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

- Rogue Medic

EMS NTG for CHF – Bolus or Infusion – Part II

Continued from Part I.

This continues my response to Too Old To Work, Too Young To Retire’s response to A Comment on Saving Patients from Low Doses of NTG.

I’d love to be able to do IV NTG in the field, but can’t seem to get our medical director interested in it. That might be because someone else has to approve the purchase of the pumps. It sure would help patients, though.

This is the biggest problem with treating CHF with IV NTG. There are too many doctors, nurses, medics, et cetera who just do not understand. They think that too much NTG is the problem, but the opposite is true. We are killing patients by not giving them enough NTG.

Where has any danger of too much IV NTG been demonstrated?

Competent people will decrease the rate of administration if there are significant drops in blood pressure. Therefore, complications do not ensue.

From 1984 through 1991, new guidelines for the use of intravenous nitrates, based on differential treatment according to blood pressure, were in use.

RESULTS:
Overall prehospital mortality rate for APE in all patients was 7.8% (50 of of 640 patients). Mortality after 1984 was significantly lower than before (5.3% versus 13%, P < .01). Nitrates were effective in reducing mortality, even in hypotensive patients. Multivariate analysis showed that outcome was significantly affected by two clinical features (dyspnea and low blood pressure), treatment with nitrates, and calendar period effects (before/after 1984).
[1]

Not just hypertensive patients, but also hypotensive patients benefited from EMS IV NTG!

Nitrates were effective in reducing mortality, even in hypotensive patients.

The CHF death rate dropped from 13% all the way down to 5.3%

 

Without prehospital IV NTG the death rate was 2 1/2 times higher.

 

2 1/2 times as much death is not a subtle difference.


Picture credit.

No. We should skip the pump and use something faster – something that works just as well for EMS.

The big question – Is any infusion pump needed?

No.

Absolutely not.

administered repeated boluses of nitroglycerin.[2]

Just one or two repeated boluses of NTG?

The mean number of nitroglycerin boluses required was 4, [2]

But the IV NTG boluses must have been low doses.

a mean dose of 1588 mcg (range 800-28,000 mcg).[2]

0.8 mg to 28 mg – not small doses of IV NTG.

Two patients had transitory dips in SBP < 100, which resolved spontaneously; both of these patients received additional nitroglycerin boluses.[2]

The deadly hypotension got better on its own.

So much for the extreme danger of too much NTG.

None (0%) of the patients required intubation (95% CI 0-7.3%).[2]

Avoiding intubation saves lives.

Prehospital NTG can should be done with IV boluses.

No pumps required.

We are already using NTG bolus treatment, so we should accept that IV boluses of NTG are not that much different from SL (SubLingual) boluses. If we push 1 mg NTG at a time, that is only the dose equivalent of two and a half NTG tabs. More is absorbed than with SL, but this is still not really a large dose.

Footnotes:

[1] Intravenous nitrates in the prehospital management of acute pulmonary edema.
Bertini G, Giglioli C, Biggeri A, Margheri M, Simonetti I, Sica ML, Russo L, Gensini G.
Ann Emerg Med. 1997 Oct;30(4):493-9.
PMID: 9326864 [PubMed – indexed for MEDLINE]

[2] A Protocol of Bolus-Dose Nitroglycerin and Non-Invasive Ventilation to Avert Intubation in Emergency Department Acute Pulmonary Edema
Piyush Mallick, Surjya Upadhyay, TS Senthilnathan, El Matit Waleed , Al Jahra Hospital, Scott Weingart, Mount Sinai School of Medicine
Prepublication abstract
PDF Download of page at EMCrit

EMCrit Podcast 1-Sympathetic Crashing Acute Pulmonary Edema
by EMCRIT on APRIL 25, 2009
Link to Podcast page

Link to page with other evidence supporting this treatment

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Comments

  1. This is certainly an area that should be studied. The problem is that in the hospital they have pumps and so don’t need to study it. In the field, it’s a major change in the way EMS provided NTG to patients and will have to be studied before any EMS system will adopt it as protocol.

    There are three problems with that. First, getting an EMS system to break the ice and propose such a study. Second, getting an IRB and the FDA to approve such a study. Third, getting the medics to participate and comply with the study directions.

    The last is probably the hardest because even in systems with tight academic ties to a university affiliated teaching hospital, medics aren’t particularly keen to do the extra paper work associated with a study.

    Solve all of that, and you can do a study.

    If you don’t do a study no one is going to change their protocols and certainly the AHA won’t adopt it as a guideline.

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