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The definition of cardiac arrest is cardiac, heart; arrest, stops. A lot of people get a heart attack and cardiac arrest or MI, myocardial infarction, and cardiac arrest mixed up. They are two completely separate situations. A myocardial infarct or an MI or a heart attack, more commonly known, is when a blood vessel supplying the heart muscle becomes blocked. When we get an embolism or a blockage of a coronary heart blood vessel, the area that that blood vessel supply becomes non-contractile, it starts to die, it becomes necrotic and doesn't beat and pump efficiently as it used to do. And if the heart attack is big enough and in the right place or in most cases, the wrong place, the heart attack will lead to a cardiac arrest, because the heart will be knocked out of sync, it will be knocked out of rhythm, it will not pump any further and your patient goes from having chest pain or having a heart attack into a cardiac arrest, but it cannot happen the other way.

So, the definition of a heart attack is a blockage or cessation of blood flow to heart muscle-damaging heart muscle itself. You can have a heart attack, which will not give you any pain whatsoever. You can have a heart attack, which gives you hiccups, or you can have a heart attack that turns into a cardiac arrest immediately. Depends on the severity, the arteries and blood vessels that are involved, that is the important point. In cardiac arrest, the heart stops, which means there is now no pumping taking place from the coronary heart muscle whatsoever. As soon as the heart stops pumping, blood flow ceases, oxygen stops being pumped around the body, waste products stop being cleared from muscles in the brain and tissue and oxygenation starts to drop immediately.

A patient then becomes hypoxic, cyanosed, and eventually, death occurs. The faster that we can actually start that pump working again, the better the outcome will be. So this is why we only check one thing in a cardiac arrest check nowadays and it is, is the patient breathing, because in a cardiac arrest situation, breathing stop, more or less immediately.

It is one of the first things that happens and it is one of the last things that come back. So we do a quick check look, listen and feel for no more than 10 seconds, is the patient breathing? No, that indicates a cardiac arrest. The only way we are gonna sort that cardiac arrest out is with efficient and effective chest compressions, which is basically creating a manual pump out of the heart, the manual pump, will push oxygen and blood that is already in the circulatory system around the body, but we have gotta remember the compressions have to be efficient and effective and done properly. Because even when they are at their most efficient, you are still only roughly 30% effective or efficient at pumping blood around the body.

The important thing is your 30% efficiency increases the blood flow to the brain more than the extremities of the body because the coronary arteries going up, in through the carotid arteries into the brain, keep the brain oxygenated for long enough to buy us some time to defibrillate the heart and get the heart started again. So good compressions are very important in part of the chain of events. Good compressions keep the brain alive. If the brain is kept alive, the rest of the organs in the body will work and will be restartable, but without the brain, unfortunately, brain death takes place and the patient is irretrievable.

And these are the types of patients that we get a lot of, that go to a hospital and two days later we, unfortunately, have to turn off life support machines, because they're deemed as brain dead. If we do good quality CPR, we keep the brain alive, we can then restart the heart with a defib and the patient is then viable and has every chance of survival. Cardiac arrest, heart stops. So finally, just to run through, it is very important that we do our checks first to definitively decide that it is a cardiac arrest. You can never assume anything in first aid or medical worlds, you have to do your checks first, so it is safety first to myself, the airway must be open, clear, and patent.

We look, listen and feel for no more than 10 seconds to check whether there is any breathing going on and remember agonal gasping. Agonal gasping happens in 40% of all cardiac arrests, it is recognized as a sign of cardiac arrest and it is a deep, laboured breath. Odd occurrences. It is not a regular metronomical breathing rate, it is the odd breath. So we look, listen and feel for no more than 10 seconds. Is the patient breathing? No? It is defined as a cardiac arrest. Is the patient breathing? Yes? It is not a cardiac arrest, and the patient is put in the recovery position and monitored and the emergency services are informed. If it is a cardiac arrest, we immediately commence CPR, BLS supplemented with automatic external defibrillators to restart that heart. So remember, never assume, do your checks first, definitively make your decision, and then follow your protocols.

  • IPOSi Unit two LO1.2, 1.3, 1.4, 2.1, 2.2 & 2.3