Effect Of Dexmedetomidine On MAC_BAR Of Sevoflurane

Objective: Different doses of dexmedetomidine were given in different ways,then we investigated the change of sevoflurane minimum alveolar concentration(MACBAR)for skin incision in patients with abdominal tumors.Methods:(1)Patients undergoing elective colon cancer surgery were randomly divided into DEX Group(a bolus dose of 1μg/㎏,continuous infusion of 0.5 μg/㎏/h)and Control Group(saline only).During the operation,maintaining the BIS at the rate of 50 ± 5 by adjusting sevoflurane.To observe the effect of DEX on hemodynamic changes,sevoflurane dosage,recovery time and postoperative sedation agitation score.(2)Patients undergoing elective abdominal surgery were randomly divided into 3 groups: Before the induction of anesthesia in 10 min pump diluted to 20 ml containing 1ug/kg DEX(D1);1.5ug/kg DEX(D2);only saline(group C).To observe the effect of DEX on the sevoflurane MACBAR and the changes of hemodynamics in patients when skin incision.(3)Patients undergoing elective abdominal surgery were randomly divided into 4 groups: Before the induction of anesthesia in 10 min intranasal administration of 2ml diluted containing 1ug/kg DEX(D1);1.5ug/kg DEX(D2);2ug/kg DEX(D3);saline(C).To observe the effect of DEX on the sevoflurane MACBAR and the changes of hemodynamics in patients.Result: 1.No differences in ages,sex ratio,weight,BMI,ASA physical status.2.Before the induction of anesthesia in 10 min pump a bolus dose of 1μg/㎏ followed by a continuous infusion of 0.5 μg/㎏/h DEX,the patient of the group have perioperative hemodynamic stability,no obvious change in the group.In the Control Group,the HR and BP of the patients were increased obviously when tracheal intubation and the stimulation of operation(P<0.05).There was no significant difference in the time of eye opening between two groups,but sevoflurane decreased by 33% and lower Sedation agitation score in the DEX Group.3.Before induction of anesthesia 10 min intravenous infusioning 1ug/ kg or 1.5ug/ kg DEX,sevoflurane MACBAR values were 2.07%,1.85% respectively compared with the Control Group 2.65% decreased by 22%,30%.Compared with the baseline values,the HR and MAP of the patients in the Control Group were significantly higher When intubation;1ug/kg and 1.5ug/kg DEX Group,compared with baseline,HR and MAP decreased before induction of anesthesia(P>0.05),whereas no significant increase in tracheal intubation(P>0.05).The HR and MAP of 1ug/kg and 1.5ug/kg DEX Group was lower than control Group when before induction and intubation(P>0.05).Further more,the HR and MAP of 1.5ug/kg DEX Group was lower than 1.0ug/kg DEX Group(P>0.05).In the overall trend graph,HR and MAP changes smoothly in 1.0ug/ kg DEX Group.4.Before the induction of anesthesia 10 min single intranasal instillation of 1ug/ kg,1.5ug/ kg,2ug/ kg,measured sevoflurane MACBAR values were 2.28 %,1.92 %,1.83 %compared with the control group 2.83% were reduced by 22%,26%,32%.The HR and MAP of patients in the Control Group and 1.0ug/kg DEX Group were significantly higher When intubation(P<0.05);1.5ug/kg and 2.0ug/kg DEX Group,compared with baseline,HR and MAP decreased before induction of anesthesia(P>0.05),whereas no significant increase in tracheal intubation(P>0.05).There was no significant difference between the four groups in baseline HR,MAP;Before induction of anesthesia,HR and MAP of DEX Group was decreased,and 2.0ug/ kg DEX group lower than other three groups.In the overall trend graph,HR and MAP changes smoothly in 1.0ug/ kg DEX Group.Conclude:1.It is helpful to maintain the stability of hemodynamics,reduce the dosage of sevoflurane and prevent the occurrence of postoperative restlessness by continuous infusion DEX in radical resection of colon cancer.2.For patients undergoing abdominal tumor resection,giving dexmedetomidine before anesthesia induction can reduce the sevoflurane MACBAR,and is beneficial to maintain the hemodynamic stability of anesthesia induction and tracheal intubation.3.For abdominal tumor resection patients,intranasal dexmedetomidine can make the patients sevoflurane MACBAR decreased.As the DEX dose increases,the sevoflurane MACBAR value increases.At the same time by nasal instillation of 1.5ug/ kg DEX can better maintain the stability of hemodynamics induction and tracheal intubation patients.