Improved outcomes from nitro

[rock_shoes]

As far as NTG actually reducing the size of the infarct, I agree with Kiwi. I do not think that NTG is as beneficial as people think. However, I think where we make our money is by preventing further infact, and reducing overall oxygen consumption, (which has been proven to have a positive effect on patient outcome) (I will try to find the study).

I think a couple of points are worth considering here.

Firstly, it is proven that providing pain control reduces patient morbidity. I think we can all agree that, provided its use is not contraindicated, Nitro has a role to play in controlling a cardiac chest pain patient's pain. The question in this case becomes whether or not using another method of pain control would be more effective.

Secondly, Nitro's mechanism of action can't help but make a difference. Reducing pre-load reduces the heart's required force of contraction. That's just physics and the human body is not exempt from the laws of physics. If an occluded coronary artery dilates there is also potential for said occlusion to move further down that coronary artery. The further down an occlusion moves the less myocardium will experience a restriction in blood flow. I think the better question regarding this particular feature of the drug is whether or not slowing cellular metabolism would have more of a beneficial effect.

[Richard B the EMT]

I'll just throw local protocols into the mix...

FDNY EMS EMTs are authorized, when not contraindicated, to administer 2 chewable baby aspirin, or assist a patient in taking their own Nitro pills.

FDNY Paramedics are authorized, when not contraindicated, to administer Nitro pills, usually carried as on board stock.

[Kiwiology]

Firstly, it is proven that providing pain control reduces patient morbidity. I think we can all agree that, provided its use is not contraindicated, Nitro has a role to play in controlling a cardiac chest pain patient's pain. The question in this case becomes whether or not using another method of pain control would be more effective.

Secondly, Nitro's mechanism of action can't help but make a difference. Reducing pre-load reduces the heart's required force of contraction. That's just physics and the human body is not exempt from the laws of physics. If an occluded coronary artery dilates there is also potential for said occlusion to move further down that coronary artery. The further down an occlusion moves the less myocardium will experience a restriction in blood flow. I think the better question regarding this particular feature of the drug is whether or not slowing cellular metabolism would have more of a beneficial effect.

That is basically what I was thinking more-or-less but didn't quite wrap my head around it sufficently to type it out

[Brandon Oto]

Thanks to those who posted studies.

This one seems good, though somewhat dated http://www.ncbi.nlm.nih.gov/pubmed/8087820?itool=EntrezSystem2.PEntrez.Pubmed.Pubmed_ResultsPanel.Pubmed_RVDocSum&ordinalpos=30

If anyone can drum up research or academic access to these ones

http://www.ncbi.nlm.nih.gov/pubmed/19681463?itool=EntrezSystem2.PEntrez.Pubmed.Pubmed_ResultsPanel.Pubmed_RVDocSum&ordinalpos=11

http://www.ncbi.nlm.nih.gov/pubmed/18347964?itool=EntrezSystem2.PEntrez.Pubmed.Pubmed_ResultsPanel.Pubmed_RVDocSum&ordinalpos=57

http://www.ncbi.nlm.nih.gov/pubmed/19445779?itool=EntrezSystem2.PEntrez.Pubmed.Pubmed_ResultsPanel.Pubmed_RVDocSum&ordinalpos=19

http://www.ncbi.nlm.nih.gov/pubmed/19445778?itool=EntrezSystem2.PEntrez.Pubmed.Pubmed_ResultsPanel.Pubmed_RVDocSum&ordinalpos=20

that would be very helpful I think.

I was charmed to see that Viagara might be better than nitro...

[Brandon Oto]

Just saw an older thread that treated with a similar topic. Some good stuff there. http://www.emtcity.com/index.php/topic/8456-evidence-based-use-of-nitro/

[Brandon Oto]

I was able to get my hands on the fulltext of one of the studies I linked (http://www.ncbi.nlm.nih.gov/pubmed/18347964?itool=EntrezSystem2.PEntrez.Pubmed.Pubmed_ResultsPanel.Pubmed_RVDocSum&ordinalpos=57). PM or email me (brandon@degreesofclarity.com) if anyone wants a copy; I think this falls within fair use.

This one seemed to find from the available evidence that nitro generally improves short-term surrogate endpoints (reduced infarct size, for instance), but the overall long-term mortality rates are either unchanged or very slightly improved. Quote:

From the available data summarised above, it can be

concluded that nitrates mechanistically have potentially

beneficial roles in the management of acute myocardial

infarction and that surrogate endpoints such as reduced

infarct size and improved residual left ventricular function

would support their use. However, the most optimistic

appraisal of the mortality data from both randomised and

observational studies would suggest only a small mortality

benefit. Concordantly, current myocardial infarct guidelines

[19, 20] only recommend their use for the treatment of

ongoing ischemic chest pain. For more extensive recom-

mendations in the use of nitrates in myocardial infarction,

several unanswered questions need to be addressed.

Some of the research was done with IV nitro but I doubt this matters too much. The evidence does seem to suggest, though, that early nitro is the only nitro that could possibly matter, which tends to mirror our current prehospital usage. (For MI, that is; angina is a separate issue and nobody really disputes its benefit there.)

[Levi]

There's mixed evidence on nitroglycerin use. It's one of those things that make sense if you understand its pharmacology, but research doesn't show much promise. The most important mechanism for nitroglycerin use is reduction in preload, and not coronary vasodilation. If you have an area of ischemia or infarction, the coronary arteries to that region are already maximally dilated anyway. Because of that, vasodilation of other branches may have two outcomes. One, you may worsen their ischemia by dilating alternate coronaries and allowing blood to travel by the path of least resistance, effectively stealing more blood away from that infarcting area. Alternatively, you may dilate a collateral branch somewhere downstream which does allow slight reperfusion of that region of myocardium.

[Dustdevil]

God, how wonderfully refreshing it is to see an EMT pursuing a deeper, intelligent understanding of complex issues!

Plus 10 on this thread.

[Brandon Oto]

Thanks DD. I'm just a nerd is all.

What's really obnoxious is how hard it is to get access to academic databases once you leave school...

Anyway, great post Levi. I guess we can probably agree that nitro is likely worth doing, give it if you've got it, but not something you'd call a high priority, and certainly don't give it in preference to other care (such as ASA).

Although now I'm waiting on the emergence of sublingual Viagra...

[Levi]

Thanks DD. I'm just a nerd is all.

What's really obnoxious is how hard it is to get access to academic databases once you leave school...

Anyway, great post Levi. I guess we can probably agree that nitro is likely worth doing, give it if you've got it, but not something you'd call a high priority, and certainly don't give it in preference to other care (such as ASA).

Although now I'm waiting on the emergence of sublingual Viagra...

Yeah I definitely agree that it is worth giving, although with no proven benefit you might want to be cautious with its use under some circumstances. Funny enough, they are actually giving Viagra to people (including women) with pulmonary hypertension!