Symptoms such as syncope (especially during exercise, while sitting or supine), palpitations, dizziness and sudden shortness of breath that are consistent with an arrhythmia should be investigated.

When a mechanical chest compression device is used, minimise interruptions to chest compression during device use by using only trained teams familiar with the device. Use direct or video laryngoscopy for tracheal intubation according to local protocols and rescuer experience. where k and c are constants, which vary between earthquake sequences. A modified version of Omori's law, now commonly used, was proposed by Utsu in 1961. [2] [3] n ( t ) = k ( c + t ) p {\displaystyle n(t)={\frac {k}{(c+t) This is achieved by continuing chest compressions during defibrillator charging, delivering defibrillation with an interruption in chest compressions of less than 5 seconds and then immediately resuming chest compressions. Right ventricular dilation in isolation during cardiac arrest should not be used to diagnose massive pulmonary embolism.Apparently healthy young adults who suffer sudden cardiac death (SCD) can also have signs and symptoms (e.g. syncope/pre-syncope, chest pain and palpitations) that should alert healthcare professionals to seek expert help to prevent cardiac arrest. An increase in ETCO 2 during CPR may indicate that ROSC has occurred. However, chest compression should not be interrupted based on this sign alone. For bradycardia caused by inferior myocardial infarction, cardiac transplant or spinal cord injury, consider giving aminophylline (100–200 mg slow intravenous injection). Minimise the risk of fire by taking off any oxygen mask or nasal cannulae and place them at least 1 m away from the patient’s chest. Ventilator circuits should remain attached.

Electrical cardioversion is the preferred treatment for tachyarrhythmia in the unstable patient displaying potentially life-threatening adverse signs. Consider extracorporeal CPR (eCPR) as a rescue therapy for selected patients with cardiac arrest when conventional ALS measures are failing and to facilitate specific interventions (e.g. coronary angiography and percutaneous coronary intervention (PCI), pulmonary thrombectomy for massive pulmonary embolism, rewarming after hypothermic cardiac arrest) in settings in which it can be implemented.

Use data-driven, performance-focused debriefing of rescuers to improve CPR quality and patient outcomes. Guidelines 2021 are based on the International Liaison Committee on Resuscitation 2020 Consensus on Science and Treatment Recommendations for Advanced Life Support and the European Resuscitation Council Guidelines for Resuscitation (2021) Advanced Life Support. Refer to the ERC guidelines publications for supporting reference material.