An Investigation On Dose Optimization Scheme Of Different Drugs Of Intravenous Induction Of General Anesthesia In Elderly Patients

Background and Objective With the improvement of the social and economic, the aging of the popul-ation is becoming more and more obvious. At the same time, with the improve-ment of medical level and the development of modern surgical technique, anes-thesia and various monitoring techniques, more and more elderly patients can be treated with surgery. But elderly patients have special physiological characte-ristics and pathological changes, if the induction of anesthesia is improper will cause great fluctuation of blood circulation of elderly patients, resulting in a number of serious complications. The main purpose of this clinical observation is to investigate the dose optimization scheme of different drugs in the intraven-ous induction of general anesthesia of elderly patients, in order to guide the dosage selection in clinical anesthesia practice.Methods 90 elderly patients undergoing elective abdominal surgery were randomized to A, B, C, D, E, F group(n = 15). According to the weight distribution method, the corresponding dosages of midazolam(0.06, 0.05, 0.04, 0.03, 0.025, 0.02mg/kg), fentanyl(5, 3, 2, 6, 4, 2.5ug/kg)and etomidate(0.24, 0.2, 0.3, 0.2, 0.3, 0.24 mg/kg) were respectively administered to the corresponding group in the intravenous induction. Anesthesia was maintained with sevoflurane inhalation during operation. Mean arterial pressure( MAP), heart rate( HR) and bispectral Index(BIS) were monitored at before anesthesia(T0), before tracheal intubation(T1), tracheal intubation period(T2) and 5 minutes after tracheal intubation(T3). The serum concentrations of catecholamine were detected by radioimmunoassay at before anesthesia(T0) and 5 minutes after tracheal intubation(T3) in the 5 patients randomly selected in each group. The patients of oxygen saturation < 90%, MAP or HR fluctuations ±20% and muscle twitch were observed and recorded during the induction of general anesthesia.Results 1. The difference of MAP, HR and BIS of each group at each time point was statistically significant(P<0.001), further analysis found that the sequence of MAP which was more stable at each time point was: group A>E >D>B>C>F, the sequence of HR which is more stable at each time point was: group A>E>D>B >F>C, the sequence of of BIS which is more stable at each time point was: group E>A>C >F >B>D. 2. The difference of serum norepinephrine and epinephrine concentration between before and after tracheal intubation in each group was statistically significant(P<0.05), the sequence of serum norepinephrine which was more stable was: group A >(B, D, E) >(C, F), the sequence of serum adrenaline which was more stable was: group D>E>A>B>F>C(D>A);There was no statistic difference in the serum concentration of dopamine in each group between before and after intubation(P > 0.05). 3. The patients of oxygen saturation < 90% or muscle twitch were not observed and there were no statistic difference in the patients of MAP or HR fluctuations ± 20% during induction of general anesthesia in all groups(P>0.05).Conclusion The dose combination scheme of midazolam 0.06 mg/kg, fentanyl 5 ug/kg and etomidate 0.24 mg/kg for intravenous induction of general anesthesia in elderly surgical patients is optimal, which provides stable heart rate and blood pressure, satisfactory depth of sedation, the serum low catecholamine levels and no adverse effects during intravenous induction of general anesthesia.