Resuscitation

EMTs own CPR

Cardiac arrest has attracted more advanced medications and technology than almost any other emergency, yet research shows that only two interventions reliably alter its outcome: quality chest compressions and early defibrillation. Both sit squarely within the EMT's scope of practice, and that is why cardiac arrest is the emergency the EMT owns.

The systems that do best treat resuscitation as a discipline. High-performance CPR means systems planning, regimented training with feedback, incident command, and a laser focus on compressions and defibrillation. Systems that practice it can push survival from witnessed arrest above 50%, against a national average under 15%.

The chain of survival (6 links)

The chain of survival describes, in order, the six links a cardiac arrest patient must pass through, each of which depends on the one before it. The 2025 AHA guidelines went back to a single chain covering every cardiac arrest — adult or pediatric, in hospital or out of it — where there had previously been separate chains for each. The six links are:

1. Recognition and emergency activation. Somebody identifies the arrest and calls for help.
2. High-quality CPR.
3. Defibrillation.
4. Advanced resuscitation. Medications, advanced airways, and where available extracorporeal CPR.
5. Post–cardiac arrest care.
6. Recovery and survivorship. Rehabilitation, follow-up, and psychological support, which continue for months to years.

The second and third links, high-quality CPR and defibrillation, are the two interventions that research shows reliably change outcomes, and they belong to the EMT.

Two details of the 2025 revision are worth knowing. The symbol for the CPR link now shows compressions and breaths rather than compressions alone, because ventilation matters in pediatric arrest and in the substantial minority of adult arrests caused by drowning or opioid poisoning. And the single chain covers adult and pediatric arrest only — a newborn at delivery follows a separate Newborn Chain of Care.

Mechanical failure vs. electrical dysfunction

An arrest has one of two underlying causes. In mechanical failure, the heart stops pumping effectively because of a structural problem: loss of normal myocardial structure, as after a myocardial infarction (MI) or with chronic hypertension; loss of valve function; or direct trauma, including pericardial tamponade. Mechanical failure can occur even while the heart's electrical function is normal. When the monitor shows an organized rhythm but the patient has no pulse, the condition is called pulseless electrical activity (PEA).

Electrical dysfunction is the more common cause. When the supply of oxygen to the heart is interrupted, the sodium-potassium pump on which its electrical activity depends is disrupted. If that disruption is complete, the result is asystole. If it is partial or chaotic, the result is a dysrhythmia such as ventricular tachycardia (V-tach) or ventricular fibrillation (V-fib), and these can often be corrected rapidly by defibrillation.

Sudden vs. asphyxial cardiac arrest

Cardiac arrest can also be classified by how it begins. Sudden cardiac arrest is the abrupt collapse caused by a dysrhythmia, and asphyxial cardiac arrest is the end point of systemic hypoxia from a respiratory problem or from shock. The distinction matters because it changes what the patient needs most. The table below sets out the differences.

Table 21.1Sudden vs. asphyxial cardiac arrest

Pediatric cardiac arrest follows the opposite pattern from the adult one. It is overwhelmingly asphyxial; only about 20% of pediatric arrests result from a sudden dysrhythmia.

Agonal respirations

Agonal respirations occur when the heart stops suddenly while residual oxygen remains in the blood. The medulla continues to send occasional impulses, and the result is intermittent gasping. These gasps actually help circulation slightly, and can be thought of as the body's attempt to resuscitate itself, but they cannot sustain themselves and they cannot sustain the patient.

Because they indicate that residual oxygen is still present, agonal respirations are a good prognostic sign. They must not confuse you, however. Gasping is not breathing. If there is no pulse, or you are uncertain whether there is one, start compressions regardless.

Recognizing cardiac arrest

Recognizing an arrest sounds simple, but the stress of the moment triggers your own fight-or-flight response, and tunnel vision is a real hazard. Three features, assessed rapidly, confirm cardiac arrest: the patient is unresponsive; the patient is apneic, remembering that agonal breathing must not be mistaken for real breathing; and the patient has no pulse, checked at the carotid artery for no more than 10 seconds. Once arrest is confirmed, the primary assessment stops and compressions begin immediately.

In pediatric patients, check the brachial or femoral pulse instead of the carotid. The threshold for compressions also differs. An infant or child with a heart rate below 60 bpm and signs of poor perfusion, despite adequate oxygenation and ventilation, is treated as nonperfusing, and compressions begin.

Coordinated resuscitation team

A resuscitation runs best when the first three providers on scene already know their jobs. This arrangement, sometimes called the "triangle of life," assigns predetermined roles: one provider performs compressions, one operates the AED, and one takes the head to manage the airway and ventilations. Additional providers who arrive later rotate in to relieve a fatiguing compressor or to carry out ALS interventions.

Step 1 — identify arrest & begin

The first step is to identify the arrest and begin compressions where the patient is found. Moving the patient before starting delays compressions, and it is a common and avoidable error. Once compressions have started, they must continue without pause for as much of the resuscitation as possible. The proportion of the resuscitation during which compressions are actually being delivered is the compression fraction, and the goal is to keep it high. Because the quality of compressions falls as the compressor tires, switch compressors at least every 2 minutes.

High-quality compressions are defined by five numbers, and they are the most examinable figures in the whole chapter:

Table 21.2Step 1 — identify arrest & begin

The infant row changed in 2025. The two-finger technique was eliminated: it did not reliably reach a third of the chest's depth. Two techniques replace it — two thumbs encircling the chest, and the heel of one hand — and when a rescuer's hands cannot physically reach around the infant's chest, the heel of one hand is the one to use.

Full recoil is the fifth, and it is the one most often lost. Let the chest come all the way back up between compressions and keep your weight off it at the top: the heart refills during the recoil, so leaning on the chest quietly reduces the blood flow from every compression that follows. Depth has an upper limit for the same reason it has a lower one — deeper than about 2.4 inches in an adult causes injury without improving flow.

Once an advanced airway is in place the ratio stops applying: compressions run continuously at 100–120 while ventilations are given about once every 6 seconds, roughly 10 per minute, in an adult (every 2–3 seconds, 20–30 per minute, in an infant or child).

Step 2 — integrate the AED

The second step is to integrate the AED. There is no benefit to delaying its application, but the order in which CPR and the AED come depends on the patient, as the table below shows.

Table 21.3Step 2 — integrate the AED

The old shorthand — “adults AED first, children CPR first” — gets this wrong. The two-minutes-of-CPR rule is about a lone rescuer having to leave an unwitnessed pediatric arrest to go and find an AED. A crew does not face that choice: one provider compresses while the other fetches and attaches the AED, at any age.

Turn the AED on first, so that it can guide you. The pads go on bare skin: remove clothing, jewelry and medication patches, shave excess hair, and offset the pads around a visible pacemaker. Do not interrupt compressions to place the pads. The analysis phase usually requires about 15 to 20 seconds during which no one touches the patient. Clear the patient before delivering a shock, and resume compressions immediately afterward without waiting for the device to prompt you. The AED reanalyzes the rhythm every 2 minutes.

Step 3 — continue the resuscitation

The third step is to continue the resuscitation through repeated cycles of compressions, analysis and shocks. In a pediatric patient, deploy the AED regardless of age; roughly 20% of pediatric arrests involve a shockable rhythm. For a child under 8 years of age, use pediatric pads if they are available, typically in an anterior-posterior placement. If no pediatric pads are available, use the adult AED anyway. It is better to over-defibrillate than not to defibrillate at all.

Return of spontaneous circulation (ROSC) often does not occur until the second, third or fourth shock, so stay ready for a rhythm change on any given analysis. Family presence during the resuscitation is a genuinely complicated question. The potential benefit, closure for the family, must be weighed against the risk that they interfere. Offer the option, and be ready to relocate the family if it becomes necessary.

Step 4 — transitioning after ROSC

The fourth step is the transition to postarrest care once ROSC occurs. There is no single reliable sign of it. A palpable pulse is the definition, but pulse checks are notoriously unreliable in this setting; spontaneous breathing, movement or a return of consciousness all suggest it, and where waveform capnography is in use a sudden sustained rise in end-tidal CO2 is the earliest and most objective clue. If you are in doubt, err on the side of continuing the resuscitation.

Once ROSC is confirmed, care shifts to the postarrest priorities: rapid transport, airway management that avoids hyperventilation, and oxygen titrated to a saturation of 92–98%. The target is a window, not a floor. Both ends of it matter: hypoxia after an arrest worsens the brain injury that has already happened, and so does hyperoxia, which is why the instruction is no longer to push the saturation as high as it will go. A 12-lead ECG belongs in the postarrest sequence too, if your service carries one and you are permitted to acquire it.

The resuscitated patient is at high risk of re-arrest. Recheck the pulse roughly every 30 seconds in a patient who has ROSC but remains unconscious. If the pulse is lost again, stop the vehicle if you are en route, resume CPR, analyze the rhythm, shock if indicated, and continue according to local protocol.

Terminating resuscitation & death notification

Once begun, CPR and defibrillation continue until one of four things happens:

• Spontaneous circulation returns.
• Care is transferred to a provider with a higher level of training.
• You are too exhausted to continue.
• A physician or other authority issues an order to cease resuscitation.

When resuscitation fails, the EMT is often the one who tells the family. Be straightforward and direct: "I'm very sorry, but your father has died." Allow the family privacy, be patient, and be genuine. Do not claim to know how they feel.

Hypothermia, submersion & moving ambulances

Several situations change the standard approach. In hypothermic cardiac arrest, defibrillate as you would for any other patient and follow the standard BLS algorithm while rewarming. The older teaching — one shock, then nothing further until the core reached 86°F (30°C) — has been dropped; withholding shocks by temperature is no longer advised. Handle the patient gently, get wet clothing off, prevent further heat loss, and transport to a facility that can rewarm actively. The window of survivability is longer in the cold patient, which is what “not dead until warm and dead” means, so do not terminate resuscitation in the field for a hypothermic patient.

Most arrests from submersion, or drowning, are asphyxial, so be aggressive with airway management and rescue breathing. Never defibrillate a soaking-wet patient. Dry the chest, or move the patient out of the wet environment, first.

Resuscitation in a moving ambulance is generally avoided. Motion reduces the quality of compressions, and some AEDs cannot analyze a rhythm while the vehicle is moving. If arrest occurs during transport, stop the vehicle to perform CPR and use the AED.

Implants & prior surgeries

Patients with implanted cardiac devices or a history of cardiac surgery are resuscitated in the same way as anyone else, with a few adjustments. The table below sets out the considerations for each.

Table 21.4Implants & prior surgeries

Sudden unexpected infant death syndrome (SUIDS)

Sudden unexpected infant death (SUID) is the death of an infant under 1 year of age with no immediately obvious cause. It is an umbrella term covering three things: SIDS, accidental suffocation or strangulation in bed, and deaths that remain undetermined after investigation. So accidental suffocation is part of the SUID category, not something ruled out of it.

SIDS is the narrower term, and it is a diagnosis of exclusion: it is what a death is called after a full investigation, autopsy and scene review have failed to find a cause — including failing to find suffocation. None of that can be determined in the field, which is why what you are looking at on scene is a SUID until somebody else decides otherwise.

The EMT's role is to resuscitate unless rigor mortis or dependent lividity is present. As the saying goes, it is better to resuscitate when it isn't necessary than to fail to resuscitate when it is.

Support for the family is critical. Remind the parents that SUIDS happens to well-cared-for babies, and never speak to them in a suspicious tone.