Remembering MONA for Heart Attack

I’ve always remembered the treatments for Heart Attack as the mnemonic MONA. But I heard that the American Heart Association (AHA) has changed their recommendation and now are recommending Aspirin as the first treatment to give for Heart Attack. How does that affect MONA?

~ Submitted by Paul

First, for those who don’t already know, MONA is a mnemonic that stands for:  Morphine, Oxygen, Nitrates, and Aspirin.  These are the 4 primary interventions that are performed when treating a patient with Heart Attack/Myocardial Infarction (MI).  However, what many students don’t realize is that MONA does not represent the order in which you should administer these treatments as a nurse.   It is a mnemonic intended to help you remember the components of MI treatment, not the prioritization of them.

In a medical setting, when you are treating a patient with MI, you give Oxygen first, then nitrates, then aspirin, then morphine.  The rationale is that we have two therapeutic goals:  1) decrease cardiac oxygen demand (usually by slowing the heart rate), and 2) increasing available oxygen.

So the Oxygen is always given first to start increasing the amount of available oxygen in the blood.  Then nitrates are given to vasodilate blood vessels, which allows more room for blood to pass through.  Then the aspirin is given to help “thin” the blood by breaking down platelet to get rid of any clots in the coronary arteries that might be contributing to the MI.  Finally, morphine can be given to reduce pain and anxiety, which in turn helps decrease oxygen demand.  Morphine also slows the heart rate and has a vasodilating effect, but it’s usually only given if the nitrates did not relieve the chest pain or if the patient is having anxiety.

You probably heard the “aspirin comes first” recommendation because if a patient calls 911 for chest pain, they will be instructed to take an aspirin while waiting for the ambulance.  But as soon as the EMTs arrive, I guarantee that they will slap on that Oxygen mask! So always look at the context of the question if you see something like this on an exam. If the patient is in a medical setting, you will probably be doing Oxygen first. If they are in a non-medical setting, then it might be nitrates first (if the patient has them available for angina episodes), or aspirin first if nitrates are not available.


  1. Matias says

    This post is misleading. The AHA no longer recommends morphine, or oxygen unless indicated. Morphine has been shown to increase mortality, probably by masking symptoms of ongoing ischemia, and should be reserved for select patients. Over-oxygenation can also be harmful, and should be reserved for patients with O2 sats below 94%, or 90% (depending on the source you look at). If paramedics “just slap on that Oxygen mask” without checking O2 sats and titrating accordingly, they are doing the patient a disservice. Additionally no studies that I know of have shown a benefit to O2 in ACS. As long as it is used judiciously, however, it probably can’t hurt.

    • says

      Thanks for the feedback, I will have to look into that further and see what their new recommendations are.

      As always, we would want to assess each patient based on their individual needs before deciding what care to give. But in order to be considered a safe, effective, beginning nurse for nursing school or NCLEX purposes (aka testing purposes!), MONA recommendations have traditionally been the way to go.

    • Ben Ruckman says

      I would like to correct your correction.

      As reguards to O2. O2 in the prehospital setting is well, like fish to water. The “HARM” that O2 toxicity and depriving a pt of their hypoxic drive is very unlikely and limited by their time on a 100% NRB. If the pt loses their hypoxic drive the EMTS/Pararmedics can simply remove the mask and breath for them (thats the primary skill for EMS).

      Most studies that claim “Over oxegenation” causes harm are studies based in the ER/ICU when a very busy nurse forgets to turn down the flow rate or pull off the NRB valves. I am a current Paramedic Student and just talked to the Medical Director of the county my school is in. He explained that 60min.

      Oh and yes we “slap O2″ on almost all pts without doing a blood gas draw. If they needed the O@ they can now say/indicate thank you, if they didn’t need it you get a “what are you doing”? and we can simply take it off. Most people who call 911 want help and mearly giving them O2 will help to calm them down (pacibo effect).

      Happy breathing!!!

      • Ben Ruckman says

        Some how my post is missing portions.
        addendum; 100% O2 via Nonrebreather Mask for 60min has been documented in the clinical/hospital setting to cause harm.

        EMTs/Paramedics are trained (Hopefully) to breath on behave of someone who cannot.
        So if we need to take over for them, we will.

  2. DR N says

    Matias is incorrect. MONA is still the approved, evidence-based emergency-dept. treatment protocol for non-STEMI ACS. We use it in our ER, and we are an accredited chest pain center.

    Oxygen “rests” the heart, and during an acute condition, O2 is absolutely NOT harmful, and will reduce pain during an ischemic episode. Matias doesn’t know of any “studies” because he is apparently NOT in the field, otherwise he would know this is solid, evidence-based practice. Look up ENA’s position on this. – RN in level I trauma center.

    • James says

      Wow, RN, that’s some scary stuff.

      Oxygen is NOT indicated in the current AHA ACLS protocols — you really need to stay on top of your continuing education!! Check out the top of page 18 here:

      Now , to some of your claims:
      – “Oxygen ‘rests’ the heart” — nope, not true at all, not sure where you pull the science on this one. During an AMI, oxygen demand by the heart is actually LOWER than at baseline (See the article in Respiratory Care in January 2013), this has been supported by several studies

      – “O2 is absolutely NOT harmful, and will reduce pain during an ischemic episode” – nope and nope. It CAN be harmful, in fact, there are many studies showing the hyperoxemia induced by supplemental O2 causes worse outcomes. It has absolutely no effect in reducing pain because it won’t correct the ischemia — blood isn’t properly reaching the ischemic area, so it doesn’t matter how much oxygen the blood has in it.

      Matias was ABSOLUTELY CORRECT! You should check your studies and consider what you claim is evidence-based practice. Sounds like you’re a lemming nurse

  3. Student nurse says

    Hi Nicole
    Did you do any research on this relating to the feedback that Matias and Dr N gave you? I am a third year nursing student looking for a topic for my thesis and if what Matias says is true, this could be a fantastic topic. I will do some research now but let me know if you found anything if you don’t mind.
    Kind regards

    • says

      I’ve only done a very minimal review, but apparently in 2010 the Emergency Cardiac Care Guidelines changed to emphasize the use of Nitroglycerin and Aspirin first, and Oxygen only if sats are below 95%. Morphine was supposedly associated with increased morbidity as Matias said, but I haven’t read the original article to see what those statistics were. Please let me know if you choose this topic and what you find out!

  4. WV RN says

    ” Emergency medical services providers administer
    oxygen during the initial assessment of patients with suspected
    ACS. However, there is insufficient evidence to support its
    routine use in uncomplicated ACS. If the patient is dyspneic,
    is hypoxemic, or has obvious signs of heart failure, providers
    should titrate oxygen therapy to maintain oxyhemoglobin
    saturation ≥94%. Morphine is indicated in STEMI when chest
    discomfort is unresponsive to nitrates. Morphine should be
    used with caution in unstable angina/non-STEMI, because
    morphine administration was associated with increased
    mortality in a large registry” – Highlights of the 2010
    A m e r i c a n H e a r t A s s o c i a t i o n
    Guidelines for CPR and ECC, retrieved from

    As a practicing RN, my facility is also still using MONA!

    • says

      Thanks for the comment! It’s starting to sound like MONA is still the commonly used method for treating clients with chest pain, even though it is not completely supported by research anymore. Very interesting!

  5. BK says

    James Im curious to know your background in HC? Just read the posts while studying for my NP and Im curious as to your EB base?

  6. Grad Student says


    I’m also curious as to why you make these statements? You and Matias are both incorrect to my knowledge. Paramedics by chance? I’m really thinking you’re wrong and by spreading false information, actually causing problems.

    • RobS says

      They are both absolutely correct, you are absolutely incorrect. The Cochrane Library released a very large meta analysis in 2010 that showed the giving oxygen to those suffering an AMI who did not have low blood oxygen levels increased mortality by over 20%. AS a result beetween 2011 and 2012 the AHA and most other international AMI guidelines have removed the recommendation to give oxygen unless the patient has low blood oxygen levels.
      Cabello, J. (2010). Oxygen therapy for acute myocardial infarction (Review). The Cochrane Library

  7. RN student says

    Hello everyone,
    I’m an LPN graduating with my RN in December. When reading the post, it says that ASA is used to “thin” the blood break down the platelets. Correct me if I’m wrong, but doesn’t ASA decrease platlet aggregation(sticking together) or making them slippery so they don’t stick together, I didn’t think it was a thinner? Just asking
    Thank you

  8. Prof Tom quinn says

    I’m one of the authors of the Cochrane review. We concluded that oxygen may be harmful in AMI but what was needed was a large randomised trial, and my colleagues in Sweden are halfway through a major RCT, so we may soon have a definitive answer.

    In the meantime, guidelines internationally (US, Europe, Australasia) have advised caution with this therapy. There is abundant evidence from animal studies suggesting mechanisms of harm, and we discuss these in our updated Cochrane review.

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