低劑量口服Midazolam術前給藥可減少兒科病人因Sevoflurane麻醉誘發的恢復期躁動的發生率及嚴重度

Premedication with Low-dose Oral Midazolam Reduces the Incidence and Severity of Emergence Agitation in Pediatric Patients Following Sevoflurane Anesthesia

背景：對兒科病人的麻醉誘導和維持而言，sevoflurane是halothane的合理取代藥物，然而sevoflurane會誘發較高比例的恢復期躁動，其生成機轉至今不明；sevoflurane麻醉快速恢復意識的特性是一個可能的機轉。吾人認為鎮靜劑如midazolam可減緩sevoflurane麻醉快速恢復意識的特性，從而減少恢復期躁動的發生率及嚴重度。本實驗的目的即測試低劑量口服midazolam術前、給藥是否能達到上述目的。方法：實驗採前趨性、控制、單盲設計。88名預定接受常規門診手術的患兒，分成實驗組（口服midazolam 0.2 mg/kg糖漿）及對照組（口服生理食鹽水糖漿）。於等候區、手術室及恢復室分別由三人評估記錄實驗數據。兩組患兒的麻醉誘導和維持方式相同：麻醉誘導使用8％ sevoflurane於50％ 02：50％ N20混合氣體，氣管插管不輔以肌肉鬆弛劑，控制呼吸維持於正常潮氣末二氧化碳濃度範圍；麻醉維持則使用3％ sevoflurane於50％ 02：50％ N20混合氣體直到手術結束，並記錄麻醉及手術步驟相關時段。患兒於恢復室的恢復狀況，恢復期躁動的發生率及嚴重度，止痛劑需求量，恢復室觀察停留時間，父母及恢復室護士的滿意度均加以記錄和評估。結果：實驗組患兒恢復期躁動的發生率較低且較不嚴重，其術後止痛需求較少且父母及恢復室護士的滿意度較高。實驗組患兒在恢復室較鎮靜，但恢復室觀察停留時間與對照組患兒比較則無明顯差異。患兒與父母分離的狀況與恢復期躁動的發生無顯著關聯。結論：低劑量口服midazolam不止是一相當安全及方便的麻醉前給藥方式，並可減少患兒因sevoflurane麻醉誘發之恢復期躁動的發生率及嚴重度，且不會明顯延長患兒於恢復室觀察停留之時間，故適用於門診兒科手術患兒。

Background: Sevoflurane is a volatile anesthetic agent with low pungency, non-irritating odor, and low blood/gas partition coefficient that makes it an attractive alternative to halothane. However, a high incidence of emergence agitation (EA) has been reported in pediatric patients after sevoflurane anesthesia. The underlying mechanism of sevoflurane-induced EA remains unclear. Rapid recovery of consciousness (emergence) from sevoflurane anesthesia has been proposed as one possible mechanism. We, therefore, hypothesized that sedatives such as midazolam may counteract sevoflurane's rapid emergence and thus reduce the incidence and the severity of sevoflurane-induced EA. Methods: A prospective, controlled, single-blinded study was carried out in 88 ASA class I or II pediatric patients scheduled for elective outpatient surgery. Patients were assigned to receive either midazolam (oral midazolam, 0.2 mg/kg as anesthetic premedication) or saline (oral normal saline as premedication) before the conduct of anesthesia. When separation from parents was due its process was watched and evaluated. Induction of anesthesia and maintenance of anesthesia were uniform in both groups. Induction of anesthesia was made possible with 8% sevoflurane and N2O in 50% O2. Intubation was performed straight without the aid of muscle relaxant and the ventilator was set to maintain normocapnia. Anesthesia was maintained with 3% sevoflurane and N2O in 50% O2 until the surgery was over. All matters of relevant time periods were recorded (induction, surgical procedure, extubation and transportation). In the post-anesthesia care unit (PACU), adverse events, the incidence and the severity of EA, analgesic requirement, duration of PACU stay, and parental as well as PACU nurses' satisfaction were evaluated. Results: A significant lower incidence and less severity of EA were noted in patients premedicated with midazolam. Less postoperative analgesia was required in patients who had received midazolam. Although midazolam- premedicated patients remained sedated after sevoflurane anesthesia, the duration of the PACU stay was not significantly different from that of saline-treated patients. Both parents and PACU nurses were more satisfied with midazolam as premedication. No solid evidence showed that there was close correlation between the process of separation from parents and the occurrence of EA. Conclusions: Premedication with oral midazolam is safe, convenient and effective in decreasing the occurrence of sevoflurane-induced EA. It does not delay discharge from PACU and is suitable for outpatient surgery.