閉鎖式循環麻醉延長Rocuronium神經肌肉阻斷的效果

Closed-circuit Anesthesia Prolongs the Neuromuscular Blockade of Rocuronium

背景：已知吸入性麻藥具有加強非去極化肌肉鬆弛劑之神經肌肉阻斷效果。而不同的全身麻醉方式對於rocuronium之神經肌肉阻斷效果則尚未研究清楚。本實驗乃利用肌電圖比較低流量閉鎖式循環麻醉及高流量半閉鎖式麻醉對於rocuronium之神經肌肉阻斷效果之影響。方法：本實驗選取五十個接受腹腔鏡子宮切除手術之正常健康婦女，將其以隨機取樣的方式分成兩組，每組二十五個病人，分別接受低流量閉鎖式循環麻醉和高流量半閉鎖式麻醉。兩組麻醉誘導皆給予fentanyl 2 μg/kg，thiopental 5 mg/kg和rocuronium 0.6 mg/kg 之後，當 T1 < 10％ 時執行插管（rocuronium之起始作用時間）。插管之後，兩組皆先以高流量氧氣(3 1/min)將2％ isoflurane洗入麻醉迴路及肺部10分鐘後，隨後即分成兩組不同全身麻醉方式。當術中兩組之肌電圖所測得之第一次T1達到25％（臨床作用間期）時，旋即給予維持劑量之rocuronium (0.15 mg/kg)以維持肌肉鬆弛，緊接之後維持兩組麻醉方式並紀錄再次T1恢復至25％之時間（維持劑量間期）及T1恢復至25～75％之時間（恢復指數）。麻醉誘導時記錄兩組rocuronium之起始作用時間及病患插管狀況。術中記錄兩組rocuronium之臨床作用間期(CD)、維持劑量間期(MD)以及恢復指數(RI)。術中並於下刀後每隔15分鐘記錄病患之血壓、心跳及isoflurane吸氣／吐氣之濃度。結果：Rocuronium之起始作用時間及插管狀況在兩組之間並無明顯差異性。於低流量閉鎖式循環麻醉組有較長之臨床作用間期、維持劑量間期及恢復指數。結論：在本實驗中，我們認為以isoflurane為主的閉鎖式循環麻醉比半閉鎖麻醉更可以延長rocuronium之神經肌肉阻斷之效果。

Background: Volatile anesthetics are known to potentiate the neuromuscular blocking effect of nondepolarizing muscle relaxants. The influences of anesthetic techniques, closed-circuit anesthesia (CCA) and high flow semiclosed anesthesia (SCA), on the neuromuscular blockade of rocuronium has not yet been studied in detail. This study was purposed to compare the effects of isoflurane conveyed in minimal flow (CCA) and in high flow (SCA) on the neuromuscular blockade of rocuronium. Methods: Fifty females scheduled for elective laparoscopic gynecological surgery were enrolled for study and randomly assigned to receive either CCA (n = 25) or SCA (n = 25). Anesthesia was induced with fentanyl 2 μg/kg, thiopental 5 mg/kg and rocuronium 0.6 mg/kg. Two percent isoflurane in high O2 flow (3 1/min) was given for 10 min to all patients initially to wash isoflurane in the functional residual capacity of both lungs and the breathing circuit. After the wash in, for CCA group, the O2 flow was reduced to 300 ml/min with isoflurane vaporizer setting adjusted to 3-5% for anesthesia maintenance, while for SCA group, anesthesia was maintained with 1.5-2% isoflurane in 3 1/min O2 flow throughout the surgery. Electromyogram was used to determine neuromuscular blockade. Rocuronium (0.15 mg/kg) was given to maintain muscle relaxation when T1 reached 25% of control. We maintained the anesthetic depth until the recordings of T1 twitch response which reached 75% was completed. Onset time, duration, recovery index and intubating conditions were recorded. The hemodynamic parameters and the inhaled/exhaled concentrations were also measured every 15 min after skin incision in both groups. Results: The onset time and intubating conditions were similar in both groups. In comparison with SCA group, longer clinical durations (54.1 ± 14.4 vs. 45.4 ± 9.2 min, P < 0.05), longer durations of maintained dose (41.1 ± 11.1 vs. 30.2 ± 8.6 min, P < 0.01) and longer recovery index (34.2 ± 10.7 vs. 20.9 ± 5.4 min, P < 0.0001) were observed in CCA group. Conclusions: We conclude that CCA may further prolong the neuromuscular blocking effect of rocuronium than SCA.