Cardiopulmonary Resuscitation (CPR)

In the last post, we defined what we mean by cardiac arrest and learnt that there are only three cardiac arrest rhythms: shockable, PEA and asystole. We also briefly covered how each of these three arrest rhythms needs to be managed. A shockable rhythm (VF or pulseless VT) must be defibrillated without delay. The reversible causes associated with PEA (the 4Hs and the 4Ts) need to be diagnosed and treated as soon as possible. Asystole usually means it’s game over, although as a lay bystander resuscitating an out-of-hospital cardiac arrest victim it’s never over until the fat lady sings (or the paramedics arrive to take over).

Unless a cardiac arrest victim is in a monitored hospital environment (such as a coronary care unit, ICU or ED resus), the arrest rhythm is shockable, and the patient is defibrillated within seconds, there will inevitably be a delay between the patient collapsing and vital equipment arriving on scene (an ECG/defibrillator, airway/breathing apparatus, adrenaline and other drugs, intravenous fluids, expert help) with which to diagnose the arrest rhythm and appropriately resuscitate the patient. This delay varies from only a minute or two if the arrest occurs elsewhere in an acute hospital to many minutes, perhaps an hour or more, for an out-of-hospital arrest. And as we saw in the last post, the clock starts ticking immediately as the brain, heart and other vital organs are deprived of life-sustaining oxygen. Cue the basic life support (BLS) element of cardiopulmonary resuscitation (CPR).

What is BLS?

There are two elements to BLS: external chest compressions and rescue breathing. However, only resuscitation providers who have been formally trained need concern themselves with rescue breathing. Merely reading this post doesn’t count! I will say a few words about it later, if for no other reason than to reassure you that NOT providing rescue breathing as a bystander in an out-of-hospital cardiac arrest has a relatively small impact on the chances of resuscitation being successful.

External chest compressions

All the while that somebody is in cardiac arrest, they have zero cardiac output. There is no blood flow. The brain, heart and other vital organs are being starved of oxygen. I know I have already said this, but it is such an important point that it bears repeating.

Cardiac arrest never sorts itself out spontaneously. If you and everyone else stand around a collapsed person, look on aghast in shock and horror, and do nothing, the person will stay dead. Their brain, then their heart, and after that their other vital organs, will die off one by one. As I mentioned in my last post, optimally performed chest compressions produce a blood flow of about a third of the normal resting cardiac output. That may not sound so great, but it’s better than nothing. Much, much, much better. It can be the difference between surviving with a good outcome and not surviving at all – or, perhaps worst of all, surviving with a poor outcome. 

Every minute’s delay in starting chest compressions reduces a victim’s chance of survival by about 10%, so it’s rather understating things when I say it’s a great shame that bystander CPR is initiated in less than half of all witnessed out-of-hospital cardiac arrests in the UK. You (and yes, I do mean YOU) can join the brave, educated minority and buy time for the victim and their vital organs by performing external chest compressions.

Why do I say brave? Because you have to show real courage, as well as presence of mind and calmness, to take the lead in such a scary, unfamiliar, and literally life-or-death situation. But take heart. You’re braver than you think and, anyway, you cannot possibly make the situation any worse than it already is. You’re looking down at a stiff, after all.

Before moving on to the mechanics of exactly what you should do if you are ever faced with such a bowel-loosening, nausea-inducing nightmare scenario, I want to mention a couple of things about BLS, which in your case is likely to be limited to performing external chest compressions. BLS is not a treatment in itself. Contrary to what you might have seen in films or in TV medical dramas, BLS won’t magically restart a heart that is well and truly stopped. BLS is a holding manoeuvre to keep the arrest victim’s vital organs from suffering severe, irreparable damage while precious time is bought to bring a definitive treatment to bear, such as electrical defibrillation in the case of a shockable rhythm, or to identify and treat one or more of the Hs and Ts.

The chain of survival

This is a sequence of critical interventions, all of which must be carried out in order and without undue delay to give an out-of-hospital cardiac arrest victim the best chance of survival with a good outcome. The chain comprises:

1.      Recognise that the victim is in cardiac arrest.

2.      Call for help/dial 999/fetch the community AED.

3.      Early bystander CPR (BLS).

4.      Early defibrillation of a shockable rhythm (using an AED if available).

First things first

Right at the top of the priority list of things to do is safety. Your safety. It’s probably not too risky to approach a person who collapses to the floor in front of you in the middle aisle of your local Aldi, but the same isn’t true if you come across them lying spark out in the middle of a busy road. Or if they’re floating in an icy canal in the depths of winter. Or if there are live electrical cables nearby, and the arrest victim was electrocuted. Wherever you are, don’t rush in heedlessly. The last thing the situation requires is two victims rather than just the one. It only takes a few seconds to evaluate your surroundings. Situational awareness, in the jargon. The first step in the cardiac arrest algorithm asks: Is it safe to approach?

Is the victim really dead?

You don’t need to have studied at medical school for five or six years to recognise if the unresponsive person in front of you is dead. What are the alternatives? Has the person lying prostrate on the ground simply fallen asleep? Unlikely, perhaps, in your local Aldi or in the middle of the A6, but quite possible in the local park on a hot summer’s day. Have they fainted? Have they had a seizure? Are they in some sort of coma, aka they’re as pissed as a fart? If you begin chest compressions without checking them out first, you are quite likely to rouse them abruptly, and they might not be best pleased. So, you need to assess them for signs of life. If they have any signs of life, they aren’t dead. Simples. They might still be seriously unwell, of course, but you’re not going to be jumping up and down on their chest. Call an ambulance instead if you think the situation warrants it.

Signs of life

People always worry about getting this wrong. Don’t worry. It’s honestly not difficult.

First, gauge the person’s responsiveness by kneeling beside them and shaking their shoulders firmly. Shout loudly down both of their ears, ‘Wake up! Are you alright?’ If they wake up and tell you to piss off, they’re not dead. If they respond in any way at all (by moaning and groaning, rolling away from you or trying to push you away), great. They’re definitely not dead.

If they don’t respond at all, check their breathing. Tilt their head back gently by placing one hand on their forehead and the other underneath their chin. This manoeuvre opens their airway. Put your ear down to just above their nose and mouth, and look along the length of their body towards their chest. In this position, you can look, listen and feel for breathing. Take a full ten seconds if necessary, but no longer. Does the chest rise regularly, even if only slightly? Can you hear breath sounds? Can you feel their breath on your ear? If the answer to all three questions is no, as far as you or anyone else is concerned, the person is dead.

When I mentioned breathing, just now, I specified regular breathing. If the victim is making only occasional, irregular, deep gasps like a fish out of water, they’re exhibiting what’s unhelpfully termed agonal breathing. It happens when a dying brainstem sends desperate, erratic nerve signals to the lungs. Agonal breathing looks and sounds as bloody awful as it is effective. Your victim is dead. If you are in any doubt whatsoever about whether what you are looking at really is agonal breathing, assume the worst. You are most unlikely to cause serious harm by performing chest compressions on somebody who doesn’t need it, but you definitely will allow serious harm to develop unchecked if you don’t perform them for someone who does.

But what about checking for a pulse, I hear you all cry? Sod that! Don’t waste time. Get on with it. I’ll explain later.

Okay, they’re definitely dead. What should I do next?

The answer to this question is, at first sight, obvious – resuscitate your patient. But that isn’t what you should do next. Remember, BLS is only a holding manoeuvre to buy time for the brain, heart and other vital organs while expert help arrives to definitively treat the cardiac arrest. The immediate priority is to ensure that such help is sought.

If you’re in the middle of a supermarket, a curious crowd of onlookers will undoubtedly have gathered to ogle what’s occurring. One of them can call for help. But don’t just yell into the ether, ‘Can somebody call for an ambulance, please?’ There is a phenomenon called the ‘Bystander Effect’ at work in emergency situations involving lay members of the public. Everyone is agitated and confused. People adopt the easy route by assuming someone else will take care of the problem while they film the scene on their phones for their next social media post or continue shopping. Instead, point aggressively at an individual you think may be relied upon, lock eyes with them and order them in no uncertain terms, ‘You with the trolley crammed full of wine and beer, call 999 right now and tell them we have a cardiac arrest. Then find out if there’s an AED nearby and bring it here as soon as you can. Have you got that?’ Keep staring at them until they indicate that they have received and understood your instructions and will carry them out.

If you’re in the middle of the park, however, there might not be any other people immediately in view. Shout as loudly as you can for help. If none appears, dial 999 yourself using your mobile. Put it in speaker mode and place it on the ground next to you. When the operator answers, they will ask what service you require. Your answer should be a clear, crisp, ‘Ambulance. I’m with an unconscious adult who is not breathing. I know how to perform external chest compressions.’

Assuming that last sentence is true (because you’ve read and digested this blog), you will already have started chest compressions. If it’s not because you skim-read this blog (naughty, naughty) and have forgotten it, or you simply don’t feel confident, the ambulance call handler will direct you. They will keep you calm and on task. They will encourage you. They will help you to perform effective chest compressions at the correct rate and with the required force. So don’t hang up on them once they inform you the ambulance is on its way!

If you don’t have mobile phone signal (or even a mobile phone on you), you must leave the victim and do whatever you can to summon help as quickly as possible. I know, I know. It sounds counter-intuitive, and it must be agonising to abandon a cardiac arrest victim. However, summoning expert help is the next essential link in the chain of survival. No matter how difficult, it really is what you must do. You will not help the victim by performing external chest compressions until you are exhausted. BLS is not a definitive treatment for cardiac arrest.

As I suggested earlier, summoning expert help is not the sole priority. These days there is increasing availability of community defibrillators (actually, AEDS – automated external defibrillators). It will sometimes be the case that one of these can be used to successfully resuscitate a person in a shockable rhythm before the paramedics even arrive on scene. We’ll go over how you use an AED shortly. It’s dead easy! So make sure someone is fetching the nearest one.

External chest compressions

Okay. You’ve recognised that the person splayed out on the floor next to you is dead, help is on the way, and somebody has been dispatched to the library across the road outside which there is an AED attached to the wall. It’s time to get down to the real work. And I do mean work.

The method of cardiac resuscitation by performing external chest compressions was discovered accidentally in 1960 during experiments on dogs. Ever since, chest compressions have remained the mainstay of basic life support resuscitation. High pressure is generated within the chest cavity with each downward compression. That pressure is transmitted through the heart, forcing blood out of the chest and into the great arterial blood vessels. Blood flows forward rather than backwards because the heart valves allow only one-way traffic. During the passive elastic recoil of the chest wall that immediately follows, negative pressure generated in the chest draws blood in from the veins that drain the body and lungs, priming the heart chambers for the next compression.

For chest compressions to be effective, they must be applied in the right area, be forceful enough, be quick enough, and be uninterrupted. This is because it takes several compressions to build up a head of pressure in the arteries to promote forward flow, which drops rapidly to zero the instant you stop compressing. Even so, the best blood flow you can expect with optimal-quality chest compressions is about a third of the normal cardiac output. But it’s enough to keep the brain, heart and other vital organs ticking over for a limited period of time.

Let’s look at each of these elements of effective chest compressions in turn.

Correct hand position

Kneel beside the cardiac arrest victim, close enough that your shoulders can easily be positioned above their sternum (breastbone). Find the centre of their chest. Don’t overthink this. It’s midway between the nipples (although do bear pendulous breasts in mind). Place the heel of one hand over that spot. Now place your other hand directly on top of the first and interlock your fingers. Only the heels of your hand should be in direct contact with the sternum. Your arms should be held straight, your elbows locked.

Force required (depth) and rate

Hard and fast is the rule. Hard enough to compress the chest by 5 cm (2 inches) at a rate of 100-120 compressions per minute (roughly 2 per second).

The force required for chest compressions to be effective, and the physical effort required from you, shouldn’t be underestimated. People who rarely need to perform CPR for real (including some trained doctors and nurses) worry about causing serious injury by pressing down too hard. It’s a fair point, but the victim of a cardiac arrest is much more likely to be damaged by ineffective chest compressions that are too airy-fairy.

Remember to allow the chest to fully recoil upward to its normal resting position by completely relaxing the tension in your arms at the end of each compression. Don’t remove your hands from the victim’s chest. Just lift your weight sharply off. This passive component of CPR is just as important as the active component.

The acknowledged gold standard method for performing chest compressions at exactly the required rate, in the absence of a metronome that you always carry around in your back pocket for just such emergencies, is to work to the beat of Stayin’ Alive by The Bee Gees, which you can sing or hum as you go. If you’re feeling more pessimistic about the final outcome, Another One Bites The Dust by Queen does the same job.

Did I mention that CPR is hard work? If you’re putting enough welly into your chest compressions, it should be really tiring, even exhausting, after more than a few minutes. This is why the resuscitation team member performing chest compressions during a hospital cardiac arrest is rotated at two-minute intervals. Unless you’re lucky enough that somebody else in the Aldi crowd knows how to perform CPR, you’re on your own.

Hopefully, for you (and the poor sod who’s arrested), one of two things will happen before you collapse in a heap from fatigue. Ideally, the paramedics will arrive. Job done. A quick handover and you can head over to the drinks aisle. No need to wait until you’ve paid at the checkout before you down a slug of gin. The second option is that somebody pitches up with an AED. Great. The odds of successfully resuscitating your patient have just skyrocketed.

You can find AEDs in shopping centres, leisure centres, gyms, sportsgrounds, bus and train stations, wherever. They are often mounted on exterior walls to ensure they are available 24/7. They’re even installed in repurposed red telephone boxes. In fact, you’ll find AEDs just about anywhere people congregate. There’s probably one close to where you live. Find out where it is and tell your partner – just in case you need it one day!

Automated External Defibrillators (AEDs)

Many people are scared at the thought of having to use an AED. They worry that they won’t be able to operate it correctly. What if I can’t get it to work? What if I shock the patient inappropriately and cause them harm? What if I accidentally electrocute either myself or a fellow bystander? These fears are understandable but entirely unfounded. An AED can’t double up as a satnav. It can’t load up the internet for you. It can’t make you a nice cup of tea. An AED can do one thing and one thing only: it safely manages a cardiac arrest, giving you clear, unambiguous instructions at all times until help arrives or the victim revives. It will absolutely not charge up unless it detects a shockable rhythm, so it’s impossible to defibrillate inappropriately. It’s also impossible to electrocute yourself or anyone else. 

While you are opening the AED box and applying the gel pads, have someone else perform chest compressions, after you have demonstrated how to do it. You probably need a breather by now, anyway. Alternatively, get them to deal with the AED.

You usually switch the AED on by pressing the great big, clearly labelled power button. Some machines do it automatically when you open the case’s hinged lid. Follow the AED’s verbal instructions to apply the sticky gel pads firmly to the victim’s bare chest. There will be idiot-proof diagrams on the outer packet of the pads and on the AED’s inner lid telling you where to position them. The AED will then continue to guide you with step-by-step, clear, simple instructions. You simply cannot get it wrong.

The next thing the AED will instruct you to do will be to halt chest compressions and take your hands off the victim while it analyses the heart rhythm. It’s your job to make sure nobody else is touching the victim. If a shock is advised, it will announce that fact and begin charging. You may hear a high-pitched whine. An illuminated button will flash when the AED is fully charged. With a final visual sweep to ensure nobody is touching the victim, shout ‘Stand clear’ in a voice that brooks no argument, then press the button.

The victim’s body will twitch violently as electrical current passes through it. This is entirely normal. As soon as the shock has been delivered, the AED will verbally instruct you to resume chest compressions for two minutes, after which you’ll get a breather while it reanalyses the heart rhythm.

If no shock is advised when the AED is first attached, it will announce that to be the case and tell you to resume chest compressions for two minutes. Don’t worry – it’s keeping an eye on the clock for you.

You keep following the machine’s instructions until the cavalry finally charges up to the rescue. Unless, of course, you and the AED have already effected a miracle and your patient is sat up, looking bemusedly around and asking, ‘Are there any wines of the week left?’

When do you stop BLS?

There are three circumstances where it is appropriate for you to stop.

1.      Expert help arrives and takes over from you. Keep going until a paramedic physically lays their hands on the victim’s chest.

2.      The victim rouses or shows any signs of life. Congratulations. You’ve saved a life.

3.      Physical exhaustion sets in. If you are alone in a remote location, you will reach a point when you simply cannot continue. Performing high-quality chest compressions is physically demanding, akin to an aggressive gym workout. Before you feel compelled to throw in the towel, however, the quality of your compressions will already have dipped and become less effective. I conducted some clinical research back in the day that showed the quality of chest compressions declined within as little as two minutes.

It all sounds so simple. Is that really all there is to it?

It really is that simple. Well, pretty much. I probably should tell you about a couple of things:

Pushing down hard on someone’s sternum can be traumatic. You may hear and feel ribs snapping. It’s deeply unsettling, and your immediate reaction is to back off and stop because you think you are harming the victim.

DO NOT STOP. A broken rib heals in a few weeks. A dead person stays dead forever.

Another unsavoury aspect of dealing with cardiac arrest victims is that acute hypoxia (oxygen deprivation) causes the body’s sphincters to relax. While it may be messy and a bit smelly at the bottom end, you can ignore it for the moment. Top end action can’t be ignored, however. It is not uncommon for people in cardiac arrest to vomit or have gastric fluid pool at the back of their throats, which then overflows from their mouths. You don’t want this fluid to get into their lungs. If this happens, don’t panic. Swiftly tip the person onto their side and let gravity do the work of clearing their airway. Then roll them back and resume chest compressions.

Common myths debunked

The precordial thump

This is when you wallop the victim in the chest with your fist right at the start. You may have watched impossibly handsome doctors in TV dramas do this with miraculous results. Don’t do it!

You’ve not mentioned checking for a pulse. Surely, it’s vital to check the victim does not have a pulse before starting CPR?

I said I’d come back to this. In a highly charged medical emergency, your adrenaline level will be through the roof, and your heart will be galloping madly. In this situation, even experienced doctors and nurses can struggle to find a carotid pulse, and they know precisely where to palpate. The throbbing pulse in your own fingers will interfere with anything there is to feel (or not) in the patient’s neck. If you muck about for a couple of minutes thinking, ‘Is that the victim’s pulse I can feel?’ you might as well pack up and go home.

Forget a pulse check. If the victim is collapsed, unresponsive and not breathing, they’ve checked out. Cashed in their chips. Popped their clogs. Kicked the bucket. Shuffled off their mortal coils. Gone to meet their maker. They’re dead, you idiot. Start chest compressions.

If it all goes horribly wrong, I’ll get sued

It can’t get any more wrong than being dead.

Having said that, there are lots of things you don’t know about the complete stranger who has collapsed in front of you. Do they have a terminal disease that makes resuscitation inappropriate? Is it the victim’s wish that they not be resuscitated in the event of a cardiac arrest for whatever reason? Do they have a community DNACPR signed off? You cannot know any of these things. You simply have to act in good faith and assume that attempting to resuscitate them is the right thing to do. No bystander has ever been successfully sued in the UK for performing CPR in good faith. You are fully protected under the law by the concept of the Good Samaritan.

The other thing you’ve not mentioned is rescue breathing – this must surely be an oversight

No, I haven’t forgotten to mention it. There are several reasons why rescue breathing is not advocated for bystander CPR. Mouth-to-mouth ventilation (the only option usually available to Joe Public) is unpalatable to most people, particularly if the victim has vomited. Mouth-to-mouth rescue breathing is also technically difficult to perform effectively without proper training. If all that isn’t bad enough, combining effective rescue breaths and chest compressions can make the whole resuscitation thing seem just so complicated and off-putting that it discourages people who might otherwise be keen to attempt resuscitation.

What’s more, compression-only BLS can be almost as effective as compression-ventilation BLS, at least for a period of time after somebody suffers an out-of-hospital cardiac arrest. How can this be true?

Well, to start with, the concentration of oxygen in the expired air from your lungs is a paltry 16% compared with the 100% a hospital resuscitation team can provide by manually ventilating a patient with a bag-valve-facemask apparatus connected to an oxygen cylinder. Secondly, although the lungs and red blood cells have limited capacity to store oxygen, there is enough to keep vital organs reasonably supplied for a few minutes until help arrives. Thirdly, vigorous chest compression, followed by its expansion during passive elastic recoil, generates some movement of atmospheric air (containing 21% oxygen) in and out of the lungs – provided the patient’s airway is held open by someone.

One last question: what about children?

I was hoping you wouldn’t ask that. It’s a very good question. From a physiological perspective, children are not simply scaled-down adults. Babies even less so. It’s also the case that young people seldom drop down dead of heart-related conditions. There are much more likely to be special circumstances involved, such as drowning, severe asthma, major trauma, etc. CPR for small children and babies differs fundamentally from adult CPR because children require rescue breaths. Tackling paediatric resuscitation is outside the scope of this article. However, please read the next short paragraph carefully.

If a collapsed, unbreathing, unresponsive child appears to you to have reached puberty (looks to be about 11 or 12), resuscitate them in exactly the same way as you would an adult. If you are confident about providing rescue breaths, go for it at a ratio of 30 compressions to 2 rescue breaths. Even if they are younger, there’s really nothing to be lost by attempting to perform external chest compressions, using only one hand for small children and babies.

Summary

1.      Think safety first.

2.      Assess response.

3.      Shout for help. Call 999. Dispatch somebody to fetch an AED.

4.      Perform chest compressions. Don’t stop unless an AED instructs you to, the patient shows signs of life, help arrives, or you are exhausted.

5.      Attach the AED and follow its prompts.

6.      Whether the victim lives or dies, regale all your mates in the pub afterwards about your heroic exploits. You won’t have to buy a round all night.

Well done for making it to the end of this post. You could save a life. It might be mine! Now, go back to the beginning and read through it once more to ensure you’ve understood all of the key points.