Cardiac arrest is a medical emergency that occurs when the heart suddenly stops beating, the blood flow to the brain and other vital organs also stops. When the heart stops, the lack of oxygen-rich blood can quickly cause death or permanent brain damage.
For every minute of cardiac arrest without CPR or defibrillation, a patient’s chance of survival falls by 7-10%.
Symptoms of sudden cardiac arrest are immediate and severe and include:
▪ Sudden collapse.
▪ No pulse.
▪ No breathing or gasping for air.
▪ Do not respond to shouting or shaking.
▪ Loss of consciousness (pass out).
However, other symptoms occur before sudden cardiac arrest. These might include:
▪ Chest discomfort.
▪ Shortness of breath.
▪ Weakness.
▪ Fast-beating, fluttering or pounding heart called palpitations.
But sudden cardiac arrest often occurs with no warning, and half of cardiac arrests happen to people who did not know they had a heart problem.
Many people confuse cardiac arrests and heart attacks.
A cardiac arrest is caused by an electrical problem in the heart that stops the heartbeat. It is often fatal unless someone takes immediate action. The most common cause of sudden cardiac arrest is an irregular heart rhythm called ventricular fibrillation. Rapid, erratic heart signals cause the lower heart chambers to quiver uselessly instead of pumping blood. Changes in the heartbeat are called arrhythmias.
On the other hand, a heart attack is caused by a blocked arteries in the heart. The loss of blood flow damages the heart muscle, but the heart usually keeps beating.
Possible warning signs of a heart attack include those listed below:
▪ Shortness of breath (more common in women than men).
▪ Extreme tiredness (unusual fatigue).
▪ Back pain.
▪ Flu-like symptoms.
▪ Belly pain, nausea, and vomiting.
▪ Chest pain, mainly angina (more common in men than women).
▪ Repeated dizziness or fainting, especially while exercising hard, sitting, or lying on your back.
▪ Heart palpitations, or feeling as if your heart is racing, fluttering, or skipping a beat.
Finally, cardiac arrests and heart attacks have similar risks factors.
Each year, approximately 300,000 persons in the United States experience an out-of-hospital cardiac arrest (OHCA), and nearly 92% of persons who experience an OHCA event die.
An OHCA is defined as cessation of cardiac mechanical activity that occurs outside of the hospital setting, and involved a person who received resuscitative efforts, including CPR or defibrillation.
Whereas an OHCA can occur from noncardiac causes (trauma, drowning, overdose, asphyxia, electrocution, primary respiratory arrests, and other noncardiac etiologies), the majority (70% to 85%) of such events have a cardiac cause.
Moreover, most people who experience an OHCA event, do not receive bystander-assisted cardiopulmonary resuscitation (CPR), or emergency medical services (EMS) personnel assistance using defibrillation which is a process where an electronic device (such as an automated external defibrillator or AED) sends an electric shock to the heart to stop a life-threatening arrhythmia.
Therefore, in 2004, the Centers of Disease Control and Prevention (CDC) established the Cardiac Arrest Registry to Enhance Survival (CARES) in collaboration with the Department of Emergency Medicine at the Emory University School of Medicine.
In 2022:
▪ CARES patients were predominately male (62.7%), and median age of OHCA patients was 65 years.
▪ Approximately half of cardiac arrests were unwitnessed (51.3%), while 37.1% were bystander witnessed, and 11.6% were witnessed by a 911 Responder.
▪ Patients with a bystander witnessed cardiac arrest were more than 3 times as likely to survive their event, while patients with a 911 Responder witnessed cardiac arrest were approximately 4 times as likely to survive compared with unwitnessed cardiac arrests.
▪ Median response time (interval from 911 call to arrival on scene) by First Responders was 6.4 minutes, and 7.8 minutes by EMS.
▪ Bystander CPR was initiated on 40.0% of CARES patients. If CPR is started before an ambulance arrives, the patient’s chances of survival dramatically increase.
▪ 29.1% of CARES patients were defibrillated in the field. The proportion of patients first defibrillated by a bystander was 5.2%, whereas 21.2% and 73.6% were first defibrillated by a First Responder or EMS personnel, respectively.
▪ The proportion of OHCA patients surviving to hospital discharge when first defibrillated by a bystander with an AED was 44%, compared with 25% of patients first shocked by a First Responder or responding EMS personnel.
▪ Around 44.0% of patients were pronounced dead on scene after resuscitative efforts were terminated in the pre-hospital setting.
▪ The rate of survival to hospital admission was 24.9%, while the rate of survival to hospital discharge was 9.3%.
▪ CARES reported 13,794 out-of-hospital cardiac arrest survivors.
In-hospital cardiac arrest (IHCA) occurs frequently in intensive care units and other monitored settings, and is associated with high morbidity and mortality.
According to the 2022 CARES Hospital Survival Report, among all patients transported to a hospital, the survival to admission rate was 44.5% and the survival to discharge rate was 16.7%.
High‐quality cardiopulmonary resuscitation (CPR) is a critical component of IHCA resuscitation care, and is associated with higher rates of survival and reduced neurocognitive disability. As such, optimizing the quality of CPR during IHCA is a key priority emphasized in scientific statements from the American Heart Association and international cardiac arrest guidelines.
Despite these educational efforts, studies have shown that CPR quality during IHCA remains suboptimal, because of a range of factors including:
▪ rescuer fatigue during prolonged resuscitation.
▪ interruptions in CPR during defibrillation, intubation, and other intra‐arrest interventions.
▪ inadequate depth and rate of chest compressions.
In contrast to conventional delivery of manual CPR, mechanical CPR devices represent a potentially appealing alternatives, as they can provide uninterrupted chest compressions at appropriate rate and depth and are not limited by human performance variability and fatigue. However, robust clinical trial data comparing the effectiveness of mechanical CPR devices in IHCA is limited.
Moreover, time required to apply mechanical CPR devices can lead to delays in initiation of CPR during the early phase of cardiac arrest, when the likelihood of achieving return of spontaneous circulation (ROSC) may be greatest.
Lastly, injuries are commonly caused by CPR, whether manual or mechanical, and include fractures of ribs and sternum, as well as damage to organs such as the liver, heart, and lungs. On the other hand, the transfer of patients with ongoing CPR to an intensive care unit (ICU) can potentially hamper the efficacy of chest compressions and impair circulatory flow time, especially when the distance to the ICU is too long. In addition, an experienced team is more inclined to terminate CPR and declare death after prolonged and unsuccessful CPR without ICU transfer.
More research is needed to establish how the balance of risks and benefits of mechanical CPR use differs in IHCA when compared with OHCA. It remains unclear how hospitals should assemble cardiac arrest teams, to guarantee the optimal management of patients suffering from IHCA.