Jump to content

JOIN THE DISCUSSION!

Want to join the discussions?

Sign up for a free membership! 

If you are a member already, log in!

(lost your password? reset it here)

99nicu.org 99nicu.org
Sign in to follow this  
Padkaer

Why dobutamine in PPHN?

Recommended Posts

When using inotropics in PPHN many guidelines advocate the primary use off dopamine up from 5-15 (20) μg/kg/min and if that fails the add on of dobutamine.

While it makes perfect sense for me to start with dopamine I fail to understand the argument for dobutamine.

It is almost exclusively a β1 active sympathomimetic with very little, if any, effect on α receptors and on blood pressure.

That makes it very attractive in the setting of cardiac failure, where one wishes to increase the contractility of the heart with out burdening the strained pump with an increased after load.

Its use in PPHN however, where you presumably have a normally functioning myocardium and primarily want to raise the peripheral blood pressure, seems illogical to me.

Instead of going with dopamine and dobutamine in high doses, I would consider

a) Switch to adrenaline

B) Add noradrenalin to dopamine

Or

c) Switch to dobutamine and noradrenalin

more logical choices.

I am aware that noradrenalin for many good reasons is considered an unattractive drug, but in this one very specific situation I think good arguments could be found for its use.

If any one could explain to me the logical argument for the use off dobutamine, or guide me to the trials, that has documented its efficacy in PPHN, I would be very thank full.

Kind regards

Edited by Padkaer

Share this post


Link to post
Share on other sites
... where you presumably have a normally functioning myocardium ...

I dont think we can assume the myocardial function to be normal in a baby with PPHN. The hypoxia associated with PPHN is sufficient to decrease cardiac function. Also if there was a history of asphyxia at birth in such a baby that will also suppress cardiac function.

One of the aims of PPHN management is optimization of the cardiac output and left ventricular function as needed with volume expansion and inotropic agents (dobutamine, dopamine, and milrinone) to enhance cardiac output and systemic oxygen transport.

A recent study has shown that decreased left ventricular size and output correlated with increased severity of PPHN and need for more advanced management.

So I think dobutamine's role in increasing cardiac output may have a place in the management of PPHN. Of course the lack of proper studies in neonatology always leaves room for speculation and assumption.

Ref:

Correlation of echocardiographic markers and therapy in persistent pulmonary hypertension of the newborn.

Peterson AL, Deatsman S, Frommelt MA, Mussatto K, Frommelt PC.

Pediatr Cardiol. 2009 Feb;30(2):160-5. Epub 2008 Sep 9.

LINK

Pharmacology Review: The Use of Dobutamine in the Treatment of Neonatal Cardiovascular Compromise. Shahab Noori, Philippe Friedlich and Istvan Seri . NeoReviews Vol.5 No.1 2004 e22

LINK

Pulmonary Hypertension in the Neonate. Robin H Steinhorn and Kathryn N Farrow.NeoReviews, Jan 2007; 8: e14 - e21. LINK

Edited by JACK

Share this post


Link to post
Share on other sites

Dear Jack and Stefan

Thank you for the links. The abstracts look very promising. I´ll get back to you once I have read the full articles.

Kind Regards

Share this post


Link to post
Share on other sites
Another aspect of dobutamine is that it has some beta2-agonist action, related to vasodilatation:

http://www.ncbi.nlm.nih.gov/pubmed/9279221

Dobutamine exists as two enantiomers + and -

(-) enantiomer of dobutamine is a highly selective alpha1-adrenoreceptor agonist, and the (+) enantiomer of dobutamine exerts a potent and selective beta1-and beta2-adrenoreceptor stimulatory effect.

The commercially available dobutamine is a racemic ( 1:1) mixture of these two enantiomers

Also one of the metabolites of Dobutamine (+)-3-O-methyldobutamine is a alpha1-adrenoreceptor blocker !!

Three more links to add more lucidity ( or confusion) to the discussion !

Anesthetist web resource

LINK1

Dobutamine is made

LINK2

Alpha receptor-Google books

LINK3

Share this post


Link to post
Share on other sites

Hi all,

This is one of my favorite subjects.

The way I look at PPHN is not far from what have been mentioned. As you know, PPHN is a complex disease characterized mainly by increased pulmonary vascular resistance that might be accompanied by systemic hypotension and myocardial dysfunction secondary to the primary or underlying disease. The main aim of therapy is to improve systemic oxygen delivery and minimize iatrogenic complications secondary to our interventions.

We have made some arguments in the introduction and discussion in the article we published

Al-Salam Z et al. The hemodynamic effects of dobutamine during reoxygenation after hypoxia: a dose-response study in newborn pigs. Shock. 2007 Sep;28(3):317-25.

Sure! This is an animal study but the discussion was mainly about human neonates.

You will find in the article why we suggest dobutamine as inotrope of choice in the condition of PPHN.

In summary, although, dobutamine has less effect on systemic blood pressure, it improves cardiac output and systemic oxygen delivery. In addition, dobutamine can decrease pulmonary vascular resistance. Moreover, dopamine and epinephrine can lead to worsening of PPHN (see references in the article).

It is very important to keep in mind when we give any of the inotropes/vasopressors that they do not only act on one side of the heart but on both sides (right and left; pulmonary and systemic). Therefore it is of paramount importance to maintain a good balance between the 2 circulations in the presence or absence of shunts.

Thanks,

Zakariya Al-Salam

Share this post


Link to post
Share on other sites

Create an account or sign in to comment

You need to be a member in order to leave a comment

Create an account

Sign up for a new account in our community. It's easy!

Register a new account

Sign in

Already have an account? Sign in here.

Sign In Now
Sign in to follow this  

×
×
  • Create New...