What Paramedics Do: Cardiac Arrest

What exactly do we, as paramedics, do for a cardiac arrest? Here’s a quick guide for the average Australian citizen.

This new series, “What Paramedic Do”, is designed to give you an idea of what paramedics do when we turn up at various jobs. I’ll occasionally post explanations of how we assess, treat, and manage patients here in Australia, aimed at educating the general population.

Recently, there was a video from Today I Found Out about what paramedics do in cardiac arrest and how long it takes before we decide they’re beyond hope and terminate resuscitation. This resulted in an absurd load of misinformation about when we can (or can’t) ‘call it’ and cease efforts. So what’s the rule in Australia? Well, like everything else, it’s complicated.

Yes, we can decide that resuscitation is futile

In all Australian services, paramedics (usually only those employed by the state service) can declare a patient as ‘beyond help.’ Usually this is seen as the term ‘recognition of life extinct’ versus ‘declared deceased’. The reasoning is that we don’t determine a cause of death – that’s the job of the certifying doctor (or the pathologist, or the coroner). We are well within our clinical and legal power to turn up and say “Nope, this is futile” and stop (or not even start) resuscitation.

Some people seem to think that only a doctor can tell us to stop – this is not true. If we turn up and find someone who has obviously been dead for hours, there’s absolutely zero value in starting and we don’t need a doctor to tell us that. Think of it rationally: why would we transport a corpse only to have a doctor glance at them and go “Yeah, they’re dead!”?

But when can we decide somebody is beyond help? How long do we go for?

How do people go into arrest?

Firstly, let’s talk a bit about the terms ‘arrest’, ‘cardiac arrest’ and other similar terms. We use the term ‘arrest’ kind of generically to refer to anybody who is either not breathing, has no pulse, or both. The term ‘cardiac arrest’ is more specifically used to refer to someone who has no pulse (or detectable cardiac output), while a ‘respiratory arrest’ refers to someone who is simply not breathing (but may or may not have a pulse). So when we say we’re going to an arrest, it simply means someone who isn’t breathing or who doesn’t have a pulse. Believe it or not, arrests aren’t a major portion of our job. In my 4 years on road, I’ve probably only been to about 6 or so that we could work on – the rest were all well and truly dead.

People go into arrest for loads of different reasons, and the sad truth is, most of them won’t come back – though the survival chances are starting to get better. The Chain of Survival describes the ‘links’ required for someone to have the best chance at living:

  1. Early recognition – that is, early notification of emergency medical services so that we head out quickly
  2. Early CPR – starting CPR as soon as somebody arrests is paramount to giving them the best chance of survival. I’ll talk about CPR soon.
  3. Early defibrillation – which I’ll cover in a second
  4. Early Advanced Life Support – which is part of what we do as paramedics

As I said, most people arrest for various reasons, but we can usually split them into three very broad categories:

  • Cardiac Arrests where it’s something that predominately affects the heart from working, for whatever reason. One of the more common reasons is a major heart attack (or myocardial infarction) where blockage or narrowing of the blood vessels supplying the heart muscle (myocardium) reduces blood supply, killing the muscle. This often puts people into an electrical heart rhythm that stops it from pumping blood properly – thus they go unconscious and start to die. Other reasons can be electrolyte changes, shock (as in poor blood flow, not “I’m shocked at these prices!”) from various causes, some drug overdoses, and loads of other causes.
  • Respiratory Arrests are due to something affecting the ability to breathe – like choking on something, or overdosing on narcotics like heroin which reduce your breathing rate and depth. As breathing drops off, the patient gets less oxygen (becomes hypoxic), which means there’s less oxygen circulating, and thus tissues start to die.
  • Traumatic Arrests are due to some sort of injury – like being in a car accident and having your chest crushed, or getting shot in the chest. These are special cases and traumatic arrest survival rates are typically awful, because the only way to survive many of them is to be on an operating table as soon as it happens. Your chances or survival depend on what the injury is, where it is, whether it’s penetrating (like a knife) or blunt (like getting crushed), how fit and healthy you are, and whether we can fix the problem in the field.

What are the initial steps for paramedics?

When we roll up on scene, our initial jobs are as such:

  1. Identify that you’re in arrest
  2. Commence basic life support measures
  3. Figure out why you’ve gone into arrest
  4. Try to fix the underlying cause

Basic Life Support involves three core things: chest compressions, defibrillation, and ventilation. Chest compressions and ventilating the patient are basically taking over from the heart and lungs that aren’t doing their job; they don’t, on their own, magically fix the problem (except in respiratory arrests in some cases). They effectively buy us time to get everything else done. Someone pumping on your chest doesn’t work as well as your proper heart, but done right it can keep blood flowing to your major organs (like your brain, your lungs, your heart, etc), while ventilating will keep oxygen going in and carbon dioxide wastes going out. This is the cornerstone of care and what goes on throughout the arrest.

Ventilation also involves airway management. When you’re unconscious you lose muscle tone, which means your tongue can fall back and occlude your airway. We can insert various kinds of airway devices (from short tubes to long tubes that go all the way down your throat) to keep the airway open, allowing us to take over breathing for you. We then use a bag valve mask to take over breathing – literally squeezing high oxygen content air down there.

Defibrillation is the magic ‘shock box’ necromancer machine – but it only works when the patient is in a shockable rhythm. Your heart is like a computer controlled pump, and there’s a system of electrical pathways that make sure it pumps properly. In some cardiac arrests, usually those related to heart disease but sometimes with overdoses or electrolyte disturbances to name a few, the heart goes into a shockable rhythm – ventricular fibrillation (VF), or ventricular tachycardia (VT). In VF, the heart muscle just sort of quivers in place and doesn’t contract. In VT, your heart is trying to pump so quickly because its rate is so fast, that it doesn’t actually fill with blood and thus doesn’t pump anything. In these cases, the defibrillator can be used to deliver a shock of energy (usually 200 joules) to ‘stun’ the heart, hopefully terminating the abnormal electrical activity and letting the normal pacemaker activity take over. A patient who has arrested in VF or VT needs defibrillation more than anything, because that’s the definitive emergency treatment – it is our highest priority to recognise the rhythm and try to fix it.

But they aren’t magical boxes that ‘restart’ hearts. In order for the defib to actually do anything, there needs to be some sort of underlying electrical activity. A ‘flatline’ (called asystole) can’t be shocked, because there’s no rhythm to take over. Normal rhythms also can’t be shocked, because they’re just that – normal and should allow for output. When these ‘normal’ rhythms don’t have cardiac output (called pulseless electrical activity) the defib won’t help, because the heart muscle either isn’t responding or something else is stopping flow. If you see a TV show shocking a flatline, they’re idiots.

Once we’ve got our basics down pat – with good quality CPR, ventilations, and defibrillation done, we start to consider reversible causes. Every 2 minutes, we’ll stop, reassess, and shock you again if needed.

Our reversible cases are typically hypoxia (low oxygen), hypovolaemia (low blood volume), hypothermia (low temperature), hypoglycaemia (low blood sugar level), hyperkalaemia (high potassium levels in the blood, which affects the electrical activity), hydrogen ions (or acidosis which affects body chemistry), toxins (or overdoses), tension (air caught in the chest cavity stopping blood flow), tamponade (blood around the heart stopping it from filling), thrombosis (a blood clot stopping flow), and traumatic causes. We call these the “Hs and Ts of reversible causes” for obvious reasons. Note: We also consider hypokalaemia (low potassium), which is just as bad, but we typically don’t infuse potassium out of hospital – it’s difficult to monitor.

From there, we set about trying to fix whatever we can identify. For example, if you’ve overdosed on heroin and stopped breathing, we have two things to fix – hypoxia (not breathing = no oxygen) and toxins (namely, the heroin – which we carry the antidote naloxone to treat). We then have to fix it by ventilating you, and considering whether to reverse it or not (we might not – it might be safer to leave you sedated and just breathe for you). If you arrested because you had a massive heart attack, we’ve got to worry about thrombosis, and figure out whether to give you a clot-busting drug to see if that helps your heart work again.

There’s loads of drugs that we carry, and we typically perform a few procedures:

  • Intravenous access (into your veins) or intraosseous access (into your bone) allows us to push drugs and fluids to see if they help you
  • Adrenaline (epinephrine) is routinely given to see if it helps stimulate the heart and to constrict blood vessels to try to improve central blood flow; though there’s little real evidence it actually helps at all
  • Fluids (usually 0.9% Sodium Chloride, or ‘normal saline’) are sometimes infused at different rates to increase the fluid blood volume component, or to flush drugs given into the blood where they can have an effect
  • There are antiarrhythmics to try to stop abnormal heart rhythms, drugs to break up clots, drugs to stimulate the heart, drugs to reverse acidosis, and loads of other stuff that are pretty situational

So that’s basically what we do: we continuously provide chest compressions and ventilate you, while we work to fix the underlying cause (if we can) – and every 2 minutes, we stop briefly to see if you’re responding.

Resuscitation is brutal. If you go into arrest, I’m going to do horrible things to your body to try to get you back. When CPR is done properly, with an adequate depth, it’ll almost always break ribs. It depends on how strong your bones are, but to get that heart pumping, I’m going to push hard. I will shove tubes through your mouth and down your throat. You’ll probably be jabbed quite a few times with needles as we try to gain IV access. If that fails, we drill into your bone instead. It’s violent, it’s brutal, there’s vomit and blood, and often a healthy dose of faeces and urine too. Is it as chaotic as you see on TV? Nope. Is it as soft as you see on TV? Hell freakin’ no.

When do you not start?

There’s very clear options for when we don’t start resuscitation (or terminate it very early):

If we walk in and see you’re obviously dead, we don’t start. ‘Obvious death’ has many definitions, but there are two broad categories: those with clinical signs of death, and those who are blatantly dead. The ‘blatantly dead’ are those who are decomposing, or who have suffered such horrific injuries that they’re quickly obviously dead. These are called ‘injuries incompatible with life‘ and would be something like being decapitated, or having most of your body crushed, or being torn in half – that sort of thing.

The ones who show signs of clinical death are people who have rigor mortis (stiffness in the body), are cold to the touch in a warm room, show lividity (discolouration that follows gravity from blood pooling when the person died), or the more subtle signs of decomposition. These patients are beyond help and we won’t start – there’s no point working on a corpse.

If an advanced health directive or Do Not Resuscitate order exists, or something similar, and we can see it and verify it’s valid, we won’t start (or we’ll stop if we already have). If we go to someone who has a terminal illness and has made clear legal orders that they do not want to be resuscitated, we won’t start – provided we can see the document and verify that it’s legal. If we can’t, we have to start – so if you (or someone you care about) has one of these, make sure there’s a certified copy kept with them at home or wherever they stay. These are typically formal documents drawn up from a hospital or doctor’s clinic and outline explicit wishes in clear, unambiguous terms. In a similar vein, if you produce documents to show that you have enduring power of attorney in health matters or similar, we may stop on your orders – but we’re going to look very closely at it before we do. We also have to make sure that the circumstances match the do not resuscitate order – if somebody chokes on a plum but they have a DNR for terminal cancer, we might ignore the DNR because they’re not dying from the cancer, but from an airway obstruction.

If a doctor tells us to cease, and it appears in accordance with good medical practice, we’ll stop or won’t start. This is a difficult one – because anybody can walk up and say “I’m a doctor” and we often have no way of verifying it. If someone identifies themselves as a medical practitioner, and we reasonably believe them to be one, and their order to withhold seems reasonable, we will stop. If it does not seem consistent with good medical practice, we WILL NOT STOP. If they come up to us and tell us to stop on the 22 year old female who overdosed on heroin and who we think we can get back, we won’t stop until we’ve given them a chance to respond – because there’s still a chance they can respond. We won’t stop on the orders of a nurse or other allied healthcare professional. A registered nurse, clinical nurse, nurse practitioner, or whatever else has no authority over us in this situation (or indeed in pretty much any out of hospital situation) – we can consider what you say, but you can’t direct us to stop. Similarly we don’t have to listen to midwives (though we usually will), physiotherapists, speech pathologists, chiropractors, or whatever else you happen to be.

When do you stop active resus?

This is the million dollar question: when is enough, enough? The protocols vary from state to state, but they typically follow a general sort of theme. I’ll reproduce some of my state protocols in a more generalised way.

Our rules for considering someone ‘life extinct’ include these criteria of death:

  • No carotid pulse
  • No heart sounds for 30 seconds
  • No breath sounds for 30 seconds
  • No response to central stimuli (namely, painful stimuli like squeezing near the neck, or rubbing the sternum)
  • Pupils are fixed and dilated

Generally, we’ll give people 20 minutes of resuscitation before we consider ‘calling it’. So from when we first start with hands on chest, we’ll go for 20 minutes at a minimum before we decide that it’s futile. If the patient is now in asystole (flat line) or a very slow pulseless electrical activity (under a rate of 10 per minute), we’ll stop. If they’re in a quicker PEA, or in a shockable rhythm, we’ll continue for about 30 minutes – the reason being that there is an opportunity that the underlying cause could be corrected. In this case, we’ll call our medical officer on duty and consult them – they will then either direct us for further treatment, for transport, or to terminate resuscitation. Most arrests will go for a period of 30 or so minutes. It generally only takes us about that time to do everything that we can to reverse the cause, and for the patient to fail to respond and their body to start dying such that they meet the criteria.

If there’s been no attempt at CPR for 10 minutes prior to our arrival, and they’re in asystole, we can stop before 20 minutes. If you walk in and find someone in arrest, and you don’t do anything for 10 minutes prior to us getting there from when you found them, and they’re flatlined, we can stop before 20 minutes. The reason is that if resuscitation isn’t started within 10 minutes of the arrest, the survival chance is almost zero – it drops off significantly with each minute that CPR is withheld. By the 10 minute mark, in most cases, blood flow to vital organs is so poor that the chance of survival is almost none, and if they do survive, they’ll be so impaired that they’ll almost certainly die later in hospital anyway. This doesn’t mean that we will stop before 20 minutes in that case – just that we have the option in the event that they aren’t responding and there are no reversible causes we can effectively work on. If they’re in a shockable rhythm or show signs of responding, obviously we’ll continue.

When we stop, we have a procedure to follow:

  • We formally go through the criteria of life extinct, as set out above
  • We check their rhythm and do a print out
  • We record the time that we declared life extinct
  • The resuscitation stops entirely

Once we’ve called it, we stop – there’s no further intervention, there’s no ‘practicing procedures’, we just straight up stop. From there, we typically clean everything up and remove our inserted devices (like cannulas, airways, etc). The exception to this is if it’s a suspicious or unexpected death likely to be subject to autopsy; in these cases, we might leave the devices in as they’ll form part of an investigation.

From there, we either notify the police (which is what we do in the vast majority of cases), or we try and contact the patient’s doctor to see if they can issue a death certificate (provided it doesn’t need to be reported to the coroner). If we can get the doctor to issue a death certificate (e.g. it was a palliative cancer patient who died at home as was expected), then we don’t need to involve the police; instead, the family contacts their funeral home of choice, and they come out and collect the deceased.

Traumatic arrests and children are different

If you die from a traumatic arrest, you’re probably screwed because you died for a very, very good reason – and often, nothing short of a surgeon’s table can save you. In a traumatic arrest, we focus entirely on trying to fix the problem, and if we can’t fix it out here, your survival chances are practically zero. Typically, we will:

  • Try to stop you from losing any more blood. If you’ve lost quite a bit of blood, we can try to replace it; but if you’ve lost a load of blood, you’re dead.
  • Try to open your airway and keep it open. If we can’t get your airway open, you’re dead.
  • Decompress your chest by shoving two big needles into it – if we suspect that you’ve got air stuck in your chest that’s compressing your heart. This is called a tension pneumothorax, where a lung collapses and lets air escape into your chest cavity; with nowhere to go, the air pushes on your lungs, heart, and major blood vessels. In some cases, a highly experienced paramedic or emergency doctor might perform a thoracotomy where they open up a hole in your chest. If this doesn’t fix it, you’re dead.

And that’s basically it. We typically won’t even do CPR on traumatic arrests, because there’s little benefit; the blood’s not pumping because something’s stopping it or because it’s not there, and if we don’t fix that problem first, CPR sure as hell won’t do anything. If we have the hands to have someone do CPR, we’ll do it – but if we don’t, we won’t bother. We’ll give you your 20 minutes of resuscitation after we’ve done the above, but if that doesn’t fix it, you’re not coming back, no matter what we do. Some services simply won’t transport blunt force traumatic arrests; but we’re a bit more optimistic here.

Children tend to be treated a little differently, because we have more hope that they can survive. Kids tend to arrest for respiratory causes, which means we can typically find and reverse the cause. Since they’re more likely to arrest from a reversible cause that we have a reasonable chance of fixing, we tend to go a little harder with kids and hope to transport them. But if they die, they die, and we can declare life extinct and cease resuscitation just the same as an adult.



And that’s it! That’s pretty much what we do in an arrest – greatly simplified, but that’s the general gist of it. How can you help? Call us early, and start chest compressions. That’s pretty much all that can be done. Unfortunately, when people go into arrest, it tends to be for a reason, and that reason usually isn’t something we can fix. We’re getting better at it, so it’s often not entirely futile from the second that they hit the deck. But the next time someone tells you that only a doctor can tell us to stop, you can tell them that they’re full of garbage.


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