Effects Of Dexmedetomidine On Heart Rate Variability Of Autonomic Nerve Function Index Under General Anesthesia In Laparoscopic Surgery

Objective:During laparoscopic surgery under general anesthesia,the linear and nonlinear indicators of heart rate variability（HRV）were observed to determine the effect of dexmedetomidine on autonomic nerve function,and to provide an important basis for maintaining circulation stability,reducing the risk of cardiovascular events,improving organ function and promoting rapid recovery.Methods:Fifty American Society of Anesthesiology（ASA）Classification of Anesthesia RiskⅠ～Ⅱ,cardiac functionⅠ～Ⅱand more than 30 years old patients who underwent laparoscopic assisted radical resection of colorectal cancer were allocated to into dexmedetomidine group（n=25）and the control group（n=25）.Dexmedetomidine group was given intravenous micropump infusion of dexmedetomidine 0.5ug/kg for 15 min before anesthesia induction and continued to 0.4 ug/（kg·h）until 30 min before the end of surgery.In the control group,the same volume of normal saline was used for intravenous pumping before and after anesthesia induction.Two groups of patients all used the same anesthesia induction and maintenance methods.Heart rate（HR）and mean arterial pressure（MAP）were collected at baseline（T0）,10 minutes after endotracheal intubation（T1）and 10 minutes after CO2 insufflation（T2）,60minutes after CO2 insufflation（T3）and at the end of surgery（T4）.To evaluate ANS balance,ECG was continuously recorded with a data acquisition system to analyze heart rate variability（HRV）.The heart rate variability to be collected included linear index RMSSD,low frequency power（LF）,high frequency power（HF）,LF/HF and nonlinear index Detrended Fluctuation Analysis withα₂（DFAα₂）,Shan En,Samp En,and SD1,SD2,SD1/SD2 in the Poincare plots.Results:（1）there were no statistically significant differences in demographic characteristics,operation time,anesthesia time,duration of pneumoperitoneum,infusion volume and blood loss between the two groups（P>0.05）.（2）There was no difference in MAP values between the two groups（P>0.05）.MAP values of the two groups decreased at T1,increased at T2,and gradually decreased at T3 and T4 compared with T2（P<0.001）.The HR value of dexmedetomidine group was lower than that of control group（P<0.05）.The HR value of dexmedetomidine group decreased with the increase of postoperative time.In the control group,HR increased at T2 compared with T1,and gradually decreased at T1,T3 and T4 compared with T0（P<0.001）.（3）At T2 and T3,RMSSD in dexmedetomidine group at T2 and T3 was higher than that in control group,with statistically significant difference（P<0.05）.RMSSD in T1,T2 and T3 was lower than that in T0 and T4 in both groups（P<0.05）.HF in dexmedetomidine group was higher than that in control group,and the difference was statistically significant（P<0.05）.HF in dexmedetomidine group decreased at T1,and gradually increased at T2,T3 and T4.In the control group,HF gradually decreased in T1,T2 and T3,and increased in T4（P<0.001）.The value of LF/HF in dexmedetomidine group was lower than that in control group at T3,the difference was statistically significant（P<0.05）.LF/HF in dexmedetomidine group at T1～T4 was significantly lower than T0（P<0.05）.DFAα2 of dexmedetomidine group was lower than that of control group,the difference was statistically significant（P<0.05）.DFAα2 in dexmedetomidine group at T1 and T2was higher than that at T0,T3 and T4;DFAα2 in the control group at T1,T2 and T3 was higher than that at T0 and T4,and DFAα2 at T2 was the highest（P<0.05）.Shan En in dexmedetomidine group was significantly lower than that in control group at T2 and T3 with statistically significant difference（P<0.05）.In the control group,Shan En in T2 and T3 was higher than that in T0,T1 and T4（P<0.05）.There was no significant difference in Samp En between the two groups（P>0.05）.The SD1 value of dexmedetomidine group was higher than that of control group at T2 and T3 and the difference was statistically significant（P<0.05）.SD1 in T0 was the highest in the two groups,followed by SD1 in T4,and the lowest in T1,T2 and T3,with statistically significant differences（P<0.05）.The SD1/SD2 of dexmedetomidine was higher at T2 and T3 than that of the control group,and the difference was statistically significant（P<0.05）.There was no significant difference in SD1/SD2 between the two groups in T0,T1,T2,T3 and T4（P>0.05）.Conclusion:During laparoscopic surgery under general anesthesia,anesthesia-induced intubation and pneumoperitoneum establishment have a great influence on heart rate variability,showing a significant increase in sympathetic nerve activity,a significant inhibition of parasympathetic nerve function,and a counterbalance of autonomic nerve function.Intraoperative continuous pumping dexmedetomidine cannot decide not to completely reverse anesthesia and pneumoperitoneum leads to the imbalance of the autonomic nervous function,but can reduce the index of sympathetic nerve activity and parasympathetic activity index rise,balance has two-way adjustment function of autonomic nervous function,to reduce the risk of vascular events art center,improve organ function state,is of great importance to promote rapid recovery.