| Objectives: Rocuronium is a new kind of non-depolarizing muscular relaxant with the middle duration of action. It has been used to clinical anesthesia gradually, due to its advantage of rapid onset time, easy reversing by antagonist, no histamine release, few of adverse effects, and so on. The duration of action of rocuronium affect its clinical application directly. The intravenous anesthetics or inhalational anesthetics which was always administered combined with rocuronium, can affect the potency of rocuronium significantly, especially the inhalational anesthetics when inhaled for a long time. This study is designed to compare the influence of isoflurane on pharmacodynamics of rocuronium, when rocuronium is administered by single dose of 2ED95 and 3ED95 in general anesthesia, and to identify if isoflusion anesthesia can potentiate its effects in the duration of action of 2ED95 or 3ED95 rocuronium, and to direct the clinical use of rocuronium for more security and efficiency.Methods: 40 adult patients scheduled for elective surgeries with general anesthesia in the First Hospital of Jilin University during 2007, Mar to 2008, Mar were included randomly, and divided into four groups, 10 cases in each group. Including standards: ASA physical status I and II, the operation time during 1 to 2 hours, ages 18 to 60, no obvious obesity, and no significant dysfunction of liver or kidney, no neuromuscular disease such as myasthenia gravis, or any obvious electrolyte disturbances or acid-base imbalance. In all patients general anesthesia were induced and the endotracheal intubation were performed in routine after induction. Induce drugs: midazolam 0.06 mg·kg-1, fentanyl 4μg·kg-1, etomidate 0.3 mg·kg-1. Patients of Group I and III received 0.6 mg·kg-1 rocuronium IV, and patients of Group II and IV received 0.9 mg·kg-1 rocuronium IV. Patients of Group I and II were administered propofol as IV infusion continuously to maintain anesthesia; patients of Group III and IV inhaled isoflurane continuously to maintain anesthesia. Keep the depth of anesthesia by adjusting the dose of propofol or isoflurane, maintain BIS at 40-50 and ETCO2 at 35-45mmHg, maintain the vital sign stable during surgery. If it is necessary , an appropriate dose of fentanyl can be administered, and a boost of rocuronium 0.15 mg·kg-1should be administered when T1 recovered to 25%. All patients were monitored ECG, NIBP and SPO2 when came into the operating room. Four time point: before anesthesia, 10 min, 30 min and 60 min after anesthesia were selected to record the HR and MAP, respectively. The degree of neuromuscular block was monitored by TOF. The duration of peak effect (from maximum block of T1 to the beginning of recovery), clinical duration (from maximum block to 25% recovery of T1), RI (25%-75% recovery of T1) were recorded respectively. All experimental data are summarized as mean±standard deviation ( x±s), and t-test was used to assess the intergroup differences. Differences were considered statistically significant if the p-value was less than 0.05.Results: In the groups maintained anesthesia by propofol, the duration of peak effect and clinical duration of rocuronium was 30.8±3.1 min, 38.25±3.8 min and 52.7±3.7 min, 59.8±5.1 min, respectively in which received 0.6 mg·kg-1 (Group I) and 0.9 mg·kg-1(Group II) rocuronium IV; and in the groups maintained anesthesia by isoflurane, the duration of peak effect and clinical duration of rocuronium was 37.9±7.0 min, 44.6±7.8 min and 72.9±7.2 min, 79.8±7.9 min, respectively in which received 0.6 mg·kg-1 (Group I) and 0.9 mg·kg-1 (Group II) rocuronium IV. The differences of the duration of peak effect and clinical duration of rocuronium between Group I and Group II were statistically significant, but the difference of RI between the two groups was not statistically significant. The differences of the duration of peak effect and clinical duration of rocuronium between Group II and Group IV were statistically significant, too, and the difference of RI between the two groups was not statistically significant either. The results indicate that the duration of peak effect and clinical duration of rocuronium in patients maintained by isoflurane are both longer than in those maintained by propofol (P<0.05), when received initial dose of 0.6 mg·kg-1 (2ED95) and 0.9 mg·kg-1 (3ED95) rocuronium IV. Neither of the differences of RI between each two groups has statistically significant.Conclusions: 1,Isoflurane potentiate the effect of rocuronium both in the duration of 0.6 mg·kg-1 (2ED95) and 0.9 mg·kg-1 (3ED95) administered immediately after induction. The longer of the inhaling time of isoflurane, the more significant of its potentiation on rocuronium. 2,It is the enhanced sensitivity of neuromuscular junction results the potentiation of isoflurane on rocuronium. Only the duration of peak effect and clinical duration can be affect, but not the process of its spontaneous recovery. 3,Isoflurane has potentiation on rocuronium even in the duration of 2ED95 rocuronium (usually less than 1hour), so the monitor of neuromuscular transmission should be emphasis in clinical anesthesia. |
