Post ROSC Syndrome
Cardiac arrests are emblematic of the types of call that draw many into the paramedic profession. The opportunity to administer life-saving treatments and potentially restore spontaneous circulation, represents the pinnacle of paramedic work. While advanced life support (ALS) training equips paramedics to excel in resuscitation, managing patients after achieving ROSC can remain a complex and less emphasized area in paramedic education. This article delves into the epidemiology of cardiac arrests, the pathophysiology of post-ROSC syndrome, and the practical aspects of managing patients post-ROSC, guided by the latest evidence.
Epidemiology of Cardiac Arrests and ROSC Rates
In the UK, emergency services attempt resuscitation in approximately 30,000 out-of-hospital cardiac arrests (OHCAs) annually, with the majority occurring at home. Around 80% of these arrests are of cardiac origin, and about 25% present with a shockable rhythm. ROSC is achieved in roughly 30% of attempted resuscitations, but this rate increases to 54% within the Utstein comparator group—patients with witnessed cardiac arrests of presumed cardiac origin presenting with an initial shockable rhythm. Despite these rates, survival to hospital discharge remains low, between 8-10% in the UK, a figure that has seen little improvement in recent years .
Pathophysiology of Post-ROSC Syndrome
Post-ROSC syndrome encompasses a range of physiological disturbances due to global hypoxia, affecting multiple organ systems. Key components include:
Hypoxic Brain Injury: This results in cerebral oedema, increased intracranial pressure (ICP), impaired autoregulation of cerebral blood flow, and subsequent hypoperfusion, exacerbating brain injury.
Myocardial Dysfunction: Following ROSC, the heart may exhibit myocardial stunning, reduced ejection fraction, and cardiac output, with areas of the myocardium experiencing hypercontracture due to calcium influx.
Systemic Reperfusion Injury: This involves widespread cellular damage and cytokine release, leading to a systemic inflammatory response. Complications include vasodilation, increased vascular permeability, microvascular perfusion failure, and post-arrest pyrexia, which can worsen hypoxia.
Precipitating Pathology: The underlying cause of the arrest (e.g., myocardial infarction, pulmonary embolism, aortic dissection) must also be managed to ensure comprehensive post-ROSC care .
Recognizing ROSC
ROSC can be recognized through several clinical indicators:
CO2 Spike: A sudden increase in end-tidal CO2 (ETCO2) is a reliable indicator of ROSC.
Pulse Detection: Although the accuracy of manual pulse checks by healthcare providers can be questionable, it remains a primary method of confirming ROSC .
Upon achieving ROSC, it is recommended to reassess the patient and wait for at least 10 minutes to stabilize them and monitor for the bimodal distribution of rearrest, which can provide insights into the patient’s immediate recovery trajectory.
Post-ROSC Management Priorities
Airway Management (A)
Post-ROSC patients may regain airway reflexes and respiratory effort, necessitating reassessment of airway devices like the i-gel. Ensuring a proper seal and considering alternative ventilation strategies, such as high-flow masks or Mapleson circuits, can improve oxygenation and reduce the work of breathing .
Breathing and Ventilation (B)
Effective ventilation involves balancing oxygenation and CO2 removal. Hyperventilation can adversely affect hemodynamics by decreasing cardiac output. It is crucial to maintain adequate ventilation without causing barotrauma or exacerbating hypoxia. Using positive end-expiratory pressure (PEEP) can help recruit alveoli and improve gas exchange while avoiding hyperoxia, which can cause further cellular damage through oxidative stress .
Circulation (C)
Maintaining mean arterial pressure (MAP) is vital for ensuring adequate perfusion. Regular monitoring and appropriate use of fluids and vasopressors, such as adrenaline, are necessary to support cardiac output. Understanding the interplay between preload, afterload, and contractility helps in managing blood pressure effectively .
Disability and Neurological Status (D)
Temperature management is critical. Current guidelines recommend maintaining normothermia and preventing pyrexia. Evidence from studies like the TTM2 trial suggests no significant benefit from therapeutic hypothermia over normothermia but highlights the importance of avoiding fever to improve neurological outcomes .
Exposure and Addressing Underlying Pathologies (E)
A comprehensive approach to patient care involves addressing the root cause of the cardiac arrest. This might include managing myocardial infarction, pulmonary embolism, or other acute conditions. Ensuring the patient is transported to an appropriate facility for definitive care, such as a center with percutaneous coronary intervention (PCI) capabilities, is essential for optimal outcomes .
Conclusion
The management of post-ROSC patients in the prehospital setting presents a series of complex challenges that require a thorough understanding of pathophysiology, evidence-based practices, and practical interventions. By focusing on the holistic care of these patients, from ensuring effective ventilation and perfusion to managing underlying pathologies and preventing secondary injuries, paramedics can significantly influence survival and recovery outcomes.
Future research, particularly large-scale trials like the EXACT trial, will continue to refine our understanding of optimal post-ROSC care strategies. In the interim, adherence to current guidelines and continuous education on the latest evidence are essential for improving patient outcomes in the critical moments following ROSC.
Epidemiology:
30,000 annual cardiac arrests in the UK, mostly at home.
80% cardiac origin; 25% present in shockable rhythm.
ROSC in 30% of cases, 54% in the Utstein comparator group.
Pathophysiology of Post-ROSC Syndrome:
Involves hypoxic brain injury, myocardial dysfunction, systemic reperfusion injury, and inflammation.
Systemic injury includes cytokine release and free radical formation.
Brain injury leads to cerebral edema and impaired blood flow.
Myocardial dysfunction reduces ejection fraction and perfusion.
Recognizing ROSC:
Look for CO2 level spike and pulses.
Pulse checks can be inaccurate; use additional indicators.
Post-ROSC Management Priorities:
Airway: Ensure functionality and adjust devices as needed.
Breathing: Balance oxygenation and CO2 removal, avoid hyperventilation.
Circulation: Maintain adequate blood pressure and perfusion using fluids and medications like adrenaline.
Therapeutic Temperature Management (TTM):
Aim for normothermia, prevent fever, avoid active warming in mild hypothermia.
Managing Reperfusion Injury:
Reduce CMRO2 with sedation and analgesia.
Control blood glucose to prevent hyperglycemia.
Transport and Extrication:
Efficient on-scene management and effective team communication.
Critical Care Support:
Critical care teams may be able to support with sedation and PHEA
References
Resuscitation Council UK. (2021). Epidemiology of Cardiac Arrest Guidelines. Retrieved from resus.org.uk.
The Lancet. (2021). Comparison of Survival Rates in Different EMS Systems. Retrieved from thelancet.com.
National Center for Biotechnology Information. (2021). Systemic Reperfusion Injury. Retrieved from ncbi.nlm.nih.gov.
New England Journal of Medicine. (2019). Targeted Temperature Management for Cardiac Arrest with Nonshockable Rhythm. Retrieved from nejm.org.
REBEL EM. (2021). Accuracy of Pulse Checks in Cardiac Arrest. Retrieved from rebelem.com.
British Journal of Anaesthesia Education. (2021). The Cardiovascular Effects of Positive Pressure Ventilation. Retrieved from bjaed.org.
American Heart Journal. (2009). Systematic Review of the Effect of Hyperoxia on Coronary Blood Flow. Retrieved from pubmed.ncbi.nlm.nih.gov.
JAMA Network. (2015). Effect of Hyperoxia on Cardiac Arrest Outcomes. Retrieved from jamanetwork.com.
Advanced Life Support Task Force. (2022). 2022 International Consensus on Cardiopulmonary Resuscitation. Retrieved from resuscitationjournal.com.
The Bottom Line. (2021). TTM2 Trial Summary. Retrieved from thebottomline.org.
JAMA Network. (2014). Prehospital Induction of Mild Hypothermia Study. Retrieved from jamanetwork.com.
https://jamanetwork.com/journals/jama/fullarticle/2798013 - The EXACT trial
https://www.thebottomline.org.uk/summaries/box-oxygen/ - The BOX Trial