Patent Foramen Ovale

[strn96]

Hi! I'm an L&D nurse and had a question for you NICU nurses. When you have a NB with Patent Foramen Ovale, what is the rationale behind using continuous blow-by per NC? I think it has something to do with pressure gradiants, but not sure exactly what; and I can't seem to find this info. Hx on the case that makes me ask: LGA term NB, on O2 originally p delivery, then weaned. About a day later started desatting c feedings, so O2 was restarted. NB was sent for echo, which found PFO, then neonatologist recommended NB have cont blowby RA by NC. This is not a case I am personally involved in, just something that happened in our (small) "well-baby" Nsy that piqued my curiousity about the rationale behind this Tx.

[lovemyjob]

I've seen some doctors give O2 to try to encourage the duct to close. I couldn't begin to explain the physiology off the top of my head. I don't want to explain it incorrectly.

That would make sense except they were doing NC by blender at 21%, if I understood correctly, and if this were somehow a syptomatic issue. But it sounds to me like it is a feeding issue since it only happens with feeding. I have not heard of PFO causing any syptoms, but if it did, I dont think these would be the symptoms.

[rnpilot]

IIRC, it had to do with C02 receptors and increased Co2. NC at 21% would mostly encourage exchange, i.e. increased C02 encourages duct to stay open for oxygenation.

[lovemyjob]

But the PFO staying open would only be important if there were another defect that required mixing, right?

[rnpilot]

It's not about the O2 per se. It's about ensuring gas exchange, thus the canula with a little positive pressure. That way ideally, CO2 is kept normalized in the hopes of encouraging closure because it's not having a negative physiological effect. Also, IIRC, the best chance of it actually working is within the first 24 hours. Considering the physiology involved in the transition from fetus to newborn, it sounds good in theory, but I think it's doubtful that it works in actual practice. I think there was only 1 time I saw it done. Also, if the infant was having problems with feedings such as desats, then it wouldn't be having good exchange. That's what I remember, however I could be wrong.

Yes, keeping the duct open is only important if there is a duct dependant defect. In that case, the infant would be on drugs to keep it open. The O2 would have nothing to do with keeping it open, however with the defect the infant would likey require more O2.