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

- Rogue Medic

Safety and Effectiveness of Field Nitroglycerin in Patients with Suspected ST Elevation Myocardial Infarction

Mon, 12 Aug 2019 17:46:11 -0400 by
 

Is prehospital use of NTG (NiTroGlycerin; GTN GlycerylTriNitrate in Commonwealth countries) safe for treating prehospital suspected STEMI (ST segment Elevation Myocardial Infarction) patients?

The evidence is limited, but does not suggest that prehospital NTG produces enough harm to discourage use in suspected STEMI. These researchers looked at the emergency department assessments of patients following prehospital NTG for suspected STEMI.  

Despite the theoretical risk, the limited retrospective studies of NTG in the prehospital setting for multiple indications suggest that the medication is safe.(10-13) However, with regard to NTG use for STEMI, the AHA International Consensus on Cardiopulmonary Resuscitation and Emergency Cardiovascular Care concluded that there was not enough evidence to determine the benefit or harm of out-of-hospital use of NTG.(14) Given the high false positive rates for STEMI identified in the field, an additional concern is that many patients treated with NTG for presumed STEMI will ultimately have an alternate etiology for their pain.(15, 16) Therefore, it is not clear that the benefits outweigh the risks of administering NTG to all patients with suspected STEMI in the field.[1]
 

This paper helps to show the safety of prehospital NTG for suspected STEMI, providing evidence that blood pressure changes were similar in suspected STEMI patients with an SBP (Systolic Blood Pressure) of 100, or higher, regardless of whether they were treated with NTG. The study is a retrospective chart review, so we do not know why some of the patients were not treated with NTG.

One reason mentioned, but not discussed, is that only 22% (96 of 440) suspected STEMI patients not treated with NTG are documented to have had pain, but there is no information on the type of pain or other cardiac symptoms of the patients. Were the paramedics avoiding treating atypical chest pain, such as pressure, heaviness, gastric discomfort, difficulty breathing, et cetera? We do not know. Was only chest pain being documented, rather than shoulder, or arm, or jaw, pain? We do not know. Did the pain resolve prior to EMS arrival? We do not know. Were the paramedics correctly recognizing when the machine interpretation of the ECGs (ElectroCardioGrams) were wrong? We do not know.

The median Initial Pain Score is documented as 8, with an IQR (Inter-Quartile Range) of 5-9 for those treated with NTG. For those not treated with NTG the Initial Pain Score is documented as 0, with an IQR of 0-0. We do not know the Initial Pain Score of those who did have pain, but were not treated with NTG. All of these patients were in an IQR that was not documented in the paper. The good news is that the suspected STEMI patients not treated with NTG act as a control group, although possibly with important differences that are not discussed in the paper.

Click on the image of the LA County protocol to make it larger.[2]

What about the 17% of suspected STEMI patients with SPB <100 mmHg who were treated with NTG?

Was medical command (California has certified MICNs [Mobile Intensive Care Nurses] providing medical command on the radio, with physicians available, as well) contacted for authorization to deviate from the protocol? If so, that is something that should be documented in the charts, which were reviewed for this paper. That information is not included in this paper. Those patients are much more interesting to me.

I do not object to using NTG to treat suspected STEMI with an SBP below 100 mmHg, but the authors seem to think that EMS should not even consider it. Do the outcomes of those patients support the approach of the authors? We do not know.

I suspect that the fears of bottoming out the blood pressure are very exaggerated, but it would be nice to have some evidence either way.

An important secondary end point was the differences between those with inferior/right ventricular STEMI, but treated with NTG.  

By vasodilating all blood vessels, and the venous system in particular, it causes a drop in blood pressure and preload. Thus, there is concern for precipitating hypotension in ACS involving the right ventricle.(1-3) Contraindications to the use of NTG, as outlined by the American Heart Association (AHA) Guidelines on the treatment of ACS, include right ventricular infarction.(4) This raises concern for use in inferior ST-segment elevation myocardial infarction (STEMI) in the prehospital setting, since many inferior STEMI result from proximal right coronary artery (RCA) occlusion and 50% involve the right ventricle.(3) Traditional 12-lead ECG is focused mainly on the left side of the heart and typically EMS protocols do not include acquisition of right-sided ECG leads. Further, in many systems, Basic Life Support (BLS) protocols allow for administration of NTG without differentiating the location of STEMI. There is also risk of other adverse events including bradycardia and cardiac arrest.(5-9)[1]
 

I have aggressively promoted the use of NTG for even hypotensive CHF/ADHF (Congestive Heart Failure/Acute Decompensated Heart Failure). Many physicians are not comfortable with that, even though the available evidence shows that aggressive IV NTG doubled the survival rate for these hypotensive patients. More research is needed on the use of NTG, especially in hypotensive patients.  

Further, we did not find an increased risk of hypotension among patients with proximal or mid RCA occlusions confirmed on coronary angiography. There are several possible reasons for our findings. First, while right ventricular involvement in inferior STEMI is common, hemodynamic instability is actually rare due to the right ventricle’s more favorable oxygen supply-demand ratio compared to the left heart and more extensive collateral flow.(3, 22) In addition, left heart occlusions may also involve the right ventricle and result in a preload dependent condition.(23-25) While limited by sample size, our results suggests that specifically avoiding NTG use in inferior STEMI, which is common in EMS systems, may be misguided. One quarter of the local EMS agencies in the state of California, for example, currently prohibit the use of NTG in inferior STEMI.(26) This analysis would benefit from additional study with a larger sample size and specific information about the infarct territory. Further studies are needed to determine which patients, in particular, are at increased risk for hypotension when treated with NTG.[1]
 

Perhaps NTG is also safe for treating patients with inferior ischemia and even right ventricular ischemia.

Footnotes:

[1] Safety and Effectiveness of Field Nitroglycerin in Patients with Suspected ST Elevation Myocardial Infarction.

Bosson N, Isakson B, Morgan JA, Kaji AH, Uner A, Hurley K, Henry TD, Niemann JT.

Prehosp Emerg Care. 2018 Dec 17:1-9. doi: 10.1080/10903127.2018.1558318. [Epub ahead of print]

PMID: 30556765

[2] Treatment Protocol: Chest Pain */ Acute MI

Reference No. 1244

LA County Paramedic Protocols

Los Angeles County Department of Health Services – Emergency Medical Services

Protocol

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Filed Under: ACLS, ACS, Assessment, Cardiology, Chest Pain, Critical Judgment, EBM, Evidence, GTN, Heresy, NTG, Research, RVI

A Comment From SEAN on The 3 Nitro BS – Part I

Sat, 05 Nov 2011 20:38:47 -0400 by
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In response to a comment from SEAN on The 3 Nitro BS – Part I –

the truth to me is in the reason for writing this in the first place. the truth is, it is redundant and anyone with any clinical expertise knows this and does not need reminding of what what you wrote here. that is the grain of truth to which i was referring.

Perhaps part of this is the suggestion that there is only a slight bit of truth in what I have written, which suggests that it is mostly false.

(a) grain of truth
even the smallest amount of truth. The attorney was unable to find a grain of truth in the defendant’s testimony. If there were a grain of truth to your statement, I would trust you.
The Free Dictionary

Then you make the statement – it is redundant and anyone with any clinical expertise knows this and does not need reminding of what what you wrote here.

Your statements are contradictory.

1. If you claim that only a tiny fraction of what I wrote is true, please point out what you claim is not true.

2. If what I wrote is so obvious that anyone with any clinical expertise knows this, are you claiming that the ACLS (Advanced Cardiac Life Support) guidelines are written by people who have no clinical expertise?

3. Are you claiming that all of the protocols that are written with limits of 3 nitro tabs/sprays are written by doctors, nurses, and medics who have no clinical expertise?

4. How many other places can you find people writing that the 3 nitro rule is baseless?

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you are right about some things, though.

I asked you to point out anything that you claim that was wrong in what I wrote, not what is right. The grain of truth suggests a tiny bit of accuracy swimming in an ocean of inaccuracy.

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hydrating someone with a right sided mi is beneficial before giving nitrates to avoid hypotension.

You will find a lot of people disagree with the idea of giving any NTG (NiTroGlycerin or GTN – GlycerylTriNitrate in Commonwealth countries) to a patient with RVI (Right Ventricular Infarction). It is interesting that the ACLS guidelines do not oppose giving NTG to RVI, but only suggest caution, while they do oppose giving more than 3 NTG to one patient.

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and as far as not doing anything, what you would do is watch.

Benign neglect is watchful waiting. Aggressive medicine is about continual reassessment and looking for specific indications to do something, rather than doing something reflexively – malignant attention.

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if someone is responding to a treatment with what are known effects of the treatment, i would observe and monitor that person to see how far this response goes and what needs to be done about it. that’s the care they need. it is not inadequate, but highly attuned to the situation at hand.

On this, we completely agree.

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one of the good things about nitro is that it can be TURNED OFF.

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I write a bit about boluses of IV NTG in these two –

Is IV NTG Too Dangerous for EMS

EMS NTG for CHF – Bolus or Infusion – Part II

IV NTG can also be bolus dosing of NTG – just as giving a tab or spray is giving a set amount all at once. However, the IV bolus is much more adjustable. With a tab, I can only adjust the dose by giving more.

Try to break a tab into smaller doses. It is difficult, if not impossible. Then there is the uncertainty of the amount of the dose being given. Is it a half – or a third – or some other dose?

We have similar problems with the spray. We can block part of the spray, but if we do that, how much is the patient receiving?

IV bolus dosing does not have these problems.

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the half life is short and people usually respond to what could be a decent perfusing pressure when you do. but there is danger in doing this as well. applying and removing the same exogenous stimulus is not therapeutic.

Yes and No.

EMS can titrate many medications much better by giving them as repeated boluses, than as infusions. Repeated boluses, with drugs that wear off quickly, can be very therapeutic. The important thing is to try to get a certain effect and keep it near there.

We should not give a dose, let it wear off, then give another dose. That is not therapeutic.

I would rather give large doses of midazolam (Versed) and need to give more in 20 to 30 minutes, than give lower doses of lorazepam (Ativan) and have it lasting much longer. In EMS, wearing off quickly allows us to safely be more aggressive.

Propofol (Diprivan) may be the ultimate in ability to titrate, but that may not mean that propofol is more therapeutic than something given in repeated boluses.

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i think it gives people the idea that we are doing something, as your article mentioned.

Doing something just for the sake of doing something is bad medicine.

Doing something just to create the impression of doing something is also bad medicine.

Unfortunately, these seem to be a significant portion of EMS protocols and ACLS.

The reason I write about these things is that I see a lack of awareness. I tend to avoid the things that everyone else is writing about, or has written about, unless I feel that I can add something different.

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Filed Under: ACLS, Critical Judgment, GTN, Heresy, Mythology, NTG, Pharmacology

The 3 Nitro BS – Part I

Fri, 04 Nov 2011 06:30:05 -0400 by
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Chris Kaiser of Life Under the Lights has written an article for JEMS called EMS Provider Questions 3-Dose Nitro Rule. This has also inspired Kelly Grayson of A Day in the Life of an Ambulance Driver to add his comments in Just So We’re Clear on the Concept . . . .

Clarity is the one thing that never was a part of treatment with NTG (NiTroGlycerin or GTN – GlycerylTriNitrate in Commonwealth countries).

Why have medical professionals stop at 3 NTG?

When I taught ACLS (Advanced Cardiac Life Support), I would tell the doctors, nurses, and medics taking the course that the reason is to encourage them to switch to IV NTG as quickly as practical.

In other words, I did the right thing – I lied. ACLS does not contain any explanation for this requirement. At one point, they left it out of the guidelines, but there was no explanation for this either. Yes, I did read the full guidelines, so when the What if . . . ? ninnies would criticize me, I could comfortably say, If you can find it, I will apologize and change my ways. Until then, you do not know what you are talking about.

I don’t know how tired their lips were when they finally stopped looking or if they ever did look beyond the ACLS flow chart for dummies algorithm that allows them to avoid reading the text. I never did have to apologize to anyone, because I knew what I was talking about and they did not know what they were talking about. Unfortunately, a couple of revisions ago, the 3 NTG rule was added back into ACLS.

There is still no explanation.

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What did they have to say in the 2005 Guidelines?

Nitroglycerin
Nitrates are used for their ability to relax vascular smooth muscle. Nitroglycerin is the initial treatment of choice for suspected ischemic-type pain or discomfort (see Part 8: “Stabilization of the Patient With Acute Coronary Syndromes”).[1]

Maybe there is some sort of footnote over there to explain this. If you read the text, there are footnotes for almost everything, because the AHA (American Heart Association) wants to show us what the evidence is for their guidelines. And they are not Standards Of Care – the ACLS guidelines are guidelines, which are meant to be deviated from when there is a good reason to deviate from the guidelines. I will look at that in Part II.

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But first, the next sentence from the ACLS guidelines contains some important information –

IV nitroglycerin is also an effective adjunct in the treatment of congestive heart failure from any cause,55 [1]

From any cause –

Systolic heart failure and diastolic heart failure and when both occur in the same individual. There is no reason to worry about excluding diastolic heart failure, but we do need to continually reassess our patients.

Back to the problem of NTG witchcraft –

nitrate-induced hypotension typically responds well to fluid replacement therapy.[1]

Again, no reference to support this claim.

This is not medicine. This is alternative medicine.

Evidence – we don’t need no stinkin’ evidence!

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Original cartoon

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The truth is that nitrate-induced hypotension typically responds well to benign neglect.

It does not matter what we do – IV fluid boluses, Trendelenburg position, epinephrine, sing silly songs, watch Marx Brothers movies, eat chicken soup, et cetera. The nitrate-induced hypotension typically goes away before any of these treatments would have any effect – except the epinephrine, which is the final solution for cardiac chest pain/

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The patient is temporarily hypotensive, begin the usual witchcraft!

Hurry up – before he gets better on his own!

Be very careful using dangerous treatments, such as IV fluid boluses, Trendelenburg position, or epinephrine. These all have dangerous side effects and are not as beneficial as benign neglect.

Remember, it does not matter what you do in the rare case of hypotension that follows administration of NTG – unless you do something baseless, reckless, and irresponsible such as IV fluid boluses, Trendelenburg position, or epinephrine.

What?

You disagree?

I am shocked/

Provide some research to support your claim.

No. Not some anecdote that you assume is related to the NTG, but actual evidence.

What?

There isn’t any?

I am shocked/

Is that because we give NTG so rarely that nobody could ever design a study to look at this?

Are we really that gullible?

I am shocked/ I think I need a nitro, but first some protective epinephrine, a bit of Trendelenburg position, and a nice fluid challenge to ward off the evil spirits.

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To be continued in Part II and maybe several more parts.

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Footnotes:

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[1] Nitroglycerin
2005 American Heart Association Guidelines for Cardiopulmonary Resuscitation and Emergency Cardiovascular Care
Part 7.4: Monitoring and Medications
Medications for Cardiovascular Support
Free Full Text with link to PDF Download

These are the 2005 guidelines, but they do not contradict the 2010 guidelines.

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Filed Under: 'Alternative' Medicine, ACLS, Critical Judgment, GTN, Heresy, Mythology, NTG, Pharmacology, Unicorn Medicine

Up to a Maximum of X Times vs. Titration

Fri, 11 Jul 2008 00:30:00 -0400 by
Over at Ridin’ the Bus, Gertrude was writing Who’s teaching the teachers? Well, my answer is that the teaching jobs are often as political as the desirable EMS jobs. Squad Y is a bunch of people friendly with So-and-So. Squad B is a bunch of people friendly with Whojamacallit. Whether these are 911 jobs, critical care jobs, flight medic/nurse jobs, or anything else does not matter. There is more of an old boy network involved than a critical examination of the qualifications of a job candidate. Teaching is no different.

The current teachers are not necessarily those who excelled in medic school, or EMT school, when they attended. They might not have learned things all that well, when they were in school. The instructor may have modified his understanding since then, but that does not mean that it was for any medical reason. A lot of what is taught is pure speculation.

I described this in several posts A, B, C, D, and E. I reference it in several others. We are poorly educated. The educators often do not know what they are doing well enough to be teaching it.

An excellent example of this is cardioversion. I have never seen anyone else do a good job of teaching cardioversion. That does not mean that it does not happen, but it is not encouraging that I do not see it taught well. ACLS (Advanced Cardiac Life Support) encourages us to just review the material, since the students are already supposed to be familiar with everything. How many nurses going to their first ACLS class have any experience with cardioversion? This is not something that you learn to do well from a book or a blog. You learn it by using the paddles, turning on the synchronizer, and delivering shocks to a mannequin or to a patient. Too many people learn, during their first cardioversion, that they never really understood cardioversion.

Anyway, the topic of Gertrude’s post was the rules that are taught to us. Her example is when a student asked her for the maximum number of times a patient can be suctioned.

Think about this.

Why do we suction patients?

We suction them because there is something in the airway that may interfere with ventilation. It may be a potential obstruction. It may be a partial obstruction. It may be a complete obstruction.

As long as we do what we can to maintain oxygenation, there is no maximum. For the complete obstruction, there is no reason to pause and ventilate in between suction attempts, or to limit the length of suctioning, unless there is the possibility that you have cleared, or partially cleared, the obstruction.

One of the other instructors had given them a number. What is a good number for this? 3? 5? 23? The patients weight in kilograms, divided by their SpO2 percent, multiplied by the number of synapses actually transmitting information in that instructor’s brain?

How about until the portable battery runs out? But remember there are other ways of creating suction – a large syringe, a bulb syringe from the OB kit, scooping things out of the airway, gravity, a vacuum cleaner in the residence. Who really cares how you do it, if you are able to provide the airway the patient needs?

Why do we feel the need to have a number? A limit on what we can do?

People like externally imposed limits. The idea of being responsible for making intelligent decisions is something that many people flee from.

“Responsibility? Just tell me what I have to do to avoid getting in trouble.”

“As long as I follow the protocol, I won’t get in trouble.”

Of course, if the protocol does not apply to your patient, or if you follow the wrong protocol (because you ignored assessment in favor of memorization of protocols) you might kill your patient in your devotion to keeping out of trouble.

Maximum of 3 NTG (NiTroGlycerin, overseas GTN – GlycerylTriNitrate).

Why?

Most likely because the AHA wants you to switch the patient to IV NTG as soon as possible. Not exactly common in the prehospital setting, but a very good idea. NTG is a drug that needs to be titrated. A maximum number prevents titration, so people teaching these maximums should not be teaching. Titration is adjusting the dose based on the response of the patient. Almost all EMS drugs need to be titrated.

Does a response mean that you stop? No, but you take that information into consideration in your continuing doses. Sometimes it will mean to stop. NTG + Syncope is more than a subtle hint to stop NTG. After blood pressure returns, then you may resume cautiously (perhaps after running a liter into the patient) or you may decide not to give any more, but initially your response should be to stop.

Atropine is not a titration drug. Fast push, a minimum adult dose of 0.5 mg and a maximum dose of 0.03 mg/kg if stable, 0.04 mg/kg if unstable. With atropine, you may get the opposite result of what you want, if you give it slowly or if you do not give enough. Another non-titration drug is adenosine. Also fast push. Maximum of 3 doses – 6 mg, 12 mg, and another dose of 12 mg. Glucagon is another drug not generally titrated (many places do not even carry more than one dose).

Some titration drugs:

Oxygen – titrate to adequate oxygenation.

Dextrose 50% in Water – titrate to adequate saccharinity.

Dopamine and dobutamine are given as drips, the dosage formula is for calculating a starting dose and for understanding the maximum dose rate, which does not mean that you stop, only that you stop increasing the dose rate.

NTG – I have given over 50 sprays (over 20 mg) to a single CHF patient on one call and the blood pressure never dropped below 200 mm/hg systolic. Maximum of 3? Not a chance.

Albuterol (Salbutamol overseas)- if the patient is not able to breathe adequately, we continue giving albuterol, but we add other beta 2 agonists, maybe some magnesium and methylprednisolone. There are some who will even tell you that you may not give albuterol to a tachycardic or hypertensive patient, since it is not completely selective for beta 2 and might make things worse. Yes, it will stimulate the heart to work harder, but if it opens the airways, the pressure and heart rate will come down in spite of that stimulus. If it doesn’t open the airways, the side effects are not the patient’s primary concern, not even a secondary concern.

Fentanyl/dilaudid/morphine – no minimum dose and no maximum dose. Only the response to treatment matters. No maximum of 6 mg, or 10 mg, or 20 mg, or even 100 mg of morphine (about 60 mcg/100 mcg/200 mcg/1 mg for fentanyl; 0.75 mg/1.25 mg/2.5 mg/12.5 mg for dilaudid). Anyone who tells you otherwise is a liar and/or incompetent.

Midazolam/lorazepam/diazepam – no minimum dose and no maximum dose. Only the response to treatment matters. No maximum of 5 mg, or 10 mg, or 20 mg, or even 100 mg of midazolam . . . .

Diltiazem is a slow push medication that has standard doses (0.25 mg/kg for the initial dose and 0.35 mg/kg for a repeat). If you are giving it slowly it isn’t just to minimize the side effects, but also to observe for side effects that would discourage you from continuing with the dose. Diltiazem is often given to little old people, who may not give much warning before dropping their blood pressure significantly. I like to keep them sitting up and talking to me while I slowly (over 5 minutes, not the recommended 2 minutes) push the diltiazem. If they are sitting up, the part of the body most likely to show signs of decreased perfusion is the brain – sooner than a repeat blood pressure, sooner than skin sign changes. If the behavior changes in any way, I stop and I do not give any more until after I have satisfied myself that this is not a sign of an adverse reaction. I can always give more later, but most likely it is an adverse reaction.

Naloxone – no minimum dose and no maximum dose. I like to give 20 mcg to 40 mcg at a time. Response is what tells me when to stop.

These are just some of the drugs that are only appropriately given when titrated.

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By Rogue Medic
Filed Under: ACLS, Adenosine, Airway Management, Assessment, Atropine, Cardioversion, Critical Judgment, Fentanyl, GTN, Heresy, Math, Midazolam, Morphine, Naloxone, NTG

Fun with explosives – NTG.

Sat, 12 Apr 2008 22:42:00 -0400 by

Let’s discuss treatment of ACS (Acute Coronary Syndrome) with NTG (NiTroGlycerin in the US, or GTN – Glyceryl TriNitrate elsewhere).

ACS?

A possible heart attack.

Well why don’t you just say that?

The AHA (American Heart Association) is trying to come up with terminology that is accurate and includes things that might develop into a heart attack if not treated effectively.

Oh.

The typical dose of NTG is 0.4 mg (400 micrograms) given as a sublingual (under the tongue) tablet or as a spray given under the tongue or on the tongue.

Only up to three.

Why?

That’s what the ACLS (Advanced Cardiac Life Support) guidelines and all of the protocols say.

What if you give NTG, the chest discomfort is completely relieved with the third tablet, but the discomfort returns?

Hmm.

Or the chest discomfort is being relieved, the patient has already taken 2 NTG and you give one NTG?

It doesn’t make sense to stop a treatment that is effective.

Patients with ischemic discomfort may receive up to 3 doses of sublingual or aerosol nitroglycerin at 3- to 5-minute intervals until pain is relieved or low blood pressure limits its use (Class I). IV nitroglycerin is indicated for ongoing chest discomfort, control of hypertension, or management of pulmonary congestion in patients with STEMI associated with LV failure (Class I). In patients with recurrent ischemia, nitrates are indicated in the first 24 to 48 hours. IV rather than long-acting preparations should be used acutely to enable titration.

What are you supposed to do for a patient who appears to be responding to NTG treatment when you reach the magic number of 3?

It does state that IV nitroglycerin is indicated for ongoing chest discomfort, but that doesn’t do the patient much good in the prehospital setting. Few EMS agencies use IV NTG.

Why?

Medical directors do not insist that their medics be able to titrate medications effectively and assume that this is beyond the abilities of medics.

Talk about creating the problem you are trying to avoid.

Are there many drugs that do not require titration?

Not really.

But the medical directors start mumbling about their creation – Medic X (the incompetent medic).

They created these bad medics and use them to justify withholding appropriate care from patients?

Of course they would never accept that it is their fault. Tradition, not titration.

Morphine sulfate is the analgesic of choice for continuing pain unresponsive to nitrates, and it is also effective in patients with pulmonary vascular congestion complicating ACS.

Apparently, the concept of NTG being effective, but requiring more than 3 is something ACLS does not address in the EMS setting and only hints at in the hospital setting.

That’s insane.

They view chest discomfort as completely responsive or unresponsive – nothing in between.

This is giving me chest discomfort.

If the purpose of morphine is to treat discomfort – not to vasodilate – fentanyl would be a much safer drug to use.

One drug at a time. Tell me more about a limit of 3 NTG.

There are few sensible reasons for a maximum of 3 NTG. One might be to discourage continuous treatment without reassessment.

Who would do that?

Medic X, who doesn’t know what he is doing, but he is blindly following an algorithm or protocol.

So even AHA encourages EMS to use incompetent people?

What do they do to discourage this?

They do appear to be afraid of upsetting the OLMC (On Line Medical Command) requirements crowd.

Anyway, back to reassessment. Whenever you treat a patient, you need to reassess. Continually reassess.

OK.

Another reason for the maximum of 3 NTG might be to encourage the people in the hospital to switch the patient to IV NTG as soon as possible. It might be nice if ACLS were clear on this.

Why IV?

NTG may be difficult to titrate, when given sublingually. IV NTG can be titrated much more precisely.

So you can give more than 3 NTG all together?

Can you think of any reason why you should not give more than 3 NTG to a patient?

Their blood pressure will crash!

The occasional patient with chest discomfort will have an adverse reaction to NTG. Most often this is a transient drop in blood pressure, sometimes accompanied by a similarly transient bradycardia, that is dramatically overreacted to by the medics, nurses, and doctors caring for the patient.

Dramatically overreacted to? The patient has no blood pressure!

For how long?

Once we start running some fluid into the patient the blood pressure comes back up.

So the blood pressure starts to recover before you are able to give enough fluid to make any difference?

Yes.

And you think that the meager amount of fluid that you gave to the patient had something to do with that?

Well, when we start giving the fluid the pressure comes back up.

Was anyone expressing displeasure with the change in the patient’s blood pressure?

A few non-FCC approved (Federal Communications Commission) words might have been used when this happened.

How do you know that these words were not the cause of the improvement in the blood pressure?

But that’s silly.

Did the patient get better after these words were used?

Yes.

Well, that was your reason for thinking that a tiny amount of IV fluid, that you had just started to run into the patient, made a difference.

The fluid is a medical treatment.

Homeopaths give larger doses and make less dramatic claims. They call it medicine, too.

Oh.

Is there any recommendation on the use of fluids for treating a typical heart attack?

Don’t give a lot.

Still, when the patient has a dramatic short term reaction to a medication, your response is to pretend that the potential heart attack is no longer a problem and just dump fluid into the patient?

But the blood pressure crashed!

And your actions had no effect on the blood pressure, but might have worsened any heart attack or pulmonary edema the patient may have.

Ouch.

The NTG may cause the patient’s blood pressure to suddenly drop.

That’s bad.

The blood pressure will probably recover within a couple of minutes regardless of what pseudoscientific methods you use.

Good.

The pseudoscience is not good, but there are plenty in medicine who preach pseudoscience.

As long as there is no real danger, why worry?

I didn’t claim that there is no danger. All medicines have risks. One of the risks of NTG is a transient drop in blood pressure.

As long as it is just transient, who cares?

If you take a patient with an evolving heart attack and suddenly drop the patient’s blood pressure, you increase the chances of arrhythmia, seizures, worsening ischemia, coronary steal ,and other adverse events that might not be so transient.

Ooh, that is bad.

Of course, the same is true, but far less common with IV starts.

What?

You’ve never seen someone become light headed, hypotensive, unconscious, or even seize during an IV start or during phlebotomy (which is not significantly different from an IV start)?

Yes, but that is not the same mechanism.

True, the IV/phlebotomy syncope tends to be in young women, while the NTG syncope tends to be in older men.

Why?

For one thing, we are not as suspicious of heart attacks in women. Women present with atypical symptoms much more often than men do. So, we give NTG to men much more often.

That sounds like another post.

OK. Here is the ACLS recommendation on treatment of post-NTG hypotension.

nitrate-induced hypotension typically responds well to fluid replacement therapy.

Oh, good. You were just pulling my leg about the lack of research to support using fluids for hypotension.

They do not cite any research to support this opinion.

On the other hand, they are writing about IV NTG – not sublingual. They probably turned down (or off) the NTG infusion as they were giving fluids. There might have been some of that charming language that will cost you millions if spoken on TV or radio. Of course, the FCC will fine you if you pronounce “FCC” on TV or radio.

I thought this was Fun With Explosives, not Fun With Expletives.

Just trying to keep this from being too boring.

Do they say anything else about hypotension?

The action of nitroglycerin is mediated through local endothelial production of nitric oxide, particularly in the venous capacitance system. Nitroglycerin is most effective in patients with increased intravascular volume. Hypovolemia blunts the beneficial hemodynamic effects of nitroglycerin and increases the risk of hypotension; nitrate-induced hypotension typically responds well to fluid replacement therapy. Other potential complications of use of IV nitroglycerin are tachycardia, paradoxical bradycardia, hypoxemia caused by increased pulmonary ventilation-perfusion mismatch, and headache.

They change what is stressed. When giving NTG, the patient’s volume status seems to have more to do with the effects of NTG than anything else.

So, if NTG is most effective when the patient has too much fluid, then why don’t we give Lasix?

That is definitely more than one other post, but no Lasix.

OK.

Sad. Now look at the full sentence on hypotension.

Hypovolemia blunts the beneficial hemodynamic effects of nitroglycerin and increases the risk of hypotension; nitrate-induced hypotension typically responds well to fluid replacement therapy.

If the patient is already hypovolemic the NTG might not do much to help and may do a lot to hurt.

Change the nitrate-induced hypotension to nitrate and hypovolemia-induced hypotension and you are looking at a totally different patient.

Are they referring to RVI (Right Ventricular Infarction)?

Changes the whole perspective. If your patient is hypovolemic and the pressure drops – give fluid.

Common sense, but why not just treat hypovolemia?

That would make too much sense.

What else?

If the patient is hypovolemic it is appropriate to give fluids. If not hypovolemic, avoid the fluids.

Here is a link to the 2005 ACLS ACS algorithm. It tries to simplify ACS treatment.

(Circulation. 2005;112:IV-78 – IV-83.)
© 2005 American Heart Association, Inc.
2005 American Heart Association Guidelines for Cardiopulmonary Resuscitation and Emergency Cardiovascular Care

Part 7.4: Monitoring and Medications

Part 8: Stabilization of the Patient With Acute Coronary Syndromes

My other posts on OLMC requirements and Medic X are:

OLMC (On Line Medical Command) Requirements Delenda Est

OLMC for President!

OLMC = The Used Car Dealers of EMS?

OLMC For Good Medics

By Rogue Medic
Filed Under: ACLS, Chest Pain, Critical Judgment, GTN, Heresy, Medic X, NTG, OLMC Requirements, Research