| Objective The purpose of this study was to compare the changes of free hexafluoroisopropanol(HFIP)concentrations metabolized by sevoflurane in elderly patients’ blood after anesthesia with different concentrations of sevoflurane,and to explore the potential effect of free HFIP on the recovery quality in elderly patients after sevoflurane anesthesia.Methods Forty-one elderly patients scheduled for laparoscopic surgery were randomly divided into three groups:G1(n=15),G2(n=13)and G3(n=13),and received sevoflurane anesthesia with preset end-expiratory concentration of 0.86%,1.71%and 2.57%for 3 hours,respectively.Propofol and remifentanil were continuously infused by intravenous approach during the period of operation to maintain the cerebral state index(CSI)at 40-60,pain state index(PSI)at 30-45,and electromyogram(EMG)<30.End-expiratory carbon dioxide partial pressure was maintained at 30-45mmHg by adjusted respiratory parameters.The administration of cis atracurium was intermittently injected according to the needs of operation.Blood samples were taken just before anesthesia,0.5 h,1 h,2 h and 3 h after end-expiratory sevoflurane concentration was maintained stable,and 1h,3h and 5 h after stopping inhalation of sevoflurane.The concentrations of sevoflurane and free HFIP in blood were determined by gas chromatography.After operation,0.02mg/kg neostigmine was routinely used to antagonize residual muscle relaxation.The time of eye opening,the recovery time of spontaneous breathing and the time of extubation of endotracheal tube were recorded.The sedation-agitation scale(SAS)and Visual Analogue Scale/Score(VAS)were observed within 4 hours after extubation.Results The concentrations of sevoflurane in blood in the three groups were G1<G2<G3 at corresponding time points,and increased continuously with the prolongation of inhalation time in each group,and decreased gradually after stopping inhalation.The free HFIP concentration in all the three groups reached its peak value at 1 hour after inhalation,then decreased gradually,and continued to decrease after stopping inhalation.The free HFIP concentration in group G2 was higher than that in the other two groups,but in group G1 it was higher than that in group G3 at each corresponding time point.There was no significant difference in the incidence of restlessness and moderate or severe pain among the three groups(P>0.05).No significant differences were found in the recovery time of spontaneous breathing,the time of opening eyes and the time of extubation among the three groups(P<0.05).Conclusion In elderly patients,the concentration of free HFIP metabolized by sevoflurane,did not always increase continuously with the increase of inhaled sevoflurane concentration.When the inhaled sevoflurane concentration reached 2.57%,the metabolism of sevoflurane was inhibited and the residual free HFIP concentration had no significant correlation with emergence agitation during recovery. |
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