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

      Dear Editor,
      There is increasing evidence of cognitive activity in relation to cardiopulmonary resuscitation (CPR) in 10–20% of cardiac arrest (CA) survivors.
      • Parnia S.
      Death and consciousness — an overview of the mental and cognitive experience of death.
      This includes consciousness and awareness, as well as recall of CPR events by survivors. Although in the past the poorly defined umbrella term of ‘near death experiences (NDEs)’
      • Greyson B.
      The near-death experience scale. Construction, reliability, and validity.
      has been used to refer to CA experiences, recent data suggest this does not adequately describe the breadth of these experiences. Survivor experiences encompass multiple themes, which can occur at different times in relation to their CA, CPR, and post-CA recovery. These include transcendent mystical experiences, visual and auditory awareness with a perceived sense of bodily detachment, dream like states, CPR-induced consciousness, as well as conscious experiences related to emergence from coma. Furthermore, it is unclear whether explicit recall reflects the entirety of conscious experiences or whether, there may also be implicit learning without recall of events, similar to accidental awareness during anaesthesia.
      • Pandit J.J.
      • Andrade J.
      • Bogod D.G.
      • et al.
      5th National Audit Project (NAP5) on accidental awareness during general anaesthesia: protocol, methods, and analysis of data.
      Although classifications and grading scales exist for NDE,
      • Greyson B.
      The near-death experience scale. Construction, reliability, and validity.
      and accidental awareness during anaesthesia,
      • Pandit J.J.
      • Andrade J.
      • Bogod D.G.
      • et al.
      5th National Audit Project (NAP5) on accidental awareness during general anaesthesia: protocol, methods, and analysis of data.
      none address all the potential possibilities for clinical, audit and research purposes. CPR-related cognitive activity, consciousness and awareness, and recall of events after ROSC may be distressing for both the patient and rescuer, and potentially contribute to long-term negative psychological outcomes such as post-traumatic stress disorder.
      • Parnia S.
      • Spearpoint K.
      • de Vos G.
      • et al.
      AWARE-AWAreness during Resuscitation — a prospective study.
      On the other hand, transcendent mystical experiences are associated with positive long-term psychological outcomes.
      • van Lommel P.
      • van Wees R.
      • Meyers V.
      • Elfferich I.
      Near-death experience in survivors of cardiac arrest: a prospective study in the Netherlands.
      We propose a classification to describe these events, to help researchers and clinicians describe and help improve our understanding (Table 1). Our proposed classification (which we accept may require modifications) recognises that even when these events occur, the rescuer report, patient recall, the type and timing of assessment, and the consequences to the patient may vary. How events during CPR and recovery and their consequences are related is uncertain. Finally, there are no standardised guidelines on how best to recognise and manage CPR-related cognitive activity, consciousness, awareness and recall, and we hope that further studies will help address this issue.
      Table 1Proposed classification of CPR-related cognitive activity, consciousness, awareness and recall.
      Answer optionsExamples
      1. During CPR — rescuer report
      A. UnconsciousYes, no, sedated, not recorded, otherNo observable evidence of consciousness
      B. Some evidence of consciousnessYes, no, sedated, not recorded, otherEye opening, localising to stimuli
      C. ConsciousYes, no, sedated, not recorded, otherClear, purposeful movements to stimuli, following commands
      D. Type of resuscitationManual, automated, E-CPR
      2. Patient assessment after ROSC
      A. No recall of awareness of eventsYes, no, sedated, no ROSC, death after ROSC, not recorded, other
      B. Recall of events (prompted)Yes, no, sedated, no ROSC, death after ROSC, not recorded, otherOn direct questioning patient recalls auditory, visual, sensory, or other events including pain or distress
      C. Recall of events (unprompted)Yes, no, sedated, no ROSC, death after ROSC, not recorded, otherPatient voluntarily recalls auditory, visual, sensory, or other events occurring during CPR
      D. Evidence of implicit learning on assessmentYes, no, sedated, no ROSC, death after ROSC, not recorded, otherRecall of auditory, visual, sensory, or other events planted during resuscitation
      • Parnia S.
      • Spearpoint K.
      • de Vos G.
      • et al.
      AWARE-AWAreness during Resuscitation — a prospective study.
      E. Near death experience (i.e. Grayson Scale
      • Greyson B.
      The near-death experience scale. Construction, reliability, and validity.
      score >7)
      Yes, no, sedated, no ROSC, death after ROSC, not recorded, otherVisual, auditory, sensory events
      3. Consequence to patient
      A. Timing of assessmentReturn of full consciousness, ICU discharge, hospital discharge/30 days, at 90 days, at 1 year
      B. No direct consequenceYes, no, sedated, no ROSC, death after ROSC, not recorded, other
      C. Psychological harmYes, no, sedated, no ROSC, death after ROSC, not recorded, otherEvidence of PTSD, night terrors, depression, anxiety
      D. Psychological benefitYes, no, sedated, no ROSC, death after ROSC, not recorded, otherNo longer afraid of death, more spiritual, closer relationships
      4. Brief summary of events
      ECPR, extra-corporeal CPR. PTSD, post-traumatic stress disorder. ROSC, return of spontaneous circulation.

      Conflict of interest

      RLW and QO — no conflict of interest.
      SP has received grants in the past for the study of awareness during CPR.
      JS is an Editor of Resuscitation and receives payment from Elsevier the publisher.

      References

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