Cardiac Arrest and Basic Life Support
A heart attack and a cardiac arrest are not the same thing, and knowing the difference tells you what to do next.
It is 6:40 on a Monday morning at a busy motor park in Ibadan. A man in his fifties, waiting for a bus to Lagos, suddenly slumps off the bench. People crowd round. Someone splashes water on his face, someone else shouts for anointing oil, a third person tries to pour Lucozade into his mouth. Four minutes pass. Nobody presses on his chest.
By the end of this course you will know exactly what that man needed in those four minutes, and you will be the person who gives it.
Definition of Cardiac Arrest
Cardiac arrest is the sudden loss of effective heart pumping, so that blood stops reaching the brain and other vital organs. The person collapses, stops responding, and stops breathing normally within seconds. There is no pulse you can rely on.
Most sudden adult arrests are caused by an electrical problem: the heart's rhythm turns into a chaotic quiver called ventricular fibrillation (VF), or a very fast rhythm called pulseless ventricular tachycardia (pVT). The muscle is still twitching, but it is not squeezing blood out.
| Heart attack (myocardial infarction) | Cardiac arrest | |
|---|---|---|
| What has gone wrong | A plumbing problem: a blocked coronary artery starves part of the heart muscle | An electrical (or pump) failure: the heart stops pumping effectively |
| Is the person awake? | Usually yes, often with chest pain, sweating, breathlessness | No, they collapse and are unresponsive |
| Breathing and pulse | Present | Absent, or only gasping |
| What the rescuer does | Call for help, keep them at rest, get them to hospital fast | Start CPR immediately and get a defibrillator |
| Link between them | A heart attack can trigger a cardiac arrest | — |
Time and Survival in Cardiac Arrest
The brain uses a huge share of the body's oxygen and stores almost none. When circulation stops, the person loses consciousness within seconds, and brain cells start to die after a few minutes without oxygenated blood. Every minute that passes without CPR and defibrillation, the chance of survival falls steeply; a figure of roughly 7–10% per minute is often quoted.
Chest compressions do not restart the heart. What they do is squeeze blood from the heart and great vessels to the brain and heart muscle, buying time until a shock from a defibrillator can reset the rhythm. CPR keeps the door open; the shock walks through it.
Definition of Basic Life Support
Basic Life Support (BLS) is the set of first, life-saving actions given to a person in cardiac or respiratory arrest, or with a blocked airway, until advanced help takes over. It covers recognising the emergency, calling for help, high-quality cardiopulmonary resuscitation (CPR), using an automated external defibrillator (AED), relieving choking and placing a breathing casualty in the recovery position.
"Basic" does not mean simple or unimportant. It means it needs no drugs and no advanced equipment, and it is the foundation every advanced intervention stands on. As a nurse, you will be expected to deliver it anywhere: on the ward, in the clinic, at the roadside.
In cardiac arrest, the two things that most improve survival are early, high-quality chest compressions and early defibrillation. Everything else in this course serves those two.
Which guideline does this course follow? Resuscitation science is reviewed internationally and published as guidelines every few years. This course follows the 2025 American Heart Association (AHA) Guidelines for CPR and Emergency Cardiovascular Care, the format most nursing BLS certification uses. Where the European Resuscitation Council (ERC) 2025 guidelines differ in a way you might meet in a textbook, we say so.
Pause & think
A woman at a wedding clutches her chest, says she feels "pressure", and is sweating heavily, but she is talking to you. Is this a cardiac arrest?
Spotted a mistake?