Research Of Analysis Of Heart Rate Variability For Assessment Of Autonomic Nervous Function During General Anesthesia In Patients Undergoing Pituitary Adenoma Resection

Objectives:Heart rate variability (HRV) refers to minor differences between cardiac cycle, which can offer a quantitative evaluation of the tenseness and the balance of the sympathetic and vagus nerve activities and their effect on cardiovascular motion.In this study, we observed the changes of the HRV during general anesthesia in the patients who undergoing Transsphenoidal resection of pituitary adenoma, in order to evaluated the functional of autonomic nervous; we also compared the changes in HRV and BIS for discover the relationship between the depth of anesthesia and HRV.Methods:Twenty-three patients scheduled for elective of pituitary adenomas resection via nasal cavity and sphenoidal sinus, under general anesthesia were studied with mean age 36±12 years old and mean weight 65±17 kg, ASAⅠ～Ⅱ. In these patients, there were 4 Prolactinoma,1 somatotrophinoma,6 gonadotropic cell tumor and 12 other non-secreting tumors.Patients with cardiac disease, diabetes, hypertension or psychoneurosis were excluded. All patients were given intramuscular injection with atropine 0.01mg/kg,Scopolamine 2mg/kg in 30 minutes before the operation. After entering the operation room, ECG, SpO2 BP were monitored, and the electrocardiosignal was collected by home-built equipment mading by soundcard. The signal was manipulated and calculated by Matlab. Patients were induced by Midazolam 0.05～0.1 mg/kg, Propofoll～2mg/kg. Atracurium 0.1 mg/kg, Fentanyl 2ug/kg. Anesthesia was maintained by propofo13-5 u g/ml, refentanyl 3～6ng/ml,Atracurium4～5mg/h. The patients' breathing were maintained by Mechanical ventilation, with tidal volume 8～10mg/kg. frequency of 10 to 12 times/min. when the patients regained consciousness after surgery,atropine 0.5mg and neostigmine 1mg intravenous injection. Extubation while the patient fully awake, and totally follow orders. The HRV signals were intercepted in 5 minutes at five time points, before induction(To). induction(Ti), operation(T2),analepsia(T3),and extubation(T4).HR, MAP and BIS were recorded at the same time of HRV.Result:(1)The hemodynamics features of patients:HR and MAP increased in response to tracheal intubation comparing to other time points.(2)BIS:Compraed to T0,BIS decreased in other time points, T2 is the lowest.T3,T4 raised but still lower than T0.(3)The results of HRV analysis:In contrast with T0, the value of SDNN decreased at T2, but increased at T1. T3; And RMSSD and triangular index decreased at T1,T2, but increased at T3 significantly. The results of Frequency-analysis:The value of TP and SD2 increased at T1 and T3, decreasing at T2 in contrast with To; The values of HF and LF decreased at T1 and T2, but increased at T3. Meanwhile the value of LF/HF increased at T1 and T2, but decreased at T3.The result of nonlinear analysis:The values of Complexity and Entropy decreased statistically, but recovered after analepsia. In the Lorenz plots analysis, the value of VAI decreased at T1 and T2, but the value of SD2 increased significantly at T1 and T3,decreasing at T2 The index of DFA increased at T2, but no significant change was observed at other time points.(4)Correlations:There are different degrees of relevance among the various indicators of HRV, exactly, SDNN and TP, SDNN and triangle index,, HF and RMSSD,SD1 and HF, complexity and ApEn, scale index and ApEn, scale index and complexity. SDNN, TP, SD2, and triangle index can reflect the activity of autonomic nervous system;SD1, HF, RMSSD can reflect the vagus nerve on heart rate control in correlation analysis.Conclusion:During general anesthesia in the patients who undergoing Transspheno-idal resection of pituitary adenomas, the function of autonomic nerve were inhibited deeply, it has been restored at the end of surgery but not yet recovered to the preoperative level. During general anesthesia, the patient's HRV analysis and the BIS which can reflect the conscious state of the cortex index correlated to a certain extent but not fully synchronized, showed that HRV may reflects the other components of the depth of anesthesia such as pain, reflex inhibition.