DOCSLIB.ORG

Clinical Electroencephalography for Anesthesiologists Part I: Background and Basic Signatures

Total Page：16

File Type：pdf, Size：1020Kb

Download full-text PDF Read full-text
Clinical Electroencephalography for Anesthesiologists Part I: Background and Basic Signatures REVIEW ArtICLE David S. Warner, M.D., Editor Clinical Electroencephalography for Anesthesiologists Part I: Background and Basic Signatures Patrick L. Purdon, Ph.D., Aaron Sampson, B.S., Kara J. Pavone, B.S., Emery N. Brown, M.D., Ph.D. Downloaded from http://pubs.asahq.org/anesthesiology/article-pdf/123/4/937/373943/20151000_0-00034.pdf by guest on 28 September 2021 ABSTRACT The widely used electroencephalogram-based indices for depth-of-anesthesia monitoring assume that the same index value defines the same level of unconsciousness for all anesthetics. In contrast, we show that different anesthetics act at different molecular targets and neural circuits to produce distinct brain states that are readily visible in the electroencephalogram. We present a two-part review to educate anesthesiologists on use of the unprocessed electroencephalogram and its spectro- gram to track the brain states of patients receiving anesthesia care. Here in part I, we review the biophysics of the electro- encephalogram and the neurophysiology of the electroencephalogram signatures of three intravenous anesthetics: propofol, dexmedetomidine, and ketamine, and four inhaled anesthetics: sevoflurane, isoflurane, desflurane, and nitrous oxide. Later in part II, we discuss patient management using these electroencephalogram signatures. Use of these electroencephalogram signatures suggests a neurophysiologically based paradigm for brain state monitoring of patients receiving anesthesia care. ( ANESTHESIOLOGY 2015; 123:937-60) The Electroencephalogram and Brain patients over time as a three-dimensional plot (power by fre- Monitoring under General Anesthesia quency vs. time).11 Fleming and Smith12 devised the density- modulated or density spectral array, the two-dimensional plot Almost 80 yr ago, Gibbs et al. demonstrated that system- of the spectrogram, for the same purpose.13 Levy14 later sug- atic changes occur in the electroencephalogram and patient gested using multiple electroencephalogram features to track arousal level with increasing doses of ether or pentobarbital. anesthetic effects. Despite further documentation of system- They stated that “a practical application of these observations atic relations among anesthetic doses, electroencephalogram might be the use of electroencephalogram as a measure of the 4,15–20 1 patterns, and patient arousal levels, use of the unpro- depth of anesthesia.” Several subsequent studies reported on cessed electroencephalogram and the spectrogram to monitor the relation between electroencephalogram activity and the the states of the brain under general anesthesia and sedation 2–6 7 behavioral states of general anesthesia. Faulconer showed never became a standard practice in anesthesiology. in 1949 that a regular progression of the electroencephalo- Instead, since the 1990s, depth of anesthesia has been gram patterns correlated with the concentration of ether in tracked using indices computed from the electroencephalo- arterial blood. Bart et al. and Findeiss et al. used the spec- gram and displayed on brain monitoring devices.21–25 The trum—the decomposition of the electroencephalogram signal indices have been developed by recording simultaneously into the power in its frequency components—to show that the the electroencephalogram and the behavioral responses to electroencephalogram was organized into distinct oscillations various anesthetic agents in patient cohorts.26 Some of the at particular frequencies under general anesthesia.8,9 Bickford indices have been derived by using regression methods to et al.10 introduced the compressed spectral array or spectrogram relate selected electroencephalogram features to the behav- to display the electroencephalogram activity of anesthetized ioral responses.26–29 One index has been constructed by This article is featured in “This Month in Anesthesiology,” page 1A. Drs. Purdon and Brown have summarized some of this work on the Web site www.anesthesiaEEG.com and have given several seminars on this topic in multiple venues during the last 2 yr. Submitted for publication April 8, 2013. Accepted for publication May 18, 2015. From the Department of Anesthesia, Critical Care, and Pain Medicine, Massachusetts General Hospital, Boston, Massachusetts, and Department of Anesthesia, Harvard Medical School, Boston, Mas- sachusetts (P.L.P.); Department of Anesthesia, Critical Care, and Pain Medicine, Massachusetts General Hospital, Boston, Massachusetts (A.S., K.J.P.); and Department of Anesthesia, Critical Care, and Pain Medicine, Massachusetts General Hospital, Boston, Massachusetts; Department of Anesthesia, Harvard Medical School, Boston, Massachusetts; Institute for Medical Engineering and Science and Harvard-Massachusetts Institute of Technology, Health Sciences and Technology Program; and Department of Brain and Cognitive Sciences, Massachusetts Institute of Technology, Cambridge, Massachusetts (E.N.B.). Copyright © 2015, the American Society of Anesthesiologists, Inc. Wolters Kluwer Health, Inc. All Rights Reserved. Anesthesiology 2015; 123:937–60 Anesthesiology, V 123 • No 4 937 October 2015 Copyright © 2015, the American Society of Anesthesiologists, Inc. Wolters Kluwer Health, Inc. Unauthorized reproduction of this article is prohibited. Electroencephalography for Anesthesiologists using classifier methods to derive a continuum of arousal lev- signatures observable in the unprocessed electroencephalo- els ranging from awake to profound unconsciousness from gram and the spectrogram. The new concept of defining the visually categorized electroencephalogram recordings.30,31 anesthetic state by using drug-specific electroencephalogram Another index has been constructed by relating the entropy signatures that relate to molecular and neural circuit mecha- of the electroencephalogram signal—its degree of disorder— nisms of anesthetic action would allow anesthesiologists to to the behavioral responses of the patients.32,33 The indices make more detailed and accurate assessments than those are computed from the electroencephalogram in near real based on electroencephalogram-based indices. The potential time and displayed on the depth-of-anesthesia monitor benefits of using the unprocessed electroencephalogram to as values scaled from 0 to 100, with low values indicating monitor anesthetic states have been recently stated.48,49 Cur- greater depth of anesthesia. The algorithms used in many rent brain monitors display the unprocessed electroencepha- of the current depth-of-anesthesia monitors to compute the logram and the spectrogram.22,31,50 Downloaded from http://pubs.asahq.org/anesthesiology/article-pdf/123/4/937/373943/20151000_0-00034.pdf by guest on 28 September 2021 indices are proprietary. To define anesthetic states in terms of drug-specific elec- Although the electroencephalogram-based indices have troencephalogram signatures that relate to molecular and been in use for approximately 20 yr, there are several reasons neural circuit mechanisms of anesthetic action, we synthesize why they are not part of standard anesthesiology practice. different sources and levels of information: (1) formal behav- First, use of electroencephalogram-based indices does not ioral testing along with either simultaneous human electro- ensure that awareness under general anesthesia can be pre- encephalogram recordings or human intracranial recordings vented.34,35 Second, these indices, which have been devel- during anesthetic administration; (2) clinical observations oped from adult patient cohorts, are less reliable in pediatric of behavior along with simultaneous electroencephalogram 36,37 populations. Third, because the indices do not relate recordings during anesthetic administration; (3) the neuro- directly to the neurophysiology of how a specific anesthetic physiology and the molecular pharmacology of how the anes- exerts its effects in the brain, they cannot give an accurate thetics act at specific molecular targets in specific circuits; picture of the brain’s responses to the drugs. Finally, the indi- (4) the neurophysiology of altered states of arousal such as ces assume that the same index value reflects the same level non-rapid eye movement sleep, coma (medically induced, of unconsciousness for all anesthetics. This assumption is pathologic, or hypothermia induced), hallucinations, and based on the observation that several anesthetics, both intra- paradoxical excitation; (5) time–frequency analyses of high- venous and inhaled agents, eventually induce slowing in the density electroencephalogram recordings; and (6) mathemat- 1,4,22 electroencephalogram oscillations at higher doses. The ical modeling of anesthetic actions in neural circuits. slower oscillations are assumed to indicate a more profound We present this new education paradigm in two parts. state of general anesthesia. Two anesthetics whose electroen- Here, in part I, we review the basic neurophysiology of the cephalogram responses frequently lead clinicians to doubt electroencephalogram and the neurophysiology and the elec- 38,39 40–42 index readings are ketamine and nitrous oxide. troencephalogram signatures of three intravenous anesthet- These agents are commonly associated with faster electro- ics: propofol, dexmedetomidine, and ketamine, and four encephalogram oscillations that tend to increase the value of inhaled anesthetics: sevoflurane, isoflurane, desflurane, and the indices at clinically accepted doses. Higher index values nitrous oxide. We explain, where possible, how the anesthet- cause concern as to whether the
Load more

Recommended publications
  • Tbi): Progress in Treating the Sig- Nature Wounds of the Current Conflicts
    S. HRG. 111–866 OVERSIGHT HEARING ON TRAUMATIC BRAIN IN- JURY (TBI): PROGRESS IN TREATING THE SIG- NATURE WOUNDS OF THE CURRENT CONFLICTS HEARING BEFORE THE COMMITTEE ON VETERANS’ AFFAIRS UNITED STATES SENATE ONE HUNDRED ELEVENTH CONGRESS FIRST SESSION MAY 5, 2010 Printed for the use of the Committee on Veterans’ Affairs ( Available via the World Wide Web: http://www.access.gpo.gov/congress/senate U.S. GOVERNMENT PRINTING OFFICE 64–440 PDF WASHINGTON : 2011 For sale by the Superintendent of Documents, U.S. Government Printing Office Internet: bookstore.gpo.gov Phone: toll free (866) 512–1800; DC area (202) 512–1800 Fax: (202) 512–2104 Mail: Stop IDCC, Washington, DC 20402–0001 VerDate Nov 24 2008 12:21 Feb 28, 2011 Jkt 000000 PO 00000 Frm 00001 Fmt 5011 Sfmt 5011 H:\ACTIVE\050510.TXT SVETS PsN: PAULIN COMMITTEE ON VETERANS’ AFFAIRS DANIEL K. AKAKA, Hawaii, Chairman JOHN D. ROCKEFELLER IV, West Virginia RICHARD BURR, North Carolina, Ranking PATTY MURRAY, Washington Member BERNARD SANDERS, (I) Vermont LINDSEY O. GRAHAM, South Carolina SHERROD BROWN, Ohio JOHNNY ISAKSON, Georgia JIM WEBB, Virginia ROGER F. WICKER, Mississippi JON TESTER, Montana MIKE JOHANNS, Nebraska MARK BEGICH, Alaska SCOTT P. BROWN, Massachusetts ROLAND W. BURRIS, Illinois ARLEN SPECTER, Pennsylvania WILLIAM E. BREW, Staff Director LUPE WISSEL, Republican Staff Director (II) VerDate Nov 24 2008 12:21 Feb 28, 2011 Jkt 000000 PO 00000 Frm 00002 Fmt 5904 Sfmt 5904 H:\ACTIVE\050510.TXT SVETS PsN: PAULIN CONTENTS MAY 5, 2010 SENATORS Page Akaka, Hon. Daniel K., Chairman, U.S. Senator from Hawaii ........................... 1 Burr, Hon.
    [Show full text]
  • Proceedings of Réanimation 2019, the French Intensive Care Society International Congress
    Ann. Intensive Care 2019, 9(Suppl 1):40 https://doi.org/10.1186/s13613-018-0474-7 MEETING ABSTRACTS Open Access Proceedings of Réanimation 2019, the French Intensive Care Society International Congress France. 23–25 January 2019 Published: 29 March 2019 Oral communications Oral communications: Physiotherapists Conclusion: We found that peak expiratory was higher with than with- out collapsible tube. In vivo measurements in patients should be done COK‑1 to confrm this fnding. Bench assessment of the efect of a collapsible tube on the efcacy of a mechanical insufation‑exsufation device Romain Lachal (speaker) Réanimation médicale, Hôpital de la Croix‑Rousse, Hospices Civils de Lyon, Lyon, FRANCE Correspondence: Romain Lachal ‑ [email protected] Annals of Intensive Care 2019, 9(Suppl 1):COK-1 Introduction: Mechanical Insufation-Exsufation (MI-E) by using a specifc device is commonly used to increase weak cough, as in patients with chronic neuromuscular weakness or in intensive care unit (ICU) patients with ICU-acquired neuro-myopathy. The assess- ment of the efcacy of MI-E device is commonly done by measuring peak cough fow (PCF). Upper airways collapse is frequently associated with neuromuscular disease and may compromise MI-E efcacy. Tra- cheomalacia is another disease that may impede PCF to increase with MI-E device. The goal of present study was to carry out a bench study to assess the efect of MI-E on PCF with and without the presence of a collapsible tube. Our hypothesis was that PCF was lower with than without collapsible tube. COK‑2 Patients and methods: We used a lung simulator (TTL Michigan Early verticalization in neurologic intensive care units Instruments) with adjustable compliance (C) and resistance (R) to with a weight suspension system which a MI-E (CoughAssist E70, Philips-Respironics) was attached, Margrit Ascher (speaker), Francisco Miron Duran, Fanny Pradalier, Claire with or without a latex collapsible tube.
    [Show full text]
  • General Anesthesia and Altered States of Arousal: a Systems Neuroscience Analysis
    General Anesthesia and Altered States of Arousal: A Systems Neuroscience Analysis The MIT Faculty has made this article openly available. Please share how this access benefits you. Your story matters. Citation Brown, Emery N., Patrick L. Purdon, and Christa J. Van Dort. “General Anesthesia and Altered States of Arousal: A Systems Neuroscience Analysis.” Annual Review of Neuroscience 34, no. 1 (July 21, 2011): 601–628. As Published http://dx.doi.org/10.1146/annurev-neuro-060909-153200 Publisher Annual Reviews Version Author's final manuscript Citable link http://hdl.handle.net/1721.1/86331 Terms of Use Creative Commons Attribution-Noncommercial-Share Alike Detailed Terms http://creativecommons.org/licenses/by-nc-sa/4.0/ NIH Public Access Author Manuscript Annu Rev Neurosci. Author manuscript; available in PMC 2012 July 06. NIH-PA Author ManuscriptPublished NIH-PA Author Manuscript in final edited NIH-PA Author Manuscript form as: Annu Rev Neurosci. 2011 ; 34: 601–628. doi:10.1146/annurev-neuro-060909-153200. General Anesthesia and Altered States of Arousal: A Systems Neuroscience Analysis Emery N. Brown1,2,3, Patrick L. Purdon1,2, and Christa J. Van Dort1,2 Emery N. Brown: [email protected]; Patrick L. Purdon: [email protected]; Christa J. Van Dort: [email protected] 1Department of Anesthesia, Critical Care and Pain Medicine, Massachusetts General Hospital, Harvard Medical School, Boston, Massachusetts 02114 2Department of Brain and Cognitive Sciences, Massachusetts Institute of Technology, Cambridge, Massachusetts 02139 3Harvard-MIT Division of Health Sciences and Technology, Massachusetts Institute of Technology, Cambridge, Massachusetts 02139 Abstract Placing a patient in a state of general anesthesia is crucial for safely and humanely performing most surgical and many nonsurgical procedures.
    [Show full text]
  • A Look at Closed Claims
    Looking at the past to improve A Look at the future: • Ethical considerations preclude direct, Closed Claims prospective experimentation to quantify Where and how can we improve? risks and predict outcomes associated with differences in anesthesia practice. • Prospective nonexperimental studies are prohibitively expensive for rare events, Mary Wojnakowski, CRNA, PhD such as anesthesia incidents. Associate Professor Midwestern University • Retrospective studies are therefore the Nurse Anesthesia Program norm, including examination of closed malpractice claims. Definitions: • Malpractice claim: demand for financial compensation for an injury resulting from medical care. • Closed malpractice claim: claim is dropped or ASA Closed Claims Project settled by the parties or adjudicated by the courts. • Closed Claim Analysis: closed claim file is reviewed by a practicing provider and consists of relevant hospital & medical records, narrative statement from involved healthcare personnel, expert & peer reviews, summaries of depositions, outcome reports, and cost of settlement. • Standardized form for data collection • Initiated in 1984 • Initial findings: unexpected group of claims • Currently contains approx 8000 claims (14 out of 900) that involved sudden dating back to 1962 from 35 cardiac arrest in relatively healthy patients participating insurance carriers. who had received spinal anesthesia. • Excludes claims for dental damage • Sudden appearance of bradycardia & hypotension, which rapidly progressed • Propose: improve patient safety and
    [Show full text]
  • National Institute for Clinical Excellence Guidance on Measuring Depth of Anaesthesia: Limitations of EEG-Based Technology
    Volume 110, Number 3, March 2013 British Journal of Anaesthesia 110 (3): 325–8 (2013) doi:10.1093/bja/aet006 EDITORIAL I Downloaded from https://academic.oup.com/bja/article/110/3/325/250090 by guest on 30 September 2021 National Institute for Clinical Excellence guidance on measuring depth of anaesthesia: limitations of EEG-based technology J. J. Pandit1* and T. M. Cook2 1 Nuffield Department of Anaesthetics, Oxford University Hospitals, Oxford, UK 2 Royal United Hospital, Bath, UK * E-mail: [email protected] Accidental awareness during anaesthesia, especially with The available evidence on the impact of the technologies on pain and subsequent recall of the event, is a terrifying pros- reducing the likelihood of intraoperative awareness is limited. Overall, [EEG-base monitors are] not associated with a statistic- pect. A high proportion of those who experience it are ally significant reduction in intra-operative awareness in reported to go on to develop symptoms similar to post- patients classified as at higher risk ... traumatic stress disorder.1 The reported incidence of recall after general anaesthesia, as ascertained by later question- What is the anaesthetist reader (or patient) to make of these ing using the Brice questionnaire, is high, 1–2 per 1000 contemporaneous and conflicting conclusions? cases (although the majority of these do not involve painful The bodies providing these two sources of advice had very experiences, are very brief recollections, or both).2 –8 There- different remits, which may explain the opposing conclu- fore, a monitor to help the anaesthetists identify those sions. The Technology Assessment Report was a review (in- patients who are awake during surgery would be extremely cluding a meta-analysis which incorporated results of a 11 useful.
    [Show full text]
  • Acute Liver Failure in Adults: an Evidence- Based Management Protocol for Clinicians
    Acute Liver Failure in Adults: An Evidence- Based Management Protocol for Clinicians Heather Patton, MD, Michael Misel, PharmD, and Robert G. Gish, MD Dr. Patton is an Assistant Clinical Abstract: With the goal of providing guidance on the provision Professor of Medicine in the Division of optimal intensive care to adult patients with acute liver fail- of Gastroenterology at the University ure (ALF), this paper defines ALF and describes a protocol for of California (UC) San Diego School of appropriately diagnosing this relatively rare clinical entity and Medicine; she is also affiliated with the ascertaining its etiology, where possible. This paper also identi- Center for Hepatobiliary Disease and fies the few known therapies that may be effective for specific Abdominal Transplantation (CHAT) in the UC San Diego Health System, both causes of ALF and provides a comprehensive approach for antici- in San Diego, California. Dr. Misel is an pating, identifying, and managing complications. Finally, one of Assistant Clinical Professor at the UC the more important aspects of care for patients with ALF is the San Diego Skaggs School of Pharmacy determination of prognosis and, specifically, the need for liver & Pharmaceutical Sciences; he is also a transplantation. Prognostic tools are provided to help guide the Pharmacist Specialist in Hepatobiliary clinician in this critical decision process. Management of patients Disease and Abdominal Transplant at CHAT in the UC San Diego Health with ALF is complex and challenging, even in centers where staff System. Dr. Gish is Chief of Clinical members have high levels of expertise and substantial experience. Hepatology and a Professor of Clinical This evidence-based protocol may, therefore, assist in the delivery Medicine in the Division of Gastroen- of optimal care to this critically ill patient population and may terology at the UC San Diego School of substantially increase the likelihood of positive outcomes.
    [Show full text]
  • NAP5 Chapter 12
    CHAPTER 121 AAGAReports during of AAGA induction after ofsedation anaesthesia and transfer into theatre James H MacG Palmer Michael RJ Sury Jaideep J Pandit HEADLINE 12.1. Approximately one in five of all reports of AAGA that NAP5 received followed intended sedation rather than general anaesthesia. The rate of reports of ‘AAGA’ following sedation appears to be as high as after general anaesthesia. The experiences of those reporting AAGA after sedation and the psychological sequelae were similar in nature, though perhaps less in severity than reports of AAGA after anaesthesia. Reports of AAGA after sedation represent a failure of communication between anaesthetist and patient and should be readily reduced, or even eliminated by improved communication, management of expectations and consent processes. BACKGROUND 12.2 NAP5 focuses on patient reports of AAGA. These 12.4 Reports of AAGA after sedation imply two reports may arise when a patient has not actually things: first that the patient does not have a received general anaesthesia. It is well recognised full understanding of the intended level of that reports of AAGA may occur after sedation consciousness, and second that the level of (Samuelsson et al., 2007; Mashour, 2009; Kent, consciousness experienced was likely undesirable. 2013). In the study by Samuelsson et al., 5% of 12.5 Esaki et al. (2009) studied 117 patients undergoing patients reporting AAGA had received intended regional anaesthesia or ‘managed anaesthesia sedation. In Kent’s study of self-reports to the ASA care’, and performed a structured interview awareness registry, 27 of 83 (33%) patients who assessing expected and experienced levels of reported AAGA had received intended sedation: consciousness.
    [Show full text]
  • Real and Illusory Perceptions of Patients in Induced Coma
    REVIEW Real and illusory perceptions of patients in induced coma Percepções reais e ilusórias de pacientes em coma induzido Percepciones reales e ilusorias de pacientes en coma inducido ABSTRACT Simone Costa SilvaI Objective: To identify, in the scientific literature, real and illusory perceptions of adult patients in induced coma. Methods: This is an integrative review of 15 primary studies from ORCID: 0000-0001-9220-6310 the Medline, Web of Science, LILACS, CINAHL and SCOPUS databases. Results: The main I memories reported after induced coma were thirst, cold, and pain. In some studies, patients Laura Menezes Silveira reported they were unable to tell whether they were awake or dreaming, whether it was ORCID: 0000-0002-2397-2553 real or unreal. Satisfactory memories were reported by patients related to the care received I and the use of bedside journals. Conclusion: Evidence showed a number of studies aiming Leila Maria Marchi-Alves to identify delirium, but without a focus on analyzing real or illusory perceptions of patients ORCID: 0000-0001-9374-8074 after induced coma. Thus, this integrative review identified scientific evidence of memories related to perceptions of sedated patients in the intensive care unit. I Isabel Amélia Costa Mendes Descriptors: Deep Sedation; Memory; Delirium; Critical Care; Nursing. ORCID: 0000-0002-0704-4319 I RESUMO Simone de Godoy Objetivo: Identificar, a partir da literatura científica, percepções reais e ilusórias de pacientes ORCID: 0000-0003-0020-7645 adultos em coma induzido. Método: Revisão integrativa de 15 estudos primários localizados nas bases de dados Medline, Web of Science, LILACS, CINAHL e SCOPUS. Resultados: As principais memórias relatadas após o coma induzido são sede, frio e dor.
    [Show full text]
  • Review Articles Intraoperative Awareness
    REVIEW ARTICLES INTRAOPERATIVE AWARENESS: MAJOR FACTOR OR NON-EXISTENT? VARINEE LEKPRASERT*, ELIZABETH A.M. FROST** AND SOMSRI PAUSAWASDI*** Introduction Intraoperative awareness has been brought to our attention and even sensationalized often by the media over the past few years, as a major problem during anesthesia. The true incidence and the actual incidence have been questioned. Others have even questioned if the complication has been reported in order to garner sympathy at the least and financial gain at the most. Certainly the incidence of intraoperative awareness under general anesthesia is rare (0.1-0.2%)1-4 but given that some 21 million anesthetics are administered annually in the United States alone, this figure translates to an occurrence of 20,000 to 40,000 cases. Worldwide the number of cases would easily reach into the millions, especially in countries that lack the resources to administer the newer inhalational anesthetics through state-of- the art anesthetic machines. To those who have experienced anesthesia awareness, it is considered a distressing complication which can cause significant psychological sequelae including post-traumatic stress disorder (PTSD)5. The syndrome and its sequelae have been discussed on television talk shows, and have been the topic of many articles and panels at national and international meetings. From Dept. of Anesthesiology, Ramathibodi Hospital, Mahidol Univ., Bangkok, Thailand. * MD, Assist. Prof. *** MD, Prof. From Dept. of Anesthesiology, Mount Sinai Medical Center, N.Y., USA. ** MD, Prof. Correspondence: Dr. Elizabeth AM Frost, Professor of Anesthesiology, Mount Sinai Medical Center, New York, N.Y, USA. E-mail: [email protected]. 1201 M.E.J.
    [Show full text]
  • Coma, Delirium, and Cognitive Dysfunction in Critical Illness Robert D
    Crit Care Clin 22 (2007) 787–804 Coma, Delirium, and Cognitive Dysfunction in Critical Illness Robert D. Stevens, MD*, Paul A. Nyquist, MD, MPH Departments of Anesthesiology/Critical Care Medicine, Neurology, Neurological Surgery, Johns Hopkins University School of Medicine, 600 N Wolfe St, Baltimore, MD 21287, USA Syndromes of global cerebral dysfunction associated with critical illness include acute disorders such as coma and delirium, and chronic processes namely cognitive impairment. These syndromes can result from direct cere- bral injury, but in many instances develop as a complication of a systemic in- sult such as cardiac arrest, hypoxemia, sepsis, metabolic derangements, and pharmacological exposures. Coma frequently evolves into phenomenologi- cally distinct disorders of consciousness such as the vegetative state and the minimally conscious state, and it must be differentiated from conditions in which consciousness is preserved, as in the locked-in state. Coma and de- lirium are independently associated with increased short-term mortality, while cognitive impairment has been linked to the poor long term functional status and quality of life observed in critical illness survivors. Advances have been made in defining, scoring, and delineating the epidemiology of cerebral dysfunction in the intensive care unit, but research is needed to elucidate underlying mechanisms, with the goal of identifying targets for prevention and therapy. Acute brain dysfunction A high proportion of patients who are admitted to the ICU develops a global alteration in cognitive function that is associated with an underlying cerebral process that can be structural or metabolic [1,2]. Terms that are used commonly to describe these disturbances include coma, delirium, encephalop- athy, acute confusional state, organic brain syndrome, acute organic reaction, * Corresponding author.
    [Show full text]
  • CORRESPONDENCE Pressure-Support Ventilation in The
    Ⅵ CORRESPONDENCE Anesthesiology 2007; 107:670 Copyright © 2007, the American Society of Anesthesiologists, Inc. Lippincott Williams & Wilkins, Inc. Pressure-support Ventilation in the Operating Room To the Editor:—I read with interest the study by Jaber et al.1 and the rhythm, and depth of breathing can be observed. Titration of anes- accompanying editorial by Tantawy and Ehrenwerth2 regarding pres- thetic agents, most notably opioids, is also facilitated. The abnormal sure-support ventilation (PSV). The Jaber study is noteworthy for ventilation/perfusion ratios that can occur during controlled ventila- documenting that the performance of PSV using modern anesthesia tion may be less likely to occur when supported spontaneous ventila- ventilators approaches the performance of an intensive care unit ven- tion is used rather than controlled mechanical ventilation. There is tilator. The editorial correctly indicates that the testing was not per- even evidence to suggest that PSV set to provide continuous positive formed under conditions of varying lung compliance and airway resis- airway pressure or bilevel positive airway pressure can be used in Downloaded from http://pubs.asahq.org/anesthesiology/article-pdf/107/4/678/364912/0000542-200710000-00037.pdf by guest on 03 October 2021 tance that influence the ventilation result obtained when using PSV. awake patients to prevent atelectasis during the preoxygenation pro- Nevertheless, PSV is most likely to find application in the operating cess.5 Finally, spontaneous ventilation offers the safety advantage of room for patients who can be allowed to breathe spontaneously knowing that the patient will likely continue to breathe even if an rather than for patients who present a significant ventilation chal- artificial airway should become dislodged.
    [Show full text]
  • Types of Brain Dysfunction in Critical Illness Robert D
    Neurol Clin 26 (2008) 469–486 Types of Brain Dysfunction in Critical Illness Robert D. Stevens, MD*, Paul A. Nyquist, MD, MPH Departments of Anesthesiology Critical Care Medicine, Neurology, and Neurological Surgery, Johns Hopkins University School of Medicine, Meyer 8-140, 600 North Wolfe Street, Baltimore, MD 21287, USA Many patients in the ICU develop a global alteration in cognitive func- tion that may be structural or metabolic in origin [1]. Terms used to describe these disturbances include delirium, acute confusional state, organic brain syndrome, acute organic reaction, cerebral insufficiency, brain failure, ICU psychosis, and encephalopathy. Etiology-specific terms, such as septic encephalopathy or hepatic encephalopathy, have been used when there is a strong presumption regarding the causative mechanism. It has been pos- tulated that many of these disorders are clinical expressions of a pathophys- iologic spectrum, collectively referred to as ‘‘critical illness brain syndrome’’ [2], ‘‘critical illness–associated cognitive dysfunction’’ [3], or ‘‘critical illness encephalopathy’’ [1]. Recently, there has been an effort to rationalize this terminology and to classify brain dysfunction in the ICU as either delirium or coma, using validated clinical criteria [4–7]. Coma Clinical assessment In the clinical realm consciousness is described in terms of two primary neurologic functions: arousal or wakefulness, and awareness of self and of the environment [8]. Awareness is the content of consciousness and includes multiple cognitive domains including perception, attention, memory, This is an updated version of an article that originally appeared in Critical Care Clinics, volume 22, issue 4. * Corresponding author. Division of Neurosciences Critical Care, Johns Hopkins University School of Medicine, Meyer 8-140, 600 North Wolfe Street, Baltimore, MD 21287.
    [Show full text]