The Effects Of Different General Anesthesia Methods On Intraoperative Nerve Monitoring In Unilateral Thyroidectomy

ObjectiveThe purpose of this study was to observe the effects of different anesthetic methods（intravenous general anesthesia and inhaled general anesthesia）on the EMG of recurrent laryngeal nerve during thyroid surgery with the same induced dose of cisatracurium.Materials and methods1.MaterialsA total of 100 patients,ASA Ⅰ-Ⅱ（American Society of Anesthesiologists Patient Physical Status Classification）,who needed Unilateral thyroidectomy for the first time were selected from Anhui Tumor Hospital.There were 19 males and 81 females,aged from 20 to 72 years,weighing 47 to 82kg.Exclusion criteria:allergy to the drugs used in the study,preoperative confirmation of recurrent laryngeal nerve injury,difficult airway,severe hypertension,hyperthyroidism,cardiac,liver and renal insufficiency,and endocrine and nervous system diseases.2.TechniqueUsing random number table method,the patients were randomly divided into two groups:intravenous anesthesia group（P group）and inhalation anesthesia group（S group）,with 50 cases in each group.Both groups were anesthetized under Narcotrend depth monitoring.At the beginning of anesthesia,dexmedetomidine with a concentration of 4ug/ml was injected intravenously with a load of lug/kg,and the infusion time was not less than 10min.The maintenance dose was 0.4ug/kg·h.Anesthesia induction:intravenous injection of hydrocortisone 100mg,sufentanil 0.5ug/kg,propofol 2mg/kg.When the depth of anesthesia reached the D state,cis-atracurium was administered 0.1mg/kg（2x ED95）.After the intubation was achieved,an EMG tracheal tube was inserted under a video laryngoscope.In group P,dexmedetomidine,propofol and remifentanil were inj ected intravenously for anesthesia maintenance.The anesthesia of group S was maintained by continuous inhalation of sevoflurane and intravenous infusion of dexmedetomidine,and the anesthesia depth was maintained at D state.For patients with intraoperative systolic blood pressure（SBP）above or below 30%of the baseline value and heart rate（50bpm or 100bpm）,the depth of anesthesia was adjusted first.When the depth of anesthesia is in D state,the blood pressure is controlled by intravenous nicardipine or norepinephrine by pump.Give atropine or esmolol treatment to adjust heart rate.3.Neural monitoringAfter anesthesia,the "loop" and "ground" electrodes were inserted into the deltoid muscle area of the shoulder and fixed.After connecting with the nerve monitor,the electrodes were detected to be in good condition,and then the operation was started and monitored.After successful intubation,the TOF ratio of the two anesthesia methods at 30min,40min,50min and 60min and the corresponding level of evoked myopotentials of the recurrent laryngeal nerve were recorded.（Amplitude larger than 100uV monitoring is effective）.Results1.There was no significant difference in age,weight,height,Narcotrend base value between P and S groups（p>0.05）.There were 19 males and 81 females,aged from 20 to 72 years,weighing 47 to 82kg.2.30min after successful intubation,muscle relaxation recovery intensity in P group was higher than that in S group.At this time point,effective EMG signals of recurrent laryngeal nerve could be detected in all patients in group P,and the amplitude was above 300 uV.The EMG signals of recurrent laryngeal nerve in 9 cases and 21 cases were lower than 100 uV in group S（p<0.05）.3.40min after successful intubation,muscle relaxation recovery intensity in P group was higher than that in S group.Both groups could detect effective EMG signals of recurrent laryngeal nerve,and the amplitude of P group was higher than that of S group,the difference was statistically significant（p<0.05）.4.50min after successful intubation,muscle relaxation recovery intensity and EMG signal amplitude of recurrent laryngeal nerve in P group were slightly higher than those in S group,but there was no statistical significance（p>0.05）.5.60min after successful intubation,there was no significant difference in the recovery intensity of muscle relaxation and the amplitude of nerve EMG signal between the two groups（p>0.05）.ConclusionCompared with inhalation anesthesia,total intravenous anesthesia can obtain effective electrophysiological monitoring EMG signals of recurrent laryngeal nerve earlier.However,with the metabolism of cisatracurium,there was no significant difference in the EMG signals of recurrent laryngeal nerve between the two groups.