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In order to deliver effective CPR, we also have to understand a little bit about the heart and what happens when the heart goes into cardiac arrest, and how the actual compressions will make a difference. So, can you tell us what's actually happening in the heart for someone who's all okay? Okay. So, as we are standing here quite nicely now, the sinoatrial node or the heart's own pacemaker is firing off impulses. And then that is going across the top two chambers of the heart and they are responding to that by just squeezing. And that's what's happening. That then gets to the middle impulses in the heart. That then goes to the AV node and then the electricity flows down. And by that then the bottom two chambers of the heart are then contracting. So that's as you and I are standing here now and we're not even thinking about it. The heart is just doing that all the time. When somebody goes into what's called a cardiac arrest, for whatever reason, that is interrupted. So, it could be due to electrolytes, so potassium maybe has interfered with it or quite often it's cardiac in nature. So, a heart attack, for whatever reason, the electrics are interfered with and they then... The electrical pathways are interfered with and the electrics just spark all over the place. And in response to that, the top two chambers of the heart and the bottom two chambers just start wriggling in the chest in response to the rhythm that they go into, which is known as ventricular fibrillation or ventricular tachycardia. And they're just wriggling in the chest and the only thing that will sort them out is defibrillation. And that's why defibrillation is the key in this instance. But, before that, we need to go on the chest and start compressions because that's what's going to keep them going. It's not going to bring them back because they need the defibrillator to sort them out. That's what's going to keep them going until the defibrillator gets there. And that's why we've got automated defibrillators all across the country and in the countryside to try and help. Because the higher chance of survival is if we get to that quicker. So, the defibrillator works by passing electricity across the heart, momentarily stunning it, allowing the heart's own pacemaker to sort itself out. Hence, like I've just said, if you get there quicker, the chance of survival are higher because you're then putting the impulse in so it will sort itself out. If it's been in that rhythm for longer, then it just stays in that and that's what the electrics will do. So, like I say, that's when they're in ventricular fibrillation or ventricular tachycardia. It's the electrics are just sparking all over and the heart is just wriggling around. There are types of cardiac arrest where the electrics are okay and there are other reasons why people have had a cardiac arrest. So, it could be that due to lack of oxygen. It could be due to a bleed, etcetera, etcetera. And that's when we will put the defibrillator on. But the defibrillator will say, "No need for... " It'll analyse and then it will say, "No need for shock". Check the patient. Check for signs of life and continue basic life support. And in that instance, the electrics are all okay but like I say, for whatever reason, the heart isn't responding. So that's when good quality compressions are vital. It's important both types of cardiac arrests but it's absolutely vital that we then are continuing good effective compressions. So, we're maintaining that rate of 100 beats per minute to a 120 when pressing down that five to six centimetres. And if we're getting tired, we must tell somebody. The guidelines from the Resuscitation Council UK say that we should be going and changing the person on the chest every two minutes. But sometimes, people get tired, which again, is absolutely fine. It can get very hot depending on where people are. And so, they must realize that effective basic life support is pressing down that five to six centimetres. Keeping that rate. They're really struggling. Go back to doing 100 beats per minute rather than 120. But pressing down that five to six centimetres. There's been research performed all across the world, mainly in America, but I say all across the world to say that that is the right rate and depth for return of spontaneous circulation. And if they're in hospital and actually to get to survival to discharge from hospital and if they need defibrillating, to actually make that first shock work better. So the breathing is important but certainly in the community and again research is showing that there's no difference in outcome whether they receive oxygen for the first five minutes or not. So it's the compressions that take priority. They are the most important. So making sure your hands are in the center of the chest and you're really pressing down. Not using your arms so using all your body weight. Your back nice and straight and keeping that depth and rate going. If you are tired, tell somebody else. Communication is vital and if you want to count those 30, if someone is there to deliver the breaths, then they know within the cycle of where they are so that you're not in silence. Everybody knows exactly what's going on and what's happening. And say, if you are tired, it's very important to say to somebody "I'm really tired." Rather than just think that a little bit is better than nothing. Because it's not. You might as well not bother. So it's keeping that rate and depth to keep the pressures up within the heart, within the coronary arteries, to get that blood and oxygen around the body. So is the release as important as the press down? Definitely. It's to allow proper recoil so that you then, yes, get the pressures up to get that blood and oxygen around. And can anybody do CPR? Yes. Yes. And, hence, the DVDs that have been out and the British Heart Foundation. It is important but you must get that right rate and depth. Get your hands in the center of the chest. And make sure that you are over them and you're really pressing down that five to six centimetres.
Understanding CPR: The Heart, Cardiac Arrest, and the Importance of Compressions
Knowing how the heart functions and the impact of cardiac arrest is crucial for delivering effective CPR. You can keep blood circulating with proper compressions until a defibrillator becomes available.
How the Heart Functions
The heart's natural pacemaker, the Sinoatrial Node, sends regular electrical impulses from the top chamber (Atrium) to the bottom chamber (Ventricle). This process keeps the heart pumping blood. In cardiac arrest, this normal functioning is disrupted, often due to electrolyte imbalances, potassium interference, or heart-related issues.
Cardiac Arrest and Ventricular Fibrillation
During cardiac arrest, the heart's electrical pathways are disrupted, causing the heart to experience ventricular fibrillation or ventricular tachycardia. In this state, defibrillation is necessary to restore normal heart function.
Effective CPR and Chest Compressions
While waiting for an Automated External Defibrillator (AED), perform effective CPR:
- Push down 5-6cm at 100-120 beats per minute.
- Place hands in the centre of the chest.
- Maintain a straight posture and use body weight.
- Switch rescuers every two minutes for optimal CPR.
- Allow the chest to recoil fully between compressions.
The Role of AEDs
AEDs work by passing electricity through the heart, momentarily stunning it and allowing the heart's pacemaker to restore normal function. In cases of cardiac arrest due to a lack of oxygen, the AED may indicate that no shock is necessary. Continue CPR and monitor the patient until emergency services arrive.
Remember: Anyone can perform CPR. The key is to maintain the correct rate and depth of compressions.