Effects of dexmedetomidine intravenous infusion on the early recovery process of patients undergoing thyroid surgery with general anesthesia

Abstract

Objective To evaluate the effects and feasibility of different intravenous infusion with dexmedetomidine (DEX)on the early recovery process of patients undergoing thyroid surgery with general anesthesia.Methods Ninety patients aged 20-59 years with American society of anesthesiologists physical status Ⅰ or Ⅱ,who were scheduled for elective thyroid surgery,were randomized into 3 groups:DEX loading dose intravenous infusion group (DEX 0.5μg/kg in 10 min,followed by normal saline,n=30,group D1),DEX continuous intravenous infusion group (DEX 0.5 μg·kg1·h-1,n=30,group D2) and control group (group C).After induction with fentanyl,propofol and rocuronium,all patients were performed tracheal intubation and mechanical ventilation.Anesthesia was maintained with sevoflurane,fentanyl and cisatracurium were given at 40 min intervals until 30 min before the end of the operation.Patients in the 3 groups were all started intravenous infusion at 10 min before the operation and discontinued at 30 min before the end of the operation.During the operation the concentration of sevoflurane was varied to maintain mean artery pressure (MAP) within ±25％ of the preinduction values and bispectral index within 45±10.The consumption of sevoflurane,the dosage of DEX,fentanyl and cisatracurium were observed.MAP,heart rate (HR),pulse oxygen saturation and bispectral index were recorded at the time-points of before induction (T0),terminal of operation (T1),before extubation (T2),immediately extubation (T3),1,3,5,10,15,30,45 min after extubation (T4-T10).The recovery time from the end of the operation to spontaneous breath,eye opening,extubation and orientation were also recorded.The cough reflex scores and sedation-agitation scale during extubation,the visual analogue scale and Ramsay sedation scale at 30 min after extubation,the preoperative and postoperative cognitive function by using mini-mental state examination,and the incidences of side effects were assessed.Results ① The consumption of sevoflurane of group D1 [(49±9) MAC (minimum alveolar concentration)· min] and D2 [(61 ± 14) MAC· min] were significantly lower than that of group C[(73±6) MAC·min](P＜0.05).② Compared with T0,values of MAP and HR increased statistically at T2-T5 in group C (P＜0.05).Compared with group C,values of MAP at T1-T4,T6-T8 and HR at T3-T6 decreased statistically in group D1 and D2 (P＜0.05).③The scores of cough reflex,sedation-agitation scale and visual analogue scale were significantly lower in group D1 and D2 than in group C (P＜0.05).③ The incidence of agitation,high blood pressure and tachycardia were significantly lower in group D1 and D2 than in group C (P＜0.05).The bradycardia incidence of group D1(46.7％)during the operation were significantly higher than that of group D2 (26.7％) and group C(16.7％) (P＜0.05).⑤ There were no significant differences in recovery time,Ramsay sedation scale,mini-mental state examination scores among the 3 groups (P＞0.05).Conclusions DEX intravenous infusion in patients undergoing thyroid surgery with general anesthesia can keep stable perioperative hemodynamics,relieve cough reflex,agitation incidence and level,while did not prolong recovery time and affect the early postoperative cognitive function.Its continuous intravenous infusion is an optimal choice than its loading dose intravenous infusion. Key words: Dexmedetomidine; Thyroid surgery; Hemodynamics; Cough reflex; Agitation; Postoperative cognitive function