2025 AHA CPR and ECC Guidelines Cardiac Arrest Chain of Survival
Cardiopulmonary resuscitation (CPR) for out-of-hospital cardiac arrest (OHCA) has long been a focus of pre-hospital medicine. Although the success rate of CPR is discouraging, no one likes the alternative. Chest compression and mouth-to-mouth resuscitation are mentioned in ancient Egyptian hieroglyphs, but modern CPR was first described and modified during the second half of the twentieth century. The challenges of wilderness CPR include limited access to medical facilities and providers, communication barriers, environmental conditions, inadequate supplies, assessment challenges, psychological stress and group dynamics, and patient transport challenges.
As with any pre-hospital emergency response, a proper scene survey is essential. We are served well by the National Outdoor Leadership School’s (NOLS) approach:
- I’m number ONE – Move the subject to a location where CPR can be more safely and effectively done. The appropriate hierarchy of safety concern is (in order):
- You as a responder
- Your team/fellow responders
- The subject
- Members of the public
- What happened to YOU? – Your visual assessment of the subject and the situation AS YOU APPROACH is one of your most significant sources of information.
- Not on ME – Appropriate personal protective equipment (PPE)
- Are there any MORE? – Consider the possibility that other subjects are not immediately apparent.
- Dead or ALIVE? – Form an initial impression of the severity of the situation early on.
The medical literature is replete with recommendations for alternative positions and configurations for CPR performed in austere conditions, including hypogravity, microgravity, in-flight, confined space, and on moving ski patrol toboggans. Although novel CPR techniques continue to emerge to address the unique challenges of extreme environments, the evidence supporting their effectiveness remains limited.
Although the rates of return of spontaneous circulation (ROSC) and favorable neurologic recovery are low in wilderness cases, there are multiple cases in the medical literature of successful outcomes after prolonged resuscitation. One includes a 29-year-old female physician who fell head-first into a waterfall gully while skiing and had a good neurologic outcome (returning to work in the same hospital in which she was resuscitated) after 9 hours of resuscitation in the face of severe hypothermia. Another includes a 19-year-old male with hypertrophic cardiomyopathy with a cerebral performance scale (CPS) of 1 after 2 hours of resuscitation without significant hypothermia. The importance of high-quality CPR is often discussed, but an intact chain of survival for OHCA is undoubtedly essential for success in these and other examples. The Utstein formula for survival states that, while medical science is fundamental, increased survival depends on educational efficiency and appropriate local implementation.
In 2011, the National Association of Emergency Medical Service Physicians (NAEMSP) published some of the first termination of resuscitation (TOR) guidelines for nontraumatic cardiopulmonary arrest. TOR may be considered when, at the time of decision of termination, all of the following conditions have been met:
- An EMS provider did not witness the arrest.
- There is no shockable rhythm by an automatic external defibrillator (AED) or other electronic monitor.
- There is no ROSC before transport.
These guidelines appropriately emphasized the importance of active physician oversight and the need to consider specific clinical, environmental, and population-based contexts in which these guidelines may not apply. Reliance on these guidelines persists in the 2025 American Heart Association (AHA) recommendations for termination of resuscitative measures in adult advanced life support. However, a 2024 systematic review and meta-analysis of 43 published studies, encompassing 29 TOR rules and 1,125,587 cases, found insufficient evidence to support the widespread implementation of TOR rules. This suggests that adopting TOR rules may lead to missed survivors and increased inappropriate resource utilization. Although CPR duration is generally inversely and independently associated with neurological outcomes, factors such as the patient population, underlying medical conditions, and the presence of a shockable rhythm must be considered on a case-by-case basis when considering termination of resuscitation in OHCA. While the likelihood of a favorable neurologic outcome is small overall, those with an initial shockable rhythm fare much better than those with an initial unshockable rhythm.
Published in High Altitude Medicine & Biology in 2024, Termination of Cardiopulmonary Resuscitation in Mountain Rescue: A Scoping Review and ICAR MedCOM 2023 Recommendations has been the most comprehensive effort to apply medical evidence to cardiopulmonary arrest in the wilderness. Its recommendations, with the level of evidence, are summarized below:
- Nontraumatic cardiac arrest: Initiate CPR in a victim with a clinical condition suggestive of a nontraumatic cause of cardiac arrest (1A).
- Safety of rescuers: If the environment is unsafe, transport the victim to a safe place before commencing resuscitation (1A).
- Termination of CPR: Terminate resuscitation if all of the following criteria apply: unwitnessed loss of vital signs, no ROSC during 20 minutes of CPR, no shock advised at any time by an AED or only asystole on a cardiac monitor, and no hypothermia or other exceptional circumstances (e.g., lightning injury, toxic ingestion) that warrant prolonged CPR. If no AED is available, terminate CPR after 20 minutes of unsuccessful CPR (1A).
- Use of automatic external defibrillator (AED): Use an AED on a victim with a primary (1A) or secondary (2A) cardiac arrest.
- Mechanical chest compressions: Use a mechanical chest compression device, if available, for prolonged CPR, during transport in difficult terrain, or if there are too few rescue personnel on scene to provide high-quality manual CPR (1A).
- Point-of-Care Ultrasound (POCUS): Use POCUS, if available, to help determine whether to terminate resuscitation (1B).
- Traumatic cardiac arrest: Withhold resuscitation in a victim with nonsurvivable trauma such as decapitation, loss of brain tissue, truncal transection, incineration, or penetrating cardiac trauma (1A). Terminate resuscitation if a victim of traumatic cardiac arrest has no vital signs after 10 minutes of CPR (1B). Medical directors of mountain rescue teams should develop local protocols for traumatic cardiac arrest, matching urban guidelines to terminate CPR if transport time is >15 minutes (1C).
- Hypothermia: Unless there are definite signs of death, start CPR in a hypothermic victim without vital signs and transport to a center capable of extracorporeal life support (ECLS) rewarming (1A).
- Drowning: Withhold CPR in a drowning victim with a submersion time >30 minutes in water >6ºC (42.8ºF) or >90 minutes in water <6ºC (2A).
- Avalanche: In an avalanche victim with burial duration of >60 minutes, in asystole, with an obstructed airway, withhold or terminate CPR (1A). Provide full resuscitative efforts for an avalanche victim with a core temperature <30ºC (86.0◦F) with a patent airway, and without lethal injuries. These patients should be transported to an extracorporeal life support (ECLS) capable center (1C).
- Lightning strike: In a victim in cardiac arrest caused by a lightning strike, perform prolonged CPR if necessary. Prolonged ventilatory support may be necessary even after ROSC (1B).
- Burns: In a victim with cardiac arrest caused by a burn injury, terminate CPR after 20 minutes without ROSC (1C).
- Poisoning: In a victim with cardiac arrest from suspected poisoning or overdose, contact a poison control center before terminating CPR (1C).
Although the AHA recommended compression-only CPR for bystanders in 2008, compression-only CPR is not appropriate for cardiopulmonary arrest in the following situations. The AHA now recognizes the importance of treatment aimed at reversing the underlying cause in cases of secondary cardiac arrest.
- Lightning Injury: Paralysis of the medullary respiratory center may last longer than paralysis of the cardiac sinoatrial node. Compression-only CPR may lead to secondary cardiac arrest if spontaneous respirations have not resumed. These patients may need prolonged respiratory support after ROSC.
- Asphyxia: In cardiac arrest due to drowning, snow burial, carbon monoxide exposure, and other low-oxygen states, it is of little value to circulate unoxygenated blood with compression-only CPR. These patients require positive-pressure ventilation to reverse their hypoxemic state.
- Pediatrics: Children generally experience secondary, rather than primary cardiac arrest (due to low oxygen states such as respiratory failure).
Absolute contraindications to any CPR include: