Awareness with recall during surgery and anesthesia occurs when the hypnotic and amnesic components of a general anesthetic fail to sustain disconnected consciousness and ablate memory. This is a rare yet significant complication that occurs in a small percentage (0.1–0.2%) of patients undergoing surgery under general anaesthesia [1]. This phenomenon involves the vivid recollection of sensory experiences during surgery, which can lead to posttraumatic stress disorders. The risk of being aware under general anaesthesia in highest in those patients who are administered muscle relaxants without sufficient hypnotics as they are unable to communicate due to paralysis. This event is frequently associated with a number of dramatic feelings (e.g., patients thinking “they were going to die,” sensations of fear and terror, feelings of being unsafe and abandoned or betrayed by doctors and nurses, and pain on being mechanically ventilated).

An unexpected number of patients suffer awareness after emergency tracheal intubation. Recent research, including a meta-analysis of randomized or nonrandomized studies (n = 941 patients)[2] revealed that an overall estimate of 12.3% of patients who receive a neuromuscular blocking agent for muscle relaxation before tracheal intubation and during mechanical ventilation in the emergency department (ED) might recover consciousness and encode memories of the intubation manoeuvre, mechanical ventilation, a bronchoscopy, or a combination of these and other painful procedures [2,3,4,5]. This occurrence could be underestimated due to factors like patient mortality before extubation, memory loss, or neurological deficits. This concerning incidence of conscious paralysis may result from a combination of factors that include the urgent nature of critical patient conditions, intubation before optimal hypnotic effects, anesthetic under-dosing to avoid hemodynamic collapse, and the lack of sedation-protocolized monitoring during invasive mechanical ventilation. Notably, patients’ pharmacogenomics, pharmacokinetics, and pharmacodynamics vary significantly, complicating the dosage-effect relationship of hypnotics and muscle relaxants [6] and clinical sedation assessments before intubation may not guarantee continued unconsciousness due to the complex interplay between hypnotics and painful stimuli.

While adjusting sedative dosages seems logical, it can be challenging in critically ill, paralyzed patients. Hemodynamic vital signs are often used as proxies for sedation, but they lack precision. Heart rate and blood pressure are unreliable for determining unconsciousness or the degree of sedation or anesthetic depth.

The development and the diffusion of depth-of-anesthesia monitors (DOA) has made intraoperative electroencephalography (EEG) more accessible and practical for detecting excessive light anesthesia, thus reducing the risk of intraoperative awareness. Modern DOA monitors help the physician with the computer processing of raw EEG traces (processed EEG, pEEG) that provide numerical indices on the sedation level (sedation index: from 100, awake patient to 0, totally suppressed EEG) [7,8,9] (Fig. 1).

Intubation, mechanical ventilation and diagnostic procedures frequently occurring in the emergency department

Full size image

Trials that compared pEEG-guided anesthesia with routine care (i.e. clinical signs as a guide for anesthesia management), showed that the risk of awareness was significantly reduced with pEEG monitoring in the overall population of patients and even more in those at higher risk for awareness [10]. A meta-analysis including 52 studies and 41,331 patients showed that pEEG guidance reduces the risk of awareness with paralysis by 64% compared to clinical signs alone, with no evidence of a difference in incidences of intraoperative awareness according to whether anaesthesia was guided by pEEG or by ETAC in a surgical population at unselected or at high risk of awareness [11]. For many reasons (e.g. drug overdose, prevention of post-operative delirium, risk for neurocognitive decline) DOA monitors have frequently been recommended for the management of both anaesthesia depth during surgery (where they are now widely applied to titrate hypnotics) [12, 13] and for the management of sedation in intensive care unit (ICU) patients.

Since sedative titration might be challenging in a critically ill, depth of sedation cannot be clinically assessed in paralyzed patient, and hemodynamic vital signs are unreliable measures of depth of sedation, the risk of awareness in emergency settings can be significantly improved by the use of DOA monitors (Fig. 1). Nowadays, monitoring devices in EDs are often relatively basic, recording only clinical responses (e.g., blood pressure, heart rate, oxygen saturation), while monitoring depth of consciousness/sedation depth is rare or in fact, never monitored. The routine application of a DOA with pEEG in every patient receiving hypnotics and muscle relaxants in every clinical setting may eventually reduce the occurrence of awareness with paralysis and its dramatic consequences, as already observed during anaesthesia and surgery.

Awareness with recall during paralysis occurs in many patients in the ED after tracheal intubation. Emergency physicians and nurses must know the risk of conscious paralysis and strive to detect and eliminate it in all patients receiving paralysis and mechanical ventilation. As clinicians, we must consider that the aim of intensive care includes much more than merely the survival of patients. In addition to taking care of physiologic parameters such as blood pressure, tissue perfusion, gas exchange, and urine output, we should also focus on brain health. ICU and ED physicians might consider use of neurological EEG-based monitoring, though further research is needed in ED and ICU settings. Sedation protocols based on pEEG monitors could represent a radical solution for this devastating complication associated with life-saving treatments. It is the responsibility of clinicians to target "zero occurrences" of awareness during paralysis in the ED and during the entire hospital stay of their patients.

No datasets were generated or analysed during the current study.

BIS:

Bispectral index

DOA:

Depth-of-anesthesia monitors

ED:

Emergency department

ETAC:

End tidal anesthetic-agent concentration

ICU:

Intensive care unit

MAC:

Minimum alveolar concentration

pEEG:

Processed electroencephalography

1. Kertai MD, Palanca BJA, Pal N, Burnside BA, Zhang L, Sadiq F, et al. Bispectral index monitoring, duration of bispectral index below 45, patient risk factors, and intermediate-term mortality after noncardiac surgery in the B-unaware trial. Anesthesiology. 2011;114:545–56.

   Article PubMed Google Scholar

2. Pappal RD, Roberts BW, Winkler W, Yaegar LH, Stephens RJ, Fuller BM. Awareness with paralysis in mechanically ventilated patients in the emergency department and ICU: a systematic review and meta-analysis∗. Crit Care Med. 2021;49:E304–14.

   Article PubMed PubMed Central Google Scholar

3. Driver BE, Prekker ME, Wagner E, Cole JB, Puskarich MA, Stang J, et al. Recall of awareness during paralysis among ED patients undergoing tracheal intubation. Chest. Am Coll Chest Phys. 2023;163:313–23.

   Google Scholar

4. Pappal RD, Roberts BW, Mohr NM, Ablordeppey E, Wessman BT, Drewry AM, et al. The ED-AWARENESS study: a prospective, observational cohort study of awareness with paralysis in mechanically ventilated patients admitted from the emergency department. Ann Emerg Med. 2021;77:532–44.

   Article PubMed PubMed Central Google Scholar

5. Fuller BM, Pappal RD, Mohr NM, Roberts BW, Faine B, Yeary J, et al. Awareness with paralysis among critically Ill emergency department patients: a prospective cohort study. Crit Care Med. 2022;50:1449–60.

   Article PubMed PubMed Central Google Scholar

6. Searle R, Hopkins PM. Pharmacogenomic variability and anaesthesia. Br J Anaesth. 2009;103:14–25.

   Article CAS PubMed Google Scholar

7. Romagnoli S, Franchi F, Ricci Z. Processed EEG monitoring for anesthesia and intensive care practice. Minerva Anestesiol. 2019;85:1219–30.

   Article PubMed Google Scholar

8. Rasulo FA, Claassen J, Romagnoli S. Broad use of processed EEG: ready for prime time yet? Intensive Care Med. 2024;50:1350–3.

   Article PubMed Google Scholar

9. Romagnoli S, Lobo FA, Picetti E, Rasulo FA, Robba C, Matta B. Non-invasive technology for brain monitoring: definition and meaning of the principal parameters for the International PRactice On TEChnology neuro-moniToring group (I-PROTECT). J Clin Monit Comput. 2024;38:827–45.

   Article PubMed PubMed Central Google Scholar

10. Chan MTV, Hedrick TL, Egan TD, García PS, Koch S, Purdon PL, et al. American society for enhanced recovery and perioperative quality initiative joint consensus statement on the role of neuromonitoring in perioperative outcomes: electroencephalography. Anesth Analg. 2020;130:1278–91.

    Article PubMed Google Scholar

11. Lewis S, Pritchard M, LJ F, Punjasawadwong Y. B,. Bispectral index for improving intraoperative awareness and early postoperative recovery in adults. Cochrane Database Syst Rev. 2019;26(9):CD003843.

    Google Scholar

12. Berger M, Schenning KJ, Brown CH, Deiner SG, Whittington RA, Eckenhoff RG. Best practices for postoperative brain health: Recommendations from the fifth international perioperative neurotoxicity working group. Anesth Analg. 2018;127:1406–13.

    Article PubMed PubMed Central Google Scholar

13. Romagnoli S, Saugel B, Thomsen KK, Matta B. Perioperative patients with hemodynamic instability: consensus recommendations of the anesthesia patient safety foundation. Call for an additional monitor. Anesth Analg. 2024;139:e25–7.

    Article PubMed Google Scholar

Download references

Authors and Affiliations

1. Department of Health Science, Section of Anaesthesia and Intensive Care, University of Florence, Florence, Italy

   Stefano Romagnoli

2. Department of Anaesthesia and Intensive Care, Azienda Ospedaliero-Universitaria Careggi, Florence, Italy

   Stefano Romagnoli

3. University of Cambridge, Cambridge, UK

   Basil Matta

4. Masimo International Irvine, Irvine, CA, USA

   Basil Matta

5. Division of Pulmonary and Critical Care, Department of Emergency Medicine, Hennepin County Medical Center, Minneapolis, MN, USA

   Brian E. Driver

6. Department of Anesthesiology, Weill Cornell Medicine, New York, NY, USA

   Lisbeth Evered

7. St. Vincent’s Hospital, Melbourne, Fitzroy, VIC, Australia

   Lisbeth Evered

8. University of Melbourne, Fitzroy, VIC, Australia

   Lisbeth Evered

1. Stefano RomagnoliView author publications

   You can also search for this author in PubMed Google Scholar

2. Basil MattaView author publications

   You can also search for this author in PubMed Google Scholar

3. Brian E. DriverView author publications

   You can also search for this author in PubMed Google Scholar

4. Lisbeth EveredView author publications

   You can also search for this author in PubMed Google Scholar

Contributions

SR conceived the manuscript, prepared the first draft of the text and figure, and invited the other authors to contribute. BM reviewed the final version of the manuscript as an expert in neuromonitoring. DBE contributed in elaborating the text as expert in the main topic of the paper. EL participated in the manuscript preparation as an expert in neuromonitoring and neurological disorders. All authors contributed to the critical revision of the paper and final approval.

Corresponding author

Correspondence to Stefano Romagnoli.

Conflict of interest

SR received grant for congress presentations from Fresenius, Masimo and Medtronic. BM is Global Senior Medical Director—Masimo International Irvine, California, USA; BED and LE declare no conflicts of interest.

Publisher's Note

Springer Nature remains neutral with regard to jurisdictional claims in published maps and institutional affiliations.

Open Access This article is licensed under a Creative Commons Attribution-NonCommercial-NoDerivatives 4.0 International License, which permits any non-commercial use, sharing, distribution and reproduction in any medium or format, as long as you give appropriate credit to the original author(s) and the source, provide a link to the Creative Commons licence, and indicate if you modified the licensed material. You do not have permission under this licence to share adapted material derived from this article or parts of it. The images or other third party material in this article are included in the article’s Creative Commons licence, unless indicated otherwise in a credit line to the material. If material is not included in the article’s Creative Commons licence and your intended use is not permitted by statutory regulation or exceeds the permitted use, you will need to obtain permission directly from the copyright holder. To view a copy of this licence, visit http://creativecommons.org/licenses/by-nc-nd/4.0/.

Reprints and permissions

Cite this article

Romagnoli, S., Matta, B., Driver, B.E. et al. A plea for enhanced monitoring of depth of sedation in patients who are intubated and ventilated. Crit Care 28, 342 (2024). https://doi.org/10.1186/s13054-024-05105-9

Download citation

• Received: 08 September 2024

• Accepted: 18 September 2024

• Published: 22 October 2024

• DOI: https://doi.org/10.1186/s13054-024-05105-9

Share this article

Anyone you share the following link with will be able to read this content:

Sorry, a shareable link is not currently available for this article.

Provided by the Springer Nature SharedIt content-sharing initiative

当全身麻醉剂的催眠和健忘成分无法维持断开的意识并消融记忆时，就会在手术和麻醉期间产生回忆意识。这是一种罕见但重要的并发症，发生在一小部分 （0.1-0.2%） 接受全身麻醉手术的患者中 [1]。这种现象涉及手术过程中对感觉体验的生动回忆，这可能导致创伤后应激障碍。在全身麻醉下意识的风险最高，那些服用肌肉松弛剂而没有足够安眠药的患者，因为他们由于瘫痪而无法交流。该事件通常与许多戏剧性的感觉有关（例如，患者认为“他们要死了”，恐惧和恐惧的感觉，不安全的感觉以及被医生和护士抛弃或背叛的感觉，以及机械通气的痛苦）。

意外数量的患者在紧急气管插管后出现意识障碍。最近的研究，包括对随机或非随机研究（n = 941 名患者）[2] 的荟萃分析，总体估计有 12.3% 的患者在气管插管前和急诊科 （ED） 机械通气期间接受神经肌肉阻滞剂用于肌肉松弛，可能会恢复意识并编码插管操作、机械通气、 支气管镜检查，或这些操作与其他疼痛操作的组合[2,3,4,5]。由于患者拔管前死亡率、记忆丧失或神经功能缺损等因素，这种情况可能会被低估。这种令人担忧的意识麻痹发生率可能是由多种因素共同造成的，这些因素包括危重患者病情的紧迫性、在最佳催眠效果之前插管、麻醉剂剂量不足以避免血流动力学崩溃，以及在有创机械通气期间缺乏镇静方案化监测。值得注意的是，患者的药物基因组学、药代动力学和药效学差异很大，使安眠药和肌肉松弛剂的剂量-效应关系复杂化[6]，由于安眠药和疼痛刺激之间的复杂相互作用，插管前的临床镇静评估可能无法保证持续的无意识。

虽然调整镇静剂剂量似乎合乎逻辑，但对于危重、瘫痪的患者来说可能具有挑战性。血流动力学生命体征通常用作镇静的替代指标，但它们缺乏精确性。心率和血压对于确定无意识或镇静程度或麻醉深度不可靠。

麻醉深度监测仪 （DOA） 的开发和普及使术中脑电图 （EEG） 在检测过度光麻醉方面更容易获得和实用，从而降低了术中意识的风险。现代 DOA 监护仪帮助医生对原始脑电图轨迹（处理后的脑电图、pEEG）进行计算机处理，这些轨迹提供了镇静水平的数字指标（镇静指数：从 100，清醒患者到 0，脑电图完全抑制）[7,8,9]（图 1）。

急诊科经常发生的插管、机械通气和诊断程序

 全尺寸图像

将 pEEG 引导麻醉与常规护理（即作为麻醉管理指南的临床体征）进行比较的试验表明，pEEG 监测在整个患者群体中的意识风险显著降低，在意识风险较高的患者中甚至更高 [10]。一项包括 52 项研究和 41,331 名患者的荟萃分析显示，与单独的临床体征相比，pEEG 指导可将麻痹意识风险降低 64%，没有证据表明在未经选择或意识风险高的手术人群中，根据麻醉是由 pEEG 还是 ETAC 引导，术中意识发生率存在差异 [11]。由于许多原因（例如药物过量、预防术后谵妄、神经认知能力下降的风险），DOA 监测器经常被推荐用于手术期间的麻醉深度管理（现在它们被广泛用于滴定催眠药）[12,13] 和重症监护病房 （ICU） 患者的镇静管理。

由于镇静剂滴定在危重病人中可能具有挑战性，无法在临床上评估瘫痪患者的镇静深度，并且血流动力学生命体征是不可靠的镇静深度测量方法，因此使用 DOA 监测仪可以显着改善紧急情况下的意识风险（图 1）。如今，急诊科的监测设备通常相对基本，仅记录临床反应（例如，血压、心率、血氧饱和度），而监测意识深度/镇静深度的情况很少见，或者实际上从未监测过。正如在麻醉和手术期间已经观察到的那样，在每种临床环境中接受安眠药和肌肉松弛剂的每位患者中常规应用带有 pEEG 的 DOA 最终可能会减少麻痹意识的发生及其严重后果。

许多在气管插管后 ED 的患者在瘫痪期间对回忆的意识发生。急诊医生和护士必须了解意识性瘫痪的风险，并努力在所有接受瘫痪和机械通气的患者中发现和消除它。作为临床医生，我们必须考虑到重症监护的目标不仅仅是患者的生存。除了照顾血压、组织灌注、气体交换和尿量等生理参数外，我们还应该关注大脑健康。ICU 和 ED 医生可能会考虑使用基于神经 EEG 的监测，但需要在 ED 和 ICU 环境中进行进一步研究。基于 pEEG 监测器的镇静方案可能代表这种与挽救生命的治疗相关的毁灭性并发症的根本解决方案。临床医生有责任在急诊科瘫痪期间和患者整个住院期间以意识的“零发生率”为目标。

在当前研究期间没有生成或分析数据集。

 BIS：

 双频指数

 DOA：

麻醉深度监测仪

 ED：

 急诊室

 ETAC：

呼气末麻醉剂浓度

 重症监护室：

 重症监护病房

 MAC键：

最低肺泡浓度

 pEEG （英文）

处理脑电图

1. 
   Kertai MD、Palanca BJA、Pal N、Burnside BA、Zhang L、Sadiq F 等人。在 B-unaware 试验中，双频指数监测、双频指数低于 45 的持续时间、患者危险因素和非心脏手术后的中期死亡率。麻醉。2011;114:545–56.

   
   文章 PubMed 谷歌学术

2. 
   Pappal RD、Roberts BW、Winkler W、Yaegar LH、Stephens RJ、Fuller BM. 急诊科和 ICU 机械通气患者瘫痪意识：系统评价和荟萃分析∗。Crit Care Med. 2021;49：E304-14。

   
   文章： PubMed PubMed Central Google Scholar

3. 
   司机 BE、Prekker ME、Wagner E、Cole JB、Puskarich MA、Stang J 等人。回忆接受气管插管的 ED 患者瘫痪期间的意识。胸。Am Coll 胸科学 2023;163:313–23.

    谷歌学术

4. 
   Pappal RD、Roberts BW、Mohr NM、Ablordeppey E、Wessman BT、Drewry AM 等人。ED-AWARENESS 研究：一项前瞻性观察性队列研究，研究从急诊科收治的机械通气患者瘫痪意识。Ann Emerg Med. 2021 年;77:532–44.

   
   文章： PubMed PubMed Central Google Scholar

5. 
   Fuller BM、Pappal RD、Mohr NM、Roberts BW、Faine B、Yeary J 等人。危重急诊科患者对瘫痪的认识：一项前瞻性队列研究。Crit Care Med. 2022;50:1449–60.

   
   文章： PubMed PubMed Central Google Scholar

6. 
   Searle R， Hopkins PM. 药物基因组学变异性和麻醉。Br J 麻醉。2009;103:14–25.

   
   论文 CAS PubMed Google Scholar

7. 
   Romagnoli S， Franchi F， Ricci Z. 用于麻醉和重症监护实践的处理脑电图监测。Minerva Anestesiol.2019;85:1219–30.

   
   文章 PubMed 谷歌学术

8. 
   Rasulo FA， Claassen J， Romagnoli S. 处理后的脑电图的广泛使用：准备好迎接黄金时间了吗？重症监护医学 2024;50:1350–3.

   
   文章 PubMed 谷歌学术

9. 
   Romagnoli S， Lobo FA， Picetti E， Rasulo FA， Robba C， Matta B. 用于大脑监测的非侵入性技术：国际技术实践神经监测组 （I-PROTECT） 主要参数的定义和含义。J Clin Monit 计算。2024;38:827–45.

   
   文章： PubMed PubMed Central Google Scholar

10. 
    Chan MTV、Hedrick TL、Egan TD、García PS、Koch S、Purdon PL 等人。美国促进康复协会和围手术期质量倡议关于神经监测在围手术期结果中的作用的联合共识声明：脑电图。阿内斯·阿纳尔格。2020;130:1278–91.

    
    文章 PubMed 谷歌学术

11. 
    刘易斯 S， 普里查德 M， LJ F， 旁贾萨瓦旺 YB，.提高成人术中意识和术后早期恢复的双频指数。Cochrane 数据库系统修订版 2019;26（9）：CD003843。

     谷歌学术

12. 
    Berger M， Schenning KJ， Brown CH， Deiner SG， Whittington RA， Eckenhoff RG.术后脑健康的最佳实践：第五届国际围手术期神经毒性工作组的建议。阿内斯·阿纳尔格。2018;127:1406–13.

    
    文章： PubMed PubMed Central Google Scholar

13. 
    Romagnoli S， Saugel B， Thomsen KK， Matta B. 血流动力学不稳定的围手术期患者：麻醉患者安全基金会的共识建议。要求额外的显示器。阿内斯·阿纳尔格。2024;139：e25-7。

    
    文章 PubMed 谷歌学术

 下载参考资料

 作者和单位

1. 
   意大利佛罗伦萨佛罗伦萨大学健康科学系麻醉与重症监护科

    斯特凡诺·罗马尼奥利

2. 
   意大利佛罗伦萨 Azienda Ospedaliero-Universitaria Careggi 麻醉和重症监护系

    斯特凡诺·罗马尼奥利

3. 
   University of Cambridge， 英国 剑桥

    巴兹尔·马塔

4. 
   Masimo International Irvine， Irvine， CA， 美国

    巴兹尔·马塔

5. 
   美国明尼苏达州明尼阿波利斯市亨内平县医疗中心急诊医学科肺病和重症监护科

    布赖恩·德赖弗

6. 
   美国纽约州纽约市威尔康奈尔医学院麻醉科

    丽斯贝丝·埃弗雷德

7. 
   圣文森特医院，墨尔本，菲茨罗伊，维多利亚州，澳大利亚

    丽斯贝丝·埃弗雷德

8. 
   墨尔本大学，澳大利亚维多利亚州菲茨罗伊

    丽斯贝丝·埃弗雷德

1. 
   斯特凡诺·罗马尼奥利查看作者出版物

   
   您也可以在 PubMed Google Scholar 中搜索此作者

2. 
   巴兹尔·马塔查看作者出版物

   
   您也可以在 PubMed Google Scholar 中搜索此作者

3. 
   布赖恩·德赖弗查看作者出版物

   
   您也可以在 PubMed Google Scholar 中搜索此作者

4. 
   丽斯贝丝·埃弗雷德查看作者出版物

   
   您也可以在 PubMed Google Scholar 中搜索此作者

 贡献

SR 构思了手稿，准备了文本和图表的初稿，并邀请其他作者做出贡献。BM 作为神经监测专家审查了手稿的最终版本。DBE 作为论文主题专家为阐述文本做出了贡献。EL 作为神经监测和神经系统疾病方面的专家参与了手稿的准备。所有作者都为论文的批判性修订和最终批准做出了贡献。

 通讯作者

与 Stefano Romagnoli 的通信。

 利益冲突

SR 获得了 Fresenius、Masimo 和 Medtronic 的会议演示资助。BM 是美国加利福尼亚州尔湾 Masimo International 的全球高级医疗总监;BED 和 LE 声明没有利益冲突。

 出版商注

施普林格·自然 （Springer Nature） 对已发布的地图和机构隶属关系中的管辖权主张保持中立。

开放获取本文根据 Creative Commons Attribution-NonCommercial-NoDerivatives 4.0 International License 获得许可，该许可允许以任何媒体或格式进行任何非商业用途、共享、分发和复制，前提是您给予原作者和来源适当的署名，提供指向 Creative Commons 许可的链接，并说明您是否修改了许可材料。根据本许可，您无权共享源自本文或其部分的改编材料。本文中的图像或其他第三方材料包含在文章的知识共享许可中，除非在材料的致谢行中另有说明。如果材料未包含在文章的 Creative Commons 许可中，并且您的预期用途未被法律法规允许或超出允许的用途，您将需要直接从版权所有者处获得许可。要查看此许可证的副本，请访问 http://creativecommons.org/licenses/by-nc-nd/4.0/。

 重印本和权限

 引用本文

 下载引文

• 
  收稿日期： 2024-09-08

• 
  录用日期： 2024-09-18

• 
  已发布： 2024 年 10 月 22 日

 使用本文

您与之共享以下链接的任何人都可以阅读此内容：

抱歉，本文目前没有可共享链接。

由 Springer Nature SharedIt 内容共享计划提供