Getting return of spontaneous circulation is only the beginning of the journey for caring for patients who have suffered a cardiac arrest.
There are still a significant number of interventions needed which can influence the ultimate outcome for patients.
The goal of this module is to begin to better understand these principles.
There are still a significant number of interventions needed which can influence the ultimate outcome for patients.
The goal of this module is to begin to better understand these principles.
In the UK, the Resuscitation Council guidelines are a key guidance to the underlying principles:
This video from the SAVED team provides a useful overview - https://vimeo.com/420213912
I have also written some more detailed (but didactic) notes here - http://www.thegasmanhandbook.co.uk/post-arrest-care.html
The Internet Book of Critical Care have also done a thorough summary here:
Physiology
The principles of supportive care revolve around normalising the patient’s physiology and supporting this.
Normal rather than supranormal values are the target, in keeping with principles of other pathologies of critical care.
Also in keeping with other critical care principles, many anti-iatrogenic measures remain fully applicable to these patients e.g. lung protective ventilation strategies.
Normal rather than supranormal values are the target, in keeping with principles of other pathologies of critical care.
Also in keeping with other critical care principles, many anti-iatrogenic measures remain fully applicable to these patients e.g. lung protective ventilation strategies.
Therapeutic Hypothermia
The notion of cooling patients post cardiac arrest is not a new one, although the method has been more controversial recently. Indeed, it is probably the component of post arrest care with the greatest controversy.
The concept arose from the anecdotal observation of neuroprotection and animal model work - if you are cold, you seem less likely to suffer neurological injury.
In clinical practice, the HACA trial and the Bernard et al. trial demonstrated benefits from implementing therapeutic hypothermia following cardiac arrest.
You can read more about these landmark papers here.
HACA - https://www.nejm.org/doi/full/10.1056/NEJMoa012689 (The Bottom Line - https://www.thebottomline.org.uk/summaries/icm/haca/)
Bernard et al - https://pubmed.ncbi.nlm.nih.gov/11856794/
However, the therapy is not without its complications, and the eagle eyed amongst you will have noted the notable pyrexia that was a feature of the untreated control patients in these studies.
As such, a new hypothesis arose around the presence of pyrexia being a principle mechanism of harm, rather than hypothermia itself being protective.
This was the basis of the targeted temperature management (TTM) trial.
TTM - https://www.nejm.org/doi/full/10.1056/NEJMoa1310519
(The Bottom Line - https://www.thebottomline.org.uk/summaries/icm/ttm/)
This suggested that there was not any real difference between a temperature of 33 or 36 degrees celsius.
Some interpretations of this had cast doubt on the very principle of therapeutic hypothermia. The argument was why bother implementing an intervention that had no (or questionable benefit).
Some of the limitations were therefore addressed by TTM-2:
TTM-2 - https://www.nejm.org/doi/full/10.1056/NEJMoa2100591?query=featured_cardiology
(The Bottom Line - https://www.thebottomline.org.uk/summaries/icm/ttm2/)
As such, there is more of a consensus arising on the nature of the intervention, although not with complete certainty.
This is that fever is probably bad, but that we gain little, if any benefit, from true hypothermia.
Given the commonality of fever following cardiac arrest, active cooling is therefore still often needed, but with less aggressive targets, and now termed targeted normothermia.
Questions that remain are around the nature of ultra-early hypothermia (pre-hospital, and probably the approach with the greatest theoretical weight) and the extrapolation to intra-hospital arrests.
The concept arose from the anecdotal observation of neuroprotection and animal model work - if you are cold, you seem less likely to suffer neurological injury.
In clinical practice, the HACA trial and the Bernard et al. trial demonstrated benefits from implementing therapeutic hypothermia following cardiac arrest.
You can read more about these landmark papers here.
HACA - https://www.nejm.org/doi/full/10.1056/NEJMoa012689 (The Bottom Line - https://www.thebottomline.org.uk/summaries/icm/haca/)
Bernard et al - https://pubmed.ncbi.nlm.nih.gov/11856794/
However, the therapy is not without its complications, and the eagle eyed amongst you will have noted the notable pyrexia that was a feature of the untreated control patients in these studies.
As such, a new hypothesis arose around the presence of pyrexia being a principle mechanism of harm, rather than hypothermia itself being protective.
This was the basis of the targeted temperature management (TTM) trial.
TTM - https://www.nejm.org/doi/full/10.1056/NEJMoa1310519
(The Bottom Line - https://www.thebottomline.org.uk/summaries/icm/ttm/)
This suggested that there was not any real difference between a temperature of 33 or 36 degrees celsius.
Some interpretations of this had cast doubt on the very principle of therapeutic hypothermia. The argument was why bother implementing an intervention that had no (or questionable benefit).
Some of the limitations were therefore addressed by TTM-2:
TTM-2 - https://www.nejm.org/doi/full/10.1056/NEJMoa2100591?query=featured_cardiology
(The Bottom Line - https://www.thebottomline.org.uk/summaries/icm/ttm2/)
As such, there is more of a consensus arising on the nature of the intervention, although not with complete certainty.
This is that fever is probably bad, but that we gain little, if any benefit, from true hypothermia.
Given the commonality of fever following cardiac arrest, active cooling is therefore still often needed, but with less aggressive targets, and now termed targeted normothermia.
Questions that remain are around the nature of ultra-early hypothermia (pre-hospital, and probably the approach with the greatest theoretical weight) and the extrapolation to intra-hospital arrests.
Prognostication
Following best supportive efforts and stabilisation there becomes a need to assess the prognostic picture of the patient.
This is because of the high likelihood of neurological injury during the lack of cerebral perfusion.
Understandably, this often links to outcomes that are highly undesirable for patients and family. Given the ongoing burdensome and unpleasant care that is often needed for such cases, having a better understanding of the likely outcomes is helpful for making appropriate decisions on care.
However, this can be very challenging.
The pathology, as well as the many confounding factors of critical care (especially sedation) can make accurate assessment difficult.
A number of patients may have had an injury so severe that they progress to brainstem death - this is a separate category of prognostication.
The resuscitation council algorithm provides a useful overview of the approach: https://www.resus.org.uk/sites/default/files/2021-04/Neuroprognostication%20Algorithm%202021.pdf
I have also written more detailed notes on the topic here: http://www.thegasmanhandbook.co.uk/prognostication.html
This is an excellent, in-depth analysis from the team at IBCC:
This is because of the high likelihood of neurological injury during the lack of cerebral perfusion.
Understandably, this often links to outcomes that are highly undesirable for patients and family. Given the ongoing burdensome and unpleasant care that is often needed for such cases, having a better understanding of the likely outcomes is helpful for making appropriate decisions on care.
However, this can be very challenging.
The pathology, as well as the many confounding factors of critical care (especially sedation) can make accurate assessment difficult.
A number of patients may have had an injury so severe that they progress to brainstem death - this is a separate category of prognostication.
The resuscitation council algorithm provides a useful overview of the approach: https://www.resus.org.uk/sites/default/files/2021-04/Neuroprognostication%20Algorithm%202021.pdf
I have also written more detailed notes on the topic here: http://www.thegasmanhandbook.co.uk/prognostication.html
This is an excellent, in-depth analysis from the team at IBCC:
As can be seen, there is a significant amount of ongoing input following successful resuscitation of patients. These interventions can make a difference to the ultimate outcome and warrant careful implementation, especially early on. These factors are all worth reflecting on as you go on to see these patients in clinical practice.
Links & References
- Resuscitation Council (UK). Post-resuscitation care. 2021. https://www.resus.org.uk/library/2021-resuscitation-guidelines/post-resuscitation-care-guidelines
- A Bersten, N Soni. Oh’s Intensive Care Manual (7th Ed). 2014. Butterworth Heinemann Elsevier.
- Post-cardiac arrest syndrome: Epidemiology, pathophysiology, treatment, and prognostication. International Liaison Committee on Resuscitation. Resuscitation. 2008. 79; 350-379
- Bernard et al. Treatment of Comatose Survivors of Out-of-hospital Cardiac Arrest with Induced Hypothermia. NEJM. 2002. 346: 557-563 (Summary here)
- The Hypothermia After Cardiac Arrest Study Group. Mild therapeutic hypothermia to improve the neurological outcome after cardiac arrest. NEJM. 2002. 346: 549-556 (Summary here)
- The TTM Trial Group. Targeted temperature management after cardiac arrest. NEJM. 2013. 369 (23): 2197-2206 (Summary here)
- The TTM2 Trial Group. Hypothermia versus Normothermia after Out-of-Hospital Cardiac Arrest. NEJM. 2021. 384:2283-2294 https://www.nejm.org/doi/full/10.1056/NEJMoa2100591?query=featured_cardiology
- Heaton, T. Post arrest care. 2016. http://www.thegasmanhandbook.co.uk/post-arrest-care.html
- SAVED. Post resuscitation care. 2020 https://vimeo.com/420213912
- Farkas, J.Post-cardiac arrest management. 2024. IBCC https://emcrit.org/ibcc/post-arrest/#top
- Heaton, T. Prognostication post cardiac arrest. 2024. http://www.thegasmanhandbook.co.uk/prognostication.html
- Farkas, J. Neuroprognostication after cardiac arrest. 2023. IBCC. https://emcrit.org/ibcc/np/
