Test Your Neonatal Critical Care Knowledge

[SteveNNP, MSN, NP]

So, by popular demand..... here is a thread dedicated to questions posed to help increase one's knowledge base in regards to the acute care NICU population. If anyone desperately wants a separate thread dedicated solely to the Well Newborn, we'll have to talk to Elvish about that one

So here's the plan. I'll pose a question drawn from an experience I've had, a clinical scenario I've formulated, or concepts I come across in the literature and board exam review. I will try to keep it in the vein of the NICU nurse, which will be interesting, since I've been saturated in NNP classes for a few years now.

Let's also keep in mind (and we all know this) that practice varies WIDELY from unit to unit. Feel free to answer based on your personal practice, but let's all keep in mind that the "book" answer may be different.

A little about me:

I have been practicing in NICU for almost 5 years, two in a level IIIb, and nearly 3 in a level IIIc quaternary NICU. I have had the privilege of caring for ECMO, pre/postop open hearts, single-lung ventilation, etc, as well as the gamut of preemie and surgical diagnoses. I finished up my NNP grad degree last December, and I'm now in the process of studying for my national certification/boards, as well as looking for a NNP position.

So here goes...

[SteveNNP, MSN, NP]

Question #1

You receive a call from the L&D charge nurse. She tells you that a 31 1/7 week gestation mother has just checked in, and was found to have Absent End-Diastolic Flow (AEDF) on ultrasound/doppler. What does this tell you is physiologically happening to the baby, and what, as the admission/resuscitation nurse should you be prepared for?

[Humbled_Nurse]

The baby has decreased blood flow from the umbilical cord. The baby may be IUGR. I would just be prepared as I would with any preterm delivery. How are the fetal heart tones? What does the strip look like? The baby may come out ok or need full resuscitative efforts. Did mom have any other problems with the pregnancy like PIH. Do they know what caused the absent end-diastolic flow? I know that reverse end-diastolic flow can be a more significant issue. Some mothers with absent end-distolic flow are on antepartum being monitored. Immediate delivery isn't always necessary.

[Humbled_Nurse]

Thanks for taking the hint and starting this thread. Love it!

[ittybabyRN, RN]

hmm I'm pretty new at this and don't work at a delivery hospital so I'm interested to find out what the answer is!

[littleneoRN]

I believe that neonates who experienced absent end diastolic flow actually tend to have enhanced lung maturity. I would think this is because these fetuses have experienced chronic in utero stress. In addition, with the known at risk pregnancy, I hope we can expect that this mom has received beta? So...significant RDS is somewhat less likely here, but of course, we shall be prepared to support ventilation as necessary. Of course all the normal expectations for a preemie, and as a previous poster mentioned, likely IUGR.

And Steve, I won't mind of some of your NNP knowledge finds it's way into this thread. :)

[SteveNNP, MSN, NP]

Here's the physiology:

End diastolic flow consists of the baby's umbilical arteries pumping deoxygenated blood at a slow flow rate towards the placenta. Even though the baby's heart is in diastole, the placenta is normally a low-pressure circuit, and the blood keeps flowing albeit slowly while in diastole.

With absent end diastolic flow, something is wrong with the placenta. The normally low pressure circuit suddenly increases in resistance, causing the flow to stop at diastole. Reverse end diastolic flow is even more ominous, when the placental resistance is so high, deoxygenated blood actually flows BACK into the baby. PIH is a very frequent cause of AEDF/REDF.

So depending on the timing and degree of AEDF/REDF, you can expect an IUGR infant. As some have mentioned, they may present as prenatally stressed, but overall well-appearing premature infants, or may require resuscitation at delivery due to decreased oxygenation. Depending on the nature of the flow restriction, a stat c/s may be in order.

So now on to question #2...

In neonatology, we often distinguish IUGR neonates as "symmetric" or "asymmetric."

1) How do we determine an infant is IUGR and not just SGA?

2) How do we determine an infant is asymmetric or symmetric IUGR?

3) How does a symmetric vs asymmetric IUGR infant appear?

4) What are the long-term neurodevelopmental sequelae of each type?

[littleneoRN]

SGA is purely based on the infant's size related to gestation, typically considered below the 10th percentile. IUGR is a more specific category for infants who have not reached their growth potential based due to abnormal genetic or environmental influences. I think also, some people limit the label IUGR to less than the 3rd percentile. Thus, all IUGR infants are SGA, but not all SGA are IUGR. An example of an SGA but not IUGR might be an Asian woman who is of small stature and has a history of having small but healthy babies.

IUGR is considered symmetric when all measurements (length, weight, OFC) plot in a similar place on the growth chart. This baby just looks small. IUGR is considered asymmetric when the OFC and possibly the length are normal (or at least higher on the growth curve) but weight is lower. This baby looks skinny and sometimes seems to have a big head compared to body. Symmetric IUGR is more often associated with factors that occur earlier in pregnancy, whereas asymmetric IUGR occurs later in pregnancy.

Outcomes vary based on the underlying pathophysiology. In general, long term outcomes are better for infants who "catch up" in growth by age two. Overall, the prognosis is more poor for symmetric than asymmetric IUGR.

[NotReady4PrimeTime, RN]

Thanks for taking the hint and starting this thread. Love it!

It was more of a poke with sharp stick, eh Steve? You rock, buddy!! Good luck on your boards. (DD is defending her PhD thesis in human genetics tomorrow so we're stressin' tonight...)

So I've been out of the nursery for too long it seems because that first one was a total "whassat?" for me. The second one I knew cold, and LittleneoRN nailed it. Off to a great start.

[littleneoRN]

Steve will rock his boards for sure! I'm hoping to be there someday too, so I'll soak up any little tidbits he's got to share!

[preemiex2]

Great thread Steve! As an NNP student half way through, I'm sure I'll find this fun and beneficial.

[SteveNNP, MSN, NP]

Good job so far, everyone!

So, the most important thing to remember is that SGA does not necessarily mean IUGR, but IUGR babies are always SGA. IUGR is something that's prenatally diagnosed, an ultrasound-detected failure of the fetus to grow at normal rates. This is usually caused by placental insufficiency, PIH, smoking, or infection.

Head-sparing, or asymmetrical IUGR is reassuring. Babies with this have a head circ >10% pct, but the length and weight plot