Effects Of Ketamine On MACBAR Of Sevoflurane In Patients During Abdominal Surgery

OBJECTIVEThe aim of the study was to determine the effects of ketamine on the end-tidal concentration of sevoflurane that prevents hemodynamic response to surgical incision in 50%patients(MAC_BAR)undergoing abdominal surgery.METHODSForty-four patients aged 30—60 yr,with American Society of Anesthesiologists physical statusâ… orâ…¡,undergoing elective abdominal surgery were randomly divided into 2 groups(n=22):control group(K₀)and ketamine groups(K₁).The patients were not premedication.Tracheal intubation was performed after infusion ofpropofol 2 mg/kg, cisatracurium 0.15mg/kg and fentanyl 3μg/kg.Anesthesia was maintained with sevoflurane inhalation(The initial end-tidal sevoflurane concentration was 3 %).Ketamine was infused 14μg.kg-1,min-1 at the same time in the K1 group.The patient's response to surgical incision was described as positive if MAP / HR increased by≥15%,or negative(MAP/HR increased by＜15%).When the response was positive,the end-tidal concentration of sevoflurane for the next patient was increased by 0.5%.If negative decreased by 0.5%RESULTSThe MAC_BAR of sevoflurane was 3.25%(95%confidence interval:3.05%-3.45%) in group K₀,2.20%(95%confidence interval:1.96%-2.44%) in group K₁.There were significant diferences between the two groups(P＜0.01).CONCLUSIONLow dose ketamine infusion can reduce MAC_BAR of sevoflurane by 32.3%in patients undergoing abdominal surgery,which can make the hemodynamic more stable.