Trouble understanding PPHN...

Specialties NICU

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Hi all I'm a NICU rn (kinda new) and I am having such a hard time understanding the physiology of PPHN. I have read descriptions over and over and just have a mental block with this subject.

I understand that PPHN occurs when fetal circulation fails to covert to newborn. So, the blood is still bypassing the lungs because of the PDA and PFO, correct? Why does this fail? Why do the lungs have high pressure? Is this just because that's the way it was in the womb? And is the high pressure preventing blood from entering the lungs, therefore causing the poor O2 sats that those babies have?

What exactly is right to left shunting?

I know I have lots of questions but I need to understand this.

Also, how for you explain PPHN to parents?

Thank you!

- Lucy

Specializes in NICU, PICU, PCVICU and peds oncology.

Steve, you missed ambrisentan... Some of our very refractory kids are on that. And we've used IV sildenafil a couple of times.

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Specializes in Neonatal ICU (Cardiothoracic).
Steve, you missed ambrisentan... Some of our very refractory kids are on that. And we've used IV sildenafil a couple of times.

Ooh Jan that's a new one for me! I've never used it before, I wonder if it's approved for neonates?

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Specializes in NICU, PICU, PCVICU and peds oncology.

Oh, I very much doubt it. Most of the drugs we use aren't! Milrinone is almost a given for every cardiac kid we have, but when you look it up the section on use in pediatrics says, "Safety and effectiveness in pediatric patients have not been established". We've been using it as long as I've worked on this unit - eleven years - so I'd say there is data...

Ambrisentan (Letairis) has a black box warning for embryo-fetal toxicity, and there's the same "Safety and effectiveness...". We've only used it for a couple of kids, one definitely an infant. One of our intensivists is an internationally-recognised expert in pediatric PH and is the leader of the task force developing new guidelines for neonatal/infant and pediatric PH. He's the one with the stash of IV sildenafil in his office.

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Specializes in NICU.
Steve NNP thanks for clarifying, when using initials some may not be familar with it is good idea to state what ""PPHN is which is what you did. Thanks I was going to my books for the meaning.

Yes, as a new grad I once went through an elaborate explanation of PPHN as "Primary Pulmonary Hypertension of the Newborn." And of course...the father was a RN! But it kind of make sense...right!?I discovered my error out soon afterwards, but it's always good to know the correct meaning of a commonly used acronym. :roflmao:

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Specializes in NICU Transport/NICU.

Funny. I was just having this conversation with a new grad in our unit yesterday. I used to old term persistent fetal circulation to help her understand it. That seemed to help a lot. PPHN is most often caused by three disease processes: Meconium Aspiration, Congenital Heart Defect, and Diaphragmatic Hernia.

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