We review the differential and evaluation of neonatal tachypnea. We are joined by Muraleedharan Sivarajan, MD, Assistant Professor of Neonatal-Perinatal Medicine at the University of Texas Southwestern Medical Center.
Dr. Neeta Goli:
Welcome to Newborn News, a podcast where we discuss educational topics for medical professionals who care for newborns. I'm your host, Dr. Neeta Goli, a pediatrician in the UT Southwestern Newborn Nursery. Welcome back to the podcast. In today's episode, we'll be discussing neonatal tachypnea. We're recording remotely due to the ongoing COVID pandemic. We are joined today by Dr. Muraleedharan Sivarajan, Assistant Professor of Neonatal-Perinatal Medicine at UT Southwestern and a colleague in the Newborn Nursery, with over 35 years of experience caring for children and a career spanning three continents.
Dr. Muralee Sivarajan:
Hello?
Dr. Neeta Goli:
Hi, Dr. Sivarajan. Thanks for joining us today.
Dr. Muralee Sivarajan:
Hi, Dr. Goli. Truly my pleasure to be back. How are you?
Dr. Neeta Goli:
Good, thank you. Today, we will be talking about neonatal tachypnea, or increased respiratory rate. So in the nursery, this is something that we get called about not infrequently. The differential for tachypnea can be pretty broad. So let's start off with definitions. How do you define neonatal tachypnea? What respiratory rate is concerning to you? And what is the physiology involved?
Dr. Muralee Sivarajan:
Thank you. This is a great topic to discuss. As you alluded, the differential can literally go from A to Z. Respiratory distress can affect around 7% of all term newborns, and the number increases with prematurity. Tachypnea is actually a compensatory mechanism, when the baby is faced with hypercarbia, hypoxemia or acidosis, which may be metabolic or respiratory. Other signs of increased work for breathing occurs due to altered pulmonary mechanics. This is usually an interplay of increased airway resistance and/or decreased lung compliance.
Dr. Muralee Sivarajan:
While tachypnea can be a sign of respiratory distress, it is important to realize that it's not specific to the respiratory system. Standard definition of tachypnea would be a respiratory rate of more than 60 per minute. Newborns do tend to have a normal variation in breathing; due to this one should preferably count for one full minute to even this out. Now, in some units, for example ours, we use a cutoff of more than 65. This is just a local variation, and this is aimed to prevent unnecessary workups, providing there are no other signs or concerns.
Dr. Neeta Goli:
Are there any specific approaches for this broad spectrum of differentials in a tachypneic baby?
Dr. Muralee Sivarajan:
Yes, so, as with most things, it's best to approach a problem systematically. While there may be different approaches, I like to put all my cards on the table for an overview from an anatomical perspective. So, with that in mind, let's just run through what other things we could face.
Dr. Muralee Sivarajan:
Let's start from the nose. Is there congestion of the nose? Which might be just a normal thing or is there something else going on like congenital syphilis? Is there some kind of obstruction there, like choanal atresia, a deviated septum, or a large hemangioma? Coming down to the mouth, is there micrognathia and an associated glossoptosis, or is that associated with a Potter or a Pierre Robin sequence? Then you want to think of any other kind of obstruction, like a hemangioma, lingual thyroid, or is this an anatomical defect in the mouth, like a cleft palate? Is there a very large tongue, again, causing obstruction?
Dr. Muralee Sivarajan:
Going down to the neck, you want to think about, is there a laryngeal web, is there a tracheoesophageal fistula? What about a vocal cord paralysis, is there a laryngo/tracheomalacia? And then moving down to the upper chest and to the lower part of the neck, you want to think of vascular rings or is this a pneumomediastinum? Or is there a mediastinal mass?
Dr. Muralee Sivarajan:
From there you might want to go to the chest itself. So you want to look at the lungs. So, is there any evidence of persistent pulmonary hypertension? Is this a congenital pneumonia? Then you want to think of the TORCH infections, or is it something acquired? This can have a varied etiology. Or is it an aspiration pneumonia? Or more common things, like transient tachypnea of the newborn, meconium aspiration syndrome, and in preterms respiratory distress syndrome due to surfactant deficiency.
Dr. Muralee Sivarajan:
And sometimes you're dealt with other structural anomalies like congenital cystic adenomatoid malformation or congenital lobar emphysema. You can also, especially in preterms, see pulmonary hemorrhage and rarer diagnosis like alveolar capillary dysplasia or pulmonary alveolar proteinosis. Then if you look into the chest cavity itself, you want to think about, is this pneumothorax, is it a chylothorax, or a pleural effusion? Is it a part of hydrops?
Dr. Muralee Sivarajan:
And then going to the heart, you want to think of pleural effusions, or a pneumo/hemopericardium, cyanotic and some non-cyanotic heart disease, congenital heart disease. Could it be myocarditis? Any arrhythmias going on there? Cardiomyopathy, is it heart failure? Then moving to the diaphragm, is it congenital diaphragmatic hernia or eventration of the diaphragm, or is the diaphragm just paralyzed due to phrenic nerve avulsion?
Dr. Muralee Sivarajan:
And then other structures in the chest, like is this trauma to the rib? Which, in some instances, especially babies coming back from home, you unfortunately need to think of non-accidental injuries. Or, it could be some kind of bone disorder like osteogenesis imperfecta, or other neurological conditions like spinal muscular atrophies, myotonic dystrophies, or arthrogryposis. Or it can be simply a pectus excavatum itself interfering with the mechanics of breathing.
Dr. Muralee Sivarajan:
And then we're moving down to the abdomen. We already talked about a diaphragmatic hernia. Then you want to think of other causes of GI obstruction, or you want to think of remote causes like renal dysplasia leading to pulmonary hypoplasia.
Dr. Muralee Sivarajan:
And then you want to look at causes in the brain. Is this seizures, is that intraventricular hemorrhage or other brain malformations? Was there birth trauma? Was there hypoxic-ischemic encephalopathy, hydrocephalus, meningitis, spinal cord injury?
Dr. Muralee Sivarajan:
And have a look at the whole baby. Is there any syndromic feature that you want to consider? And just remember pain itself can be a reason, so you might want to just have a good look over. Is that a hair intertwined around the digit, fracture of the clavicle or hip dislocation, or pain due to syphilitic bone involvement? Then, want to think of more remote causes. Are there any inborn errors of metabolism, neonatal abstinence syndrome? And then things even more remote, like hypoglycemia, polycythemia or anemia, electrolyte imbalances of magnesium and sodium, especially acidosis, sepsis, and temperature, can be a low or high temperature, can all give you issues. So, that's a broad spectrum of which you want to have some kind of idea about when you approach tachypnea.
Dr. Neeta Goli:
So, easy-peasy. Right?
Dr. Muralee Sivarajan:
Absolutely.
Dr. Neeta Goli:
So, that was impressive. But again, that's a very intimidating list, especially when you get this call saying, "Baby is tachypneic, please come assess." How do you try to make sense of this in the context of a tachypneic baby that you're evaluating?
Dr. Muralee Sivarajan:
Excellent question. How to deal with this mess, right? So, actually, by a combination of good history, a thorough physical, a few basic tests as indicated, one can pretty much narrow down your diagnosis by sound clinical reasoning, most of the time. Though, sometimes the work up needs to be more broad, and this is something we often do. So it is intimidating, but if you approach it systematically... So again, thoroughness is the key.
Dr. Muralee Sivarajan:
For example, you're called to a meconium stained fluid delivery. Then, common things being common, you want to think about meconium aspiration syndrome as one of your primary concentrations. Sometimes life is more complicated. You may have prolonged rupture of membranes in a GBS-positive mother thrown in with meconium. Then you might want to extend your diagnosis. Could it be an infection and meconium aspiration syndrome? So, it gets a little bit complicated like that.
Dr. Muralee Sivarajan:
Again, if you're seeing a preterm baby, you might want to consider is it respiratory distress syndrome due to surfactant deficiency? Or is it some issue which was known antenatally? The prenatal sonogram is available in most of the moms these days. So you might be on the lookout for a heart disease or diaphragmatic hernia right at delivery, a micrognathia, hydrops baby, or polyhydramnios to suggest GI obstructions, or oligohydramnios to suggest lung hypoplasia and renal issues. Or you might be seeing a baby who's choking on feeds, blowing bubbles. Okay, so then you might want to think about is this tracheoesophageal fistula, or else try suggesting laryngo/tracheomalacia or a vocal cord paralysis. Some babies may be pink on crying, and then strangely become dusky when they're not crying. Then you want to think is this choanal atresia, and do the fog test by seeing air movement and misting over the nostrils.
Dr. Muralee Sivarajan:
So sometimes on ausculation you might find the shift of mediastinum, or more commonly in our practice, what we see is muffling of the heart sounds. Then you want to think is there pneumothorax, especially if this baby had some kind of positive pressure ventilation at delivery. A scaphoid abdomen, and bowel sounds in the chest suggest diaphragmatic hernia. A heart murmur, with maybe a gallop rhythm, femoral pulses not well felt or a large liver. You want to think about congenital heart disease.
Dr. Muralee Sivarajan:
Or is the baby just hot? Which is often seen in the delivery room, especially in a chorio mom. Then it may just need a temperature adjustment. Is there any jitteriness, to suggest hypoglycemia? Is the baby looking plethoric, to suggest polycythemia, or just pale suggesting some kind of severe hemolytic disease going on? Is there a bulging fontanelle that you want to think about? Is this possibly some kind of intraventricular hemorrhage, or is there a history of a traumatic delivery, which might point towards the diaphragmatic paralysis? So also, you have to be a good detective. You have to collect all these bits and pieces and then try to make good clinical judgment.
Dr. Neeta Goli:
So, I think stressing the importance of the history and physical exam. And always, for our listeners, you will never be wrong to go examine the baby. So, that's always the first thing you want to do when you get a phone call about a tachypneic baby, or any other baby in any sort of distress.
Dr. Muralee Sivarajan:
Couldn't agree more.
Dr. Neeta Goli:
Yeah. Now, we will often talk about whether the tachypnea is early-onset or late-onset. What is the timeframe for each of these? How do you determine?
Dr. Muralee Sivarajan:
Yeah, so this is another way of approaching tachypnea. Around four hours postnatal would be a good cutoff for early versus late, keeping in mind that overlaps always occur.
Dr. Neeta Goli:
And then, how does that change your differential? So, what would your differential be for, let's say, early-onset tachypnea?
Dr. Muralee Sivarajan:
So, transient tachypnea of the newborn would be a common reason in term babies. Especially if there was a history of a precipitous delivery or a ceasarean section. So, those babies with mild tachypnea, less than 70 without desaturations, we may just watch closely in the newborn nursery. But if it persists beyond a few hours, or worsens, then they need a work up and continuous monitoring. And then, that usually means a NICU transfer in our set up. Preterm babies, due to RDS with surfactant deficiency. Again, it manifests early. Other reasons would be congenital issues, like a diaphragmatic hernia. So heart disease, choanal atresia, CCAM, glossoptosis, tracheoesophageal fistula, pneumothorax, or other peripartum events like intraventricular hemorrhage, fractures, meconium aspiration. So, all these need to be considered.
Dr. Neeta Goli:
And then what would be your differential for a late-onset tachypnea?
Dr. Muralee Sivarajan:
So, infections become more important. The organ overlaps can occur, it can even present earlier. But pneumonia, septicemia, again, hypoglycemia can happen even later, tension pneumothorax, it may be a small pneumothorax earlier, but it's building up pressure, then it starts manifesting after four hours. Interestingly, congenital heart disease also is a common presenter in this timeframe, especially those which are duct-dependent. When the duct starts to close off they start manifesting in this timeframe. And even later, other causes become more obvious, like inborn errors of metabolism. You need enough substrate to get into the baby to develop all those acidosis and so forth and manifest themselves as tachypnea. Can be, also, neonatal abstinence syndrome and non-accidental injuries also need to be considered this timeframe.
Dr. Neeta Goli:
And for the most part, so far, we have been talking about term babies. You did mention surfactant deficiency in our preterms. What additional considerations might you have for a late-preterm infant?
Dr. Muralee Sivarajan:
So, preterm babies are always prone to develop hypoglycemia. So that's usually a part of the protocol, that we screen them for hypoglycemia. But they usually are done at specific intervals, they can still develop hypoglycemia in between, so that needs to be always considered. Infections are another common reason in preterm. They are a pretty immunosuppressed group of people. So, that's a very important reason. Temperature instability. They don't have a very good, mature central mechanisms or fat stores, of glycogen reserves, and so forth. So, they always have these issues with temperature. In addition, those earlier than 34 weeks, respiratory distress syndrome, intraventricular hemorrhage, birth asphyxia, all become more prominent.
Dr. Neeta Goli:
And I think we already addressed this when you were going through your head to toe checklist, but is there any additional information you should gather from mom's or baby's history?
Dr. Muralee Sivarajan:
Yeah, there's a whole bunch of things. Some of them, as you said, we touched on, but often moms have an antenatal sonogram, always is a great boon. So, that gives you a chance to look out for things. But in spite of that, we often see moms with no prenatal care coming in. So, just because we don't have that, we shouldn't forget all these things, but you want to think about, historically also, is there any maternal substance use? Has she got diabetes, which increases the risk of surfactant deficiency? Did she have any viral infections during pregnancy or does she have a history of herpes, which is an important virus to consider? And, does she have any infections like pyelonephritis close to delivery, which is almost always a septicemic illness? Does she develop chorioamnionitis? What is her GBS status and how was the meconium? Well, I mean, was there any meconium in the fluid, or was the fluid bloody?
Dr. Muralee Sivarajan:
What's the gestational age? Durational rupture of membranes? Oligo- or polyhydramnios? Was the mode of delivery a Cesarean? What medications did she get, especially magnesium or in the case of preterm babies, steroids. But you want to look at peripartum events, like what was the APGAR score? What kind of resuscitation was required? Was there any positive pressure ventilation required or chest compressions? Then you want to think about traumatic events also.
Dr. Muralee Sivarajan:
Or did this present during feeding, or were there any abnormal moments like seizures? How does the baby handle when you are handling the baby? Is the baby crying in pain? Other signs of distress, like retraction, grunting, duskiness. Then you want to also look at the family history of heart disease. You want to think of pets in the house like cats and toxoplasmosis, congenital toxoplasmosis. So neonates following up in home, coming with some respiratory distress, you want to think, what is the health of other family members? Is anybody suffering from some GI or respiratory illness?
Dr. Neeta Goli:
And when you go to assess these babies, what is your initial evaluation and management?
Dr. Muralee Sivarajan:
Don't panic. As always, go and attend to the ABCs, see if the airway, breathing and circulation is all right. If not, you start your neonatal resuscitation or other first aid measures that you have learned. So, after stabilization, you complete any outstanding vital signs, and then you titrate any oxygen required to target saturations. How we normally do things is we immediately get a bedside glucose check. We often include an initial hematocrit with the heel stick so those two differentials can be looked at. And then, you can proceed to do a thorough examination once stabilized. In the meantime, get someone to get a good history, or you can review that once you’ve finished your exam. Main thing is to make sure the baby is in an environment where close monitoring is possible while the tachypnea persists. You don't want the baby crashing in the mother's room where there might not be monitoring equipment.
Dr. Muralee Sivarajan:
So, we usually bring up these babies to our newborn nursery. We sometimes tend to watch them for a while, if it's borderline tachypnea. But if there is significant or persistent distress, then you may have to escalate things. So, usually it's a chest x-ray, we try to get two views, a CBC with differential, and a blood culture. And then depending on how things progress, if you still can't get a handle, you may need to escalate to an EKG or perhaps an echo, or you might need to do another set of blood work, which will include basic metabolic profile, which looks at electrolytes and acid-base balance. And you may need to add ammonia, lactate, add other inborn errors of metabolism work up, and also maybe add a head ultrasound, if you're considering some CNS issue. And if you're considering seizures, an EEG.
Dr. Muralee Sivarajan:
So, you're not doing all of these things together. You kind of escalate them. You start with the basic workup first and then try to get a handle on the situation. And then that might point you in one direction, but sometimes you may not. And then you just have to start escalating things and throw in the carpet, as it were. Often, persistent distress warrants IV antibiotic coverage. Usually ampicillin and gentamycin is what we use. It should cover the gram-negative, gram-positives including listeria. Chest x-ray findings of neonatal pneumonia maybe subtle and they're masquerade like TTN. So, neonatology is one of the disciplines where we have a low threshold to start antibiotics.
Dr. Neeta Goli:
So, what factors would lead you to transfer a baby to a higher level of care, or the NICU, due to tachypnea?
Dr. Muralee Sivarajan:
Any baby in significant or persistent respiratory distress. Like the baby is flaring the nostrils, grunting and retracting, or breathing very fast. Or if there is an unresolved mild tachypnea which started and it's now getting worse. Or if they're needing oxygen. All of these babies need higher levels of care. Babies breathing in the 80s are at a risk for aspiration when you feed orally, so they need IV fluids. Again, you need to be in a situation where that can be accomplished. When continuous monitoring is needed, NICU care is indicated.
Dr. Neeta Goli:
And I know that was quite a broad differential that we discussed earlier, but what is the expected prognosis or resolution, at least for some of the more common etiologies that we talked about earlier?
Dr. Muralee Sivarajan:
Right, so around 15% of term and 29% of late-preterm infants who get admitted to NICU develop significant respiratory morbidity. This is even higher for infants born before 34 weeks gestation. Failure to diagnose and treat the underlying condition can lead to short- and long-term complications, or even death. So, the prognosis will basically vary depending on the etiology.
Dr. Muralee Sivarajan:
Some things just need time, like TTN, they tend to resolve with minimal support. Occasionally they need oxygen, and this might go on for one to three days and they usually leave no sequelae, but when you're needing oxygen for that period of time, usually we end up doing cultures and antibiotics as well. Hypoglycemia should respond to oral feeding or some IV dextrose, but then you should also look at underlying conditions and do regular glucose checks. Other things like respiratory distress in a very preterm can be more complex because they touch on multiple systems and prognosis will vary depending on the complex interplay between them. Heart disease, prognosis also varies depending on the diagnosis, but the crux of the issue is early diagnosis and care, which will limit the sequelae.
Dr. Neeta Goli:
To end the episode today, what is your favorite part of your workday?
Dr. Muralee Sivarajan:
Well, there are many favorite parts, but one of the enjoyable parts I would say would be rounding with my residents and medical students and taking them to the patient for some good old-fashioned bedside medicines. What is yours?
Dr. Neeta Goli:
I think just talking to the parents, watching them enjoy their new baby. You know, you see that this is a happy time in their lives for the most part. So, just to be able to be a part of that is really fun for me.
Dr. Muralee Sivarajan:
Yeah, absolutely. For the most part, newborn medicine is a happy place.
Dr. Neeta Goli:
Yeah. Thank you again for joining us, Dr. Sivarajan.
Dr. Muralee Sivarajan:
My pleasure. Thanks Dr. Goli, have a nice day.
Dr. Neeta Goli:
Thank you, you too.
Dr. Neeta Goli:
Thanks for listening to Newborn News. We hope you join us next time. If you like what you hear, make sure to subscribe and leave us a review. If you have questions, comments, feedback, or suggestions for future episodes, please email me at NewbornNews@utsouthwestern.edu. As a reminder, this content is educational and is not meant to be used as medical advice. Views or opinions expressed in this podcast are those of myself and my guests, and do not necessarily reflect the views of the university.