group C without this management.Blood samples were taken from radial artery and internal jugular vein simultaneously for blood gas analysis at 5 min before induction of anesthesia(T1),10min of two lung ventilation(T2),30 min(T3)and 1h(T4)after one lung ventilation and at 10 min after restoration of TLV(T5).Meanwhile,intrapulmonary shunt(Qs/Qt).arteriovenous blood O2 content different(Da-jvO2)and cerebral O2 extraction rate(CERO2)were calculated at the same time.1 day before surgery,immediately after the surgery,1,3 d after surgery,venous blood samples were taken to determine the concentrations of serum S-100β and NSE by enzyme-linked immunosorbent assay.The patient’s cognitive function was assessed using Montreal Cognitive Assessment 1 day before operation and 1,3 days after operation.Results1.Blood gas analysis results:Compared with group C,the PaO2 and PvO2 were both significantly increased in CPAP group at T3-4(P<0.05),The PaCO2 of CPAP group was significantly decreased at T3-4(P<0.05),The SaO2 of CPAP group was increased in T3(P<0.05),the PvCO2 was significantly decreased at T3-5(p<0.05),the Qs/Qt of CPAP group was significantly decreased at T3-4(p<0.05).2.Cerebral oxygen metabolism results:Compared with group C,both the ScO2 and Sjv02 were significantly increased at T3-5(P<0.05),both the Da-jvO2 and CERO2 were significantly decreased at T3-4(P<0.05).3.Postoperative cognitive results:Compared with group C,the MoCA score of CPAP group was significantly increased 1 days after surgery(P<0.05),and the there was no significantly difference between two groups at 3 days after surgery(p>0.05).There is no significant difference in incidence of POCD among two groups at 1 or 3 days after surgery(p>0.05).4.Serum results:Compared with group C,the serum concentration of S-100βwas significantly decreased at immediately after operation and 1 day after operation(p<0.05),NSE was decreased at 1 day after operation(p<0.05),but there was no significant differences in serum concentration at 3 days after surgery(p>0.05).Conclusions1.CPAP can effectively reduce pulmonary shunt,increase oxygenation and reduce the incidence of hypoxemia.2.CPAP can effectively increase cerebral oxygen saturation and reduce cerebral oxygen metabolism,which has a protective effect on cerebral function of the elderly patients with one-lung ventilation.At the same time,MoCA Score of elderly patients with one lung ventilation can be improved,which may partly related to the decreased of serum S-100β and NSE concentration.