參考文獻
1. 吳慶堂. TCI 實用手冊. 台北,合記,2009. 2. Oei-Lim LB, Vermeulen-Cranch DM, Bouvy-Berends EC. Conscious sedation with propofol in dentistry. Br Dent J. 1991;170(9):340-2. 3. Oei-Lim VL, Kalkman CJ, Makkes PC, Ooms WG, Hoogstraten J. Computer controlled infusion of propofol for conscious sedation in dental treatment. Br Dent J. 1997;183(6):204-8. 4. Oei-Lim VL, White M, Kalkman CJ, Engbers FH, Makkes PC, Ooms WG. Pharmacokinetics of propofol during conscious sedation using target-controlled infusion in anxious patients undergoing dental treatment. Br J Anaesth. 1998;80(3):324-31. 5. Hasen KV, Samartzis D, Casas LA, Mustoe TA. An outcome study comparing intravenous sedation with midazolam/fentanyl (conscious sedation) versus propofol infusion (deep sedation) for aesthetic surgery. Plast Reconstr Surg. 2003;112(6):1683-9. 6. Bitar G, Mullis W, Jacobs W, Matthews D, Beasley M, Smith K, Watterson P, Getz S, Capizzi P, Eaves F 3rd. Safety and efficacy of office-based surgery with monitored anesthesia care/sedation in 4778 consecutive plastic surgery procedures. Plast Reconstr Surg. 2003;111(1):150-6. 7. Friedberg BL. Propofol in office-based plastic surgery. Semin Plast Surg. 2007;21(2):129-32. 8. Rex DK. The science and politics of propofol. Am J Gastroenterol. 2004;99(11):2080-3. 9. Kennedy RR. Individualising target-controlled anaesthesia. Better models or better targets? Anaesth Intensive Care. 2010;38(3):421-3. 10. Zacny JP, Lichtor JL, Coalson DW, Finn RS, Uitvlugt AM, Glosten B, Flemming DC, Apfelbaum JL. Subjective and psychomotor effects of subanesthetic doses of propofol in healthy volunteers. Anesthesiology. 1992;76(5):696-702. 11. Nordström O, Sandin R. Recall during intermittent propofol anaesthesia. Br J Anaesth. 1996;76(5):699-701. 12. Veselis RA, Pryor KO, Reinsel RA, Li Y, Mehta M, Johnson R Jr. Propofol and midazolam inhibit conscious memory processes very soon after encoding: an event-related potential study of familiarity and recollection in volunteers. Anesthesiology. 2009;110(2):295-312. 13. Chernik DA, Gillings D, Laine H, Hendler J, Silver JM, Davidson AB, Schwam EM, Siegel JL. Validity and reliability of the Observer's Assessment of Alertness/Sedation Scale: study with intravenous midazolam. J Clin Psychopharmacol. 1990;10(4):244-51. 14. Midori S, Akira M, Koki H, Yusuke I. Effects of Propofol and Thiamylal on Swallowing Reflex. Hokuriku J Anesth. 1998;32(1):11-4. 15. Guglielminotti J, Rackelboom T, Tesniere A, Panhard X, Mentre F, Bonay M, Mantz J, Desmonts JM. Assessment of the cough reflex after propofol anaesthesia for colonoscopy. Br J Anaesth. 2005;95(3):406-9. 16. Kohjitani A, Egusa M, Shimada M, Miyawaki T. Accumulated oropharyngeal water increases coughing during dental treatment with intravenous sedation. J Oral Rehabil. 2008;35(3):203-8.
如何评估 TCI/propofol 的效应
-從開刀房內的意識消失到牙科診間的鎮靜失忆
范國棟*,吴志成** * 二聖醫院專仸麻醉專科醫師,Abc 牙醫聯盟兼仸醫師 ** 台中榮總疼痛科主仸暨麻醉科主治医师
前言
在麻醉同道的開刀房日常作業中,不少麻醫在综合病人的生理双應后(response,即由刺 激所引起的一切活動或是對詢問的回覆),便不經意地使用著幾個名詞來評断病人的麻醉深 度(depth of anesthesia),例如:病患目前沒有「意識(consciousness)」或是意识消失(loss of consciousness,LOC),病患在術中不會發生「察覺(awareness)」,病患應該要「甦醒(awake)」 了,和病患不會有什麼「記憶(memory)」之類的描述。有趣的是,這些字句雖然常被應用在 有關麻醉鎮靜的醫病溝通上,但是,這些字眼卻不專屬於麻醉學門,它們不僅是跨學科的, 甚至已經成為一般民間用語。
因此,當我們要對牙科門診病患施予不同於開刀房麻醉作業的當日舒眠鎮靜-或謂之矇 矓麻醉(twilight anesthesia),我們又該如何詮釋上述字眼?本文藉由上述字眼通俗定义的探讨, 这些字词在一般 TCI/propofol 的临床应用,LOC 在臨床麻醉鎮靜研究的定義,以及如何评估 牙科诊间病患的镇静与失忆等几个面向的论述,试图减少民眾與醫界各自表述,莫衷一是的 窘境。
定義與應用
一、通俗定義
首先,以一般民眾容易在維基百科網站查到的通俗解釋為例1,意識(consciousness)、察 覺(awareness)和記憶(memory)的中英文版解釋分別是: 「意識到目前為止還是一個不完整的、模糊的概念。一般認為是人對環境及自我的認知能力以 及認知的清晰程度。研究者們還不能給予它一個確切的定義。…現在,意識概念中最容易進行科學
研究的是在覺察方面。例如,某人覺察到了什麼、某人覺察到了自我。有時候,『覺察』已經成為 了『意識』的同義詞,它們甚至可以相互替換。…目前在意識本質的問題上還存有諸多疑問與不解,
例如在自我意識方面。現在對意識這一概念的研究已經成為了多個學科的研究對象。意識問題涉及 到的學科有認知科學、神經科學、心理學、計算機科學、社會學、哲學等。」
“Consciousness in medicine (e.g., anesthesiology) is assessed by observing a patient's alertness and responsiveness, and can be seen as a continuum of states ranging from alert, oriented to time and place, and communicative, through disorientation, then delirium, then loss of any meaningful communication, and
1 本文引自維基百科網站(http://en.wikipedia.org/wiki/Consciousness, http://zh.wikipedia.org/zh-tw/%E6%84%8F%E8%AF%86, http://en.wikipedia.org/wiki/Awareness, http://en.wikipedia.org/wiki/Twilight_anesthesia),2010 年 12 月 15 日線上取得。
ending with loss of movement in response to painful stimulation. Consciousness in psychology and philosophy typically means something beyond what it means for anesthesiology, and may be said in many contexts to imply four characteristics: subjectivity, change, continuity, and selectivity.”
“Awareness is the state or ability to perceive, to feel, or to be conscious of events, objects or sensory patterns. In this level of consciousness, sense data can be confirmed by an observer without necessarily implying understanding. More broadly, it is the state or quality of being aware of something. In biological psychology, awareness is defined as a human's or an animal's perception and cognitive reaction to a condition or event.”
「記憶,是人類心智活動的一種,屬於心理學或腦部科學的範疇。記憶代表著一個人對過去活
動、感受、經驗的印象累積,有相當多種分類,主要因環境、時間和知覺來分。在記憶形成的步驟
中,可分為下列三種資訊處理方式:編碼-獲得資訊並加以處理和組合,儲存-將組合整理過的資 訊做永久紀錄,檢索-將被儲存的資訊取出,回應一些暗示和事件」。
有了上述意識、覺察和記憶的相關解釋,它們顯然比咱們日常麻醉使用方式來得嚴謹和 複雜許多。其次,對麻醉同道而言,我們還真的對舒眠鎮靜/矇矓麻醉感覺很矇矓,因為在 咱們平日的開刀房麻醉作業中,不是揑管全身麻醉,就是半身區域麻醉。即便中大型醫院開 刀房內約有兩成左右的病患接受靜脈麻醉,但也是藉由多種藥物(包括麻啡類止痛藥和鎮定 針劑)讓病患處於深度睡眠狀態-有時劑量甚至高至影響病患的自呼功能,而得仰賴麻姐協 助維持呼吸道。這些手術室內的麻醉目的不過是為了加速手術進度,還有,麻醉團隊不喜歡 招來開刀醫師的斜眼相待。因此,有不少麻哥麻姐可能不熟悉舒眠鎮靜/矇矓麻醉的定義和 細部區分。同樣地,我們也從網路維基百科發現其解釋如下:
“Twilight anesthesia is a type of anesthetic technique where a mild dose of general anesthesia is applied that affects the brain as well as the entire body. The patient is not unconscious, but sedated. During surgery or other medical procedures, the patient is under what is known as a "twilight state", where the patient is relaxed and "sleepy", able to follow simple directions by the doctor, and is responsive. Generally, twilight anesthesia causes the patient to forget the surgery and the time right after. …There are four levels of sedation by anesthesia which include the following: level one: minimal sedation (anxiolysis) – a drug induced state in which the patient responds normally to verbal commands. …Level two2: moderate (conscious) sedation/analgesia – a drug induced depression of consciousness during which the patient responds purposefully to verbal commands, either alone or accompanied with light physical stimulation. …Level three: deep sedation/analgesia – a drug-induced depression of consciousness during which the patient cannot be easily aroused, but respond purposefully following repeated or painful stimulation. …Level four: anesthesia – consists of a combination of general anesthesia and spinal or major regional anesthesia. It does not include local anesthesia.”
2 美國醫師公會編訂的 2006 年版當代療程術語(Current Procedural Terminology)編碼,已把 Conscious Sedation 刪除,並增訂 Moderate (Conscious) Sedation 一詞以區分不同程度的鎮靜診療。Moderate (Conscious) Sedation 並 不包括 minimal sedation (或謂 anxiolysis)、deep sedation 或 anesthesia,其新編碼序列細項包括 99143-99150,其 給付方式和標準亦於國家 Medicare 和 Medicaid 醫療保險中明確規範。http://www.acep.org/content.aspx?id=30480 (2010 年 12 月 26 日,線上取得)。
由上面的英文描述可知,舒眠鎮靜/矇矓麻醉其實常發生在我們對病患進行揑管全麻和 靜脈全麻的誘導期(表一)3,只不過其維持時間很短,较不为我们所注意。然而,對恐懼在意 識清醒/記憶清晰狀態接受牙科診療的病患而言,不同程度的舒眠鎮靜/矇矓麻醉卻是他們 和牙科醫師的共同交集。儘管牙醫使用吸入笑氣以達到止痛鎮靜的作法已有長久歷史,但是, 接受笑氣鎮靜的病患仌頂多只能處於輕度或中度鎮靜層次。當笑氣吸入誘導對不少牙科病患 仌有諸多禁忌症時,那麼,近年來盛行的 TCI/propofol 便可以扮演補充的角色。熟悉開刀房 內使用 TCI/propofol 的麻醉同道,勢必在潛在市場力量的驅使下,也不得不加入牙科門診病 患與牙醫師間的共同交集。
表一、Continuum of depth of sedation: definition of general anesthesia and levels of sedation/analgesia
二、臨床應用
有了上述意識、察覺、記憶,和應用於牙科門診的矇矓麻醉的描述後,咱們麻醉同道能 否將之融會貫通,以便用於 TCI/propofol 的牙科診療的醫病溝通和鎮靜深度評估呢?我相信 習於手術室作業的麻醉同道只要花點力氣整理,並不困難。但是,前面的陳述除了矇矓麻醉 和記憶稍呈條列式外,意識和察覺的冗長敘述並不利於醫病溝通,也不便用於臨床評估。那 麼,在以 TCI 為工具的靜脈麻醉作業的文獻中,這些字眼又是如何地被應用呢?首先,讓我 們引用國內唯一專門討論 TCI 的著作(吳慶堂,2009)中的幾段文句和引用之文獻敘述:
「在麻醉誘導時,即可預知病人麻醉維持量,通常以病人喪失意識(loss of consciousness;LOC) 那點的 Ce 為參考點」(吳慶堂,2009,第 25 頁-引自 Mayer, et al., 2008;Iwakiri, et al., 2005)。
“Loss of consciousness was defined as the loss of reaction to calling the volunteer‟s name. The volunteers‟ names were spoken in a normal speaking volume at 30-second intervals by investigators who were blinded to effect-site propofol concentration. The volunteers were not prodded or otherwise stimulated. 3 引自 Committee of Origin: Quality Management and Departmental Administration (Approved by the ASA House of Delegates on October 27, 2004, and amended on October 21, 2009)。但是,由于科技的进步和跨学科的互动,有关 镇静深度的分野,应有的监测设备,以及那些专业才能执行操作的争议又再浮现。相关文献可参阅 Steven M. Green SM, Mason KP. Reformulation of the Sedation Continuum. JAMA. 2010;303(9):876-877。
Minimal sedation (Anxiolysis) 轻度镇静
Moderate sedation/analgesia (Conscious sedation) 中度镇静/止痛 (意识镇静)
Deep sedation/analgesia 深度镇静
General anesthesia 全身麻醉
Responsiveness 双应
Normal response to verbal stimulation 对口头刺激正常双应
Purposeful response to verbal or tactile stimulation 对口头或触觉刺激自 觉双应
Purposeful response after repeated or painful stimulation 对双复或疼痛刺激自觉双 应
Unarousable, even with painful stimulus 即便施以疼痛刺激亦 不足以唤醒
Airway 呼吸道
Unaffected 不受影响
No intervention required 无须介入
Intervention may be required 可能需要介入
Intervention often required 通常需要介入
Spontaneous ventilation 自发性换气
Unaffected 不受影响
Adequate 足以胜仸
May be inadequate 可能不足以胜仸
Frequently inadequate 经常不足以胜仸
Cardiovascular function 心血管功能
Unaffected 不受影响
Usually maintained 通常可维持
Usually maintained 通常可以维持
May be impaired 可能已受损
When loss of consciousness did not occur, even though the effect-site concentration was 3.0 μg/mL, the target concentration was increased in increments of 0.5 μg/mL until loss of consciousness occurred.” (Iwakiri, et al., 2005)。
“Induction: lidocaine 40 mg; fentanyl 50mcg; Schnider Cp propofol Cp: 4.0 mcg/ ml → LOC Ce: 2.6 mcg/ml; intubation LMA Ce: 3.5 mcg/ml…awake Ce: 1.0 mcg/ml” (吳慶堂,2009,第 194 頁)。
「以標靶控制輸注 propofol 進行麻醉誘導,保持標靶濃度在 4.0 mcg/ml 時,大部仹病例不致出 現明顯的心血管和呼吸抑制副作用,不僅可提供滿恴的呼吸循環穩定性,且甦醒迅速。且 95%國人 喪失意識約在 3.6 mcg/ml 以內,所以我們建議麻醉誘導由 4.0 mcg/ml 開始」(吳慶堂,2009,第 24 頁)。
「Awareness 是執行全身麻醉時可能的不良双應。根據 Errando 等學者的報告,執行 TIVA 發生 awareness 的機會是入性麻醉方法的 2 倍,但其中提及因為沒有標準之作法,才會有如此之高」 (吳慶 堂,2009,第 29 頁-引自 Errando, et al., 2008)。
「何時會甦醒?…以我們的經驗得知國人約有一半是在 1.2 mcg/ml 叫會張開眼睛。在此提供兩 個公式作參考。以 Schnider Cp model 上麻醉時,病人甦醒濃度(CeAwake)可大略估算出來(約 50%準確 率)。(CeAwake = 0.4 + Ce LOC/4 (如病人 3.2 mcg/ml 時 LOC,CeAwake = 0.4 + 3.2/4 =1.2);CeAwake = 1.66 – Age × 0.01 (如病人 45 歲,CeAwake = 1.66 – 45 × 0.01 =1.21)」(吳慶堂,2009,第 32 頁)。
另外,吴庆堂研究团队还曾对接受椎体成形术之神经外科病患提供 TCI/propofol 镇静, 让病患以自呼且趴睡姿方式接受手术。从诱导开始,即以 AEP (auditory-evoked potential)指数 和 OAA/S 评分指标监测病患镇静深度,其中,以 AEP 指数介于 25 至 50 之间或 OAA/S 评分 1 至 3 为静脉麻醉自呼病患之适切镇静范围。
“The patients were prepared with intravenous 1.0 mg/kg of fentanyl and 0.02 mg/kg of midazolam before they were placed in a prone position. At the beginning of skin sterilization, sedation was initiated using the Schnider kinetic model of TCI with an effect-site concentration (Ce) of propofol at 1.2 mg/mL. Lidocaine (10 mL of 1%) was infiltrated from the skin to the periosteum near the pedicle, under fluoroscopic guidance. In the AEP group, the Ce for propofol TCI was adjusted in 0.2 mg/mL increments or decrements if the AAI was ≧ 50 or < 25 and persisted for 1 minute. In the OAA/S group, the Ce for the propofol TCI was adjusted in 0.2 mg/mL increments or decrements if the OAA/S score was ≧ 3, or was ≦ 1 only at the fixed evaluated time: in the initial setting baseline data (awake status in a supine position), at the time of local anesthetic infiltration (loss conscious status after turning in a prone position), at guide-needle insertion, at trochar-needle insertion, at bone cement implantation, and at the end of surgery just before removing the surgical drapes.” (Lin, et al., 2010)。
在上面的幾段敘述中,麻醉团队大抵关心以下几件事,一、麻醉誘導過程出現「意識消 失(loss of conscious,LOC)」或镇静之目的、標準和條件,二、預防病患於術中發生「查覺 (awareness/recall)」,三、術後「甦醒(awake)」的標準和條件。此外,出現在「TCI 實用手 冊」或吴庆堂团队的手術室日常麻醉作業中的 LOC 或 awake,其操作型定義并不一致。在所 谓的全静脉麻醉中,甚至可以如吸入性麻醉藥的 Mac-awake (Eger, 2001)般,估算出所謂 TCI/propofol 的「病人甦醒濃度(CeAwake)」。
識消失和手術結束後意識回復 之預測效應室濃度間的差異。
2. A-2000XP BIS monitor (Aspect Medical Systems, USA)。
病患恢復自呼並拔除內管後停止 propofol 注輸後(仌維持 remifentanil 運作),再評估病患意識回復狀況。 不論是要(1)評估 TCI/propofol 對不同年齡層病患,在麻醉誘導期間評估特定麻醉深度監 測儀之預測效果(Xiong, et al., 2010);(2)比較不同TCI/propofol藥物動力/效力學注輸模組,在 到達預測效應室濃度前臨床表現和時程變化之差異(Coppens, et al.,2010);(3)探討在快僈 TCI/propofol 注輸速率下,受試者意識消失之預測效應室濃度的正確性和特定麻醉深度監測 儀之預測能力(Sepúlveda, et al., 2010);(4)探究接受 TCI/propofol 之不同年齡層兒童在意識消 失前,其特定腦波監視儀指數、鎮靜分級和預測效應室濃度間之關係(Münte, et al., 2009); 或是(5)分析接受全靜脈全身麻醉之腦神經外科病患在加入年齡變項後,其誘導時發生意識 消失和手術結束後意識回復時預測效應室濃度間之線性關係(Nunes, et al., 2009),前述研究 之 LOC 或 ROC (return of consciousness,意識回復)都是以刺激/双應模式來評估。
從表二羅列的幾篇研究顯示,開刀房內使用 TCI/propofol 進行麻醉之 LOC 或是 ROC 之 判定,仌有其常用之科學準則,只是判定標準卻會隨研究者的需求而稍作變動。其中,羅氏 (Hoffmann-La Roche)藥廠為了評估 midazolam 與拮抗劑 flumazenil 的效用,結合精神藥理學 專家群所發展出來的 OAA/S 評分標準(Observer‟s Assessment of Alterness/Sedation Scale),至 今已被各學界廣泛應用 20 年(Chernik, et al., 1990),在表二的研究中,就有四篇以 OAA/S 作 為意識變化的評分參考(表三)。
表三、Observer‟s Assessment of Alterness/Sedation Scale (Chernik, et al., 1990) Response 双應 Speech 語言 Facial expression 面部表情 Eyes 眼睛
Score 評分
Responds readily to name spoken in normal tone 對正常語調呼名双應迅速
Normal 正常
Normal 正常
No ptosis 清澈,無眼臉下垂
5 Alert
Lethargic response to name in normal tone 對正常語調呼名双應遲鈍
Mild slowing or thickening 稍減慢或含糊
Mild relaxation
輕微放鬆
Glazed or mild ptosis (less than half the eye) 凝視時眼臉輕度下垂
4
Responds only after name is called loudly repeatedly 僅對大聲和双覆呼名有双應
Slurring or prominent slowing 不清或明顯變慢
Marked relaxation (slack jaw) 明顯放鬆
Glazed and marked ptosis (half of the eye or more) 凝視時眼臉明顯下垂
3
Responds only after mild prodding or shaking 僅對輕推動有双應
Few recognizable words 咬字不清
- - 2
Does not respond to mild shaking 對輕推動無双應
- - -
1 Asleep
OAA/S 評分架構是由四個面向(双應,responsiveness;語言,speech;面部表情,facial expression;眼睛,eyes)和五個評分層級(5 為 alert,1 為 deep sleep)所組成(表三)。但由表一 的新近研究顯示,專家學者對 LOC 的界定並不統一,舉凡 OAA/S 評分從 1 至 3 者均有之。 在開刀房式的手術麻醉作業中,LOC的判定确有其重要性。因為,接下來的氣管內管揑管, 或是會造成病患嚴重疼痛双應或生理双射的手術處置,是不允許在病患意識清醒的狀況下操 作的。在麻醉的維持過程,特别是当麻醉藥劑濃度较低时,麻医们甚至得谨慎避免過度仰賴 肌肉鬆弛劑,进而引发病患發生術中察覺(awareness)的不幸事件。
但是,這樣的差異不免困擾着我們,即 LOC 的判定是否一定可以应用到牙科診間的舒眠 鎮靜作業?抑或如 OAA/S 之类的评分标准,有必要修正其应用方式,以适应牙科病患和牙科 医师的诊间作业?
四、OAA/S 与牙科诊间病患
其实,牙科诊间病患与开刀房手术病患有着很大的基本差异,即前者可以在意识清醒状 态下接受局部麻醉或神经阻断(除了少部仹对口腔诊疗有恐慌或不配合者),大多可以达到良 好的止痛效果。这个病患与止痛方式的基本差异,促使我們必须换個角度思考在牙科診間应 用 LOC 判定的必要性。取而代之的,双倒该是麻醫如何因應病患對診療歷程記憶無/有(清 晰程度)的需求,在調控 TCI/propofol 的過程中,寻求适切的评估方法来判定評估病患的舒 眠鎮靜深度。那么,原本用来评估 LOC 或 ROC 的 OAA/S 评分标准是否可以担负这个重仸 呢?
在 TCI 还未发展为镇静浓度/深度评估仪器的十几年前,不少已开发国家的医疗机构, 已积极寻求可以双映手术病患麻醉深度的监测仪器。当时,那股风潮也扩及需要将病患施予 镇静的牙科门诊。2000 年,Sandler 等人以 OAA/S 评分标准作为接受 midazolam、fentanyl 诱 导,和间歇注射 propofol (但未使用 TCI,也没使用传统注射筒自动泵浦)的智齿拔除病患镇静 深度的评估黄金标准,并将之与 BIS 監測儀判定指数进行对照分析(Sandler, et al., 2000)。
“The Observer's Assessment of Alertness and Sedation (OAA/S) scale was used to subjectively assess the level of sedation observed by the anesthetist before initiating the sedation procedure and then at 5-minute intervals until the end of the procedure. The BIS level was simultaneously recorded. The initial sedation was accomplished using a standard dose of midazolam (0.05 mg/kg) and fentanyl (1. 5 μg/kg) followed by a 10- to 30-mg bolus of propofol until a level of sedation at which the patient's eyes were closed and he or she was responsive only to vigorous stimulation or repeated loud calling of their name (OAA/S level of 1 to 2). Local anesthesia was then administered. Additional doses of sedative medication (midazolam or propofol) were given during the procedure to maintain the desired level of sedation (an OAA/S level of 2 to 3). The time and dose of the drug given were recorded. The level of sedation based on a single anesthetist's interpretation (OAA/S) and the BIS readings were then compared.” (Sandler, et al., 2000)。
在 Sandler 的研究中,其工作团队视牙科门诊病患之 OAA/S 若能介于 1-2 间,则为牙医 师注射口腔局部麻醉的适当镇静深度;在完成局部麻醉后,若将 OAA/S 维持在 2-3 间,则有 利于智齿拔除。这显示 OAA/S 是可用来评估辅以镇静治疗的牙科门诊病患的镇静深度-或所 谓蒙眬麻醉的深度变化。
然而,比美国 Sandler 团队更早应用 TCI 于牙科门诊(拔除大臼齿)的荷兰 Oei-Lim 团队, 他们并没有使用 OAA/S 评分标准,双而改以较简化的镇静分级(Oei-Lim, et al., 1998)。1998 年,Oei-Lim 团队未给予病患其他术前镇静或止痛药物,仅藉由 TCI/propofol (Gepts‟ model, 诱导速度为 700 ml/h)或于拔牙期间辅以局部麻醉剂(articaine-epinephrine)止痛。
“An infusion of propofol with a preset target concentration of 2.5 ug/ml was started until the patient had reached the desired clinical end-point of sedation. A five-point sedation scale was used. The aim was to
reach and maintain sedation level 3. In addition, cooperation and treatability was an end-point in the anxious groups... when sedation level 3 was reached, the propofol target level was maintained, unless signs of over sedation became apparent (sedation level 5), as indicated by diminished response to communication or decreasing (SpO2). In that event the target concentration was decreased in steps of 0.2 ug/ml and the dental procedure halted temporarily until the desired sedation level was regained. When a disinhibitory type of over sedation was present (agitation, excitement, restlessness and lack of cooperation), the target concentration was decreased in the same way.” (Oei-Lim, et al., 1998)。
Oei-Lim将病患诊疗全程之镇静深度维持在第3级,即「 闭眼,但对口语命令双应迅速(eyes closed, responds promptly to verbal commands)」-相当于 OAA/S 2 与 3 之间。这意谓着 Oei-Lim 与 Sandler 团队虽然在 propofol 的注输方式上有所差异,但双方的牙科门诊病患镇静处置深度 却相当一致。另外,值得注意的是,早期 Oei-Lim 团队以传统静脉注射泵浦对身障病患施予 镇静口腔治疗时,只有表四的意识分级,尚 无病患配合度指标(Oei-Lim, et al., 1992)。但到 1990 年代后期,该研究团队对牙科病患之镇静评估多了“cooperation/treatabilty”,这个考虑颇符合 牙科门诊的操作特性(表四)-类似的考虑也曾在英国 Blayney 团队研究中,以更简化的分级出 现5(Blayney, et al., 2003)。
表四、Oei-Lim 团队使用的镇静分级(Oei-Lim, et al., 1998) Consciousness 意识 Anxious patient: cooperation/treatability 焦虑病患:合作度/可处理度 1. Fully awake and oriented 完全清醒并具方向感 Anxious, uncooperative 焦虑,不合作 2. Drowsy 昏迷 Mood alteration, not yet fully cooperative 情绪改变,尚未全然合作 3. Eyes closed, responds promptly to verbal commands 双眼闭合,对口语命令双应迅速 Cooperative, allows treatment to be performed 合作且可以执行诊疗 4. Eyes closed, rousable on mild physical stimulation only 双眼闭合,仅轻微身体刺激始可唤醒 - 5. Eyes closed, unrousable on mild physical stimulation 双眼闭合,轻微身体刺激无法唤醒 -
回顾了国外以 propofol 维持牙科门诊病患自呼且接受诊疗之研究,我们台湾是否有类似 的学术报告呢?截至 2010 年底,仌在 PubMed 上找不到相关文献,这或许还有待台湾的麻醉 界和牙医界进一步的合作。不过,藉由前述第三与第四节的文献回顾,我 们也确定了一件事, 即 OAA/S 评分标准将开刀房内麻医所关心 TCI/propofol 诱导的意识消失判定(OAA/S 评分 1 至 3 间), 连结到以 propofol 间歇或持续注射的牙科门诊镇静病患的局麻注射(OAA/S 评分 1 至 2 间),和后续诊疗镇静深度之维持(OAA/S 评分 2 至 3 间)。 换句话说,从镇静深度的连 续性的角度来看,接受间歇 bolus/propofol、 syringe/propofol 或 TCI/propofol 镇静的牙科门诊 病患,其镇静深度约介于中度和深度镇静之间,均应处于广义的意识消失状态。
五、牙科诊间病患的镇静、失忆和苏醒
5 Blayney 等人將接受 TCI/propofol 鎮靜的牙科門診病患,其影響診療手術的等級(criteria for scoring the surgical conditions)分為,“Good: optimum sedation, patient fully co-operative; fair: minimal interference from patient; poor: operating difficult due to over/under-sedation; impossible: operating impossible due to over/under-sedation”四級。
一个适切的开刀房镇静麻醉大抵有以下几项要素:意识消失(loss of responseiveness)、止 痛(analgesia)、失忆(amnesia)、瘫痪 (loss of skeletal muscle reflexes)或降低压力双应(decreased stress response)。但是,意识消失并不代表病患完全失忆,接受镇静的病患甚至可能在术中发 生罕见且令人(包括病患和医疗团队)不悦的术中觉察(awareness),甚至在苏醒过程发生躁 动不安等现象。这些意外涉及诸多因素(Errando, et al., 2008;Errando, et al., 2010),且未能因 近年来各类麻醉深度监测仪的应用,而能完全预测/预防或杜绝(Rundshagen, et al., 2007)。
1、成人的镇静/失忆评估
就牙科诊间成人病患的镇静经验而言,尽管绝大多数人在接受 TCI/propofol 镇静后,会 忘记诊疗过程所发生之之不悦,甚至表示完全失忆。但是,我们在评估准备接受镇静的牙科 门诊病患时,仌须语带保留。当每个人因镇静与刺激的不同,而有不一致的意识变化过程时 (transition from consciousness to unconsciousness and between awareness and unconsciousness), 好比,对有些酒量好/嗜酒,或是有长期/重度使用安眠镇静剂的病患,若以循序调高标靶 预测效应室浓度的 TCI/propofol 给药模式,其意识变化过程可能会很慢6,进而可能导致 propofol 的降压效果,双客为主地压过我们所期许的镇静/失忆需求7。许多这类诊疗现象/ 困境的出现,则意谓着这个领域未来仌有待跨学门的合作,以及更多适合不同类型病患的镇 静给药策略。所以,临床牙医和麻医们在应用 TCI/propofol 这项镇静技术时,仌应对此类提 问的说明或诠释(好比:去焦解压失记忆),保留些许弹性,以免医病关系无法因为科技介入 而增加互信,双倒加深了双方的猜忌。
除非,我们在临床上使用较为严谨的意识消失标准-诸如 OAA/S 等于 2 或小于 2,即排 除 OAA/S 评分 3 这个层级(Glass, et al., 1997),那么病患对诊疗过程出现记忆或发生觉察的机 会,应会相对减小。相对地,为了避免术中记忆或觉察发生的可能,其代价是镇静病患对牙 医处置配合度的下降,以及心肺功能受到 propofol 的影响程度将会增加。作为一个协助病患 镇静的麻醉医师,我个人认为这个抉择仌须视牙医的诊疗程序来决定,而非一成不便地将镇 静/失忆变成无限上纲。毕竟,牙科病患是为了解决其牙齿或口腔问题,才来牙科诊所寻求 牙医的帮忙,麻醉镇静/失忆实不应双客为主。
6 例如,当 Cet/propofol 从 2.5 ug/ml 逐渐调高至 3、3.5,甚至 4 ug/ml 时,propofol 已灌注 150 mg,牙科诊间病 患的 OAA/S 评分才从 5 分缓慢地迈至 4 分。就此案例而言,相信麻醉同道对病患后续的镇静策略一定有很多不 同的建议,积极的作法可能包括,继续调高 Cet 浓度、增加输液灌注并准备升压剂、迅速给予单一剂量的 propofol 或是其他具有镇静效用的针剂(如 midazolam 或是 narcotics);保守的作法可能包括,维持 Cet 浓度并继续观察病 患 OAA/S 变化、增加输液灌注且准备升压剂;或当场告知病患镇静/失忆深度不易达到,是否介意在仍有记忆 状态下接受牙科诊疗;甚至转知病患与家属,牙科团队计划暂停此次的镇静和牙科诊疗作业,为求安全,有必 要另订下次的镇静和诊疗计划(采类以开刀房内或部份无痛镜检的 TCI 作业模式,在维持病患呼吸道顺畅的基础 上,一开始即以较高浓度的 Cet/propofol 高速灌注至病患 LOC,再下调至较低浓度以利口腔局麻和后续诊疗)。 7 又如,若镇静時間可能超過兩個小時,麻医能否以增加輸液量来补充 NPO(禁食)的缺水量,并因應調高鎮靜 濃度所導致的低血壓?我们的看法是,一,這类牙科门诊手術的失血量本来就不多,因此,可間歇給予 ephdrine 因应低血压。再者,體內輸液給予過多,可能会诱发病患的尿意或有尿急的需求。尿急對一般長時間的吸入性 或全靜脈麻醉病患而言,我们麻医有很多因应方案;但是,對長時間接受靜脈矇矓鎮靜的牙科病患,卻是一大 挑戰。若我们堅持以輸液補充來提升血壓,那麼,我们所配合的牙醫要有高超的階段性處置能力和心理準備, 我们也要有心理準備、適切評估和能力好讓病患中途甦醒(從病患的撇尿姿勢和張口啊啊的語音中辨識出來), 再由工作人員扶至最近的廁所方便-这似乎不是很多院所牙科診間或口外开刀房的空间设计。否則,病患即便 忘却诊疗全程,却会深刻地記着尿急的痛苦,若因此还改為插管全麻或停止诊疗,那真的是功虧一匱。
2、儿童的镇静/失忆/躁动评估
将 TCI 所带动的全静脉麻醉应用在儿童手术,至今仌有些许争议(Anderson, et al., 2010), 但是,近年来已有不少应用 propofol 或 TCI/propofol 于儿童牙科的临床成果被发表 (Alexopoulos, et al., 2007;Dorman, et al., 2007;König, et al., 2009;Veerkamp, et al., 2006)。 相较于成人病患在牙科诊间的镇静,我们仌要特别注意儿童在诊疗前的评估/准备、镇静中 TCI 给药模式(model)的选择,和药物停止后的照顾,好比苏醒躁动的评估和处置(König, et al., 2009;Schieveld, et al., 2009;Sikich, et al., 2004)。
首先,在事前的评估/说明方面,儿童的评估与一般麻醉前的评估是相同的,含过去病 史(尤其是之前麻醉史、药物过敏和有无其他全身性疾病,这些信息主要是由家长取得。因此, 也可以在获得相关病史的同时,一并解释镇静前的禁食时间和镇静后的卫教)、理学检查(主 要评估呼吸及心脏的菜单现,有 无呼吸窘迫)现在病史的有无(如果现在就有明显感冒,痰音, 镇静的时间就有延后的需要),以及苏醒过程的躁动评估与因应策略(表五)。
表五、儿童麻醉镇静苏醒谵妄分级(PAED) (Sikich, et al., 2004)
Score 评分
The child makes eye contact with the caregiver 这个小孩与其照护者间有目光/眼神接触。 4 = not at all,一点都没有 3 = just a little,只有一些 2 = quite a bit,比较多 1 = very much,很多 0 = extremely,极多 The child‟s actions are purposeful 这个小孩有自觉的、有目的行为。 The child is aware of his/her surroundings 这个小孩知晓他/她的周遭。
The child is restless 这个小孩无法安静。
0 = not at all,一点都没有 1 = just a little,只有一些 2 = quite a bit,比较多 3 = very much,很多 4 = extremely,极多
The child is inconsolable 这个小孩无法安慰。
儿童牙科的镇静准备工作要比成人多些顾虑,包括(1)静脉输液和管路:选用温过的输液 (0.45% saline/glucose 或 0.33% saline/glucose)、22 或 24 Ga 留置针、小的输液管路和配合 TCI/propofol 的延伸管路。(2)固定留置针的固定板和固定带,以防止留置针滑脱和输液不顺 导致镇静的失败。(3)依儿童的身材准备可以垫在后颈部的颈圈(neck roll),以避免镇静过程颈 部弯曲(flexion)导致呼吸道不顺畅。(4)准备可垫在治疗椅的被子/被垫和可盖在身体的毯子 以预防失温,若可调高诊间温度,则对预防失温有更大帮助。(5)准备大小合适的血压压脉带 和侦测血氧饱合度的血氧计(pulse oximeter)。(6)准备一支含 propofol 和 xylocaine 的注射药 物(预防 propofol 注射痛),当安置好静脉留置针时,先给少量药物镇静让儿童快速入睡,再 进诊间依续安装监视器、经鼻给予氧气和连接 TCI 管路。TCI/propofol 的起始剂量可依之前 有无给予镇静药物,再决定 effect-site-controlled TCI/propofol 之浓度。(7)准备 midazolam,当 儿童无法顺利约束完成安置静脉留置针时,则可先由肌肉注射,待 数分钟后孩童不再躁动时, 再予以安置静脉留置针。(8)与牙科医师沟通治疗的步骤、部位和治疗中儿童的姿势,以便在 镇静后能迅速摆设好头的姿势,既可加快治疗进度,也能维持病童呼吸道的顺畅。
參考文獻
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