Without evidence of benefit, an intervention should not be presumed to be beneficial or safe.

- Rogue Medic

Potentially Reversible Causes of Cardiac Arrest – Another, Better, Mnemonic

In the comments to Potentially Reversible Causes of Cardiac Arrest – Arrhythmia, Jeff B of JB on the Rocks wrote,

I use COLD PATCH rather than Hs/Ts…

Cold (hypothermia), Oxygen deficit, ‘Lytes, Drugs, Pulmonary Embolus, Acidosis, Tension Pneumo, Cardiac Tamponade, Hypovolemia.

I have been thinking about this for a bit, because the eD of the mnemonic I was using (PATCHeD) includes stuff that I think is important. My hesitation was not over the value of his mnemonic, it is much better than mine, just how to include the little, but not insignificant parts that I cover with eD. I was thinking that COLD PATCHeD would work, but just doesn’t feel right. It is the best I have been able to come up with. I will cover all of these in more depth, over the next month or so. Since the eD part is last, they will be covered last. The e part belongs at the beginning, since it is a reminder to cover the basics. The remaining D, since COLD moves on D farther up, is a way to transition to postresuscitation care, so it belongs at the end.

COLD reminds you that the C is for hypothermia – being very cold, sometimes we forget the obvious in resuscitation attempts, so it doesn’t hurt to put extra reminders in a mnemonic.

O for Oxygen deficit or hypoxia.

L for Lytes. This works better as a mnemonic for the in hospital crowd, but there is nothing wrong with getting EMS to think more about electroLytes. Hypokalemia and Hyperkalemia – too little and too much potassium.

D for Drugs (OD or OverDose, poison, wrong drug, wrong dose, . . .).

This does an excellent job of making it easier to remember each of the Hs, by changing them to something more memorable.

Jeff B comes up with some excellent ways of teaching all things that fall into the emergency medical field. My only complaint is that he doesn’t write about these enough on his JB on the Rocks blog.



  1. Good one! I love mnemonics.

  2. ERP,Thank you, I feel the same way about them when they work. That is why I borrowed this one that is better than the one I have been using for so long.