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"Impossible to see, the future is”: Neuroprognostication after cardiac arrest

Written by: Sofia Skebo, MSc'25 (Candidate)

On October 26, 2023, the Queen’s University Medical Grand Rounds had the pleasure of listening to a thought-provoking lecture by Dr. Gordon Boyd. Entitled ‘“Impossible to see, the future is”: Neuroprognostication after cardiac arrest’, Dr. Boyd’s lecture detailed current prognostic tools available for predicting neurological outcomes of patients following resuscitation efforts.

 

Neuroprognostication is the prediction of how well a patient will recover after serious injury to the brain(1). Cardiac arrest is typically associated with a high mortality rate, but favourable neurological outcome(2). While there will always be uncertainty regarding the timeline for patient improvement, utilizing all the available tools for prognostication can lead to the most robust understanding of prognoses.

 

In his presentation, Dr. Boyd outlined the various prognostic methods available. The clinical exam is most important, which is daily examinations of ICU patients. This includes checking pupil dilations in response to light(3). However, pupillary response only becomes accurate 48-hours after cardiac arrest. Examining the motor response to pain is not very indicative of neurological outcome, as over one-third of patients who do not have a pain response are still able to make a full recovery(3). An electroencephalogram (EEG) showing absent brainwaves typically results in poor recovery. EEG’s can also be a good predictor of whether the patient has brain activity. Evoke potentials, where major nerves are stimulated to see the motor response, are only helpful if the EEG pattern is abnormal(3). Imaging of the brain though CT scans or MRI’s can also help detect the degree of injury, by identifying hypoxic or hemorrhaged areas(4). Finally, higher levels of certain brain biomarkers such as neuron-specific enolase (NSE) found in the blood can be an indication of poorer neurological outcomes or long-term neurodegenerative diseases4.

 

On top of utilizing these predictors, Dr. Boyd explained that time is potentially the best prognostic tool neurologists have. While many families want to know the prognosis of their loved one immediately, the first 48 hours after the return of spontaneous circulation are critical for the patient. When the patient is stable and on life sustaining measures, clinicians begin to order prognostic tests to determine neurological outcomes. Dr Boyd described that if these tests are inconclusive, the question becomes how long do we wait for these patients?

 

Drawing attention to the NORCAST study, Dr. Boyd outlined that while most patients wake up 5-6 days post cardiac arrest, patients comatose up to day 25 are still able to make a complete neurological recovery(5). On top of this, waiting a long time for these patients to recover does not result in worse neurological outcomes, and patients either wake up in good neurological condition, or don’t wake up at all(5). Despite this evidence, even at hospitals in Kingston, doctors will typically withdraw life support within 3-4 days based on the likelihood of poor neurological recovery. However, the prognostic tools used for these cases were not robust and underutilized to properly make these life-altering decisions. To avoid this, ICU doctors are encouraged to provide time for patients to recover, as well as to fully utilize all the prognostic tools available to create a well-rounded picture before making decisions.

 

In the post grand round discussion, Dr. Boyd and TMED students focussed on how these decisions made in the ICU can significantly affect the mental health of patients and their families. Post-ICU syndrome is the decline in mental health after exposure to the acute care setting and is thought to occur in 25-50% of patients(6). Despite the growing awareness for mental health disorders, there exist only 6 post-ICU follow up clinics across Canada which highlights the need for more resources in this area(6). Not only this, but Dr Boyd explained that due to the interdisciplinary nature of workers in the ICU setting, there is a need for all different forms of healthcare workers present in these post-ICU follow-up clinics to ensure the patient’s mental and physical needs are met. It is important to remember the long-term impacts of the ICU on patients and to understand that care should not cease once they leave this setting.

 

Overall, Dr. Boyd’s advice to those listening, was to use all the prognostic tools available, be empowered to convey uncertainty to patients, and give patients enough time to recover. TMED students were able to understand the importance of utilizing research to make critical decisions in the ICU. 

 

It was a pleasure to hear Dr. Gordon Boyd’s presentation, and on behalf of the TMED graduate program, I would like to thank him for his time and expert insight.

 

References:

1          Fischer, D., Edlow, B. L., Giacino, J. T. & Greer, D. M. Neuroprognostication: a conceptual framework. Nature Reviews Neurology 18, 419-427 (2022). https://doi.org:10.1038/s41582-022-00644-7

2          Sandroni, C., D’Arrigo, S. & Nolan, J. P. Prognostication after cardiac arrest. Critical Care 22 (2018). https://doi.org:10.1186/s13054-018-2060-7

3          Sandroni, C. et al. Prediction of poor neurological outcome in comatose survivors of cardiac arrest: a systematic review. Intensive Care Medicine 46, 1803-1851 (2020). https://doi.org:10.1007/s00134-020-06198-w

4          Kondziella, D. Neuroprognostication after cardiac arrest: what the cardiologist should know. European Heart Journal-Acute Cardiovascular Care 12, 550-558 (2023). https://doi.org:10.1093/ehjacc/zuad019

5          Nakstad, E. R. et al. Late awakening, prognostic factors and long-term outcome in out-of-hospital cardiac arrest – results of the prospective Norwegian Cardio-Respiratory Arrest Study (NORCAST). Resuscitation 149, 170-179 (2020). https://doi.org:10.1016/j.resuscitation.2019.12.031

6          Stapleton, K., Jefkins, M., Grant, C. & Boyd, J. G. Post-intensive care unit clinics in Canada: a national survey. Canadian Journal of Anesthesia/Journal canadien d'anesthésie 67, 1658-1659 (2020). https://doi.org:10.1007/s12630-020-01741-1