Acute MI

Virgo_RN, BSN, RN · Dec 15, 2009

You tell me....

Emergency RN · Dec 15, 2009

Well, MORPHINE is probably the drug of choice over a nitrate, and can be used judiciously if the pressure isn't too low. MORPHINE can be reversed with NARCAN, have an analgesic effect, AND vasodilate to drop preload and reduce work for the heart. A nitrate like NITROGLYCERINE SL would only work to vasodilate and reduce preload (thus relieving pain). If the NTG drops their pressure even more, you can't take it back with NARCAN.

Also, one needs to investigate the mechanism of what is actually causing the hypotension; is it pump failure or volume depletion, dehydration? IV fluids may remedy the low BP, provide better cardiac filling and output via a Frank-Starling mechanism, and ultimately decrease heart rate. This may also have an overall effect on pain. Replacing volume may also allow increased doses of MORPHINE as blood pressure is better managed.

medicrn13 · Dec 15, 2009

How low are we talking? Mid-90s? If so then nitrates could still be used.

I'd be careful giving fluids to anyone with an acute MI until the type and extent of the infarct are known. If BP is already low, you could be looking at a rather large infarct that has impaired the heart's pumping ability, adding more fluid will only strain the heart more. As well, if the patient is suffering a right sided infarct, adding to preload with IVF will cause more problems.

If you suspect your pt is having an acute MI, or what's more you KNOW he/she is, getting them definitive treatment in the form of reperfusion therapy is the BEST way to relieve their pain.

GilaRRT · Dec 15, 2009

How low are we talking? Mid-90s? If so then nitrates could still be used.
I'd be careful giving fluids to anyone with an acute MI until the type and extent of the infarct are known. If BP is already low, you could be looking at a rather large infarct that has impaired the heart's pumping ability, adding more fluid will only strain the heart more. As well, if the patient is suffering a right sided infarct, adding to preload with IVF will cause more problems.
If you suspect your pt is having an acute MI, or what's more you KNOW he/she is, getting them definitive treatment in the form of reperfusion therapy is the BEST way to relieve their pain.

Yes and no regarding fluids as the localization of the MI will be very important. A hypotensive anterior/septal MI will have different implications than an inferior wall MI. In the setting of inferior wall MI, you can expect ~30-50% of these patients to have a concomitant right ventricular infarct (RVI). With RVI, preload reduction will be the last thought to consider, as increasing preload is the way to essentially "force" blood through the right ventricle. This is commonly done with fluids. Clearly, an MI involving significant portions of the LV will have much different implications and treatment modalities. This is also why people need to be aware of alternative lead placement strategies to locate other areas of infarct. posterior and right sided leads being the most common, also called a modified 15 lead ECG.

With that, people seem so caught up on morphine. I am not sure why this is so? There are highly effective agents that are known to have little effect on hemodynamics. Why not consider fentanyl for borderline or hypotensive patients? Fentanyl, unlike morphine is not typically associated with histamine release and hypotension, and thus should be a consideration for a potentially compromised patient.

medicrn13 · Dec 15, 2009

Ah...wow I can't believe what I wrote lol.

Emergency RN · Dec 16, 2009

Ah...wow I can't believe what I wrote lol.

Yeah, we all know you meant left sided, but I gave you a kudo anyways for running him to the cath lab quickly

meandragonbrett · Dec 16, 2009

With that, people seem so caught up on morphine. I am not sure why this is so? There are highly effective agents that are known to have little effect on hemodynamics. Why not consider fentanyl for borderline or hypotensive patients? Fentanyl, unlike morphine is not typically associated with histamine release and hypotension, and thus should be a consideration for a potentially compromised patient.

Because everybody had MONA drilled into their brain during nursing school! Fentanyl is probably the most underrated opiate that we use in the hospital setting today. Everybody always screams "you're gonna drop the blood pressure" "Turn the fentanyl gtt off, they JUST now became hypotensive" etc. We need some serious education on the mechanism of action of opiate related hypotension! Fentanyl is a great drug in those borderline hypotensive patients, patients on pressors, or even patients are are hypotensive but still need a touch of opiate for pain control.

GilaRRT · Dec 16, 2009

I wanted to expand on the hypotension concept because so many nurses have a poor understanding of ACS localization and the implications of the said localization. I agree, many people are told MI = MONA + PCI and thats the end of the story.

If only we would spend more time teaching future nurses things that matter like real pharmacology instead of hours upon hours of nursing diagnoses. I digress however.

The fentanyl statement is correct. In fact, people who have cardiac surgery experience may not be surprised when I say fentanyl in used in cardiac inductions. However, instead of mcg, these patients are often given mg of fentanyl.

marlboroking · Dec 16, 2009

Thanks for the comments.

Reading from the above posts it seems like fentanyl may be a better alternative than morphine for patients with low blood pressure?

I should have posted this scenario in my original post.

My Scenario is this: A patient is having and MI, has a low blood pressure (like 70/40), and fluid is contraindicated and yet they are awake, alert, oriented and complaining of severe pain. PCI is what's needed, but while you are waiting for the cath team what could you give?

I see that some of you think that fentanyl is a good choice. So I am thinking that fentanyl won't affect your blood pressure as much as morphine, correct? Granted every patient is different.