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

- Rogue Medic

Unreasonable Fear of Hypotension and High-Dose NTG – Part I

ResearchBlogging.org
 

Peter Canning writes about a study of high-dose SL (SubLingual) NTG (NiTroGlycerin – GTN GlycerylTriNitrate in Commonwealth countries) by EMS for CHF (Congestive Heart Failure).[1]

I have some problems with the study.
 


Click on images to make them larger.
 

This is just moderate-dose, not high-dose.

I have had protocols that allow for more aggressive dosing (every 3-5 minutes) going back to 2008.[2]
 


 

I have probably given more triple-dose NTG than was given to the entire intervention group. I have given over 50 SL NTG to just one patient, while they only managed to give a total of 87 tablets in 29 triple doses in the entire study.
 


 

It is good to provide more evidence that multiple dose NTG is safe, but we have had good evidence that prehospital high-dose IV NTG dramatically improves outcomes since the 1990s.

We need more prehospital aggressive IV (IntraVenous) NTG research.
 

Administration of high-dose nitroglycerin is an effective treatment that has been shown to improve the respiratory symptoms associated with ADHF, and decrease the incidence of death due to myocardial infarction and mechanical ventilation, particularly when initiated early.4 – 6 [3]

 

I agree with that.

However, EMS is the best earliest place to start IV NTG.
 

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).
[4]

 

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%
 


 

Am I complaining that the current study is useless?

Not at all.

There is some excellent information that debunks much of the dogma against multiple-dose NTG.
 


Look at the cases of hypotension – systolic blood pressure less than 100 mm/Hg.

3 cases, but only in the double dose group.

All of the hypotension went away without any treatment.

Zero cases in the triple dose group and the quadruple dose patient did not become hypotensive.
 

For CHF, more NTG does not produce more of a drop in blood pressure.
 

Disagree?

Provide evidence, not anecdotes.

Part II will look at the evidence of safety from this study more closely.

Also see –

Nitroglycerin for Treatment of Acute, Hypertensive Heart Failure – Bolus, Drip or Both?
Wed, 17 Oct 2012

Is a half a bottle of nitro too much for a single dose?
Sun, 18 Nov 2012

NTG and the Hero Medic
Street Watch
November 7, 2012

Footnotes:

[1] Safety of High Dose Nitro in CHF
StreetWatch: Notes of a Paramedic
August 29, 2013
Peter Canning
Article

[2] Congestive Heart Failure
5002– ALS – Adult/Peds
2008, 2011, and 2013 Statewide ALS Protocol
Pennsylvania
Page with link to Full Text Download of Full Protocols in PDF format.

[3] Prehospital High-dose Sublingual Nitroglycerin Rarely Causes Hypotension.
Clemency BM, Thompson JJ, Tundo GN, Lindstrom HA.
Prehosp Disaster Med. 2013 Aug 21:1-4. [Epub ahead of print]
PMID: 23962769 [PubMed – as supplied by publisher]

[4] 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]

Clemency BM, Thompson JJ, Tundo GN, & Lindstrom HA (2013). Prehospital High-dose Sublingual Nitroglycerin Rarely Causes Hypotension. Prehospital and disaster medicine, 1-4 PMID: 23962769

Bertini G, Giglioli C, Biggeri A, Margheri M, Simonetti I, Sica ML, Russo L, & Gensini G (1997). Intravenous nitrates in the prehospital management of acute pulmonary edema. Annals of emergency medicine, 30 (4), 493-9 PMID: 9326864

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Comments

  1. We were just talking about this today in Medic class. I was curious as to why it is alright to give NTG or another Nitrate every 3-5 minutes without worrying about the BP tanking, but didn’t have time to ask. Can you elaborate on this a little for me?

  2. 50 NTG tabs for 1 patient? Holy cow, that sounds labor intensive!

    Did you have to have another ALS unit intercept to re-supply you with more little brown bottles?

  3. My question is how long did the study go on that one patient received over 50 NTG tablets and is still functioning. I didn’t think that an individual was supposed to receive more than 3 NTG tablets in 5 minutes intervals before professional medical assistance. I know the earlier NTG is administered, the better but I think that there should be a limit on how much can be can be administered to one patient in a 48 hour period before more serious medical attention should be sought. I know when my mom had a prescription for NTG she was only told to take two, NTG tablets and if a third was needed to call paramedics. And that it was needed two days in a row that she needed to stay in the hospital for observation.

Trackbacks

  1. […] are a couple of important comments to Unreasonable Fear of Hypotension and High-Dose NTG – Part I. In one, Brooks Walsh writes – […]

  2. […] the comments to Unreasonable Fear of Hypotension and High-Dose NTG – Part I is the following from Kasey Marshall on the patient I treated with over 50 NTG (NiTroGlycerin – […]

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