Reversible Causes Of Cardiac Arrest (The Hs & Ts)

In today’s micro-lecture, Australian Paramedical College Hon. Snr. Lecturer Sam Willis talks about the reversible causes of cardiac arrest.


Hey guys, today we’re going to talk about the reversible causes of cardiac arrest. Now those of you who’ve already completed workshop one and are preparing to go into workshop two, it really is worth your while to get onto the advanced life support website and take a look at their guidelines, because these are the guidelines that you will be following for managing a cardiac arrest. Now in today’s session, we’re going to talk specifically about the reversible causes of cardiac arrest, which as you can see here, are called the four Hs. One, two, three, four and the four Ts. So we’re going to go through these together.

Now, in the context of this ALS algorithm, this is the rhythm that you will use to manage your patient. So let’s go from the beginning and start CPR. You’ve established a cardiac arrest is occurring, so you’ve got onto the chest, you’ve done your 30 compressions and you’re getting the defib pads onto your patient. You’ve charged a defib up, you’ve given a shock. Then you’ve got onto the airway and you put the OPLA in and you’ve got the BVM into the patient’s mouth. You’ve requested your second crew and you’re starting your CPR, CPR, CPR. That’s the most important part in a medical, non traumatic cardiac arrest is your CPR. Eventually when it all stabilizes out, when your second crew arrives and somebody is doing the shocks, someone’s doing the CPR and somebody has got the laryngeal mask airway. Somebody put a cannular in and he’s given the adrenaline every three to five minutes. Then eventually you can step back and start looking at the Hs and Ts.

So this is what your trainer will be expecting from you at some point in this demonstration that you will be doing. So just to say as well, these are the advanced life support guidelines, level two of the Australian Resuscitation Council. Okay. Hs and Ts. Number one, hypoxia. So the patient can actually come back after this cardiac arrest situation if you address hypoxia. So when you we say address hypoxia in the context of cardiac arrest, what we mean is that you’ve tipped the head back and you’ve used the BVM and you’ve got a laryngeal mask airway in and there’s no signs of a tension pneumothorax and you’re doing everything possible to administer oxygen. Then once you’ve done that, you move down to hypovolemia. You’ll look for catastrophic hemorrhage, you address that first. You consider that there might be internal hemorrhage, but there’s not too much that you can do about that. Hypo, hyperkalemia or metabolic disorders. Now that’s really, hyper and hypokalemia is high levels of potassium, which you can’t do anything about.

Metabolic disorders the only thing that you can do is measure the blood sugar levels and provide Iv Glucose if there’s signs of hypoglycemia. Hypo or hyperthermia so you can take a body temperature and if they’re cold you can put a blanket on them. If they’re hot, you can cut their clothes off, which we’re hoping you’ve already done it at this stage anyway. Tension pneumothorax, you can watch the chest rise and fall as you’re bagging the patient. You can also have listen with a stethoscope as you’re bagging one, two. If that’s normal then great, if there is a sign of a tension pneumothorax you have to decompress the chest using a 14 gauge cannula. Cardiac tamponade is not something we can do about. Cardiac tamponade is when you have blood inside the pericardial sac and it stops the heart from beating.

Toxins can be anything that’s in abundance to overwhelm the body systems. I think it can include legal or illegal drugs and even certain types of bacteria. Again, the only thing you can do is check the temperature. If the temperature is high, that could be an indication for some kind of septicemia. And you can check the pupils for pinpoint pupils as well. And thrombosis, which is a sign of a blood clot. And again, the only thing you can use are things in the environment such as medications or medical history. So not a lot you can do about thrombosis. So we’ve talked through the Hs and Ts, your tutor will expect to see some kind of acknowledgement of these in the workshop.

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