# Nitrates in ACS.



## Melclin (Jul 19, 2011)

At what point in a cardiac chest pain job do you switch from nitrates to morph/fentanyl? 

I see a variety of opinions amongst medics here. Some give an initial 300mcg Nitro dose and put the bottle away in favour of continuing with morphine. Others snow pts with nitrates dropping their pressure as far as they can within guideline limits while being very careful with the morphine. Most are somewhere in between. 

What guides you in finding that sweet spot where you have maximum preload/afterload reduction without going to far and increasing o2 demand when you've dropped things too much and you end up with a relflex tachy and increased sympathetic outflow?


----------



## sir.shocksalot (Jul 19, 2011)

Personally, if at two to three doses of NTG there is no improvement in their pain then further doses probably won't help. Getting someone's cardiac chest pain under control is more important to me than having some benefit from decreasing afterload and decreasing preload in the prehospital setting. Last study I read said you only need to drop systolic by 10 mmHg for benefit, which usually is done with one or two tabs.

If the nitro helps their pain then I know I can fix the problem by further dilating coronary vessels. Then I'll keep giving NTG until their pain resolves or pressure gets too low.


----------



## the_negro_puppy (Jul 19, 2011)

In ACS type pain we give GTN every 5 minutes as long as the pain symptoms exist and not contraindicated byt BP or HR.

Generally once we suspect ischaemic chest pain we go-

1 X GTN
1 x Aspirin
1 X GTN + IV access
Morphine + GTN repeated while pain symptoms exist.


I know its common practice in the US to gain IV access before giving nitrates but here everyone generally gives  one 400 mcg spray and evaluates the effects along with an aspirin before/while starting an IV. A 6 lead at least is done before any drugs are given, and any inferior changes would probably see a 12 lead with V4R done & caution before using any nitrates.


----------



## Melclin (Jul 19, 2011)

sir.shocksalot said:


> Getting someone's cardiac chest pain under control is more important to me than having some benefit from decreasing afterload and decreasing preload in the prehospital setting.
> 
> If the nitro helps their pain then I know I can fix the problem by further dilating coronary vessels. Then I'll keep giving NTG until their pain resolves or pressure gets too low.



The reduction in pain is related to a reduction in preload and afterload. While nitrates do appear to cause some coronary artery dilation, my understanding is that it is unlikely that it has any affect on pain.

What contraindicates nitro for you?



the_negro_puppy said:


> In ACS type pain we give GTN every 5 minutes as long as the pain symptoms exist and not contraindicated byt BP or HR.
> 
> Generally once we suspect ischaemic chest pain we go-
> 
> ...



I generally like to cannulate first where their BP is borderline or they are beta blocked, but otherwise GTN first.

Where do you go after that first Morphine + GTN. Is it one dose of morph and continued GTN OR a third and final GTN/morphine from now on OR continued doses of both? 

Where do you take their perfussion status? A pt who has a normal bp of 170/95 probably doesn't benefit from ending up 105/55 with a reflex tachy, looking pale, colder extremities. Is anyone looking at fluid in these situations?


----------



## Smash (Jul 19, 2011)

Melclin said:


> Where do you take their perfussion status? A pt who has a normal bp of 170/95 probably doesn't benefit from ending up 105/55 with a reflex tachy, looking pale, colder extremities. Is anyone looking at fluid in these situations?



It depends entirely on the patient, there is no one size fits all treatment pathway. If the patient is a hyperdynamic anterior MI with a booming BP I might continue nitrates in conjunction with morphine to reduce workload. If the BP is ok but pain persists there is probably no point in continuing nitrates, it's obviously not achieving anything. If they have a condition that is going to impair their ability to modify stroke volume or they are preload dependent I will be very cautious or even hold off nitrates altogether. 

There is no proven mortality benefit with nitrates, so while I appreciate the physiological rationale behind using them, I'm not too fussed if I have to put them aside either. I'm aware of the concerns with morphine administration, but I'm skeptical about the CRUSADE registry: it raises more questions than it answers. 

I think the seesawing approach of giving fluids to raise preload, then nitrates to reduce preload is a bit absurd. The degree of coronary artery dilation brought about by nitrates in the patient with occluded, stenosed and calcified arteries is probably not significant, so I certainly don't hang my hat on that having a great effect. 

If I have caused a significant fall in BP through administration of nitrates (it does happen, although with a cautious approach it should be pretty rare) then I'll stop the nitrates and wait for them to wear off. Fluid won't help that much in that setting, so a pressor may be needed, such as phenylephrine or metaraminol. It doesn't often come to that though.


----------



## MrBrown (Jul 19, 2011)

Once we suspect ischaemic chest pain really, give aspirin then try GTN

We only repeat GTN if it is clearly associated with improvement, repeated GTN in the absence of improvement is inappropriate


----------



## Melclin (Jul 19, 2011)

Smash said:


> It depends entirely on the patient, there is no one size fits all treatment pathway. If the patient is a hyperdynamic anterior MI with a booming BP I might continue nitrates in conjunction with morphine to reduce workload. If the BP is ok but pain persists there is probably no point in continuing nitrates, it's obviously not achieving anything. If they have a condition that is going to impair their ability to modify stroke volume or they are preload dependent I will be very cautious or even hold off nitrates altogether.




[/QUOTE]

What conditions give you cause to worry stroke volume?



> We only repeat GTN if it is clearly associated with improvement



What kind of doses are we talking here? What if the pt simply requires a little more. Esp those who are GTN tolerant.


----------



## sir.shocksalot (Jul 19, 2011)

Melclin said:


> The reduction in pain is related to a reduction in preload and afterload. While nitrates do appear to cause some coronary artery dilation, my understanding is that it is unlikely that it has any affect on pain.
> 
> What contraindicates nitro for you?


Other than phosphodiasterase inhibitors within the last 24-48 hours, nothing. I should have been more clear (hard to get my point across on my phone). What I mean is that after a few doses of NTG without change in pain level my priority shifts to pain control instead on NTG dosing.

My personal view is that after one or two shots of NTG you should be able to figure out if the chest pain is anginal or not, if it doesn't reduce the pain then it's probably not angina and should probably switch gears to pain meds and get that under control and start heading to somewhere with a cath lab. If the NTG does work and relieve the pain, well then, mystery solved (kinda). 

I should say that most of my thought process looks like this.
Chest Pain -> 12 lead, ASA, NTG (after IV)
Pain relief with NTG?
Yes-> More NTG
No-> Pain meds
More time on Hands? -> NTG and 2nd 12-lead

I don't work somewhere where I have a lot of time to play around, so often 2-3 doses of NTG is about as far as I can get.

Also in regards to the physiology of the pain relief, my understanding is that the pain is reduced when the heart stops being ischemic. That being said, knowing the desparity in our eductation, I would imagine that you are correct about the reduction in preload/afterload. I will sure look it up tonight. ^_^


----------



## MrBrown (Jul 19, 2011)

What kind of doses are we talking here? What if the pt simply requires a little more. Esp those who are GTN tolerant.[/QUOTE]

0.4 or 0.8mg


----------



## thegreypilgrim (Jul 22, 2011)

I would rather use TDD nitrates on someone I suspect of presenting with ACS. It seems like a more controlled regimen rather than the SL spray we carry. With the SL administration, though, if it hasn't appreciably reduced the patient's discomfort in 2-3 doses there's probably no point in continuing it.

Like Smash rather comprehensively pointed out, nitrates are not proven to reduce mortality so I wouldn't worry about holding off on it and switching to morphine.


----------



## Tommerag (Jul 26, 2011)

Our protocols say we have to give 3 doses of nitro before we can switch to morphine.


----------



## Shishkabob (Jul 26, 2011)

We have SL nitro, and Tridil for our nitro drip.  If the SL nitro has been working and decreasing the pain, I will start a Tridil drip.

If it hasn't, I go to Fent.


----------



## ah2388 (Jul 26, 2011)

Generally, 

Chest Pain with suspected cardiac etiology receives ASA and a 6/12 lead almost immediately.

If positive for stemi, 1 SL NTG followed by IV access, then Tridil, typically somewhere in the ballpark of 10mcg/min titrated q 5 up to ~200mcg/min..

this given in conjunction with analgesia as appropriate.

More importantly, transport to a facility with PCI capability.

If not positive for stemi, SL NTG and analgesia PRN to relief of pain.

Oftentimes I don't administer any more than 3 SL NTG sprays..however "it depends"


----------



## MrBrown (Jul 26, 2011)

ah2388 said:


> If positive for stemi, 1 SL NTG followed by IV access, then Tridil, typically somewhere in the ballpark of 10mcg/min titrated q 5 up to ~200mcg/min..
> 
> If not positive for stemi, SL NTG and analgesia PRN to relief of pain.
> 
> Oftentimes I don't administer any more than 3 SL NTG sprays..however "it depends"



Depends on what?

GTN does not really have a role in STEMI and repeated GTN is inappropriate unless associated with improvement.


----------



## Shishkabob (Jul 26, 2011)

Pretty sure his "depends" was based on the "I don't just do cook-book medicine and have a hard limit of what I will do, I take every call and every patient individually" type of reply....


----------



## MrBrown (Jul 26, 2011)

Linuss said:


> Pretty sure his "depends" was based on the "I don't just do cook-book medicine and have a hard limit of what I will do, I take every call and every patient individually" type of reply....



Fair enough that is what Brown likes to hear, however Brown is interested as to how this bloke says he doesn't usually give more than 3 doses of GTN

Does he only give 3 doses of GTN to somebody when associated with improvement?

Does he give 4 doses of GTN to somebody who has no improvement with GTN?


----------



## Shishkabob (Jul 26, 2011)

I'm going to assume he's like me... if NTG works after 3, Tridil (nitro drip) is the next step instead of doing the up/down/up/down of SL nitro.

However, I'm probably not going to start a Tridil drip if I've seen no benefit from administering nitro beforehand.


----------



## ah2388 (Jul 26, 2011)

Dr. Senor Grandmaster Brown,
I intended to convey that 3 is my "benchmark" trial for nitrates.  I am willing to admit that I have no "fact based" evidence to support why 3 is my benchmark, I suppose that through trial and error, I have found that by the third SL nitro, the pt is either going to be receiving the therapy well, or they arent.  If they are, the medication is often continued assuming no contra indications exist.  Whether it is SL or IV is going to depend largely on the receiving facility, as some physicians would prefer that Tridil is not initiated by ambulance personnel.

A pt who is responding well to nitrates, will receive more nitrates, and possibly supplemental IV analgesia as well.

A pt who is not responding well to nitrates, will no longer receive nitrates.

The first paragraph of this statement is not to say that I have never or will never given two NTG and discontinue..1 spray etc.

hopefully this explains my position somewhat


----------



## MrBrown (Jul 26, 2011)

Sounds pretty good ... and please, Dr Senor Grandmaster Brown sound so formal, Your Excellency will suffice


----------



## RealMedic (Jul 29, 2011)

*ACS AMI pdf*

Here's a quick nice review from a gent in NM. 
RM


----------



## Smash (Jul 30, 2011)

RealMedic said:


> Here's a quick nice review from a gent in NM.
> RM



I presume that was aimed at a BLS level, however there are quite a few things that aren't really that flash in this presentation.

The discussion on O2 seems to focus on the patient who is ventilated (may cause lung damage at high pressure, may cause ventilator dependency) ignoring the potential harm that comes from O2 given to ACS patients and the lack of rationale for it's use.

The bizarre insistence on increasing preload in RVI infarcts with fluids (a good idea), only to reduce it with nitrates (a very bad idea) gets trotted out again.  Strangely it seems that reducing preload with beta-blockers is bad, but reducing it with nitrates is good.  Odd. 

I did enjoy the slides that state that the beneficial effects of morphine/fentanyl is pain relief, but the downside is... pain relief (and of course QTc elongation - I presume they mean prolongation)   and I had to laugh out loud at plavix being "well tested" with a "well established patient safety profile"!

The author should probably also review the actions of heparin.


----------



## RealMedic (Jul 30, 2011)

*Reply to Smash on ACS/Nitrates post*

Hi Smash, Yeah well the title "quick review" was a dead give away for it not going into great detail for ya. Glad you enjoyed it though and your opinions and thoughts relating to the presentation/material are interesting as well. 
Be safe friend!
RM


----------

