Nitroglycerin

nitro

I rate Nitro 8 out of the 33 drugs we carry.

Nitro has two main indications Ė for cardiac chest pain and for pulmonary edema. It is of minor utility in one, and lifesaving in the other.

I once gave Nitro all the time to any type of chest pain. If they improved, I deduced the chest pain was cardiac, if they didnít it was plueritic pain. Wrong assumptions. I later read that Nitro as a smooth muscle relaxant is as likely to resolve non-cardiac chest pain as it is cardiac. I also recognized that nitro, other than a wishful thinking effect, quite often had very little effect on patients having obvious STEMIs. It also had a tendency to drop the blood pressure of certain patients.

When I started as a medic no one ever taught us about right-sided MIs. Looking back at old run forms, I dropped the blood pressure in quite a few people having inferior MIs. I thought their heart attack was just making them worse. Preload? What’s preload got to do with it?

On top of all this, studies came out that showed that nitro makes no difference at all in mortality or morbity in patients having MIs.

Here’s some of what the American Heart Association says about Nitro for ACS in the 2005 Guidelines – Stabilization of the Patient With Acute Coronary Syndromes:

The treatment benefits of nitroglycerin are limited, however, and no conclusive evidence has been shown to support routine use of IV, oral, or topical nitrate therapy in patients with AMI. With this in mind, these agents should be carefully considered, especially when low blood pressure precludes the use of other agents shown to be effective in reducing morbidity and mortality (eg, beta-blockers and angiotensin-converting enzyme [ACE] inhibitors).

We were finally taught to use caution in the use of Nitro if the patient is having a right-sided MI. I then routinely did right-sided ECGs until one ED doctor I greatly respect told me he just assumes all inferior MIs are right-sided and just doesnít give them nitro. The possible danger to the patient’s preload is just too great too risk for no benefit in outcome. With other tasks to be done during a chest pain, while doing a right-sided 12-lead can produce an Iím a smart medic look at me moment, it is of less priority since it doesn’t effect my treatment.

It is amazing to me sometimes how poorly we do spreading knowledge to medics or even doctors. The 2005 AHA guidelines prohibit the use of Nitro in chest pain under the following three conditions (Class III, which means harmful):
1. Patients with hypotension (SBP 30 mm Hg below baseline),
2. Bradycardia (100 bpm)

Less than 90 was always apparent. We use 30 below baseline I had been unfamilar with. I had thought <100 applied to all patients. So if someone started out with a BP of 180, I just kept dropping it down until it hit 100. And I had routinely given Nitro to ACS patients with heart rates above 100.

I brought in a recent inferior MI with a heart rate of 112. The doctor asked me if I had given Nitro. I said "No, heís tachycardiac, its contraindicated." I could see in the doctorís eye a little Hmm going on. She did not then order Nitro. I have had other doctors thank me for not giving nitro in inferior MIs.

So, if Nitro was just for chest pain, it would not be in my Essential Eight. It would be pretty far down the list. (I should point out IV Nitro, which we don't carry, has earned more positive recommendations for its use).

Nitro for pulmonary edema, on the other hand, is a different story.

Jems magazine ran a picture a few years ago in a story about CHF that had vials of Lasix and Morphine with the circle with the slash through it sign over the vials. The article said what is being widely taught now that CPAP and Nitro are the front line against CHF, while Lasix and Morphine our on the way out the door completely. Pulmonary edema is frightening call, and I pound the Nitro into my patients, and have seen great results. You donít stop at 3, but keep giving it every 3-5 minutes as long as their pressure holds. The Nitro with the CPAP is an awesome combo. CPAP doesnít cure the patient, merely keeps them from crashing until drugs (like Nitro) can be given to stop the event.

We used to carry Nitro paste, but are getting rid of it in favor of continual Nitro under the tongue every 3-5 minutes. Our doctors feel Nitro paste is too unreliable as its absorption varies so widely from patient to patient.

One last point on Nitro. If you have ever struggled to get a patient to lift their tongue up so you can squirt the Nitro underneath, read this: Lingual Nitro. Bottom line — and it was new to me until a reader pointed it out — Nitro Ligual works just fine on top of the tongue.

***

Nitroglycerin

Class: Vascular smooth muscle relaxant

Action: Systemic vasodilator which decreases myocardial workload and oxygen consumption.

Indication: Angina Pectoris
Pulmonary edema

Contraindication: Hypotension
Children under 12 yrs
Use of Erectile Dysfunction drugs within 48 hours

Side effect: Hypotension, rarely brief asystole,
Headache and facial flushing
Dizziness, decreased LOC

Dose: 0.4mg may repeat q 3-5 minutes, titrate to pain, effect and blood pressure

Route: Sublingual – spray or tablet

6 Comments

  • Matt says:

    I like the nitropaste for patients on CPAP, because I don’t have to take off the face-mask every 3-5 minutes. I still use it, but I’m told that it takes 30 minutes to begin to work, so I end up doing SL nitro most of my transport anyway (we don’t have the spray). I’m going to have to look into some data about onset–you’re saying that might even be sporatic.
    My other concern about the q3-5 dosing is that I potentially have a lot going on, so if I’m not in that two minute window, I get worried about rebound (relative) hypertension.

  • CBEMT says:

    We’re on the verge of getting nitropaste. Figures that even with a protocol update, we’ll STILL be behind.

  • totwtytr says:

    For CHF, CPAP is more important than NTG. That aside, the best way to give NTG would be IV via infusion pump. Which should be coming in EMS on a wide spread basis, but probably isn’t.

    NTG was long used (and still is in EMS) as a means to differentiate unstable Angina or MI from stable angina. In theory, we shouldn’t get 9-1-1 calls from people with stable angina as, again in theory, they take NTG and it resolves their symptoms. We also know the reality is that people call 9-1-1 even after their pain resolves or if they don’t have or didn’t remember to take NTG. We work up a lot of patients with ischemic chest pain who are not having MIs. For them, NTG is also beneficial. Not all cardiac related chest pain is MI, much of it is ischemic and well treated by NTG.

  • Tracy T says:

    After discussing this topic with my wife, just finishing her 3rd year in medical school, she said that Nitro will have next to no effect unless the patient has collaterals. If the patient has stenosis, angina or other heart history, their body has compensated with collaterals. No collaterals, no (or little) effect on MI. That’s why we see some PTs benefit from Nittro in MIs, and no response from others. I learn a lot during our dinner table discussions.

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Peter Canning

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