Cardiac arrest and cardiopulmonary resuscitation

Cardiac arrest is the sudden cessation of cardiac function and blood circulation, manifesting as apnea, pulselessness, and loss of consciousness. In adults, cardiac arrest is most commonly caused by cardiac conditions (e.g., coronary artery disease), but it can also have noncardiac etiologies (e.g., hypothermia), whereas in children, etiologies are more varied and more frequently related to profound hypoxia (e.g., due to airway obstruction). Cardiopulmonary resuscitation (CPR) is a lifesaving procedure that artificially maintains circulation and ventilation until cardiac function is hopefully restored. Immediate initiation of high-quality chest compressions is the most important factor for survival after cardiac arrest.

There are two clinical algorithms to provide CPR: basic life support (BLS) for lay rescuers and medical professionals alike and advanced cardiac life support (ACLS) solely for medical professionals. BLS involves checking responsiveness, calling for help, performing chest compressions and rescue breaths, and, if available, using an automated external defibrillator (AED). ACLS includes additional measures (e.g., resuscitation medications, airway management) and identifying and treating reversible causes of cardiac arrest (e.g., Hs and Ts). Modifications to BLS and ACLS are required for children and neonates.

After the return of spontaneous circulation (ROSC), comprehensive postresuscitation care is essential for good neurological and functional outcomes. This involves neuroprotective measures, hemodynamic support, critical care admission, monitoring for organ dysfunction, and treatment of underlying causes and complications.

Recommendations in this article are consistent with the 2020 American Heart Association (AHA) and the International Liaison Committee on Resuscitation (ILCOR) guidelines and consensus statements. Practice may vary according to regional authorities and resources. Consult local protocols whenever possible. ^[1]

Chain of survival ^[2][3][4]

The initial approach to cardiac arrest is influenced by the rescuers (e.g., number of rescuers, training received), patient factors (e.g., age, pregnancy), and location (i.e., in-hospital vs. out-of-hospital).

• Identify cardiac arrest and initiate an emergency response.
• Begin BLS (i.e., immediate CPR, especially chest compressions).
• Defibrillate shockable rhythms.
• Transition care to ACLS providers.
• Initiate postresuscitation care.
• Provide comprehensive support throughout recovery.

Algorithms

Overview of life support algorithms
	Key components
BLS algorithm		Activation of emergency response High-quality CPR Automated external defibrillation
ACLS algorithm		High-quality CPR Defibrillation Rhythm recognition in cardiac arrest Resuscitation medications Treatment of reversible causes of cardiac arrest
Special patient groups	Newborns: See “Neonatal life support.” Prepubertal children: See “Pediatric BLS.” Postpubertal children: Follow the adult BLS algorithm and/or ACLS algorithm. Pregnant individuals: See “Cardiac arrest in pregnancy.” Trauma patients: See “Traumatic cardiac arrest.”
Postresuscitation care	Airway management Maintenance of hemodynamic and respiratory parameters within target ranges PCI for suspected cardiac causes, e.g., STEMI Targeted temperature management Management of acute seizures Other neuroprotective measures

Approach

• For sudden cardiac arrest, use the CAB approach to begin chest compression as soon as possible.
  1. Chest compressions
  2. Airway
  3. Breathing
• Prioritize airway and breathing (i.e., ABC approach) for cardiac arrest secondary to respiratory arrest.
• Minimize interruptions to CPR. ^[3]
• If the diagnosis of cardiac arrest is uncertain, initiating CPR is preferable to withholding CPR. ^[2]

Chest compressions ^[2]

Chest compression technique differs in children, infants, and neonates; see “Basic life support in infants and children” and “Neonatal life support.”

• Key targets for high-quality chest compressions
  • Compression rate: 100–120 per minute
  • Compression depth for adults: 5–6 cm (2–2.5 inches)
  • Allow full chest recoil between compressions.
• Provider positioning and technique (adults and children; excluding infants)
  • Kneel or stand next to the patient depending on whether they are on the ground or in a bed, respectively.
  • Center the hands (one on top of the other, fingers interlaced) over the sternum.
  • Keep the arms straight (do not bend the elbows); the shoulders should be directly above the hands.
  • Use full body weight to deliver rapid, firm compressions.
• Patient positioning: supine on a firm surface
• Minimizing interruptions
  • Restart CPR between rhythm analysis and shock delivery (while the defibrillator is charging).
  • Resume CPR immediately after shock delivery.

High-quality chest compressions are associated with better survival rates.

Mechanical CPR devices ^[5]

• Provide automated chest compressions through various means
• Consider if high-quality manual chest compressions cannot be consistently provided, e.g.: ^[6][7]
  • Prolonged CPR needs: e.g., hypothermic cardiac arrest
  • Manual compressions carry a high risk to providers (e.g., pandemic settings)
  • Limited emergency response systems

Rescue breathing ^[2]

• Mouth-to-mouth
  1. Open the airway using the head-tilt/chin-lift maneuver.
  2. Pinch the patient's nose closed.
  3. Form a tight seal over the patient's mouth.
  4. Breathe slowly into the patient's mouth for ∼ 1 second; check for chest rise to confirm sufficient ventilation.
  5. Move away from the patient's mouth between breaths to allow air to escape, ensuring the patient's airway remains open.
• If equipment is available: Ventilate with 100% O₂; select a modality based on patient factors and provider expertise. ^[8]
  • BMV (with or without basic airway adjuncts): Administer 2 breaths after every 30 chest compressions.
  • Advanced airway
    • Maintain an uninterrupted rate of 10 breaths/minute.
    • Do not interrupt CPR for > 10 seconds to facilitate placement of an advanced airway.
    • Return to BMV if an advanced airway has not been secured within 10 seconds.

Continuous compression-only CPR is a reasonable alternative to mouth-to-mouth rescue breathing if the provider is uncomfortable administering rescue breaths or there is concern for infectious disease transmission.

Withholding CPR

Only consider allowing natural death in limited situations, e.g.: ^[9]

• Presence of an advance directive or valid DNR prohibiting CPR
• Situations that may pose a significant risk to the rescuer
• Signs of irreversible death

Initiate CPR if there is any uncertainty regarding the validity of a DNR or the irreversibility of death.

The BLS algorithm allows appropriately trained individuals to recognize cardiac arrest, provide high-quality chest compressions, deliver ventilations, and utilize an AED.

BLS algorithm ^[1][10]

The optimal sequence of some BLS steps varies between single-rescuer BLS and two-rescuer BLS.

• Assess scene safety: e.g., check for fire and other hazards, don PPE for infectious or toxic exposures
• Assess patient responsiveness : Proceed with BLS if no response or only abnormal breathing (e.g., gasping).
• Call for help: Shout for assistance and/or activate the emergency response.
• Retrieve an AED or defibrillator: e.g., from the nearest crash cart
• Assess for signs of life: Check pulse and respiration simultaneously.
  • Perform airway opening maneuvers as needed.
  • Look, listen, and feel for air movement.
  • Check for a central pulse for no longer than 10 seconds.
  • If no palpable pulse, apnea, and/or agonal respirations: Begin CPR immediately.
  • If respirations are normal: Place the patient in the recovery position before continuing with medical assessment.
• Perform high-quality CPR.
  • Position patient supine on a hard surface (activate CPR mode on the bed if present). ^[1]
  • Maintain appropriate CPR ratio: 30:2 for adults, i.e., 30 chest compressions followed by 2 rescue breaths per cycle
  • Regularly switch roles if performing two-rescuer CPR.
  • Minimize interruptions to CPR.
• Defibrillate as needed.
  • Use an AED or defibrillator as soon as it is available.
  • Perform 5 cycles (2 minutes) of CPR between each rhythm analysis and/or shock.
• Endpoints ^[2]
  • The patient shows clear signs of life: e.g., coughing, breathing, movement of the extremities
  • Rescuers are too fatigued to continue
  • ACLS-trained providers arrive

Minimizing the interruption and delays to the initiation of high-quality CPR and early defibrillation of shockable rhythms are the most important factors for survival and reducing long-term complications after cardiac arrest.

For a collapsed patient, remember the DRs ABCD: Check the environment for Danger, assess for a Response, shout for help, open the Airway, check for Breathing, start CPR, and attach the Defibrillator.

Single rescuer vs. two rescuers

Automated external defibrillator (AED)

• Description: a portable electronic defibrillator that independently identifies shockable rhythms and delivers a shock; designed to be used by lay rescuers in out-of-hospital settings
• Applying pads
  • Dry the skin where the pads will be applied, if necessary.
  • Anterior-lateral placement: Place one pad on the right chest (above the nipple) and the other on the left side of the thorax (below the nipple).
  • Anterior-posterior placement: Place one pad anteriorly on the chest and the other posteriorly on the back.
• Rhythm analysis
  • Pause CPR during rhythm analysis.
  • Repeat analysis every 2 minutes (5 cycles of CPR).
• Delivering shocks
  • The AED will indicate if a shock is advised and may begin to charge.
  • Resume CPR while the AED is charging.
  • When advised by the AED, clear the surroundings , then deliver the shock.
• Resume CPR immediately after shock delivery: Perform for 2 minutes (5 cycles) prior to the next rhythm analysis.

Special situations ^[1][10][11]

• Drowning: Prioritize ABC approach and rescue breaths; perform CPR prior to calling for help.
• Foreign body aspiration (FBA): See “Unresponsive patient with suspected FBA” for details.
  • Check airway for dislodged foreign body (FB) during 2-minute pulse check and remove if present.
  • Avoid blind finger sweep if FB is not visible.
  • If CPR unsuccessful, consider emergency airway procedures for FBA.
• Hypothermia
  • Requires specialized vital signs assessment
  • CPR generally continued until fully rewarmed, e.g., using ECLS
  • Consider mechanical CPR devices.
  • See “Hypothermic cardiac arrest” for details.
• Temporizing measure for shockable rhythms: not routinely recommended ^[10]
  • Precordial thump maneuver: a sharp, high-velocity blow delivered to the mid sternum using the ulnar aspect of the fist with the goal to interrupt life-threatening V-fib or V-tach.
  • Consider only if all the following criteria are met:
    • Witnessed onset of an unstable ventricular tachyarrhythmia in a monitored patient
    • Functioning defibrillator not immediately available
    • Maneuver can be performed without delaying CPR or defibrillation

The ACLS algorithm adds the following to the BLS algorithm: rhythm recognition in cardiac arrest, resuscitation medications, treatment of reversible causes of cardiac arrest, and advanced airway management. Maximizing high-quality CPR and early defibrillation remain the most important factors for survival and good neurological outcome. ^[12]

ACLS algorithm ^[10][12]

• Priority 1: CPR
  • Perform high-quality CPR for at least 2 minutes before the first rhythm check.
  • Avoid interrupting CPR unless it is for rhythm and pulse checks and/or shock delivery.
  • Consider an advanced airway only if necessary and feasible without major interruption of CPR.
• Priority 2: rhythm and pulse check
  • Attach monitors and/or defibrillator pads.
  • Pause CPR for no longer than 10 seconds for rhythm recognition in cardiac arrest.
  • Shockable rhythms (Vfib or pulseless VT): Proceed to defibrillation; draw up epinephrine PLUS either amiodarone OR lidocaine.
  • Nonshockable rhythms (PEA or asystole): Do not defibrillate; draw up epinephrine.
  • Repeat rhythm and pulse check every 2 minutes, resuming CPR in between each check.
• Priority 3: defibrillation of shockable rhythms
  • Deliver a shock (e.g., 200 J biphasic) as soon as Vfib or pulseless VT is recognized.
  • Resume CPR immediately after shock and continue for 2 minutes until next rhythm and pulse check.
  • If a second attempt at defibrillation is unsuccessful, administer resuscitation medications.
• Priority 4: resuscitation medications
  • Obtain peripheral IV/IO access and administer medications without interrupting CPR.
  • Nonshockable rhythms: Administer epinephrine; 1 mg IV/IO as soon as possible; repeat every 3–5 minutes as needed.
  • Shockable rhythms
    • After 2^nd unsuccessful cycle of defibrillation; : administer epinephrine 1 mg IV/IO; repeat every 3–5 minutes as needed.
    • After 3^rd unsuccessful cycle of defibrillation, administer:
      • Amiodarone 300 mg IV/IO once, then 150 mg IV/IO once after 3–5 minutes
      • OR lidocaine 1–1.5 mg/kg IV/IO once, then 0.5–0.75 mg/kg IV/IO once after 3–5 minutes
  • Reevaluate indications and dosage at each subsequent rhythm and pulse check.
• Priority 5: Hs and Ts
  • Address these in parallel with CPR, defibrillation, and resuscitation medications.
  • See “Reversible causes of cardiac arrest” for targeted therapies.
• Endpoints
  • ROSC identified during rhythm and pulse check: Begin postresuscitation care.
  • Termination of resuscitation decision is made: Follow procedure for declaration of death.

Evaluate and treat reversible causes of cardiac arrest (e.g., Hs and Ts) without stopping CPR, defibrillation, or administration of resuscitation medications.

Continue CPR and defibrillation attempts as long as the patient has a shockable rhythm.

Rhythm recognition in cardiac arrest

In prolonged cardiac arrest, rhythms frequently degenerate into asystole; check with emergency providers if another rhythm was detected prior to admission.

Avoid pausing CPR for longer than 10 seconds for rhythm and pulse checks.

Defibrillation

Defibrillate as soon as possible once a shockable rhythm is recognized to maximize survival.

Procedure

1. Set the defibrillator to unsynchronized mode.
2. Place the paddles or pads firmly on the patient's thorax.
3. Set energy dosage and press the charge button.
   • Biphasic defibrillator (preferred) ^[10][13]
     • First shock: 120–200 J
     • Additional shocks: 200–360 J
   • Monophasic defibrillator : 360 J for all shocks
4. Resume CPR while the defibrillator is charging.
5. When fully charged, “clear” the patient, i.e., ensure no other personnel and equipment are in contact with the patient or pads.
6. Administer the shock.
   • Paddles: Simultaneously hold down both shock buttons located under each thumb.
   • Pads: Press the shock button on the defibrillator.
7. Resume CPR immediately after defibrillation for a full 2-minute cycle. ^[12]

Ensure the defibrillator is set to unsynchronized mode when treating cardiac arrest with a shockable rhythm.

Pitfalls and troubleshooting

• Provide interval CPR if there is a delay between rhythm recognition and shock delivery.
• Conducting gel may be required for paddles.
• Direct, firm contact between the pads or paddles and the skin is essential.
• Consider shaving the patient's chest if there is a lot of hair.
• Turn oxygen off or divert the flow away from the patient.

Resuscitation medications ^[10]

Obtain peripheral IV access or IO access for medication administration without interrupting CPR. All resuscitation medications should be administered while CPR is ongoing to ensure their circulation to the heart and brain.

• Shockable rhythms
  • Epinephrine 1 mg IV/IO
    • First dose: after second unsuccessful defibrillation attempt
    • Repeat every 3–5 minutes.
  • Amiodarone 300 mg IV/IO (OR lidocaine 1–1.5 mg/kg IV/IO)
    • First dose: after third unsuccessful defibrillation attempt
    • An additional dose of 150 mg of amiodarone or 0.5–0.75 mg/kg of lidocaine can be given after 3–5 minutes.
• Nonshockable rhythms: Administer epinephrine 1 mg IV/IO.
  • First dose: as soon as possible
  • Repeat every 3–5 minutes.

Crisis resource management ^[12]

Effective teamwork is essential to the success of resuscitative efforts. The following roles, responsibilities, and communication strategies are recommended during ACLS:

• Assign a designated team leader prior to starting resuscitation.
  • All communication about patient status and treatments delivered should go through the team leader.
  • Final decisions about which treatments to pursue and when to stop resuscitation should be made by the team leader after discussion with other team members.
• Other suggested roles include:
  • At least two CPR performers: one for chest compressions and one for airway and ventilation
    • Providers of chest compressions should be swapped every 2 minutes to prevent fatigue.
    • Coordinate changeovers to minimize interruptions to CPR.
  • Provider(s) in charge of IV/IO access and medications
  • Provider(s) in charge of rhythm and pulse checks and defibrillation
  • Provider in charge of specific procedures (e.g., intubation, pericardiocentesis, point-of-care ultrasound)
  • Timekeeper and/or note taker
• Prior to each pause, ensure team members are aware of their roles to minimize interruptions to CPR.

Apply the following for patients with Vfib or pulseless VT identified at any time during cardiac arrest. Simultaneously evaluate for and treat reversible causes of cardiac arrest, e.g., Hs and Ts.

1^st defibrillation attempt

• Continuous high-quality CPR started.
• Defibrillator turned on and set to unsynchronized mode.
• Pads or paddles placed appropriately
• Device charged
  • 200 J for biphasic defibrillators
  • OR 360 J for monophasic defibrillators.
• Shock administered after clearing patient
• CPR resumed until the next rhythm and pulse check (2 minutes or 5 cycles of CPR).

2^nd attempt

• Shock administered after clearing patient
• CPR resumed until the next rhythm and pulse check (2 minutes or 5 cycles of CPR).
• First dose of epinephrine given

3^rd attempt

• Shock administered after clearing patient
• CPR resumed until the next rhythm and pulse check (2 minutes or 5 cycles of CPR).
• First dose given of:
  • Amiodarone
  • OR lidocaine

4^th attempt

• Shock administered after clearing patient
• CPR resumed until the next rhythm and pulse check (2 minutes or 5 cycles of CPR).
• Repeat dose of epinephrine given

5^th attempt

• Shock administered after clearing patient
• CPR resumed until the next rhythm and pulse check (2 minutes or 5 cycles of CPR).
• Second dose (half of the first dose) given of:
  • Amiodarone
  • OR lidocaine

Endpoints

• If persistent VF or pulseless VT:
  • Continue CPR and defibrillation attempts.
  • Continue repeating epinephrine at regular intervals.
• If PEA or asystole: Immediately resume CPR and follow acute management checklist for nonshockable rhythms.
• If ROSC: Begin postresuscitation care.

Precharge the defibrillator prior to the next rhythm and pulse check to minimize interruption of CPR.

The following applies to patients with PEA or asystole identified at any time during cardiac arrest. Simultaneously evaluate for and treat reversible causes of cardiac arrest, e.g., Hs and Ts.

First identification of nonshockable rhythm

• CPR started and continued until next rhythm and pulse check (2 minutes or 5 cycles of CPR).
• First dose of epinephrine given as soon as possible

Subsequent identification of nonshockable rhythm

• CPR resumed until next rhythm and pulse check (2 minutes or 5 cycles of CPR).
• Repeat dose of epinephrine given at 3–5 minute intervals.

Endpoints

• If persistent PEA or asystole:
  • Continue CPR and repeat doses of epinephrine. ^[10][14][15]
  • Consider termination of resuscitation on an individual basis.
• If VF or pulseless VT: Defibrillate, resume CPR, and follow acute management checklist for shockable rhythms.
• If ROSC: Begin postresuscitation care.

Only consider pausing CPR if a lifesaving procedure requiring access to the chest must be performed, e.g., pericardiocentesis.

Overview of causes ^{[10][11][13][16]}

• The Hs and Ts can be used to help remember the most common reversible causes of cardiac arrest. ^[13]
• Other causes include hypoglycemia, hypocalcemia, hypomagnesemia, anaphylaxis, and asthma.

Bedside diagnostic studies

• Rapid glucose and electrolytes (K⁺, Ca²⁺, Mg²⁺)
• ABG/VBG ± CO-oximetry
• Core body temperature
• POCUS: eFAST exam to identify hemoperitoneum, pericardial effusion, and lung sliding

Hs

Ts

Other reversible causes of cardiac arrest ^{[10][11][13][16]}

Several other reversible causes of cardiac arrest exist and may be screened for and treated during cardiac arrest.

Avoid routine dextrose administration for cardiac arrest (e.g., in potentially normoglycemic or hyperglycemic patients) as it can worsen survival and neurological outcomes. ^[26]

Return of spontaneous circulation (ROSC) ^[13]

• Indications of ROSC
  • Clear signs of life, e.g., breathing, coughing, or movement
  • Return of palpable pulse and blood pressure or presence of arterial waveform with intraarterial monitoring
  • An abrupt and sustained increase in expiratory CO₂ measured with capnography
• Management
  • Begin postresuscitation care.
  • Consult specialists for neuroprognostication.
  • Identify and treat complications of CPR and/or cardiac arrest.

Termination of resuscitation (TOR) ^[29]

Indications for TOR (in-hospital cardiac arrests)

No clear guidance exists on when to terminate CPR in hospitals. Decisions should take into account the following factors:

• The patient's wishes: Terminate resuscitation efforts if a valid DNR or an advance directive prohibiting resuscitation is discovered.
• Experience of the provider and resuscitation team
• Factors associated with poor outcomes ^[14]
  • Patient factors: older age, poor functional status, terminal malignancy, organ failure
  • Resuscitation factors: delay to onset of CPR, delay to defibrillation

Important considerations

Evidence does not support using any single clinical decision rule to guide in-hospital TOR. See also “Tips and Links” below for AHA guidelines on the ethics of withholding CPR and terminating resuscitative efforts.

• End-tidal CO₂: The AHA suggests that an EtCO₂ < 10 mm Hg after 20 minutes of resuscitation may be considered alongside other factors in the decision to terminate resuscitation; it should not be used alone to determine TOR. ^[10][30]
• Shockable rhythms: Resuscitation should typically continue as long as the patient remains in a shockable rhythm. ^[10][14]
• Nonshockable rhythms: There is no recommended duration of asystole at which resuscitation should cease. ^[15]
• Prolonged resuscitation is typically appropriate in the following circumstances: ^[10][14]
  • Hypothermia: Continue until adequately rewarmed (e.g., core temperature > 35°C/95°F).
  • Toxicity (e.g., local anesthetic toxicity): Prolonged resuscitation may allow toxins to be metabolized and excreted.
  • Pulmonary embolism: Continue resuscitation for at least 60–90 minutes after administration of thrombolytic agents.

The post-ROSC phase of cardiac arrest focuses on optimizing hemodynamic support, identifying and treating the underlying cause of arrest, and minimizing secondary brain injury through neuroprotective measures.

Initial postresuscitation stabilization ^[10]

• Airway: Secure the airway in comatose patients with early placement of an endotracheal tube.
• Target respiratory parameters: Titrate FiO₂ and initiate waveform capnography.
  • Respiratory rate: Start at 10 breaths/minute.
  • Titrate oxygen therapy to reach SpO₂ of 92–98% and PaCO₂ of 35–45 mm Hg.
• Target hemodynamic parameters: Administer IV fluids as needed and consider vasopressors and/or inotropes.
  • Systolic blood pressure > 90 mm Hg
  • Mean arterial pressure > 65 mm Hg
• Obtain 12-lead ECG: to elevate for acute ST-segment elevation

Additional management and urgent interventions ^[10]

• Address the cause of arrest: See “Reversible causes of cardiac arrest.”
• Identify patients requiring urgent coronary angiography.
  • All patients with ST-segment elevation on ECG
  • Unstable, comatose patients with a suspected cardiac cause of arrest
  • All patients with any other indication for coronary angiography.
• Diagnose and manage seizures.
  • Perform an EEG on all comatose patients.
  • Consider antiepileptic drugs to manage acute seizures.
  • Seizure prophylaxis is not recommended.
• Avoid fever: Aim for a body temperature of < 37.5°C. ^[31]
• Consider targeted temperature management (TTM), e.g., a body temperature of 32–36°C for at least 24 hours. ^[10]
• Initiate other neuroprotective measures: See “Secondary brain injury and neuroprotective measures.”
• Admit to ICU: for further management and neuroprognostication

Don't forget the ABCs of postresuscitation care: Obtain an ABG, BP, and Chest x-ray, Draw blood for laboratory studies, and ensure an ECG is performed. Talk to the Family, Give thanks to the team, consider initiation of Hypothermia, and admit to ICU.

Neuroprognostication ^[10]

• Neuroprognostication after cardiac arrest is complex and should be conducted by specialists.
• The extent of irreversible loss of brain function can be estimated clinically (e.g., neurological examination, apnea testing) and using ancillary brain death tests (e.g., EEG).
• Brain death assessment is typically carried out 72 hours after cardiac arrest or cessation of TTM.
• See also “Ethical issues concerning brain death.”

Organ donation ^[4][9]

• Consider organ donation for all patients with ROSC in whom brain death is declared.
• If ROSC does not occur, kidney and liver donation may still be possible, depending on the center.
• See “Organ and tissue donation” for related clinical, systemic, legal, and ethical issues.

• Airway: Secure the airway with early placement of an endotracheal tube.
• Breathing: target SpO₂ 92–98% and PaCO₂ 35–45 mm Hg
  • Start ventilation with 10 breaths/minute.
  • Titrate FiO₂.
  • Initiate waveform capnography.
• Circulation: target systolic blood pressure > 90 mm Hg and mean arterial pressure > 65 mm Hg
  • Administer IV fluids.
  • Consider vasopressors and/or inotropes.
• Obtain 12-lead ECG: to identify any ST-segment elevations requiring urgent PCI
• Admit to ICU: for additional management and urgent interventions
  • Consider targeted temperature management.
  • Identify and treat the underlying cause: See “Hs and Ts”.
  • Identify and treat any complications (e.g., seizures, fever, cardiac arrhythmias).
• Monitor postresuscitation targets: See “Neuroprotective measures.”

Complications of CPR

• Rib fractures
• Hemothorax
• Hemopericardium
• Hemoperitoneum
• Solid organ injuries, e.g., liver
• Skin burns
• Complications of intubation

Complications of cardiac arrest

• Ischemic cardiomyopathy
• Acute kidney injury
• Shock liver
• Multiorgan dysfunction syndrome
• Neurological dysfunction

Anoxic-ischemic encephalopathy ^{[32][33][34][35]}

• Definition: global brain injury caused by complete cessation of blood flow during cardiac arrest
• Epidemiology: most common cause of death in patients surviving cardiac arrest ^[32]
• Pathophysiology: cardiac arrest → cessation of blood flow to the brain → anoxia → irreversible neuronal damage and death
• Clinical features
  • Neurological deficits (determined by the severity of injury and the affected structures)
    • Comatose state
    • Absent or abnormal motor response (e.g., extensor posturing)
    • Absent spontaneous eye movements
    • Absent brainstem reflexes (e.g., pupillary light reflex, oculocephalic reflex)
  • Convulsions (e.g., status epilepticus)
• Diagnostics
  • Clinical features consistent with cardiac arrest
  • It is imperative to exclude other causes of coma (e.g., toxic and metabolic encephalopathies, shock).
  • Laboratory studies (e.g., CBC, serum electrolytes, toxicology screens)
  • Imaging
    • CT brain
      • Usually normal within the first 2 days
      • Findings of anoxic injury: cerebral edema, inversion of gray-white matter density
    • MRI brain: allows for early detection of brain injury
  • EEG
    • Characteristic pattern: slowing of the EEG followed by delta activity and, eventually, EEG flattening
    • Some EEG patterns are markers of a poor prognosis (see below).
• Differential diagnosis: hypoxic-ischemic encephalopathy
• Management
  • Postresuscitation care (see above)
  • Avoid hyperthermia. ^[36][37]
  • Prevention of hyperglycemia
• Complications
  • Brain death
  • Coma
  • Persistent vegetative state
  • Minimally conscious state
  • Seizures
• Prognosis
  • The majority of cases have a poor prognosis, indicators of which include:
    • Increased duration of anoxia
    • Clinical markers
      • Absent brainstem reflexes (e.g., pupillary light reflex, corneal reflex)
      • Persistent dilated pupils
      • Absent or abnormal motor response
      • Myoclonic status epilepticus
    • Other specific markers
      • Laboratory studies: elevated serum level of neuron-specific enolase
      • EEG: nonreactive or presence of burst-suppression pattern (suggestive of myoclonic status epilepticus)

We list the most important complications. The selection is not exhaustive.

Cardiac arrest in pregnancy

• Maternal cardiac arrest is rare.
• The majority of BLS and ACLS algorithms remain the same, including drug and defibrillation dosages.

Modifications to BLS and ACLS ^[11][38]

• Initiate an appropriate emergency response (e.g., maternal code blue).
• Place IV lines above the level of the diaphragm.
• Anticipate a difficult airway.
• Left uterine displacement: Displace the uterus manually to the left to relieve aortocaval compression. ^[11]
  • One-handed manual displacement: Standing on the patient's right, push the uterus up and away.
  • Two-handed manual displacement: Standing on the patient's left, pull the uterus up and towards the rescuer.
• Consider the following causes in addition to the common causes of cardiac arrest (see “Hs and Ts”): ^[11]
  • Amniotic fluid embolism
  • Uterine atony
  • Placenta abruption or placenta previa (see “Antepartum hemorrhage” for details on management)
  • Eclampsia
    • Administer magnesium
    • In patients who were receiving treatment with magnesium prior to cardiac arrest, consider hypermagnesemia as a potential cause (see “Other reversible causes of cardiac arrest” for further management).

Perimortem cesarean delivery (PMCD) ^[38]

• General overview
  • PMCD reduces aortocaval compression and increases the likelihood of ROSC.
  • Early PMCD also maximizes the chance of survival for a viable fetus by reducing anoxia.
• Indications
  • ROSC has not occurred within 4 minutes of cardiac arrest.
  • AND the fetus is viable
  • OR the uterus is thought to be causing aortocaval compression
• Target: PMCD ideally within 5 minutes of cardiac arrest onset
• Technique
  • Preferred: cesarean delivery via vertical incision
  • After cesarean delivery, normal ACLS should continue for the mother.
  • See also “Neonatal resuscitation.”

Cardiac arrest in patients with trauma ^[39]

• Cardiac arrest due to trauma rarely responds to standard ACLS treatment.
• Management is primarily surgical, i.e., emergency chest decompression and/or emergency thoracotomy followed by operative intervention.
• See “Traumatic cardiac arrest” for details.

BLS in infants and children

Technique modifications ^[23]

• Compression rate: 100–120/minute
• Compression-to-breath ratio
  • Single rescuer: 30:2
  • Two rescuers: 15:2
• Postpubertal children/adolescents: Same CPR technique as for adults
• Children ≥ 1 year of age until puberty
  • Chest compressions: Deliver with one hand for smaller children.
  • Compression depth: 5 cm
• Infants < 1 year old ^[40]
  • Compression depth: 4 cm
  • Rescue breaths: Form a seal over both the nose and mouth.
• Defibrillation
  • Children 1–8 years old: If available, use an AED with pediatric attenuation (if no other device is available, use an adult AED).
  • Infants < 1 year old: If available, use a manual defibrillator (if no other device is available, use an adult AED). ^[40]

Greater emphasis is placed on ventilation compared to CPR in adults, as hypoxia is a more common cause of cardiac arrest in infants and children.

Algorithm modifications ^[10][23][41]

For simplification, similar algorithms are recommended for adults and children in North America, despite their physiological differences. ^[42][43]

• Initial steps (identical to BLS algorithm for adults): Assess scene safety and patient responsiveness, and call for help.
• Check for signs of life
  • Pulse present, no breathing
    • Administer rescue breaths: 1 breath every 2–3 seconds (20–30 breaths/minute)
    • If heart rate is ≤ 60 beats/minute: Start CPR.
  • No pulse, gasping, or no breathing: Start CPR.
• Single rescuer sequence
  • Perform 2 minutes of CPR (30:2 with a compression rate of 100–120/minute) before calling for help or retrieving an AED (if it requires leaving the patient's side).
  • If a cell phone is available, make an immediate emergency call and perform CPR with the phone on speaker.
• Two-rescuer sequence
  • Direct the second rescuer to call for help and retrieve a defibrillator.
  • Start CPR at a ratio of 30:2, changing to 15:2 when both rescuers are able to provide CPR.
  • If an advanced airway is in place, consider ventilating at a rate of 20–30/minute. ^[23]
• Rhythm assessment and defibrillation
  • Shockable rhythm: Defibrillate using pediatric AED pads for children 1–8 years old and continue CPR.
  • Nonshockable rhythm: Continue CPR immediately.
• Endpoints: identical to BLS algorithm for adults.

Pediatric modifications to advanced life support ^[23]

Advanced life support for children requires different drug and defibrillator dosages. The same algorithm for ACLS in adults should be followed for pediatric patients.

• Defibrillator dosage: If using a manual defibrillator, the shock dose should be set as follows.
  • First shock: 2 J/kg
  • Second shock: 4 J/kg
  • Subsequent shocks: ≥ 4 J/kg (max. dose 10 J/kg) or until the adult dose is reached
• Resuscitation medications: Drug dosages should be adapted as follows.
  • Epinephrine
    • Concentration: 0.1 mg/mL (1:10,000)
    • Dosage: 0.01 mg/kg (0.1 mL/kg) IV/IO every 3–5 minutes (max. dose 1 mg)
  • Lidocaine 1 mg/kg IV loading dose once^[23]
  • Amiodarone 5 mg/kg IV bolus; may be repeated up to a maximum of 3 doses in shockable rhythms

Use the Broselow tape in pediatric patients to rapidly determine medication dosages, equipment sizing, and defibrillator shock dosages.

Neonatal life support ^[23]

See “The newborn infant" for a more complete neonatal resuscitation algorithm. The most important differences in CPR technique in neonates compared to in infants and children are as follows:

• Compression rate: 100–120/minute
• Compression-to-breath ratio: 3:1 (as hypoxia is the most common cause of arrest in neonates).
• Chest compression technique in neonates
  • Single rescuer: two-finger technique
    • Perform chest compressions using two fingers (the index and middle fingers) on the lower half of the sternum, just below the intermammary line.
    • Allows for faster changes between compressions and delivering breaths if only a single provider is present
  • Two rescuers: two-thumb-encircling hands technique
    • One rescuer performs chest compressions while the other delivers breaths.
    • Encircle the chest with both hands, with the thumbs placed over the lower third of the sternum.
    • Compress the lower sternum with both thumbs.
    • Results in more effective compressions and higher coronary artery perfusion than the two-finger technique

Extracorporeal membrane oxygenation (ECMO)

• Extracorporeal CPR (ECPR) uses ECMO for patients in cardiac arrest to support end-organ perfusion while underlying causes are treated.
• Venoarterial ECMO can be started during resuscitation in specialized centers with skilled and experienced providers.
• ECPR is not currently routinely recommended ^[8][10]

• One-Minute Telegram 65-2022-2/3: Better outcomes with alternative defibrillation strategies
• One-Minute Telegram 57-2022-1/3: Cooling after out-of-hospital cardiac arrest mitigates the association between higher epinephrine doses and poor neurological outcomes
• One-Minute Telegram 37-2021-2/3: Vasopressin plus methylprednisolone for cardiac arrest: Can a cocktail save lives?

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