| Objective This clinical study is to investigate the most suitable sedative dosage and opportunity for laryngeal mask insertion with premedication of dexmedetomidine prior to induction with sevoflurane, in order to provide the clinical suggestion or help to fully suppress reaction to laryngeal mask(LMA) insertion.Methods 100 patients aged between 45 to 65(ASA I~II,BMI 18~30 kg·m-2) undergoing cystoscopy, ureteroscopy and ureteroscopic lithotripsy whose operation time is no more than 60 minutes by general anesthesia were enrolled in this study. The whole study is divided into two parts(test 1 and test 2). In the test 1, 60 patients were randomly selected, and randomly divided into control group(C group) and dexmedetomidine group(D1 group and D2 group). Other 40 patients were in the part 2 of the study. All of the 100 patients use no premedicant. After entering the operation room, all patients in the test are established the right upper limb peripheral vein with the same type of venous indwelling needles, continuous monitoring of ECG, NIBP, HR, BIS, Pet CO2, Sp O2, end-tidal sevoflurane concentration. Open anesthesia machine’s overpressure overflow valve and pre-charge circuit with 6% sevoflurane. In the first part of the study, before inhalation induction, Group C:10 ml saline are pumped, Group D1: 1μg·kg-1 of dexmedetomidine(DEX) are pumped, Group D2: 2μg·kg-1 of dexmedetomidine(DEX) are pumped,(DEX in D1 and D2 are diliuted to 10 ml by saline), the liqiud is pumped out in 10 minuntes, afer that the induction begin. First, inhaled 6% sevoflurane, 8L·min-1 of oxygen flow rate. Reduce the oxygen flow rate to 2L·min-1 and set the exhale concentration of inhalation anesthetics at 2.0 MAC when the patients lose consciousness(responseless to shout and Eyelash reflex disappearing). To all the patients, laryngeal mask are inesrted 5min after induction by the same anesthesiologist. Observe the reaction to laryngeal mask insertion and hemodynamic changes of the three groups, and record MAP, HR, Sp O2 and BIS when entering room(T0), before induction(T1), 1min after induction(T2), 2min after induction(T3), 5min after induction(T4), 10 min after induction(T5). Body movement during laryngeal mask insertion(cough, unconscious body buckling and head rising). Get the most suitable concentration of dexmedetomidine by test1, and it is used as the preadministrition concentration in test 2 that the same method to induction as test 1. The point when the laryngeal mask should be inserted is chosen according to the sequential method. The ratio of time to increase or decrease is 1.1. Calculate the optimum time to insert the laryngeal mask by Probit regression analysis method. The positive reaction of intubation is defined as: MAP and HR at any point(T2-T4) increase greater than or equal to 20% comparing with that at T0 after intubation at the satisfied intubation condition.Results(1) Premedication of dexmedetomidine prior to induction with 6% sevoflurane could be used in short-time surgery. After premedication of dexmedetomidine, LMA insertion can be done successfully with a well anesthetic effect and smaller influence on patients’ circulatory system under the condition that using no muscle relaxant and holding spontaneous respiration. Based on the result of this experiment, the most appropriate premedication concentration of dexmedetomidine is 1μg·kg-1.(2) Premedication of dexmedetomidine(1μg·kg-1) prior to induction with 6% sevoflurane using no muscle relaxant, the time that 50% patients are successfully LMA inserted in first try is 3.29 mins(95% CI is 2.82~3. 80 mins);the time that 95% patients are successfully LMA inserted in first try is 4. 54 mins(95% CI is 3.88~12.49 mins);the time that 99% patients are successfully LMA inserted in first try is 5.19 mins(95% CI is 4.21~21.52 mins)... |
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