Basic life support training is vital for public safety professionals, first responders, and healthcare providers in a medical emergency. This is especially important when a sudden cardiac arrest occurs.
In this situation, prompt emergency response can save a patient’s life, including CPR, rescue breathing, and even defibrillation with an automated external defibrillator (AED-use).
Let’s look at the principles of Basic Life Support and go over the BLS skills required to care for a patient.
We’ll also discuss how to stabilise the patient until first responders arrive!
Last reviewed: September 2026 — checked against Resuscitation Council UK Guidelines 2025.
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What Is Basic Life Support (BLS)?
Basic Life Support (BLS) is a type of medical care typically administered by doctors and nurses in the hospital and by emergency medical services (EMS) or qualified bystanders out of hospital.
Basic Life Support is characterised by its quick emergency cardiovascular care, rescue breathing, chest compressions, and even early defibrillation to restore normal breathing in adults and children (with the head tilt-chin lift maneuver).
It primarily cares for cardiac arrest victims, an obstructed airway, or abnormal breathing. This lifesaving system requires knowledge of Cardiopulmonary resuscitation (CPR), AEDs, and clearing airway obstructions.
Anyone can do this first aid procedure with the proper BLS skills and BLS certification. When done correctly, CPR can jumpstart a heart and bring people back to life!
A first aid practitioner is taught how to check for a response, call 999 and then assess breathing before they learn anything else in a first aid certification course. Under Resuscitation Council UK Guidelines 2025 the 999 call is made for any unresponsive person, before you assess their breathing, and lay rescuers do not check for a pulse at all.
They are taught how to perform high-quality chest compressions and conduct a full BLS survey (from airway assessment to recovery position) until an ambulance arrives.
What Is the Basic Life Support (BLS) Algorithm?
The BLS Algorithm is a list of steps to take when responding to a situation that may require basic life support (BLS).
It allows first aid practitioners to assess their ability to help in a crisis.
This is because a situation that requires basic life support (BLS) skills often involve multiple casualties. It is impossible to conduct first aid if you are also in danger of getting injured.
A person who is not breathing normally needs CPR straight away, so basic life support also covers opening and clearing the airway before and during resuscitation.
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What Is the Importance of DR ABC?
This acronym is a reminder of steps to take when conducting first aid relating to basic life support (BLS).
Before you spring into action as a first-aid practitioner, let’s take a look at what to consider.
Danger
It is vital to assess the danger of the situation before activating your first aid status (if you are not an emergency responder). Before inserting yourself into the scene, you must ensure that the external situation has stabilised.
Response
Once you activate yourself, it is important to determine your patient’s condition. This entails forcefully tapping them on the shoulders while asking them if they’re alright.
If they are unconscious or unresponsive, it is time to proceed with the BLS survey.
Shout / Send for Help
If the casualty is unresponsive, shout for help and, if you know you are out of your depth, send someone to call 999 for an ambulance and ask for an AED. An NHS ambulance can get to the scene in a matter of minutes.
Your role will be to start CPR straight away if the person is not breathing normally, to increase the chances of survival.
Airway
You would need to check your patient for signs of cervical spine injury and debris if an incident caused their cardiac arrest. Patients will not be receptive to rescue breathing if their airway is blocked.
As a lay rescuer you do not need to feel for a pulse at the carotid artery. Checking for one wastes time and is unreliable – unresponsive and not breathing normally is enough to act on.
Breathing
The number 1 sign to begin CPR is an unresponsive person who is not breathing normally. Occasional gasps, or slow, noisy or laboured breathing, are not normal breathing – treat them as a cardiac arrest.
Once your subject stops breathing, showing no signs of chest rise, you will need to check their patent airway.
Airway blockages (in the throat, mouth, and nose) greatly decrease the chances of survival because they lead to abnormal breathing or even a lack of breath.
Circulation
In the UK primary survey, do not waste time checking for a pulse. If the person is unresponsive and not breathing normally, assume a cardiac arrest: call 999 (or ask a bystander to), start CPR immediately and send for an AED. You must move quickly if your subject has stopped breathing even after clearing their mouth and airway.
You will need to conduct high-quality chest compressions in the centre of the chest, over the lower half of the sternum. Compress at a rate of 100-120 per minute, to a depth of at least 5 cm but not more than 6 cm, allowing full chest recoil between compressions.
Give 30 chest compressions followed by 2 rescue breaths, and keep repeating this 30:2 cycle. Apply an AED as soon as one is available and follow its spoken instructions, continuing CPR until the person shows signs of life or professional help takes over.
What Are the 7 Components of the Basic Life Support (BLS) Algorithm?
Here are the major components of the BLS algorithm. This formula allows first aid practitioners and medical personnel to save a patient’s life.
1. Prompt Recognition of Cardiac Arrest
Knowing the signs of a cardiac arrest will allow those around the patient to react quickly. The symptoms will be a sudden collapse, no response when you shout at and gently shake them, and no normal breathing.
If the patient got into an accident that led to their condition, responders would also need to check for obstructions of the mouth and airway.
2. Call for Urgent Medical Emergency Assistance
Under Resuscitation Council UK Guidelines 2025 you call 999 for any unresponsive person, before you assess their breathing. Rescuers no longer have to confirm that the breathing is abnormal before phoning. Ask a bystander to make the call and to fetch the nearest AED; if you are alone, put your phone on speaker so both hands stay free.
Even a doctor or nurse would call for an ambulance if they responded to a cardiac arrest patient while out in public. This is because they lack the tools to ensure lifesaving care like an AED.
Medical emergencies also tend to draw in a crowd of spectators. You will thus need a certain amount of crowd control as well.
3. Open the Airway and Check Breathing
With the 999 call already under way, tilt the head back, lift the chin and spend no more than 10 seconds checking for normal breathing – look for chest movement, listen for breath sounds and feel for breath on your cheek.
Do not check for a pulse. Lay rescuers are no longer taught to, because it wastes time and is unreliable. If the person is unresponsive and not breathing normally, treat it as a cardiac arrest; if you are unsure, the 999 call handler will help you decide.
4. Early Effective CPR (Cardiopulmonary Resuscitation)
Cardiopulmonary resuscitation involves performing high-quality chest compressions (30 at a time) and rescue breaths (2 immediately after), repeated as a 30:2 cycle. Compress the centre of the chest to a depth of 5-6 cm at a rate of 100-120 per minute, letting the chest come all the way back up between compressions.
Suppose you perform lifesaving techniques, including CPR, and the patient is bleeding or unsanitary.
In that case, it is best to perform rescue breathing only if you have a barrier device to keep your lips away from theirs.
If you have not been trained to give rescue breaths, or you are unwilling to give them, give continuous chest compressions without stopping. This is hands-only CPR, and it is far better than doing nothing – the 999 call handler will keep you on pace.
5. Early Defibrillation (AED)
An AED is not a last resort for when CPR appears not to be working. Attach it as soon as one arrives and carry on with CPR while it is being fetched and switched on. Anyone can use an AED; no training is needed.
This entails attaching an AED to the chest of the victim. You can then follow the machine’s instructions and press the shock button to jolt the patient’s pulse back up in a way that CPR cannot.
The advantage of using an AED over a traditional defibrillator is that it allows you to conduct chest compressions and rescue breath in between jolts without unplugging the machine.
6. Early Advanced Life Support
Once paramedics have arrived and stabilised the patient for transport, they can use a bag mask to help the subject take manual breaths while their pulse is weak.
This includes CPR and other compressions performed on the victim before paramedics arrive!
They can thus be transported to the hospital, where they can be put on a ventilator.
7. Integrated Post-Cardiac Arrest Care
This care is meant to give the patient the best possible chance of a full recovery and a good quality of life after their cardiac arrest.
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What Are the 5 Steps of BLS Assessment?
Let’s examine the important steps when performing basic life support and adult CPR.
These steps are also known as the BLS survey. The BLS survey includes every external and internal factor to consider, from circulation to defibrillation of the patient.
These are the first things taught at BLS certification training and are drilled into first-aiders until they finish it perfectly.
Step 1: Scene Safety
It is vital to assess the area before entering, as scene safety will determine if it is safe to start CPR without worrying about debris, shrapnel, malicious intent, or other conditions.
Step 2: Check for a Response
Kneel beside the casualty, gently shake their shoulders and ask loudly, “Are you all right?” If they answer, move, or react in any way, they are responsive and this is not a cardiac arrest.
If there is no response at all, shout for help and go straight to Step 3. Do not stop to assess breathing first.
Step 3: Activate EMS – Call 999 Before You Assess Breathing
Under Resuscitation Council UK Guidelines 2025, you call 999 for any unresponsive person, before you check whether they are breathing normally. Rescuers no longer have to confirm that the breathing is abnormal before phoning – the call goes in the moment you find someone who will not respond.
If a bystander is with you, send them to call 999 and to fetch the nearest AED. If you are on your own, put your phone on speaker so both hands stay free, and keep the line open. The ambulance call handler will help you decide whether the breathing is normal and will talk you through CPR.
Step 4: Open the Airway and Check Breathing
With the 999 call under way, place one hand on the forehead and two fingertips under the point of the chin, then tilt the head back to open the airway. Spend no more than 10 seconds looking, listening and feeling for normal breathing.
Occasional gasps, or slow, noisy or laboured breathing, are not normal breathing – they are a sign of cardiac arrest. Do not check for a pulse. Lay rescuers are no longer taught to, because it wastes time and is unreliable. If the person is unresponsive and not breathing normally, treat it as a cardiac arrest and start CPR.
Step 5: CPR (Chest Compressions) and the AED
Give chest compressions in the centre of the chest, 5-6 cm deep at a rate of 100-120 per minute, in sets of 30 followed by 2 rescue breaths, letting the chest come all the way back up between compressions.
If you have not been trained to give rescue breaths, or you are unwilling to give them, give continuous chest compressions without stopping – hands-only CPR. It is far better than doing nothing, and the 999 call handler will keep you on pace.
The right speed and cadence to have when performing chest compressions are gained by following the beat to the BeeGees’ hit song “Staying Alive.” It has been a mainstay when chest compressions are concerned.
Many public spaces now have their own AED machine, and anyone can use one – no training is needed. Attach it as soon as it arrives and follow its spoken instructions; it will not deliver a shock to someone who does not need one. Keep going until the person shows clear signs of life or a paramedic takes over.
Conclusion
Adult CPR training is a useful skill to have. It allows qualified bystanders to increase the chances of survival for patients experiencing a heart attack.
Before you initiate CPR, you must first ensure your safety and competence. Certain companies will even sponsor the BLS+CPR training of their employees.
This will allow you to provide a more comprehensive BLS emergency response and keep loved ones or patients alive until the public safety professionals arrive.
If you would like to learn live saving skills, we provide a range of first aid courses starting from only £30PP.
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