背景：手術後噁心嘔吐是全身麻醉之後常見的問題，有時候可能比傷口疼痛更令人感到不適。雙頻譜腦波指數（BIS）可以經由分析腦波的變化來評估全身麻醉的深度。有些研究發現，藉由BIS 的使用可以減少全身麻醉藥物的用量、加快麻醉後恢復的速度，並且可以減少全身麻醉後發生嘔吐的機率。和其他研究不同的地方是，我們嘗試從麻醉深度的角度來觀察手術後噁心嘔吐的發生率是否會因為麻醉深度的差別而受到影響。方法：這是一個雙盲，有對照組的隨機試驗。在本院的醫學倫理委員會同意之後，共有62 位接受婦科常規手術的住院病人，分成適度麻醉（BIS 50 到60）與深度麻醉（BIS 30 到40）兩組，以BIS 的指數作為基準，在容許的麻醉深度內調整sevoflurane 的濃度，並觀察兩組手術中sevoflurane 的使用量和手術後噁心嘔吐的發生率。結果：手術中sevoflurane 的總使用量，研究組明顯高於對照組（68 公克比50.3 公克）。而在術後噁心嘔吐方面，研究組則略低於對照組（38.7% 比54.8%），不過統計上則未達顯著的差異。結論：影響手術後噁心嘔吐的因素太過於複雜，單就sevoflurane 的麻醉深度一項來看，可能沒有決定性的影響。

Background and purpose: Postoperative nausea and vomiting (PONV) is one of themost common adverse effects of general anesthesia; it may be more discomforting than woundpain. The Bispectral Index (BIS) is a derived electroencephalographic parameter that has beenextensively validated for monitoring the depth of anesthesia. Some studies have shown that usingBIS to monitor anesthesia depth could minimize usage, recovery time, and side effects (nauseaand vomiting) of general anesthetics. Unlike other studies, our study aims to evaluate the effect ofdeep anesthesia on PONV. Methods: After obtaining approval from the Ethics Committee of ourhospital, 62 women scheduled to undergo elective inpatient gynecological procedures were studiedusing a prospective randomized controlled study design. Sevoflurane was titrated to maintain theBIS value between 30 and 40 in the study group (deeper anesthesia) and between 50 and 60 inthe control group (optimized anesthesia) during the surgery. Sevoflurane consumption and PONVincidence between the 2 groups were compared. Results: The total sevoflurane dose was higherin the study group (68 g vs. 50.3 g); the difference was statistically significant. PONV incidencewas found to be lower in the study group (38.7% vs. 54.8%); however, the difference was notstatistically significant. Conclusions: Since the PONV mechanism is so complex, the depth ofsevoflurane anesthesia may not be the determinant factor of PONV.