Application Of Different Doses Of Dexmedetomidine In Laryngomicrosurgery

Objective: To find out the appropriate loading dose of dexmedetomidine(DEX),We compared the effects of different doses of DEX in hemodynamics,catecholamine and scores during tracheal extubation in laryngomicrosurgery.Methods: 100 patients, ASA I-II, aged 20-55 years old, undergoinglaryngomicrosurgery were randomly divided into 5 groups: 0.9% SodiumChloride Injection group (NS group), Dexmedetomidine 0.4ug/kg group (D1group), Dexmedetomidine 0.6ug/kg group (D2 group), Dexmedetomidine0.8ug/kg group (D3 group) and Remifentanil group (R group).1. Beforeanesthesia induction, NS group was given 0.9% Sodium Chloride Injection 10ml, D1 group was given 0.4μg/kg DEX 10ml, D2 group was given 0.6μg/kgDEX 10ml, D3 group was given 0.8μg/kg DEX 10ml and R group was given0.9% Sodium Chloride Injection 10 ml. These drugs needed to be pumped in10 min. 2.Protocol of anesthesia induction: patients in NS group, D1 group,D2 group, D3 group were induced by intravenous injection of 2ug/kg fentanyl,2mg/kg propofol, 1.5mg/kg scoline; in the R group, intravenous injection of2ug/kg remifentanil, 2mg/kg propofol, 1.5mg/kg scoline was given. 3.Maintenance of anesthesia: patients kept a maintenance infusion of propofol10mg/kgï¹'h , scoline 3mg/kgï¹'h in NS group , D1 group , D2 group and D3group; intravenous injection of 10mg/kgï¹'h propofol, 3mg/kgï¹'h scoline and0.2ug/kgï¹'min remifentanil for anesthesia maintenance in R group. All theanesthetic drugs were stopped when the surgery finished. 4. The MAP andheart rate were recorded when 10min after entering the operating room (T0), after induction (T1), immediately after intubation (T2), immediately after thebeginning of operation (T3) and tracheal extubation (T4). Venous blood wascollected at three time points: T0, T2and T3for the analysis of theconcentration of adrenalin and noradrenalin. The recovery time ofspontaneous breath and extubation was recorded after the operation. The doseof atropine, urapidil and the additional quantity of propofol were recorded.The OAAS score，cough score and vision analog score (VAS) was recordedimmediately at extubation and 5min, 10 min, 20min , 30min after trachealextubation. At the same time, the side effects, including delirium, bucking,nausea and vomiting were recorded.Results:1. The hemodynamics of the patients in D2 group, D3 group and R groupwas more stable than it in NS group with statistic significance. Thehemodynamics of the patients in D2 group, D3 group and R group was morestable than it in D1 group.2. The concentration of adrenalin and noradrenalin in D1 group, D2group, D3 group and R group was lower than it in NS group at T2andT3. Theconcentration of adrenalin and noradrenalin at T2was lower than it at T0inD1 group, D2 group, D3 group and R group except for NS group.3. The time of extubation in D3 group was significantly longer than it inother groups. The recovery quality of patients in D1 group, D2 group and Rgroup was better than that in D3 group. The recovery time of spontaneousbreath in D3 group was significantly longer than it in NS group, D1 group andD2 group, there was significant statistical difference between them.4. The VAS in NS group was higher than it in other groups, there wassignificant statistical difference between them. The VAS in D2 group, D3 group decreased from10 min to 30 min after extubation, but it increased in Rgroup. Compared to R group, the VAS at 10min after extubation wassignificantly higher than it in D2 group and D3 group.5. The dose of atropine in R group was significantly more than it in othergroups.6. The additional quantity of propofol and the dose of urapidil in NSgroup were significantly more than it in other groups.Conclusion: A loading dose of Dexmedetomidine infused beforeanesthesia can improve the stability of hemodynamics during trachealintubation and operation in laryngomicrosurgery. A loading dose of 0.6ug/kgDexmedetomidine by intravenous infusion before anesthesia can not onlyimprove the stability of hemodynamics, but also have no effect on therecovery quality, which provide a better condition for tracheal extubation, soit is a recommend method in laryngomicrosurgery.