Effect Of Neoadjuvant Chemotherapy On MAC-BAR Of Sevoflurane In Gastretomy Patients

Objectives: To evaluate the impact of preoperative neoadjuvantchemotherapy on MAC-BAR of sevoflurane.Methods: Forty-eight patients aged40-64yrs, male or female, withAmerican Society of Anesthesiologists physical status Ⅰ-Ⅱ,18kg/m2<BMI<30kg/m2, had no neurological, mental, breathing and severe cardiovasculardiseases, no history of drug or alcohol dependence, excluding those who haddifficulty in tracheal intubation. According to whether the patients couldreceive the preoperative neoadjuvant chemotherapy, patients were divided intotwo groups: the control group of non-chemotherapy (C) and the chemotherapygroup (H). In chemotherapy group, before operation, all patients should havehad chemo for two cycles (one cycle of chemotherapy,14days), thechemotherapy was the regimen of oxaliplatin combined with DeFazio, andafter three weeks of the chemotherapy, it was time to conduct surgerychemotherapy.No patients of the two groups received premedication. After entering theoperating room, open the peripheral intravenous pathways, monitor theelectrocardiogram, pulse oxygen saturation and bispectral index (BIS), andthen when patients were in local anesthesia the radial artery puncture andintubation was conducted, and invasive artery pressure could be monitored.Anesthesia induction: target-controlled infusion of propofol (its target plasmaconcentration was2μg/ml) and remifentanil (its target plasma concentrationwas4ng/ml), after the effect-site concentration and the plasma concentrationwere balanced with each other, observe whether the patients lost theirconsciousness, and if the patients did not lose their consciousness, then eachtime raise0.5μg/ml of propofol target concentration until that theconcentration could cause patients can lose their consciousness. After intravenous injection of rocuronium bromide0.6mg/kg and the conduction oftracheal intubation, mechanical ventilation was conducted, the tidal volumewas up to8ml/kg and the inspiratory to expiratory ratio was1:1.5, and thenthe respiratory rate was adjusted to make it maintain at the level of PETCO235to45mmHg. As soon as the induction was finished, the infusion of propofoland remifentanil was stopped, and then sevoflurane volatilization tank wasadjusted to make the end-tidal concentration of sevoflurane be up to the targetend-tidal concentration and maintained more than15min. The target end-tidalconcentration was adjusted in accordance with the sequential method: thetarget end-tidal concentration of the first patients in both two groups was3%,and then the end-tidal concentration of other patients was increased ordecreased by1.2times with the geometric level according to patients’reactions to the skin incision: if the reaction was positive, it should choose ahigher level of the end-tidal sevoflurane concentration for the next patient, andif it was negative, it should choose a lower level of the end-tidal sevofluraneconcentration for the next patient. Until no less than6alternating waveformsof negative and positive reactions sequentially appeared, the trial was finished.Heart rate (HR) and mean arterial pressure (MAP) were respectivelyrecorded as well as the average of HR and MAP before and after the skinincision were respectively calculated2min (T1) before skin incision,1min(T2) before skin incision, the immediateness (T3) before skin incision and theimmediateness (T4) after skin incision,1min (T5) after skin incision and2min (T6) after skin incision. By comparing the changes of HR and MAPbefore and after skin incision, judge the reactions of sympathetic adrenaline: ifthe average of HR and MAP after skin incision was higher than or equal to15%of that average before skin incision, it was judged as positive cases; viceversa, it was judged as negative cases. If the MAP <50mmHg before skinincision,6mg of intravenous ephedrine was conducted; and if HR <50times/min,0.5mg of intravenous atropine was conducted and at the same timethe trial was eliminated.According to the formula of half effect dosage of sequential method, the sevoflurane MAC-BAR and its95%confidence interval (95%CI) werecalculated.Results:1The comparison of the ages, gender ratios and body mass indexes of thetwo groups had no statistical significance (P>0.05);2There were no significant differences (P>0.05) among the comparisonof heart rates, mean arterial pressures and BIS values before induction; whilethe differences of hemoglobin and the levels of albumin of the two groups hadno statistical significance (P>0.05);3Comparing with those before anesthesia induction, both heart rates andmean arterial pressure of the two groups decreased significantly, while thecomparison of heart rates and mean arterial pressure in their own groups hasno statistical significance, and it has no statistical significance among groups;4According to the sequential method, it can work out the trend diagramfor the reactions of different end-tidal sevoflurane concentrations to skinincision in the two groups; the sevoflurane MAC-BAR value of Group C was3.0%(95%CI2.8-3.2%), the value of Group H was2.2%(95%CI2.0-2.3%).By comparison, MAC-BAR values of the two groups were differentsignificantly (P <0.05);Conclusions: The preoperative neoadjuvant chemotherapy can reducethe sevoflurane MAC-BAR for radical gastrectomy patients, and improve thesensitivities of the radical gastrectomy patients to sevoflurane.