A person is in cardiac arrest (CA) when their heart has stopped beating or is beating erratically, meaning it can no longer pump blood round the body and, in particular, supply the brain with oxygen.
Causes
In adults, cardiac arrest:
- is most often of cardiac origin; it is linked to a cessation of all effective mechanical activity of the heart. It most commonly occurs as a result of the heart functioning in a disorderly manner, preventing it from circulating blood effectively. This condition may be secondary to a myocardial infarction, certain forms of poisoning or other heart diseases. Sometimes, cardiac arrest occurs without any known pre-existing condition: this is known as sudden death.
- may have a respiratory cause, due in particular to:
- a severe airway obstruction where attempts to clear the obstruction have failed;
- trauma to the skull, spine or chest;
- an accident involving water (drowning), electricity or hanging.
- may occur as a result of significant blood loss (haemorrhage).
In children and infants, cardiac arrest is most often caused by respiratory factors. It is the result of a lack of oxygen. It is particularly common in the following situations:
- suffocation (plastic bag);
- strangulation (games);
- a serious airway obstruction;
- drowning (water-related accident).
Cardiac-related syncope in children and infants is much rarer than in adults. It most often occurs as a result of a heart condition or abnormality, which is frequently undiagnosed. In such cases, as in adults, it occurs suddenly and causes the child to fall whilst playing or engaged in another activity.
It can also occur as a result of severe bleeding, electrocution or serious trauma (to the skull, spine or chest).
Risks & Consequences
Within a matter of minutes, the life of a victim suffering a cardiac arrest is at risk.
When a victim stops breathing and their heart ceases to function effectively, air can no longer reach the lungs, blood circulation stops, and the entire body is deprived of oxygen. The brain is the organ most sensitive to a lack of oxygen. If no first aid is administered, brain damage occurs within seconds in children and infants, or within minutes in adults.
Gradually, these injuries become irreversible, reducing the chances of survival to virtually zero within a few minutes (around eight minutes in adults).
Signs
The signs of cardiac arrest are identified within a few seconds during the emergency assessment. A first-aider must also be able to identify them if they are responsible for receiving the emergency call.
A victim is considered to be in cardiac arrest if:
- she does not respond when called or stimulated (loss of consciousness);
- she is not breathing or is breathing abnormally (gasps).
Sometimes, these symptoms may be accompanied by brief convulsions.
Checking for a pulse is not routinely carried out to confirm cardiac arrest. However, if it is carried out, the time spent checking for a pulse whilst also checking for breathing must never exceed 10 seconds, and it must not delay the commencement of the first-aid procedures set out in the table below.
This research is carried out at the following level:
- carotid artery in adults and children
- femoral in children or infants
If a pulse cannot be felt, or if there is any doubt as to whether a pulse is present, in a victim who has lost consciousness – even if they are still breathing – CPR should be started or continued. This is because early CPR performed by bystanders can help restore breathing through chest compressions, even without restoring circulation.
In some cases, in adults, cardiac arrest may be preceded by warning signs, in particular a persistent, distressing, constricting chest pain that may radiate into the neck and arms. This pain is sometimes accompanied by difficulty breathing and sweating.
Principle of emergency response
The rescue operation must, except in cases of certain death (where the head is severed from the torso, or the victim is torn apart, dismembered or in a state of rigor mortis), enable a series of actions to be carried out that increase the victim’s chances of survival:
- recognise the warning signs of AC;
- to alert the emergency medical services at an early stage;
- to perform or supervise early cardiopulmonary resuscitation (CPR);
- to ensure that early defibrillation is carried out.
These various steps, combined with early medical intervention, form a chain of survival that can increase the survival rate of victims by between 4 and 40 per cent. Every minute saved in deploying an automated external defibrillator (AED) can increase the victim’s chances of survival by 10 per cent.