Effects Of Different Doses Remifentanil On Hemodynamic Responses To Tracheal Intubation

Effects of different doses remifentanil on hemodynamic responses to tracheal intubationObjective:To investigate the effect of different dose remifentanil combined with propofol on trachea intubation hemodynamic changes during induction of general anesthesia, to compare the superiority of trachea intubation between remifentanil with fentanil,and to optimize the dosage of remifentanil during this phase. The results can help to determine the doses of remifentanil in the rapid induction of general anesthesia, also can explore to select the best anesthesia drug in short surgical.Methods:Sixty ASA physical statusⅠ-Ⅱpatients, undergoing major surgery, were randomly assigned to 4 groups,15 patients in each group. When they were in the operating room, all of them were administered with 1mg penehyclidine intravenously, and then they order to administered medicine as following, F group:midazolam0.03mg/kg+ propofol 1.5mg/kg+fentanil 2.5μg/kg+vecuronium 0.1mg/kg, the trachea was intubated 3 min after the medicine infusion; R group:midazolam 0.03mg/kg+propofol 1.5mg/kg+vecuronium 0.1mg/kg, after loss of consciousness, then administered intravenous remifentanil 1μg/kg (R1group),1.5μg/kg (R2 group),2μg/kg(R3 group) (injection duration >30s), assisted respiration, and the trachea was intubated 60s after the medicine infusion. Then mechanical ventilation, respiratory rate 10-12 beats per min, tidal volume 8-10ml/kg, maintaining end-tidal carbon dioxide partial pressure 35-45mmHg, I:E= 1:2. During the phase, not any stimulus was given. Hypotension (SBP<80mmHg for>60s) was treated with ephedrine 10-15mg i.v. or atropine 0.25mg i.v. (if HR<50 beat per min). Intubation condition and hemodynamic changes in trachesl intubation were observed. HR, SBP, DBP and MAP were moniroed at the time point when of the patients were in the operating room (TO), induction (T1), immediately before intubation (T2), after intubation lmin (T3),2min (T4),3min (T5),5min (T6). According to Hellbo-Hanson to the scoring system, the doctor evaluated the intubation conditions using single blind trial technique. Side effects of the patients, such as intraoperative awareness, cough, laryngospasm, chest wall rigidity, laryngospasm bronchus, trunk muscle stiffness, low blood pressure (MAP <60mmHg, duration>60 seconds), bradycardia (HR<50 beats per min, duration>60 seconds) were record.Results:Tracheal intubation was successful in all patients(P>0.05)Compared with T0 and T1, the other index in 4 groups all decreased after induction of anesthesia(P<0.05或P<0.01). Blood pressure began to increase right after the catheter insertion since, but it is still below the baseline (P<0.05). One minute and 2 minutes after intubation, SBP,MAP in R1 group were dramatically increased, and the difference between groups was statistically significant (P<0.05) compared with another 3 groups. In R2 and R3 groups, the blood pressure began to rise immediately after the tube was inserted, and it was still below the level before anesthesia. Two cases occurred hypotension after the induction of remifentanil 2.0μg/kg, though compared with R1, R2 group was not significant. It last for more than 1 minute, and need to be treated with ephedrine or dopamine.Conclusion:Combined with propofol, both remifentanil and fentanil can inhibit cardiovascular responses during induction of general anesthesia. Intravenous administeration of remifentanil at dosage 1μg/kg for one time can not effectively inhibit cardiovascular responses. The dose of 1.5μg/kg and 2.0μg/kg remifentanil for one time can induce good cardiovascular stress response after intubation, The dose of 1.5μg/kg may well inhibit the cardiovascular stress response after intubation, hemodynamic change a little and can be maintained at a relatively stable level. The dosage 1.5μg/kg is ideal dose during tracheal intubation.