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Cardiac Arrest

By

Shira A. Schlesinger

, MD, MPH, Harbor-UCLA Medical Center

Reviewed/Revised Apr 2023
View PATIENT EDUCATION

Cardiac arrest is the cessation of cardiac mechanical activity resulting in the absence of circulating blood flow. Cardiac arrest stops blood from flowing to vital organs, depriving them of oxygen, and, if left untreated, results in death. Sudden cardiac arrest is the unexpected cessation of circulation within a short period of symptom onset (often without warning).

Sudden cardiac arrest occurs outside the hospital in more than 400,000 people/year in the United States, including an estimated 5000 infants and children, with a > 90% mortality rate.

(See also the American Heart Association [AHA] 2023 update of heart disease and stroke statistics for out-of-hospital and in-hospital cardiac arrest.)

Etiology of Cardiac Arrest

In infants and children, cardiac causes of cardiac arrest are less common than in adults. The predominant cause of cardiac arrest in infants and children is respiratory failure due to various respiratory disorders (eg, airway obstruction, drowning Drowning Drowning is respiratory impairment resulting from submersion in a liquid medium. It can be nonfatal (previously called near drowning) or fatal. Drowning results in hypoxia, which can damage... read more , infection, sudden infant death syndrome [SIDS] Sudden Unexpected Infant Death (SUID) and Sudden Infant Death Syndrome (SIDS) Sudden unexpected infant death (SUID) is a term used to describe any unexpected and sudden death in a child less than 1 year of age, which often occurs during sleep or in the infant's sleep... read more , smoke inhalation Smoke Inhalation When smoke is inhaled, toxic products of combustion injure airway tissues and/or cause metabolic effects. Hot smoke usually burns only the pharynx because the incoming gas cools quickly. An... read more ). However, sudden cardiac arrest (the unexpected cessation of circulation without warning) in children and adolescents is most commonly due to arrhythmia Overview of Arrhythmias The normal heart beats in a regular, coordinated way because electrical impulses generated and spread by myocytes with unique electrical properties trigger a sequence of organized myocardial... read more Overview of Arrhythmias resulting from a channelopathy Overview of Channelopathies Channelopathies are a group of genetic, autoimmune, or inflammatory conditions that alter cardiomyocyte ion channel function in a manner that predisposes to bradyarrhythmias or tachyarrhythmias... read more or underlying structural cardiac abnormality (1, 2, 3, 4 Etiology references Cardiac arrest is the cessation of cardiac mechanical activity resulting in the absence of circulating blood flow. Cardiac arrest stops blood from flowing to vital organs, depriving them of... read more ).

Etiology references

Pathophysiology of Cardiac Arrest

Cardiac arrest causes global ischemia with consequences at the cellular level that adversely affect organ function even after resuscitation and restoration of perfusion. The main consequences involve direct cellular damage and edema formation. Edema is particularly harmful in the brain, which has minimal room to expand, and often results in increased intracranial pressure and corresponding decreased cerebral perfusion postresuscitation. A significant proportion of successfully resuscitated patients have short-term or long-term cerebral dysfunction manifested by altered alertness (from mild confusion to coma), seizures, or both.

Decreased adenosine triphosphate (ATP) production leads to loss of membrane integrity with efflux of potassium and influx of sodium and calcium. Excess intracellular sodium is one of the initial causes of cellular edema. Excess calcium damages mitochondria (depressing ATP production), increases nitric oxide production (leading to formation of damaging free radicals), and, in certain circumstances, activates proteases that further damage cells.

Abnormal ion flux also results in depolarization of neurons, releasing neurotransmitters, some of which are damaging (eg, glutamate activates a specific calcium channel, worsening intracellular calcium overload).

Inflammatory mediators (eg, interleukin-1B, tumor necrosis factor-alpha) are elaborated; some of them may cause microvascular thrombosis and loss of vascular integrity with further edema formation. Some mediators trigger apoptosis, resulting in accelerated cell death.

Symptoms and Signs of Cardiac Arrest

In critically or terminally ill patients, cardiac arrest is often preceded by a period of clinical deterioration with rapid, shallow breathing, arterial hypotension, and a progressive decrease in mental alertness. In sudden cardiac arrest, collapse occurs without warning, occasionally accompanied by brief myoclonic jerks or other seizure-like activity.

Diagnosis of Cardiac Arrest

  • Clinical evaluation

  • Cardiac monitoring and electrocardiography (ECG)

  • Sometimes testing for cause (eg, echocardiography, chest imaging [x-ray, ultrasonography], electrolyte testing)

Diagnosis of cardiac arrest is by clinical findings of apnea, pulselessness, and unconsciousness. Arterial pressure is not measurable. Pupils dilate and become unreactive to light after several minutes.

The patient is evaluated for potentially treatable causes; a useful memory aid is "Hs and Ts":

In pediatric cardiac arrest, hypoglycemia is another potentially treatable cause.

Unfortunately, the cause of cardiac arrest often cannot be identified during cardiopulmonary resuscitation (CPR). Clinical examination, chest ultrasonography during CPR, and chest x-rays taken after return of spontaneous circulation following needle thoracostomy can detect pneumothorax, which suggests tension pneumothorax Diagnosis Tension pneumothorax is accumulation of air in the pleural space under pressure, compressing the lungs and decreasing venous return to the heart. (See also Overview of Thoracic Trauma.) Tension... read more Diagnosis as the cause of the arrest.

Rapid bedside blood tests can detect abnormal levels of potassium, helping to confirm suspicion that cardiac arrest was caused by an arrhythmia secondary to hyperkalemia.

History given by family or rescue personnel may suggest overdose.

Treatment of Cardiac Arrest

Rapid intervention is essential.

(See also the 2020 American Heart Association [AHA] guidelines for CPR and emergency cardiovascular care and 2022 AHA Interim Guidance to Health Care Providers for Basic and Advanced Cardiac Life Support in Adults, Children, and Neonates With Suspected or Confirmed COVID-19.)

Cardiopulmonary resuscitation (CPR Cardiopulmonary Resuscitation (CPR) in Adults Cardiopulmonary resuscitation (CPR) is an organized, sequential response to cardiac arrest, including Recognition of absent breathing and circulation Basic life support with chest compressions... read more ) is an organized, sequential response to cardiac arrest; rapid initiation of uninterrupted chest compressions ("push hard and push fast") and early defibrillation of patients who are in VF or VT (more commonly adults) are the keys to success in achieving return of spontaneous circulation (ROSC). The 2020 AHA guidelines for treatment of cardiac arrest also advise rapid administration of a first dose of epinephrine for patients who have nonshockable rhythms.

In children, who most often have asphyxial causes of cardiac arrest, the presenting rhythm is typically a bradyarrhythmia followed by asystole. However, about 15 to 20% of children (particularly when cardiac arrest has not been preceded by respiratory symptoms) present with VT or VF and thus also require prompt defibrillation. The incidence of VF as the initial recorded rhythm increases in children > 12 years.

After immediate initiation of high-quality and uninterrupted chest compressions, defibrillation, and initial epinephrine, primary causes must be promptly treated. If no treatable conditions are present, treatment is determined by the cardiac rhythm. For patients in refractory ventricular fibrillation or pulseless ventricular tachycardia, defibrillation is done every 2 minutes and epinephrine is given every 3 to 5 minutes; amiodarone or lidocaine may also be given. For non-shockable rhythms, early administration of epinephrine has been associated with improved neurologically intact survival (1, 2 Treatment references Cardiac arrest is the cessation of cardiac mechanical activity resulting in the absence of circulating blood flow. Cardiac arrest stops blood from flowing to vital organs, depriving them of... read more ). IV fluid (eg, 1 L 0.9% saline, whole blood, or a combination for blood loss) should be given as needed to optimize volume status. If response to IV fluid is inadequate, clinicians may give one or more vasopressor drugs (eg, norepinephrine, epinephrine, dopamine, vasopressin). However, there is no definitive evidence that vasopressor administration during cardiac arrest improves return of spontaneous circulation or neurologically intact survival.

After return of pulses, postresuscitative care focuses on determination and treatment of cause, stabilization and prevention of rearrest, and optimization of neurologic outcome. In addition to treatment of cause, postresuscitative care may include methods to optimize oxygenation and ventilation and rapid coronary angiography in patients who have a ST-segment elevation (STEMI). The 2020 AHA guidelines suggest delayed coronary angiography should also be considered for patients without STEMI. Current recommendations are for targeted temperature management to therapeutic normothermia < 37.5° C, although AHA 2020 guidelines still recommend a lower temperature range. Research is ongoing to determine whether targeted temperature management with controlled hypothermia (32° C to 34° C) benefit select cardiac arrest survivors (3 Treatment references Cardiac arrest is the cessation of cardiac mechanical activity resulting in the absence of circulating blood flow. Cardiac arrest stops blood from flowing to vital organs, depriving them of... read more ).

Treatment references

  • 1. Okubo M, Komukai S, Callaway CW, Izawa J: Association of Timing of Epinephrine Administration With Outcomes in Adults With Out-of-Hospital Cardiac Arrest. JAMA Netw Open 2021;4(8):e2120176. Published 2021 Aug 2. doi:10.1001/jamanetworkopen.2021.20176

  • 2. Perkins GD, Ji C, Deakin CD, et al: A Randomized Trial of Epinephrine in Out-of-Hospital Cardiac Arrest. N Engl J Med 379(8):711-721, 2018. doi:10.1056/NEJMoa1806842

  • 3. Wyckoff MH, Greif R, Morley PT, et al: 2022 International Consensus on Cardiopulmonary Resuscitation and Emergency Cardiovascular Care Science With Treatment Recommendations: Summary From the Basic Life Support; Advanced Life Support; Pediatric Life Support; Neonatal Life Support; Education, Implementation, and Teams; and First Aid Task Forces. Circulation 2022;146(25):e483–e557, 2022. doi:10.1161/CIR.0000000000001095

Prognosis for Cardiac Arrest

Survival to hospital discharge, particularly neurologically intact survival, is a more meaningful outcome than simply return of spontaneous circulation.

Survival rates vary significantly; favorable factors include

While the American Heart Association 2020 Advanced Cardiac Life Support (ACLS) guidelines recommend cooling to a temperature range between 32° C and 36° C, more recent recommendations from the International Liaison Committee on Resuscitation Advanced Life Support (ALS) suggest actively preventing fever with a target temperature of ≤ 37.5° C rather than active cooling. It is still unclear whether certain groups of patients with cardiac arrest will have improved neurologically intact survival with targeted hypothermia management rather than with maintaining normothermia (1, 2, 3, 4, 5 Prognosis references Cardiac arrest is the cessation of cardiac mechanical activity resulting in the absence of circulating blood flow. Cardiac arrest stops blood from flowing to vital organs, depriving them of... read more ).

If many factors are favorable (eg, VF is witnessed in an intensive care unit or emergency department), 50% of adults with inpatient cardiac arrest may survive to hospital discharge. Overall, survival to hospital discharge in patients experiencing in-hospital arrest varies from 25 to 50%.

When factors are uniformly unfavorable (eg, patient in asystole after unwitnessed, out-of-hospital arrest), survival is unlikely. Overall, reported survival after out-of-hospital arrest is about 12%.

Only about 10% of all cardiac arrest survivors have good neurologic function, defined as minimal to moderate cerebral disability with ability to perform the majority of activities of daily living independently, at hospital discharge.

Prognosis references

More Information

The following English-language resources may be useful. Please note that THE MANUAL is not responsible for the content of these resources.

  • American Heart Association 2020 Guidelines: These guidelines for cardiopulmonary resuscitation (CPR) and emergency cardiovascular care (ECC) are based on the most recent review of resuscitation science, protocols, and education.

  • Wyckoff MH, Greif R, Morley PT, et al: 2022 International Consensus on Cardiopulmonary Resuscitation and Emergency Cardiovascular Care Science With Treatment Recommendations: Summary From the Basic Life Support; Advanced Life Support; Pediatric Life Support; Neonatal Life Support; Education, Implementation, and Teams; and First Aid Task Forces. Circulation 2022;146(25):e483–e557, 2022. doi:10.1161/CIR.0000000000001095

Drugs Mentioned In This Article

Drug Name Select Trade
Adrenaclick, Adrenalin, Auvi-Q, Epifrin, EpiPen, Epipen Jr , Primatene Mist, SYMJEPI, Twinject
Cordarone, Nexterone, Pacerone
7T Lido, Akten , ALOCANE, ANASTIA, AneCream, Anestacon, Aspercreme with Lidocaine, AsperFlex, Astero , BenGay, Blue Tube, Blue-Emu, CidalEaze, DermacinRx Lidocan III, DermacinRx Lidogel, DermacinRx Lidorex, DERMALID, Dologesic, Ela-Max, GEN7T, Glydo, Gold Bond, LidaFlex, LidaMantle, Lido King Maximum Strength, Lidocan, Lidocare, Lidoderm, LidoDose, LidoDose Pediatric, Lidofore, LidoHeal-90, LIDO-K , LidoLite, Lidomar , Lidomark, LidoPure, LidoReal-30, LidoRx, Lidosense 4 , Lidosense 5, Lidosol, Lidosol-50, LIDO-SORB, Lidotral, Lidovix L, LIDOZION, Lidozo, LMX 4, LMX 4 with Tegaderm, LMX 5, LTA, Lubricaine For Her, Lydexa, Moxicaine, Numbonex, ReadySharp Lidocaine, RectaSmoothe, RectiCare, Salonpas Lidocaine, Senatec, Solarcaine, SUN BURNT PLUS, Tranzarel, Xyliderm, Xylocaine, Xylocaine Dental, Xylocaine in Dextrose, Xylocaine MPF, Xylocaine Topical, Xylocaine Topical Jelly, Xylocaine Topical Solution, Xylocaine Viscous, Zilactin-L, Zingo, Zionodi, ZTlido
Levophed
Intropin
Pitressin, Vasostrict
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