Treatment algorithm

Please note that formulations/routes and doses may differ between drug names and brands, drug formularies, or locations. Treatment recommendations are specific to patient groups: see disclaimer

INITIAL

unwitnessed cardiac arrest

1st line – CPR

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INITIAL
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unwitnessed cardiac arrest
1st line – 

CPR

Circulation of the blood by means of CPR is a demonstrated therapy in patients with sudden cardiac arrest and is thought to work by raising intrathoracic pressure, as well as providing direct cardiac compression.[108]

Each cycle: 30 compressions (at a rate of 100-120 compressions/minute) and 2 breaths for a total of 5 cycles (2 minutes).[1] The compression depth should be at least 5 cm. Full chest wall recoil should be allowed between chest compressions. Interruptions in compressions should be minimised.[1][51]

American Heart Association guidelines specify that compressions should be performed as the first priority.[1] Untrained lay-rescuers should perform compression-only CPR.[1] If a rescuer is trained in using compressions and ventilation, it is reasonable to do rescue breaths in addition to chest compressions.[1][51]

The patient should be transferred to an emergency care setting as soon as possible.

ACUTE

shockable rhythms (pulseless ventricular tachycardia or ventricular fibrillation)

1st line – CPR and defibrillation

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ACUTE
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shockable rhythms (pulseless ventricular tachycardia or ventricular fibrillation)
1st line – 

CPR and defibrillation

Circulation of the blood by means of CPR is a demonstrated therapy in patients with sudden cardiac arrest and is thought to work by raising intrathoracic pressure, as well as providing direct cardiac compression.[108]

Each cycle: 30 compressions (at a rate of 100-120 compressions/minute) and 2 breaths for a total of 5 cycles (2 minutes).[1] The compression depth should be at least 5 cm. Full chest wall recoil should be allowed between chest compressions. Interruptions in compressions should be minimised.[1]

Compressions should be performed as the first priority.[1] Untrained lay-rescuers should perform compression-only CPR.[1] If a rescuer is trained in using compressions and ventilation, it is reasonable to do rescue breaths in addition to chest compressions.[1][51]

Defibrillation in the setting of pulseless ventricular tachycardia or ventricular fibrillation can restore normal sinus rhythm and should be initiated promptly, as its success diminishes over time.[109]

For a witnessed arrest, electrical defibrillation should be attempted as soon as possible, not necessarily after 5 cycles (2 minutes) of CPR.[1]

For unwitnessed out-of-hospital cardiac arrest (OHCA), 5 cycles (2 minutes) of CPR before defibrillation yields more favourable outcomes.[110]

CPR should be re-started immediately after defibrillation rather than doing an immediate post-shock rhythm check.[1]

Guideline recommendations are 120-200 J for biphasic defibrillators and 360 J for monophasic defibrillators.[1]

The International Liaison Committee on Resuscitation suggest that use of a double sequential defibrillation strategy or vector change defibrillation strategy may be considered for adults who remain in pulseless VT/VF after 3 or more consecutive shocks (this is a weak recommendation, based on very low certainty evidence).[87]​ If a double sequential defibrillation strategy is used, it is good practice for one single operator to activate the defibrillators in sequence.[87]​​

Plus – adrenaline (epinephrine)

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ACUTE
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shockable rhythms (pulseless ventricular tachycardia or ventricular fibrillation)
Plus – 

adrenaline (epinephrine)

Treatment recommended for ALL patients in selected patient group

Given as soon as possible and every 3-5 minutes thereafter.[1][54]​​

Adrenaline is a potent agonist of alpha- and beta-adrenergic receptors.

The use of adrenaline during cardiac arrest has been shown to increase the rate of achieving return of spontaneous circulation and to increase short-term survival.[70][71][72][73] However, adrenaline use during cardiac arrest has not been shown to lead to significantly improved neurological outcomes, and may lead to higher rates of severe neurological impairment among survivors.[70][71][72][73]

Despite controversial data on its benefit in resuscitation, adrenaline has been used extensively in treating patients with sudden cardiac arrest and occupies a prominent role in the algorithms of advanced cardiac life support.[1][70]

Endotracheal drug administration may be considered when other drug routes are unavailable; however, this leads to unpredictable drug concentrations and is not recommended in the UK.[1]

Primary options

adrenaline (epinephrine): 1 mg intravenously/intraosseously every 3-5 minutes; consult specialist for guidance on endotracheal dose

Consider – anti-arrhythmic

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ACUTE
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shockable rhythms (pulseless ventricular tachycardia or ventricular fibrillation)
Consider – 

anti-arrhythmic

Additional treatment recommended for SOME patients in selected patient group

Amiodarone or lidocaine can be considered for pulseless ventricular tachycardia (VT)/ventricular fibrillation (VF) that is unresponsive to defibrillation.[1][54]​ There is evidence that both amiodarone and lidocaine independently increase the rate of return of spontaneous circulation in the setting of pulseless VT/VF refractory to defibrillation, but ultimately lead to no significant difference in the rate of survival to hospital discharge.[111]

Amiodarone is predominantly a class III anti-arrhythmic agent that also has alpha- and beta-adrenergic blocking properties.

Use of lidocaine in VT/VF is predominantly based on studies showing its efficacy in suppressing ventricular arrhythmias following acute myocardial infarction.

Primary options

amiodarone: 300 mg intravenously/intraosseously as a single dose initially, followed by 150 mg as a single dose if required

OR

lidocaine: 1 to 1.5 mg/kg intravenously/intraosseously as a single dose initially, followed by 0.5 to 0.75 mg/kg every 5-10 minutes, maximum 3 mg/kg total dose

Consider – magnesium

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ACUTE
|
shockable rhythms (pulseless ventricular tachycardia or ventricular fibrillation)
Consider – 

magnesium

Additional treatment recommended for SOME patients in selected patient group

In patients with sudden cardiac arrest due to torsades de pointes, giving magnesium may restore a perfusing cardiac rhythm.[88]

Primary options

magnesium sulfate: 2 g intravenously as a single dose over 5-10 minutes

non-shockable rhythms (pulseless electrical activity or asystole)

1st line – CPR and adrenaline (epinephrine)

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ACUTE
|
non-shockable rhythms (pulseless electrical activity or asystole)
1st line – 

CPR and adrenaline (epinephrine)

Circulation of the blood by means of CPR is a demonstrated therapy in patients with sudden cardiac arrest and is thought to work by raising intrathoracic pressure, as well as providing direct cardiac compression.[108]

Each cycle: 30 compressions (at a rate of 100 compressions/minute) and 2 breaths for a total of 5 cycles (2 minutes).[1]

Compressions should be performed as the first priority.[1] Untrained lay-rescuers should perform compression-only CPR.[1] If a rescuer is trained in using compressions and ventilation, it is reasonable to do rescue breaths in addition to chest compressions.[1][51]

Adrenaline is a potent agonist of alpha- and beta-adrenergic receptors. The use of adrenaline during cardiac arrest has been shown to increase the rate of achieving return of spontaneous circulation and to increase short-term survival.[70][71][72][73] However, adrenaline use during cardiac arrest has not been shown to lead to significantly improved neurological outcomes, and may lead to higher rates of severe neurological impairment among survivors.[70][71][72][73]

Despite controversial data on its benefit in resuscitation, adrenaline has been used extensively in treating patients with sudden cardiac arrest and occupies a prominent role in the algorithms of advanced cardiac life support.[1][54]​​[70]

Endotracheal drug administration may be considered when other drug routes are unavailable; however, this leads to unpredictable drug concentrations and is not recommended in the UK.[1]

Primary options

adrenaline (epinephrine): 1 mg intravenously/intraosseously every 3-5 minutes; consult specialist for guidance on endotracheal dose

ONGOING

return of spontaneous circulation

1st line – post-resuscitation care

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ONGOING
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return of spontaneous circulation
1st line – 

post-resuscitation care

Should be instigated immediately and involves continued monitoring, organ support, correction of electrolyte imbalances and acidosis, safe transfer to a critical care environment, and identification and correction of risk factors and underlying causes.

A 12-lead ECG is recommended immediately after return of spontaneous circulation to determine whether signs of ST-elevation myocardial infarction (STEMI) are present.[1] In patients with STEMI, emergency coronary angiography, with or without percutaneous coronary intervention, should be performed.[54]​ Emergency coronary angiography is also reasonable for select patients with suspected acute coronary syndrome without ST elevation, including those with haemodynamic/electrical instability or signs of ongoing ischaemia.[54]​ It is not recommended over delayed angiography in patients with ROSC in the absence of ST elevation, shock, electrical instability, signs of significant myocardial damage, or ongoing ischaemia.[54]

Anoxic brain injury is a frequent complication of sudden cardiac arrest. One systematic review of the literature demonstrates that targeted temperature management (TTM) protocols improve survival and neurological outcome following resuscitation from sudden cardiac arrest, with guidelines continuing to support their use.[1][91]​​​​ The American Heart Association (AHA) recommends that all patients unable to follow commands (i.e., are comatose) receive treatment that includes temperature control, regardless of their arrest location or presenting rhythm.[54]​ There is a range of target temperature, with more recent evidence suggesting that maintaining normothermia (i.e., avoidance of fever) may be equivalent to targeting hypothermia. One large randomised controlled trial (TTM2) which studied patients with coma after OHCA found no difference in 6 month survival or neurological outcome in patients treated with hypothermia (target temperature of 33°C [91.4°F]) compared with normothermia (target temperature ≤37.5°C [≤99.5°F]).[92] An earlier trial (TTM) found that a targeted temperature of 33°C (91.4°F) conferred no benefit compared with 36°C (96.8°F).[93]

For comatose adult patients with return of spontaneous circulation (ROSC), AHA guidelines recommend targeting a temperature between 32°C and 37.5°C (89.6°F and 99.5°F) for at least 24 hours, and avoiding fever after the initial temperature control phase.[54][94]​ The 2024 International Liaison Committee on Resuscitation guidelines recommend actively preventing fever by targeting a temperature of ≤37.5°C (≤99.5°F) for 36-72 hours, commenting that the benefits of targeting hypothermia between 32°C and 34°C (89.6°F and 93.2°F) in selected sub-populations of patients remains uncertain.[51] European guidelines recommend targeting a temperature between 32°C and 36°C (89.6°F and 96.8°F).​[95]

TTM has 3 phases: induction, maintenance, and rewarming. Induction and/or maintenance can be achieved by: simple ice packs with or without wet towels, cooling blankets or pads, water- or air-circulating blankets, water-circulating gel-coated pads, transnasal evaporative cooling, intravascular heat exchanger, extracorporeal circulation.[95]

Routine pre-hospital cooling of patients after return of spontaneous circulation with rapid infusion of cold intravenous fluids is not recommended.[1][51][95]

Rewarming should be achieved slowly (0.25°C to 0.50°C [0.45°F to 0.90°F] of rewarming per hour) to avoid rebound hyperthermia, which is associated with worse neurological outcomes.[95]

There is evidence that patients who receive post-resuscitation care at specialised centres have higher rates of neurologically intact survival, suggesting that post-resuscitative treatment should ideally be performed in this setting.[96][97] Cardiac arrest centres have been shown to display higher coherence with guidelines compared with non-cardiac arrest centres.[98]

In-patient neurological rehabilitation may be helpful for survivors who have suffered hypoxic-ischaemic brain injury, although specific guidelines and evidence are lacking in this patient population.[95] Many patients will also be eligible for cardiac rehabilitation programmes, which have been shown to reduce cardiovascular mortality and hospital admissions, and improve quality of life. They are mostly generic programmes, in which patients with different cardiac diseases (e.g., post acute coronary syndrome, heart failure, or post cardiac surgery), can participate. They involve exercise training, risk factor management, lifestyle advice, education, and psychological support.[95]

Long-term management focuses primarily on prevention of recurrence. Patients should abstain from toxic substances. Use of implantable cardioverter-defibrillators (ICDs) has shown a significant reduction in mortality compared with anti-arrhythmic drug therapy in the secondary prevention of sudden cardiac arrest.[7][99]

no return of spontaneous circulation

1st line – continue or consider termination of resuscitation

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ONGOING
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no return of spontaneous circulation
1st line – 

continue or consider termination of resuscitation

The decision to terminate resuscitation is an ethically challenging issue when treating patients for whom spontaneous circulation does not return in a timely fashion. There is no single factor that can determine when to terminate resuscitative efforts; rather it should be a decision of clinical judgement and respect for human dignity. In prehospital settings where Basic Life Support (BLS) Emergency Medical Services (EMS) are providing care, and Advanced Life Support (ALS) providers are not available or will be significantly delayed, resuscitation may be terminated based on a validated rule if all of the following criteria are met: EMS did not witness the arrest; the patient had no ROSC before transport; and no shock was administered before transport.[1][100][101]

In the prehospital setting where ALS EMS are providing care, resuscitation may be terminated based on a validated rule if all of the following criteria are met: arrest was not witnessed; no bystander CPR was provided; the patient had no ROSC before transport; and no shock was administered before transport.[1]

Resuscitative measures should be terminated if there is documentation that the patient has a valid 'do not resuscitate' order. Termination of resuscitative measures may also be considered on the basis of the following parameters: delayed initiation of CPR in unwitnessed cardiac arrest, unsuccessful resuscitation after 20 minutes of advanced cardiac life support guideline-directed therapy, or conditions that compromise the safety of the emergency care providers.

After sudden OHCA with unsuccessful resuscitation, organ donation may be considered, but is commonly overlooked. Data from a single-centre study in the UK suggest that only 39% of patients who did not recover after OHCA were referred for organ donation. Of those who were referred, consent was obtained in only 68%, and 25% actually went on to donate an average of 1.9 organs per patient.[106] The American Heart Association recommends that organ donation is considered in all resuscitated patients who meet the neurological criteria for death or before planned withdrawal of life-sustaining therapies.[54]

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Please note that formulations/routes and doses may differ between drug names and brands, drug formularies, or locations. Treatment recommendations are specific to patient groups. See disclaimer

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