Cardiac arrest and basic advanced life support

• Cardiac arrest is the sudden failure of the heart to pump blood. Recognition means an unresponsive person with abnormal or absent breathing: agonal gasps, slow laboured breaths and panting all count as abnormal breathing. ^[1]
• The single most effective action is to start high-quality chest compressions as soon as possible and to send someone for an automated external defibrillator, because defibrillation within minutes of a shockable rhythm produces the best chance of survival. ^[2]
• Compressions are given 100 to 120 per minute, 5 to 6 cm deep in an adult, with full recoil and as few interruptions as possible; ventilations are added at 30 compressions to 2 breaths, or at 10 per minute once an advanced airway is in place. ^[1]
• The rhythm is then either shockable (ventricular fibrillation or pulseless ventricular tachycardia) or non-shockable (pulseless electrical activity or asystole). Shockable rhythms are defibrillated; non-shockable rhythms receive adrenaline as soon as possible. ^[2]
• While resuscitating, look for and treat reversible causes (the Hs and Ts) in parallel, and after return of spontaneous circulation target oxygenation, blood pressure, temperature control and coronary angiography when indicated. ^[2][3]

By the end of this page you should be able to:

1. Recognise cardiac arrest from unresponsiveness and abnormal breathing and act without waiting for certainty.
2. Perform adult high-quality CPR with the correct rate, depth, recoil, ventilation and interruption limits.
3. Distinguish shockable from non-shockable rhythms and state the definitive treatment of each.
4. Apply the doses and timing of adrenaline and amiodarone, and describe the defibrillation strategy and energy levels.
5. List and explain the reversible causes of cardiac arrest and how to look for them during resuscitation.
6. Outline post-arrest care: targets for oxygen, carbon dioxide, blood pressure and temperature, coronary angiography and neuroprognostication.
7. Run the bradycardia and tachycardia algorithms and state when pacing, cardioversion or drugs are indicated.
8. Describe current ILCOR, AHA and Resuscitation Council (UK) guidance and the ethics of when to withhold or stop resuscitation.

Cardiac arrest is not a single disease. It is the final pathway of many conditions in which the heart stops generating a cardiac output, either because electrical activity becomes chaotic (ventricular fibrillation) or stops (asystole), or because organised electrical activity fails to produce a pulse (pulseless electrical activity). ^[2] The learner should therefore think of resuscitation as two jobs happening at once: restoring circulation and identifying why the heart stopped, because treating the cause is what prevents re-arrest. ^[2]

These guidelines represent current practice. The Resuscitation Council (UK) 2025 guidelines translate the International Liaison Committee on Resuscitation (ILCOR) 2025 Consensus on Science with Treatment Recommendations and the European Resuscitation Council (ERC) 2025 guidelines into UK practice. ^[4] The American Heart Association 2025 Guidelines for Cardiopulmonary Resuscitation and Emergency Cardiovascular Care provide parallel guidance, including the values-based and legal considerations for decisions to withhold, continue or stop resuscitation. ^[5] Both agree on the fundamentals: compressions at 100 to 120 per minute, depth 5 to 6 cm, early defibrillation, adrenaline in non-shockable rhythms, and the search for reversible causes. ^[1][2][6]

Cardiac arrest is recognised clinically rather than by monitors. Suspect it in any unresponsive person. Call for help (999 or its local equivalent) as soon as possible, and assess breathing while the call is answered. ^[1] Slow, laboured breathing, agonal gasping, and even a near-normal or panting pattern early after arrest, especially in an athlete, are all abnormal and mean cardiac arrest until proven otherwise. ^[1] A short seizure-like episode can occur at the onset of arrest and makes diagnosis harder; once the shaking stops, assess breathing. ^[1] If there is any doubt, assume cardiac arrest and start compressions, because the risk from CPR in someone not in arrest is small and the risk of withholding it is death. ^[1]

Ambulance dispatchers have a critical role: they ask standard questions and, once arrest is suspected, give chest-compression-only instructions, moving to 30 to 2 if the caller says they can give breaths. ^[1] In hospital, early warning scores, rapid response teams, and clear escalation policies aim to identify deterioration before arrest, because many arrests have premonitory signs. ^[2]

Every hospital system should aim to recognise arrest, start CPR immediately, defibrillate a shockable rhythm within 3 minutes, give adrenaline rapidly for a non-shockable rhythm, and identify and treat reversible causes. ^[2] A hospital cardiac arrest call number should be standard (for example 2222 in the UK), and resuscitation equipment standardised and immediately available. ^[2]

Resuscitation is the default, but it is not mandatory in every circumstance. Current guidance offers the following positions:

• Attempting CPR would place the rescuer at serious risk of physical harm (for example an unsafe scene or an ongoing threat). ^[5]
• There are objective signs of irreversible death. ^[5]
• A valid advance care plan requests "do not attempt CPR". Written and signed directives are honoured; verbal requests from family are accepted in some systems with medical oversight. ^[5]
• A person with severe comorbidity and no realistic prospect of benefit: some systems describe informed non-dissent, where the clinician informs the family that resuscitation will not be attempted unless they object. ^[5]
• Uncertainty about benefit should be resolved in favour of starting while wishes and better information are established; harm and benefit are difficult to assess under time pressure, and the default remains resuscitation when in doubt. ^[5]

Termination is a team decision made holistically, using patient values, duration of CPR, absence of reversible causes, and absence of response to advanced life support. ^[4] A reasonable practical trigger is persistent asystole from the time of confirmation of arrest despite at least 45 minutes of advanced life support with no reversible cause and no factor arguing against stopping. ^[4] Persistently low end-tidal carbon dioxide is a strong supportive marker but must not be used alone, and cardiac ultrasound, blood gases, and pupil reactivity should not be the sole basis for stopping. ^[4] Termination rules validated for out-of-hospital arrest must not be applied as the sole strategy in hospital, and are not supported for children or newborns. ^[2][4] After stopping, debrief the team immediately. ^[4]

Other ethical points worth knowing: families should be offered the choice to be present during resuscitation; ^[4] organ donation should be considered in every patient who initially achieves return of spontaneous circulation and later dies, or who is declared dead after unsuccessful resuscitation; ^[3][4] and systems should reduce disparities in who receives bystander CPR and defibrillation, since protected characteristics must not influence resuscitation decisions. ^[4][5]

The aim of external compressions is to pump blood from the chest. The heel of one hand is placed on the lower half of the sternum in the centre of the chest; the heel of the other hand goes on top, fingers interlocked so pressure is not applied over the ribs. ^[1] Arms are kept straight and the shoulders placed vertically above the chest. ^[1] If clothing stops you seeing the sternum, displace or remove it. ^[1] The person is best on a firm surface, but do not move them off a bed; compress a little deeper to compensate for a soft mattress. ^[1]

Defibrillator pad placement matters: place one pad to the right of the sternum below the clavicle and the other in the mid-axillary line below the armpit, making sure the lateral (apical) pad sits directly below the armpit rather than too high on the chest. ^[2] For vector change after three failed shocks, move to an antero-posterior position (anterior to the left of the sternum, posterior centred just medial to the left scapula). ^[2] Keep pads at least 8 cm from an implanted pacemaker or defibrillator. ^[2] If the person is prone, use an alternative position such as bi-axillary. ^[2]

A resuscitation attempt needs: personal protective equipment; a firm surface; a defibrillator that can deliver manual shocks or operate as an AED; electrode pads; oxygen and airway equipment (bag-valve-mask with reservoir, oral and nasal airways, supraglottic airway, tracheal tube and waveform capnography); suction; vascular access (intravenous cannulae, intraosseous needles); drugs; and a clock or timer. ^[1][2]

Important distinctions: automated external defibrillators (AEDs) can be used by anyone and should be in unlocked cabinets accessible 24 hours a day, signposted clearly; ^[1] manual defibrillators are used only by rescuers who can recognise an arrest rhythm within 5 seconds and shock with minimal interruption to compressions; ^[2] waveform capnography is essential for confirming tracheal tube placement and for monitoring compression quality. ^[2] Mechanical compression devices are not superior to high-quality manual compressions but may be used when manual compressions are impractical or unsafe, for example during transfer or prolonged resuscitation. ^[6] Intra-arrest ultrasound (point of care ultrasound) may be used by a skilled operator to look for tamponade or tension pneumothorax but must not interrupt compressions. ^[2]

In hospital, resuscitation teams should meet at the start of each shift to introduce members and allocate roles (compressor, airway, team leader, recorder). ^[2] Staff should have standardised equipment and an accredited advanced life support course; the resuscitation call should be answered by a team that can perform manual defibrillation, advanced airway management, intravenous and intraosseous access, and identification of reversible causes. ^[2] Team introductions may sound administrative, but role clarity is what keeps the hands-off time under 5 seconds when the rhythm is re-checked. ^[2]

Best practice also includes debriefing after every arrest, ideally data-driven and performance-focused, using recordings of compression depth, rate, and fraction. ^[2] Rescuers should be told in advance that CPR can cause consciousness without return of spontaneous circulation, which is uncommon but distressing; small doses of sedative or analgesic drugs (such as fentanyl, ketamine, or midazolam) may be given, and neuromuscular blocking drugs should never be used alone in a conscious person. ^[2]

Advance care planning makes a difference before the arrest. Plans such as ReSPECT (Recommended Summary Plan for Emergency Care and Treatment) record patient values, CPR recommendations, and other treatment preferences in a single document that travels across settings, and clinicians are expected to have these conversations early, honestly and repeatedly. ^[4][5] When views genuinely differ, seek a second opinion, an ethics opinion, or legal advice. ^[4]

See the recognition section above. Call first, because the call handler can prompt the assessment of breathing and begin compression instructions. ^[1] If you are alone without a phone, shout for help, quickly assess breathing, and if no one responds, leave briefly to call, then return and start CPR if the person is still unresponsive and not breathing normally. ^[1]

The 2025 standard is precise and should be memorised exactly:

• Rate: 100 to 120 compressions per minute. ^[1]
• Depth: at least 5 cm but not more than 6 cm. ^[1]
• Recoil: allow the chest to recoil completely after each compression; avoid leaning on the chest. ^[1]
• Interruptions: as few as possible, in practice aiming for a chest compression fraction of at least 60 percent and peri-shock pauses under 10 seconds. ^[6]
• Surface: CPR is most effective on a firm surface; do not delay to move someone from a bed. ^[1]
• Position and landmark: lower half of the sternum, hands as described above. ^[1]

Total peri-shock pauses longer than 10 seconds reduce both return of spontaneous circulation and survival to hospital discharge. ^[6] A single shock followed by immediate resumption of compressions is preferred over stacked shocks. ^[2][6]

High-quality CPR should also include checking rhythm and perfusion signs during the brief rhythm check: return of consciousness or purposeful movement, a pulsatile arterial waveform, or a sharp rise in end-tidal carbon dioxide. ^[2] A sharp rise in carbon dioxide alone is suggestive but chest compressions should not stop on that sign alone. ^[2]

Give rescue breaths if trained to do so: 30 compressions to 2 breaths. ^[1] Each breath is delivered over about 1 second, just enough to produce a visible chest rise (roughly 400 to 600 mL); avoid excessive ventilation, which increases intrathoracic pressure and reduces venous return. ^[2][6] If you are not trained to give breaths, perform continuous chest compressions only. ^[1]

Once an advanced airway (supraglottic airway or tracheal tube) is in place, ventilation changes: pause compressions only if ventilation through the device is not adequate, otherwise ventilate at 10 breaths per minute while compressions continue uninterrupted. ^[2][6] Give the highest feasible inspired oxygen concentration during CPR. ^[2] If bag-mask ventilation is used, a two-person technique improves seal and patency. ^[2]

Airway management after ROSC is described in the aftercare section. Aspiration must always be considered: if you cannot inflate the chest after two attempts, think of a foreign body and follow the emergency care algorithm for choking. ^[1]

Defibrillation is the treatment for ventricular fibrillation and pulseless ventricular tachycardia, and the earlier it is delivered the better. Continue CPR while the defibrillator is brought and pads applied, then shock as early as is practical. ^[2] A useful framing is that compressions buy time for the brain and heart while defibrillation fixes the rhythm. ^[2] In a witnessed arrest with a defibrillator immediately available, it is reasonable to shock before starting compressions. ^[6]

Strategy points supported by current guidance:

• Use a single shock, then immediately resume compressions. ^[2][6]
• Manual or automated rhythm analysis should follow the same principle: compressions continue through charging and stop only at the moment of shock. ^[2][6]
• Initial biphasic energy should be at least 150 J (or the manufacturer's recommended setting); 360 J for monophasic waveforms. ^[2][6]
• If the first shock fails, escalate energy for subsequent shocks. ^[2][6]
• Use standard energy in obese patients. ^[2]
• Stacked (three in a row) shocks are reserved for witnessed, monitored arrest with a defibrillator immediately available, for example during cardiac catheterisation; even then they are counted as the first shock for the purposes of giving adrenaline and amiodarone. ^[2]
• For refractory ventricular fibrillation, after ensuring correct pad placement, use a vector change to antero-posterior pads after the third failed shock. ^[2] Double sequential defibrillation is not routinely recommended because the evidence is limited and the technique is cumbersome. ^[2][6]
• Charge the defibrillator in anticipation of the rhythm check where possible, and keep oxygen sources at least 1 metre from the chest; do not defibrillate during manual compressions even with gloves. ^[2]
• If an implanted defibrillator fires during your compressions you may feel a shock; if it fails to terminate the rhythm, deliver external shocks with pads placed more than 8 cm from the device. ^[2]

A crucial practical note: whenever a diagnosis of asystole is made, inspect the electrocardiograph carefully for P waves, because true asystole is more likely to respond to pacing than ventricular standstill with atrial activity. ^[2]

Begin with basic airway techniques and progress stepwise according to the skills available: manoeuvres to open the airway, then bag-mask ventilation (two person if possible), then a supraglottic airway or tracheal tube. ^[2] Each breath takes about 1 second and should make the chest visibly rise. ^[2] Only rescuers who succeed very often with the tracheal tube should place one in a cardiac arrest (above 95 percent within two attempts) and with continuous waveform capnography; the aim is an interruption of less than 5 seconds. ^[2] Once an advanced airway is in place, confirm it with a sustained carbon dioxide trace; without one, assume oesophageal placement. ^[2] Videolaryngoscopy is preferred to direct laryngoscopy when it is available. ^[2]

If a mechanical ventilator is used during compressions, set it to a volume-controlled mode with a tidal volume 6 to 8 mL per kg of ideal body weight, respiratory rate 10 per minute, maximum inspired oxygen, inspiratory time 1 to 2 seconds, PEEP 0 to 5 cm H2O, peak pressure alarm 60 to 70 cm H2O, and the flow trigger off. ^[2] Check that ventilation is effective; if not, return to manual ventilation. ^[2] Should basic and advanced techniques both fail, trained rescuers should attempt a surgical cricothyroidotomy. ^{[2] [6]}

Vascular access first: attempt intravenous access before intraosseous, and if two attempts fail within a reasonable time, switch to intraosseous. ^[2][6]

Adrenaline (epinephrine) is the vasopressor of cardiac arrest: give 1 mg intravenously or intraosseously. ^[2][6]

• For a non-shockable rhythm (asystole or pulseless electrical activity), give adrenaline 1 mg as soon as possible after vascular access. ^[2][6]
• For a shockable rhythm (ventricular fibrillation or pulseless ventricular tachycardia), give adrenaline 1 mg after the third shock according to Resuscitation Council (UK) and ERC 2025 guidance. ^[2] (Some AHA-aligned 2026 guidelines give adrenaline after the second defibrillation attempt instead. ^[6])
• Repeat adrenaline 1 mg every 3 to 5 minutes while resuscitation continues. ^[2][6]
• In a highly monitored arrest with an arterial line in place, consider smaller initial increments (50 to 100 micrograms) before moving to 1 mg doses if there is no response. ^[2]

Amiodarone is the antiarrhythmic: give 300 mg intravenously after a total of three shocks in ventricular fibrillation or pulseless ventricular tachycardia, and a further 150 mg after a total of five shocks. This timing applies whether the shockable rhythms occur in sequence (refractory) or recur intermittently. ^[2][6] When amiodarone is unavailable, or local policy prefers it, lidocaine 100 mg intravenously is the alternative drug, with an additional 50 mg after five shocks. ^[2][6]

Thrombolysis: consider immediate thrombolytic therapy when pulmonary embolism is the suspected or confirmed cause, and in selected patients perform CPR for 60 to 90 minutes after administration. ^[2][6]

Fluids: give fluids only if the arrest is hypovolaemic, using isotonic saline or balanced crystalloids. ^[2][6]

Do not routinely give calcium, sodium bicarbonate or corticosteroids during arrest. ^[2][6]

Monitoring-quality adjuncts: waveform capnography is used to confirm tracheal tube placement, guide compression quality, and note a possible return of spontaneous circulation; a sudden rise in end-tidal carbon dioxide should prompt the team to look at the patient but not to stop compressions without other signs. ^[2] Use physiological targets during physiology-guided CPR: aim for a diastolic blood pressure of at least 30 mmHg with an arterial line and an end-tidal carbon dioxide of at least 3.3 kPa (25 mmHg), and consider starting compressions if systolic pressure falls and remains under 50 mmHg despite treatment. ^[2] A sudden fall in end-tidal carbon dioxide can signal arrest in a monitored patient. ^[2]

Reversible causes (often listed as the 4 or 5 Hs and 4 or 5 Ts) must be considered from the outset and in parallel with standard resuscitation, because correcting the cause shortens the arrest and reduces re-arrest. ^[2][6]

Task-directed detail on selected causes:

• Hypovolaemia: an empty ventricle, as in haemorrhage, severe dehydration, or a ruptured aneurysm. Correct by stopping bleeding, giving fluids, and, if the rate is fast enough, blood products. ^[2][6]
• Hypoxia: a blocked or flooded airway, severe asthma, or pneumonia. Correct by opening the airway, delivering high-flow oxygen, and intubating early if needed. ^[2][6]
• Hydrogen ion (acidosis): severe tissue hypoperfusion or toxin. Current guidance says do not routinely give sodium bicarbonate; correct ventilation, perfusion, and cause instead ^[2][6]
• Hyper- or hypokalaemia: particularly after renal failure, crush injury, succinylcholine, or insulin excess. Treat hyperkalaemia with calcium, insulin and glucose, beta-2 agonists, and bicarbonate as indicated; hypokalaemia with potassium. ^[3]
• Hypothermia: low core temperature. Do not give up: outcomes can be good with prolonged CPR. Rewarm gradually alongside standard CPR and post-arrest care. ^[2]
• Tension pneumothorax: look for distended neck veins (if present), tracheal deviation, absent breath sounds, and hyper-resonance. Relieve with needle decompression followed by a chest drain. ^[2][6]
• Tamponade: in trauma, after cardiac surgery, or with cancer or infection. Beck's triad (hypotension, distended neck veins, muffled heart sounds) may be present. Relieve with pericardiocentesis or thoracotomy. ^[2][6]
• Toxins: poisoning and overdose (opioids, local anaesthetic, organophosphates, beta-blockers, calcium channel blockers). Use specific antidotes (for example naloxone for opioid poisoning, lipid emulsion for local anaesthetic systemic toxicity) alongside high-quality CPR. ^[2][6]
• Thrombosis: coronary (acute coronary syndrome) or pulmonary (massive pulmonary embolism). For massive pulmonary embolism, thrombolysis or percutaneous or surgical embolectomy should be considered even during arrest. ^[2][6]

Point-of-care ultrasound may reveal tamponade or gross right ventricular dilatation suggestive of massive pulmonary embolism, but right ventricular dilatation alone should not be used to diagnose pulmonary embolism. ^[2]

These algorithms apply to an unstable patient immediately before or after cardiac arrest, or a patient who has achieved return of spontaneous circulation.

Bradycardia is defined as a heart rate under 50 beats per minute. ^[6] Not every bradycardia needs treatment; intervene when there are adverse signs: hypotension (systolic below 90 mmHg), syncope, heart failure (pulmonary oedema or raised jugular venous pressure), or myocardial ischaemia or chest pain. ^[2]

• Atropine: give 500 micrograms intravenously, repeating every 3 to 5 minutes to a maximum of 3 mg. ^[2] In another resuscitation council's convention the same drug is given as 0.6 mg repeated to 3 mg. ^[6]
• If atropine fails or is contraindicated: use isoprenaline (starting at 5 micrograms per minute) or an adrenaline infusion of 2 to 10 micrograms per minute. ^[2]
• Transcutaneous (transthoracic) pacing is a temporary measure: it buys time until a transvenous wire can be placed, and it is the only option where one cannot. ^[2]
• Aminophylline 100 to 200 mg by slow intravenous injection is useful for bradycardia after cardiac transplantation or spinal cord injury; atropine should not be given in cardiac transplant recipients because it can worsen atrioventricular block. ^[2]
• Glucagon should be considered if beta-blockers or calcium channel blockers are suspected to be the cause. ^[2]
• Do not give atropine in high-degree atrioventricular block with a wide QRS: it is ineffective and may worsen the block. ^[2] Atropine may also be ineffective in second-degree Mobitz type II or complete heart block. ^[6]
• Whenever a diagnosis of asystole is suspected, look for P waves, as this rhythm (atrial standstill with ventricular asystole) is more likely to respond to pacing. ^[2]
• If atropine fails and no pacer is at hand yet, rhythmic blows with a fist over the heart (fist pacing) can be tried until the equipment arrives. ^[2]

Electrical cardioversion is the treatment for a tachyarrhythmia in an unstable patient (shock, syncope, heart failure, or myocardial ischaemia) immediately after return of spontaneous circulation. ^[2] A conscious patient needs careful anaesthesia or sedation first, and beware haemodynamic deterioration from the sedative. ^[2] Cardioversion shocks must be synchronised with the R wave. ^[2]

Energy levels for the first shock:

• Atrial fibrillation: an initial synchronised shock at maximum output is reasonable. ^[2][6]
• Atrial flutter and paroxysmal supraventricular tachycardia: 70 to 120 J, with stepwise increases after that. ^[2][6]
• Ventricular tachycardia with a pulse: 120 to 150 J for the initial shock, with stepwise increases. ^[2]
• Unstable wide complex tachycardia: 100 J escalating to the maximum permitted by the defibrillator. ^[6]
• Polymorphic ventricular tachycardia and torsades de pointes: do not activate synchronisation (the defibrillator may fail to detect the R wave); give amiodarone with a normal QT interval, magnesium 1 to 2 g over 15 minutes if the QT is prolonged. ^[6]

If cardioversion fails and the patient remains unstable, give procainamide 10 to 15 mg per kg (maximum 1 g) over 20 minutes, or amiodarone 300 mg intravenously over 10 to 20 minutes, then re-attempt cardioversion; the amiodarone load may be followed by an infusion of 900 mg over 24 hours. ^[2] Pharmacological treatment may be considered in stable patients with monomorphic ventricular tachycardia. ^[2]

For atrial fibrillation, consider digoxin or amiodarone for acute rate control in instability with severely reduced left ventricular ejection fraction; for stable patients with an ejection fraction under 40 percent, consider digoxin or a beta-blocker to reach a heart rate under 110 per minute. ^[2]

Supraventricular tachycardia can also be managed medically: vagal manoeuvres first in a stable patient, then adenosine 6 mg rapid intravenous bolus followed by a second dose of 12 mg and then 18 mg if needed; intravenous verapamil 5 to 10 mg or diltiazem 0.25 mg per kg are alternatives with monitoring. ^[6] Beta-blockers and calcium channel blockers should be used cautiously in heart failure with reduced ejection fraction and avoided in pre-excitation. ^[6]

Post-arrest care should be systematic, starting at the bedside immediately after return of spontaneous circulation and continuing in the intensive care unit. ^[2][3]

• ABC approach: insert an advanced airway (tracheal intubation where skills are available) for comatose patients, confirm tube placement with waveform capnography, and provide lung-protective ventilation (6 to 8 mL per kg ideal body weight). ^[3]
• Oxygen: use 100 percent oxygen immediately until oxygen saturation can be measured, then titrate to an arterial oxygen saturation of 94 to 98 percent. Avoid hypoxaemia (partial pressure of oxygen under 8 kPa or 60 mmHg) and hyperoxaemia. ^[3][6]
• Carbon dioxide: target normocapnia (35 to 45 mmHg, 4.7 to 6.0 kPa) and avoid hypocapnia, with arterial blood gas monitoring. ^[3][6]
• Blood pressure: aim for systolic above 100 mmHg or mean arterial pressure above 60 to 65 mmHg; treat with fluids, noradrenaline, or dobutamine as needed, and avoid hypokalaemia and hyperkalaemia. ^[3]
• Diagnosis: prioritise immediate coronary angiography for ST-segment elevation or other high suspicion of coronary occlusion. ^[3][6] If angiography does not show the cause, a head-to-pelvis computed tomography (including CT pulmonary angiography) should be considered. ^[3]
• Temperature control: actively prevent fever, targeting 37.5 degrees C or less in comatose patients for at least 36 to 72 hours. ^[3][6] Do not actively warm a comatose patient who is mildly hypothermic (32 to 36 degrees C) to normothermia. ^[3] Previous practice of routine deep cooling is no longer the standard: current guidelines emphasise fever prevention over routine deep cooling. ^[3][6] Some AHA-aligned protocols still describe a target range of 32 to 37.5 degrees C for at least 36 hours. ^[6] Pre-hospital infusion of large volumes of cold fluid is not recommended. ^[3]
• Seizures: perform EEG from day 1, treat clinical or electrographic seizures with levetiracetam or sodium valproate; do not give prophylactic antiepileptic drugs. ^[3]
• Do not routinely give prophylactic antiarrhythmics, prophylactic antibiotics, steroids, or neuromuscular blocking agents in post-arrest patients, although have a low threshold for antibiotics if pneumonia is suspected. ^[3]
• General care: nurse 30 degrees head-up, short-acting sedation with daily holds, low-rate ("trophic") gastric feeding, stress-ulcer prophylaxis when coagulopathic, and normal glucose management. ^[3]
• Neuroprognostication: in comatose patients, assess after excluding confounders, using clinical examination (pupil and corneal reflexes, myoclonus), EEG, somatosensory evoked potentials, neuron-specific enolase, and brain imaging, with a multimodal strategy at 72 hours or later; no single predictor is 100 percent accurate. ^[3] Decisions about withdrawal of life-sustaining therapy are separate from the prognosis and should consider age, comorbidity, general function, and patient preferences. ^[3]
• Rehabilitation: early mobilisation, ICU diaries, functional assessment before discharge, cardiac rehabilitation as indicated, and follow-up within three months. ^[3]
• Unexplained arrest merits structured investigation (toxicology, genetic testing, device interrogation, repeated ECG and monitoring, cardiac MRI, exercise testing) because of the risk of recurrence. ^[3]

Complications arise from both the arrest and its treatment:

• Rib or sternal fractures, pneumothorax, haemothorax, and rarely liver or splenic injury from compressions. These are common and are not a reason to withhold CPR, because a live person with a fracture is preferable to a dead one. ^[2]
• Hypoxic-ischaemic brain injury, seizures, myoclonus, and persistent coma after resuscitation. ^[3]
• Airway injury, aspiration, and hypotension or cardiogenic shock after return of spontaneous circulation. ^[3]
• CPR-induced consciousness during compressions. ^[2]
• Renal and multi-organ dysfunction from prolonged low flow. ^[3]

Ideally teams discuss and learn from these events in debrief, since even experienced teams have mechanical quality deteriorate over time. ^[2]

• Recognise cardiac arrest as unresponsiveness plus abnormal breathing (including gasping and panting) and act immediately; calling first brings compression instructions. ^[1]
• Compressions at 100 to 120 per minute, 5 to 6 cm deep, full recoil, as few interruptions as possible, and a hands-off time under 5 seconds around shocks. ^[1][2]
• Defibrillate ventricular fibrillation or pulseless ventricular tachycardia as early as possible, single shock, then resume compressions immediately. ^[2][6]
• Adrenaline 1 mg is given as soon as possible in non-shockable rhythms and after the third shock in shockable rhythms, repeated every 3 to 5 minutes. ^[2][6]
• Amiodarone 300 mg after three shocks and 150 mg after five; lidocaine is an alternative. ^[2][6]
• Ventilation is 30 to 2 without an advanced airway and 10 per minute with one, each breath over 1 second to visible chest rise. ^[1][2][6]
• Treat reversible causes (the Hs and Ts) in parallel, not after the fact. ^[2][6]
• Post-arrest care: oxygen 94 to 98 percent, normocapnia, mean arterial pressure above 60 to 65 mmHg, prevent fever at 37.5 degrees C or less, coronary angiography for ST elevation or strong suspicion, and multimodal neuroprognostication at 72 hours or later. ^[3][6]
• Bradycardia with adverse signs: atropine 500 micrograms repeated to 3 mg, then isoprenaline or adrenaline, then pacing; transcutaneous pacing if no transvenous option. ^[2] Do not give atropine in high-degree wide-complex block. ^[2]
• Tachyarrhythmia with adverse signs: synchronised cardioversion (R-wave triggered); energy 120 to 150 J for ventricular tachycardia with a pulse, 70 to 120 J for flutter/supraventricular tachycardia, maximum output for atrial fibrillation. ^[2]
• Stopping resuscitation is a team decision; consider after 45 minutes of advanced life support with persistent asystole and no reversible cause. ^[4]
• Current guidelines emphasise fever prevention rather than routine deep cooling in comatose post-arrest patients. ^[3][6]

Plain text only (no links): shock; severe haemorrhage and blood products; sepsis; anaphylaxis; airway assessment and management; stroke; acute coronary syndromes; pulmonary embolism; eclampsia and pregnancy emergencies; therapeutic hypothermia and fever control; organ donation; communication of poor news; resuscitation ethics.