Efficacy Of Dexmedetomidine In Preventing Pituitrin-induced QT Interval Extension In Patients Undergoing Gynecological Surgery

Objective:During laparoscopic myomectomy under general anesthesia in female patients,cardiovascular adverse reactions are likely to occur when pituitrin is injected into the surrounding muscle layer of fibroids.This study mainly investigated whether pumping0.5?g·kg^-1·h^-11 dose of dexmedetomidine could prevent the extension of QT interval and increase of blood pressure induced by pituitrin,and whether it had significant influence on heart rate,so as to explore a safer and more stable perioperative environment.Methods:60 female patients with laparoscopic myomectomy under general anesthesia were selected,aged 25-55 years old,BMI18-25kg/m²,ASAI or II,no abnormalities in preoperative electrocardiogram,370ms<QTc<440ms.According to the random number table,the patients were randomly divided into two groups,with 30 cases in each group.None of the patients used preoperative drugs.After the patients entered the operating room,routinely monitor the HR,BP,SpO₂,and II lead ECG and BIS value.Venous access was established,and the patient was placed in a quiet position for 10min,and the nasal catheter was oxygenated for 2L/min.Both groups were treated with endotracheal intubation and total intravenous anesthesia.Midazolam was 0.05mg/kg,etomidate was0.3mg/kg,sufentanil was 0.4?g/kg,and rocuronium was 0.9mg/kg for induction of anesthesia,followed by endotracheal intubation after 3min.Adjust mechanical ventilation V_T6-8ml/kg,RR 12-14 times/min,maintain P_ETCO₂35-45 mm Hg.Propofol4-8mg·kg^-1·h^-1,remifentanil 8-12?g·kg^-1·h^-11 anesthesia maintenance,intraoperative additional sufentanil and rocuronium as needed,ensured BIS value 40-60.In the experimental group D,dexmedetomidine was infused intravenously with a micro pump at a dose of 0.5?g·kg^-1·h^-1,from the induction of anesthesia to the end of the operation.In control group C,a micro pump was used for intravenous infusion of equal volume saline,which was maintained from the induction of anesthesia until the end of the operation.After the anesthesia was stable in both groups,the head was low and the height was 30°,lithotomy position,and the pneumoperitoneal pressure was 8 to 13 mm Hg.Before the hysteromyoma resection,the pituitrin 6U+0.9%sodium chloride 20ml diluent was punctured into the surrounding muscle layer of the fibroid tumor under the laparoscopic monitoring by puncture needle,and the injection was completed within 10s after no blood was drawn back.Atropine 0.5 mg was given at a heart rate<50beats/min.HR,MAP and II-lead ECG were recorded after the patients entering the operating room?T₀?,at the injection of pituitrin?T₁?,and 3 min?T₂?,5 min?T₃?,10min?T₄?,20 min?T₅?,30 min?T₆?after injection of pituitrin,calculate the QTc value.The occurrence of adverse events such as HR<50 beats/min,SBP>180 mmHg,QTc>440 ms,and arrhythmia were recorded.Results:General information?age,height and weight?of patients in the two groups was compared,and the difference was not statistically significant.Compared with T₀,the HR of the two groups decreased significantly from T₁ to T₆?P<0.05?;MAP significantly decreased in the two groups at T₁?P<0.05?,and significantly increased in the two groups at T₂-T₆?P<0.05?,and reached the highest level at T₄;The QTc values of group C significantly increased from T₁ to T₆?P<0.05?,the QTc values of group D significantly decreased when T₁-T₂,T₄-T₆?P<0.05?,and the QTc values of group D increased at T₃,but the difference was not statistically significant?P>0.05?,the QTc values of both groups reached the highest at T_3.Compared with group C,the HR of group D significantly decreased at T₂-T₆?P<0.05?,the MAP of group D significantly decreased at T₃-T₆?P<0.05?,the QTc values significantly decreased at T₁-T₆in group D?P<0.05?.2patients in group C developed HR<50 beats/min,and 3 patients in group D developed HR<50 beats/min,but the heart rates were not less than 45 beats/min.There was no significant difference in the incidence rate?P>0.05?,and they all returned to normal after0.5 mg atropine treatment.SBP>180mmHg occurred in 1 patient in group C,and no SBP>180mmHg occurred in group D.In group C,the incidence of QTc>440ms occured in 23 cases of patients,but 1 case in group D.None of the two groups developed SBP<80mmHg and arrhythmia.Conclusion:In female patients undergoing general anesthesia for laparoscopic myomectomy,the use of pituitrin may cause a decreasing in heart rate,an increasing in blood pressure,and an increasing in QT interval?QTc?.Intraoperative pumping of 0.5?g·kg^-1·h^-11 dose of dexmedetomidine could effectively prevent the extension of QT interval?QTc?and increasing of blood pressure induced by pituitrin.It further reduced heart rate,but the heart rates were not less than 45 beats/min.It would not increase the incidence of HR<50 beats/min and would not cause arrhythmia.