key: cord-1006901-6gxw90fu
authors: West, Rebecca L.; Otto, Quentin; Drennan, Ian R.; Rudd, Sarah; Böttiger, Bernd W.; Parnia, Sam; Soar, Jasmeet
title: CPR-related cognitive activity, consciousness, awareness and recall, and its management: A scoping review
date: 2022-05-09
journal: Resusc Plus
DOI: 10.1016/j.resplu.2022.100241
sha: d0cd1246852e0d4b9d21aca1026fee54476378e6
doc_id: 1006901
cord_uid: 6gxw90fu

BACKGROUND: There are increasing numbers of reports of cognitive activity, consciousness, awareness and recall related to cardiopulmonary resuscitation (CPR) and interventions such as the use of sedative and analgesic drugs during CPR. OBJECTIVES: This scoping review aims to describe the available evidence concerning CPR-related cognitive activity, consciousness, awareness and recall and interventions such as the use of sedative and analgesic drugs during CPR. METHODS: A literature search was conducted of Medline, Embase and CINAHL from inception to 21 October 2021. We included case studies, observational studies, review studies and grey literature. RESULTS: We identified 8 observational studies including 40,317 patients and 464 rescuers, and 26 case reports including 33 patients. The reported prevalence of CPR-induced consciousness was between 0.23% to 0.9% of resuscitation attempts, with 48–59% of experienced professional rescuers surveyed estimated to have observed CPR-induced consciousness. CPR-induced consciousness is associated with professional rescuer CPR, witnessed arrest, a shockable rhythm, increased return of spontaneous circulation (ROSC), and survival to hospital discharge when compared to patients without CPR-induced consciousness. Few studies of sedation for CPR-induced consciousness were identified. Although local protocols for treating CPR-induced consciousness exist, there is no widely accepted guidance. CONCLUSIONS: CPR-related cognitive activity, consciousness, awareness and recall is uncommon but increasingly reported by professional rescuers. The data available was heterogeneous in nature and not suitable for progression to a systematic review process. Although local treatment protocols exist for management of CPR-induced consciousness, there are no widely accepted treatment guidelines. More studies are required to investigate the management of CPR-induced consciousness.

Cardiopulmonary resuscitation (CPR) related cognitive activity, consciousness, awareness, and recall is increasingly reported. Cases include documentation of patients moving, perceived consciousness and awareness, as well as recall of CPR events by survivors. 1 Although in the past the poorly defined umbrella term of 'near death experiences' 2 has been used to refer to cardiac arrest reported experiences, these descriptions do not adequately describe the breadth of these experiences. 3 There is no current consensus or guidance on how CPRinduced consciousness should be managed. While some settings have developed local protocols most professional rescuers have no guidance on how to manage CPR-induced consciousness.

The Advanced Life Support (ALS) Task Force of the International Liaison Committee on Resuscitation (ILCOR) considered it timely to undertake a scoping review to identify literature related to cognitive activity, consciousness, awareness and recall of patients who received CPR and the impact of potential interventions such as the use of sedative and analgesic drugs during resuscitation. A scoping review rather than a systematic review was undertaken in order to systematically describe the limited available evidence using a broad literature search and to identify current interventions and knowledge gaps.

This review was undertaken on behalf of the ILCOR ALS Task Force as part of its continuous evidence evaluation process, and the protocol developed adhered to the ILCOR guidance on Task Force scoping reviews. 4 It was drafted using the preferred reporting items for systematic reviews and Meta-analysis protocols extension for Scoping Reviews (PRISMA-ScR). 5 The following population, interventions, comparators and outcomes were decided a priori:

Population: Adults in any setting with consciousness during CPR.

Intervention: Sedation, analgesia, or any other intervention to prevent consciousness.

Comparison: No specific intervention for consciousness. Outcomes: Any patient clinical outcome. Arrest outcomes and psychological wellbeing post arrest.

Other relevant outcomes identified from the review where included such as rescuer outcomes including, rescuer distress, trauma, and uncertainty.

Study designs: Randomized controlled trials (RCTs) and nonrandomized studies (non-randomized controlled trials, interrupted time series, controlled before-and-after studies, cohort studies) were all eligible for inclusion. For the purpose of the scoping review, we also included review articles, case reports and case series, grey literature and unpublished studies (e.g., conference abstracts, trial protocols). Articles based around the Lazarus phenomenon 6 and cough CPR 7 as well as narrative articles referring to near-death experiences and consciousness were excluded. Children and animal studies were excluded.

Time frame, language and study group: All years and languages were included providing an English title or abstract was given.

We searched Medline, Embase, EMcare and CINAHL (via EBSCO) from inception to 26 Nov 2020 with a repeat search conducted on 21 October 2021. The search included keyword and subject terms relating to consciousness or awareness and CPR, and search filters were used to limit to adults and humans. The strategy is outlined in Appendix 1. We also screened reference lists of included papers. Grey literature (including local protocols) was identified by asking ILCOR colleagues to share articles, no specific separate additional search for grey literature was conducted.

On receiving the identified articles, they were uploaded onto a standardised review platform (Rayyan) and duplicates identified and resolved within this platform. Article title and abstracts were then reviewed for relevance by two independent task force members (RW and QO) and any deemed to be irrelevant were excluded. Both reviewers and a third reviewer (JS) reviewed those studies where there was initial disagreement. Full text review and initial data extraction was conducted by RW, and checked by QO and JS. Identified articles were grouped as case studies, observational studies, review studies, grey literature and protocols. We included both quantitative and qualitative data from articles.

As this is a scoping review, critical appraisal of sources of evidence and systematic comparison was not conducted.

Spreadsheet tables were created and piloted for data extraction using Excel by two reviewers (RW and QO). Different data were extracted for observational studies, case reports, review articles and sedation protocols (see Tables 1-4 ). Our focus was to identify, where possible, the population; arrest type; evidence of CPR-related cognitive activity, consciousness, awareness and recall; and any management or outcome data. Data were extracted by two reviewers (RW and QO) with oversight from a third author (JS) in an iterative process including discussion on what was relevant to our study.

Studies were grouped by article type and relevant data extracted and synthesised within these groups. A presentation to the ILCOR task-force on 1st Feb 2021 generated discussion of results and guided the authors' narrative discussion presented in this review.

The results of the search strategy are summarised in the PRISMA flow diagram in Fig. 1 .

We identified observational studies, case studies, review papers and protocols for use of sedation for CPR-induced consciousness. We identified 8 observational studies with a total of 40,317 patients and 464 rescuers, 26 case reports including 33 patients, 3 review papers and 4 sedation regimens (Tables 1-4 ). The Cohen's kappa for agreement between reviewers at initial screening was 0.85.

Two types of cognitive activity and awareness were identified. The first includes visible signs of consciousness such as combativeness, groaning, and eye opening and was referred to as CPRinduced consciousness. The second, a perception of lucidity with visual and auditory awareness and recall without external signs of consciousness. 9 Observational studies estimated that CPR-induced consciousness occurred in 0.23% to 0.9% of all CPR attempts with combativeness or agitation reported in 34.6% cases as the most common sign. 10, 12 An estimated 48-59% of 'experienced' healthcare professionals reported observing a patient with CPR-induced consciousness during resuscitation. It is unclear whether this high rate reflects the true prevalence of CPR-induced consciousness or the study designs and small sample sizes. Rescuer reports of CPRinduced consciousness interfering with the CPR attempts included 44 When giving mechanical chest compressions: Fentanyl 2mcg/Kg or Midazolam 2.5 mg Wellington Free Ambulance service guidelines 45 If movement significant enough to interfere with resuscitation: Ketamine IV 1 mg/Kg If continuing significant movement rocuronium (if ETT in place) Ambulance Victoria guidelines 46 If patient interferes with CPR, has present gag reflex, or appears to be aware: Fentanyl 25mcg IV, repeat every 3-5 min If critical care trained Ketamine 20 mg IV/IO, repeat every 3-5 min the patient resisting having chest compressions or trying to pull out vascular access devices, the need to pause CPR and reassure the patient, and the need to use sedative or paralysing drugs and physical restraint. [13] [14] [15] CPR-induced consciousness was mainly reported in patients with VF/pVT arrests witnessed by a healthcare professional in observational studies (Table 1 ) and case reports ( Table 2) . CPR-induced consciousness was associated with increased ROSC, survival to hospital admission and survival to discharge. 10, 12 In one observational study, after risk adjustment for arrest factors, CPR-induced consciousness was associated with increased odds of survival to hospital discharge in unwitnessed/bystander witnessed arrests but not EMS witnessed arrests 10 A single observational study reported that 27% of cardiac arrest survivors who had CPR-induced consciousness went on to develop PTSD. 8 In an international multicentre observational study 55 (39%) of 140 cardiac arrest survivors reported having perceived a sense of awareness from the time of being unconscious, but without any explicit recall of resuscitation related events or other cognitive memories. 9 32 of a subgroup of 101 survivors had cognitive recollections that comprised multiple themes, including fear. 9 survivors recalled memories that were consistent with near-death experiences and 2 described awareness with explicit recall of seeing and hearing events during CPR. In this study, there was no objective evidence of signs of consciousness such as agitation, eye opening, or localising by patients who were able to perceive memories/recall of the resuscitation. This suggests that awareness may be present without overt signs of consciousness.

Two case reports describe CPR-induced consciousness causing rescuer distress and unease for a considerable time after the event. 20, 38 In an observational study of physicians who had reported CPR-induced consciousness, over 90% reported it having a detrimental effect on them with 52% reporting personal discomfort and 7% reporting sleeplessness, nightmares and mood change. 14 Patient sedation or analgesia was rarely reported in the management of CPR-induced consciousness ranging from 12% to 39% in the included observational studies ( Table 1 ) and 26% of the case reports (Table 2) . Two studies commented on the effects of sedation and analgesia on patients. One study observed that boluses or infusion of sedation or analgesic drugs during resuscitation was not associated with a decrease in PTSD in survivors. 8 Another study observed that sedation or analgesia use was associated with a worse outcome including an increase in termination of resuscitation at the scene, increased time to ROSC, and decreased survival to hospital admission. 42 When sedation was used there was a variety of drugs used, ranging from midazolam and ketamine to rocuronium and diazepam (Tables 1-3) . We identified 4 local policy guidelines found (Table 4 ) with ketamine, midazolam and fentanyl alone or in combination being the most commonly used drugs.

The concept of CPR related cognitive activity, consciousness, awareness, and recall is complex. Our scoping review found both visible signs of consciousness (such as combativeness, groaning and eye opening); and the perception of lucidity, visual/auditory awareness, and near-death experiences (with or without recall). Interestingly, patients with awareness or recall of events do not always present with visible signs of consciousness.

Instances of CPR-induced consciousness appear to be more common in professional rescuer witnessed sudden cardiac arrests caused by shockable rhythms with presumed cardiac aetiology, possibly giving us a starting point to try and predict the patients who are at greater risk of CPR-induced consciousness. 10, 12 There is also evidence that CPR-induced consciousness causes a degree of distress to rescuers, including sleeplessness and mood changes, 14 with mixed evidence regarding patient outcomes. Witnessed cardiac arrests with an initial shockable rhythm and early CPR and defibrillation have the best chance of survival and CPR-induced consciousness may suggest favourable cerebral perfusion during CPR.

There are multiple narrative articles exploring the theory of physical entity, the mind, consciousness and how these are interlinked and related to CPR-induced consciousness and instances of awareness or recall after CPR. 47, 48 A recurring feature reported is a paradoxical perception of separated external visual and auditory awareness, which has at times been referred to using the illdefined and ill-understood phenomenon of "out of body experiences". Unlike overt signs of consciousness, such as movement, obeying commands and speaking as mentioned in several of the studies, patient awareness and recall is much more difficult to define. The term near death experience has previously been used to describe the range of memories, thoughts, feelings and auras that patients experienced post cardiac arrest, and attempts have been made to categorise and study these through the Near-Death Experience Scale developed by Greyson. 2 Parnia has identified multiple cognitive themes, including fear, that do not fit into the classical near-death experience definition, suggesting that this term may not encompass the entire patient experience. 9, 11 Furthermore, in one study 2 patients reported a sense of separated external visual and auditory awareness and in one case, the accuracy of the perceived recollections by the patient was able to be confirmed. Whilst we have limited understanding on the processes behind this phenomenon, we have even less understanding on the long-term implications for both patient and rescuer. It is well known that sufferers of cardiac arrest are at risk of PTSD. 8 It could be assumed that pain and distress would be expected in patients showing overt physical signs of consciousness through CPR. On the other hand, there have also been cases documented where survivors experiencing more transcendental post cardiac arrest experiences whilst not showing signs of pain or distress have benefited from the experience with it having a positive impact on the patient's life. 11 When considering treatment options, it may be beneficial to consider these two experiences as two separate entities. Further difficulty remains with survivors being able to distinguish awareness and recall during cardiac arrest and CPR from experiences during ICU care and emergence from coma. Clinicians may struggle to quantify and define these patient experiences, and this may lead to difficulty in recording, validating and addressing them, including providing appropriate mental health support.

Our scoping review suggests there is limited evidence to best inform whether management of CPR-induced consciousness or the long-term psychological impact of awareness and recall in survivors is necessary, and if it is what the optimal strategy is.

One review article has suggested that if medication was being used, the ideal drug should have a fast smooth onset of action, be rapidly destroyed in the bloodstream without redistribution, not cause cardiorespiratory depression, not increase cerebral blood flow or intracranial pressure and it should increase the seizure threshold. 49 The ideal available drug is not clear and ketamine and midazolam use appears most common in reported protocols.

The ILCOR ALS Task Force consensus on cardiopulmonary resuscitation and Emergency cardiovascular care science with treatment recommendations (2021) includes a summary of this review with good practice statements. 50 

As only a scoping review was conducted, we did not critically appraise each study for its strengths, weaknesses and biases, nor did we assess the certainty of evidence overall or attempt to make treatment recommendations. There are still gaps in our knowledge and more research in these areas is needed.

We did not specifically investigate phenomena surrounding CPRinduced consciousness such as the Lazarus phenomenon, coughassisted CPR and consciousness during cardiac arrest with a ventricular assist device in situ. Nor did we look in depth into neardeath experiences, their prevalence or the pathophysiology potentially causing these experiences.

CPR-related cognitive activity, consciousness, awareness and recall is uncommon but increasingly reported by professional rescuers. The data available was heterogeneous in nature and not suitable for progression to a systematic review process. Although local treatment protocols exist for management of CPR-induced consciousness, there are no widely accepted treatment guidelines. In settings in which it is feasible, rescuers may consider using sedative or analgesic drugs doses to prevent pain and distress to patients who are conscious during CPR. More studies are required to investigate the management of CPR-induced consciousness.

This research did not receive any specific grant from funding agencies in the public, commercial, or not-for-profit sectors.

RLW, QO, IRD, SR, BWB declare no conflicts of interest. SP has received grants in the past for studies of awareness during CPR. JS is an Editor of Resuscitation and received payment from the publisher Elsevier. 

BET 2: Pain management in patients who show awareness during CPR

The near-death experience scale. Construction, reliability, and validity

A proposed classification for CPR-related cognitive activity, consciousness, awareness and recall

Evidence Evaluation Process and Management of Potential Conflicts of Interest: 2020 International Consensus on Cardiopulmonary Resuscitation and Emergency Cardiovascular Care Science With Treatment Recommendations

PRISMA Extension for Scoping Reviews (PRISMA-ScR): Checklist and Explanation

Autoresuscitation (Lazarus phenomenon) after termination of cardiopulmonary resuscitation -a scoping review

The effect of alternative methods of cardiopulmonary resuscitation -Cough CPR, percussion pacing or precordial thumpon outcomes following cardiac arrest. A systematic review

Life after death: posttraumatic stress disorder in survivors of cardiac arrest-prevalence, associated factors, and the influence of sedation and analgesia

AWARE-AWAreness during REsuscitation-A prospective study

Consciousness induced during cardiopulmonary resuscitation: An observational study

Abstract 387: Awareness and Cognitive Activity During Cardiac Arrest

Insights into the epidemiology of cardiopulmonary resuscitation-induced consciousness in out-of-hospital cardiac arrest

CPR-induced consciousness: A cross-sectional study of healthcare practitioners' experience

CPRinduced consciousness: attention required for caregivers and medication

An exploration of UK Paramedics' experiences of Cardiopulmonary resuscitation induced consciousness

Maintenance of consciousness during closed-chest massage

The efficiency of cardiac massage in ventricular fibrillation. Description of an instance of recovery of consciousness without spontaneous heart beat

CPRdependent consciousness: evidence for cardiac compression causing forward flow

Need for sedation in a patient undergoing active compression-decompression cardiopulmonary resuscitation

Code blue stories. Awake and aware in the emergency department

Ultra long cardiopulmonary resuscitation with intact cerebral performance for an asystolic patient with acute myocarditis

Prolonged retention of awareness during cardiopulmonary resuscitation for asystolic cardiac arrest

A hemodynamic profile for consciousness during cardiopulmonary resuscitation

Life signs in 'dead' patients

New CPR devices save lives, Medical College study finds

Total recall-is it ethical not to sedate people during successful resuscitation?

Mechanical CPR Helps Save the Day-and the Patient

Awareness during resuscitation

Ventricular fibrillation and consciousness are not mutually exclusive

Is It Possible to Maintain Consciousness and Spontaneous Ventilation with Chest Compression in the Early Phase of Cardiac Arrest?

CPR Induced Consciousness During Out-of-Hospital Cardiac Arrest: A Case Report on an Emerging Phenomenon

CPR induced consciousness: It's time for sedation protocols for this growing population

Six Cases Of CPR-Induced Consciousness In Witnessed Cardiac Arrest

Consciousness with cardiopulmonary resuscitation

What do you do when a patient regains consciousness during mechanical CPR?

Cardiopulmonary resuscitation induced consciousness a case report in an Elderly Patient

Having a Conscious Patient During Cardiopulmonary Resuscitation: Is It Not Time to Consider Sedation Protocol?: A Case Report

Awareness during cardiopulmonary resuscitation

Video of cardiopulmonary resuscitation induced consciousness during ventricular fibrillation

Cardiopulmonary resuscitation-induced consciousness

Reanimation bei Kammerflimmern -Wachheit während der Wiederbelebung

Return of consciousness during ongoing cardiopulmonary resuscitation: A systematic review

Approach to cardiopulmonary resuscitation induced consciousness, an emergency medicine perspective

Landelijk Protocol Ambulancezorg, Version 8.1, Chapter

Clinical Procedures and Guidelines

Clinical Practice Guidelines ALS and MICA Paramedics Version

Do reports of consciousness during cardiac arrest hold the key to discovering the nature of consciousness?

Near death experiences in cardiac arrest: Visions of a dying brain or visions of a new science of consciousness

Sedation during and after CPR-efforts: is it worth a guideline?

International Consensus on Cardiopulmonary Resuscitation and Emergency Cardiovascular Care Science With Treatment Recommendations: Summary From the Basic Life Support; Advanced Life Support; Neonatal Life Support; Education, Implementation, and Teams; First Aid Task Forces; and the COVID-19 Working Group

The authors are grateful to the ILCOR ALS Task