Pulmonary Hypertension Is Not All the Same: What NICU Nurses Need to Know

If you've followed me on social media over the past week, you've probably heard me say this a few times:

Pulmonary hypertension is not all the same.

And I think understanding that matters a lot, especially for us NICU nurses. Understanding pulmonary hypertension isn't just about knowing that pulmonary pressures are high or recognizing that a baby is receiving inhaled nitric oxide or sildenafil. The physiology should change what you notice and how you assess your patient. And it should help you understand why seemingly small nursing interventions can matter so much.

So let's connect the physiology to what you're actually seeing and doing at the bedside.

First, what is supposed to happen after birth?

Before birth, pulmonary vascular resistance (PVR) is naturally high. The fetal lungs aren't responsible for gas exchange yet because the placenta is. Pulmonary blood flow is relatively low, and blood can bypass the lungs through the fetal shunts, the ductus arteriosus and the foramen ovale.

Then the baby is born.

The lungs expand, oxygen tension rises, pulmonary blood vessels dilate, PVR falls, and pulmonary blood flow increases dramatically. That drop in PVR is a huge part of a successful transition to extrauterine life.

But what happens when it doesn't occur normally?

That depends on the baby. And this is where I think our thinking about "pulmonary hypertension" needs to become more nuanced.

Pressure isn't only about resistance

Pulmonary artery pressure isn't determined by PVR alone. It's actually a relationship between three things:

• pulmonary vascular resistance

• pulmonary blood flow

• the pressure downstream of the lungs in the left atrium.

Those are three different problems. They can all produce elevated pulmonary pressure, but they don't necessarily call for the same treatment.

PPHN in the term or near-term infant: when transition doesn't happen normally

Persistent pulmonary hypertension of the newborn, or PPHN, occurs when PVR fails to fall appropriately after birth. Once upon a time we called this "Persistent Fetal Circulation." Keeping that in mind (persistent fetal circulation) really helps us to understand what is going on with our patient.

As pulmonary pressures remain elevated, blood follows the path of least resistance. Instead of traveling through the pulmonary circulation to pick up oxygen, blood may shunt right-to-left across the patent ductus arteriosus and/or the foramen ovale. This results in decreased pulmonary blood flow and hypoxemia. Sometimes incredibly labile hypoxemia.

That physiology explains a lot of what you may see at the bedside.

What might you observe as the bedside nurse?

You may see:

• Significant or labile hypoxemia

• Rapid changes in oxygen saturation with handling, agitation, procedures, or other stress

• A difference between preductal and postductal oxygen saturations when right-to-left ductal shunting is present

• Increasing oxygen requirements or respiratory support

• Changes in perfusion, blood pressure, urine output, lactate, or other indicators of systemic blood flow

• Evidence of right ventricular strain or dysfunction on echocardiography

Preductal and postductal saturations tell a story

A gap of 5% or more between preductal (right hand) and postductal (either foot) saturations raises real suspicion for right-to-left shunting across the ductus arteriosus. A widening gradient may suggest increasing right-to-left ductal shunting and should prompt reassessment of the baby's oxygenation and hemodynamics.

Though, a normal gradient should not fully reassure you. The absence of a difference does not rule out pulmonary hypertension. It might just mean the shunting is happening somewhere your saturation probes can't show you.

Nursing Considerations: Why does keeping this baby calm matter?

Agitation isn't just unpleasant for a baby with severe pulmonary hypertension: In an already labile infant, it can contribute to physiologic deterioration

Agitation and procedural stress can worsen oxygenation and ventilation, and the resulting hypoxemia and acidosis are potent pulmonary vasoconstrictors. In fact, these babies are so labile that even small changes in their environment can trigger acute pulmonary vasoconstriction and rapid decompensation (Ball et al., 2021).

This reframes what containment and clustered care are actually doing. Holding a baby's arms and legs in flexion during a painful procedure isn't only about comfort. It's limiting a stimulus that could destabilize this baby's already labile physiology. Planning care so a baby isn't handled five separate times in an hour helps reduce how many times you ask an already labile pulmonary circulation to react.

Experienced NICU nurses build their whole practice around this idea, and it shows up in ways that might look like small details but are actually deliberate protection.

Arterial access is so helpful: These babies need frequent labs and blood gases. Secure arterial access, whether that's a UAC or a peripheral arterial line, lets you get what you need quietly. You can draw a gas without the painful poke. Avoiding that pain reduces painful stimulation that could destabilize an already labile infant.

Minimize unnecessary stimulation and maintain normothermia: Cold hands, a cold stethoscope, and cold equipment can all cause stress in a baby with PPHN. A cold baby has to work to generate heat, and that work raises oxygen consumption and metabolic demand. In a baby who's already walking a tightrope with their oxygenation, that extra demand can be enough to tip them into hypoxemia and acidosis. And we already know what those two things do to PVR. Maintaining normothermia and minimizing unexpected tactile stimulation are important developmental care practices for any labile baby. Warming the gel for an echo, warming your hands before an exam are part of the same protective, comfort-oriented strategy as containment.

Suctioning deserves real caution: Suctioning can cause important physiologic disturbances, including hypoxemia, bradycardia, and changes in blood pressure and cerebral hemodynamics. Unnecessary suctioning should be avoided. Follow your institutional policies and procedures, which may include a two-person approach, briefly increasing FiO2 before suctioning, and assess and address pain or agitation when clinically indicated.

So the next time you see a baby with PPHN desaturate hard during a procedure think about what may have contributed to that instability, and what you can adjust next time to protect them from it.

Lung recruitment matters too: PVR is affected by lung volume. Atelectatic, poorly recruited lungs can increase PVR. But more pressure isn't automatically better either. Excessive lung inflation can also compress pulmonary vessels and adversely affect pulmonary vascular resistance and venous return.

Pulmonary hypertension management is much more nuanced than just giving more oxygen.

This is where your relationship with your respiratory therapist really matters. I always refer to the RTs as my BFFs. Ventilator management is a team sport. While the RT brings respiratory expertise to ventilator management, stay involved in the big picture with them. Optimize recruitment while avoiding both atelectasis and overdistension, with ventilation individualized to the underlying lung phenotype rather than a single universal target.

When your patient's oxygenation deteriorates, think beyond the FiO2 knob: Is the baby adequately recruited? Is there worsening lung disease? Is the ET tube still where it should be? Are they fighting the ventilator? Has their CO2 or pH changed? Has their hemodynamic status changed?

Rethinking oxygen balance: When a baby with pulmonary hypertension desats, it's tempting to just turn up the FiO2 and move on. But it shouldn't be the only thing we do.

Both too little oxygen and too much oxygen can work against this baby. Hypoxemia triggers vasoconstriction, which you already know. But hyperoxia carries its own risk. Overshooting the oxygen target adds oxidative stress without providing additional pulmonary vasodilation once adequate oxygenation has already been achieved.

So the goal for these babies isn't maximum oxygen. It's the right amount to keep the pulmonary vasculature relaxed, without pushing past it. Paying close attention to saturation targets matter so much for this population.

What about systemic blood pressure? You may have seen us work to increase systemic vascular resistance (SVR) to make systemic pressures higher than pulmonary pressures and reduce right-to-left shunting. But our goal should NOT be to create supraphysiologic systemic blood pressure.

A baby with pulmonary hypertension can also have myocardial dysfunction, particularly right ventricular dysfunction, and vasoactive medications have different effects on systemic vascular tone, pulmonary vascular tone, and cardiac function. So in cases of hypotension, vasoactive medications may be indicated. When providing vasoactive meds, our goal is adequate systemic perfusion while supporting the relationship between the pulmonary and systemic circulations. Look at the blood pressure, perfusion, lactate, urine output, echocardiographic findings, and the baby's overall clinical picture when evaluating this support.

Fluid management and protecting a struggling right ventricle: A right ventricle pumping against high pulmonary pressures is already under strain, and indiscriminate volume loading can add to that strain and tip a compensated baby toward decompensation.

But a failing right ventricle still needs adequate preload to function. The goal is avoiding volume overload while maintaining the filling this ventricle actually needs, not restricting fluids reflexively.

As the nurse we need to watch for the fluid that's easy to lose track of: medication volumes, line flushes, blood products, and boluses can quietly add up and push a baby past their total fluid goal without anyone intending it to happen.

When medical management isn't enough: Most babies with PPHN respond to supportive care and pulmonary vasodilator therapy. When severe, acute PPHN is refractory to everything else, ECMO may be considered. ECMO is reserved for severe, refractory hypoxemic or cardiorespiratory failure in eligible infants despite optimized conventional management, and the decision depends on many factors beyond just severity, including gestational age, bleeding risk, and the underlying diagnosis.

Acute pulmonary hypertension in the premature infant with RDS

Now let's change the patient.

Imagine a 25-week premature infant during the first days of life with significant RDS and evidence of pulmonary hypertension.

Is that exactly the same disease as PPHN in a term baby with meconium aspiration?

No.

The preterm pulmonary circulation is still developing. Pulmonary vascular growth has been interrupted by premature birth, the pulmonary vessels are immature, and RDS can contribute to hypoxemia, atelectasis, abnormal lung volumes, and impaired transition.

Research increasingly describes pulmonary vascular disease of prematurity as a spectrum, including severe early PH associated with hypoxemic respiratory failure, delayed pulmonary vascular transition, early PH, and later chronic pulmonary vascular disease.

Nursing Interventions for the Preterm Baby with PH

The care you provide to a premature baby with PH is quite similar to care you'd provide any premature baby. It's important that you understand how that care affects the physiology of PH:

• Handle thoughtfully: Cluster care when appropriate, provide containment, maintain normothermia, and minimize unnecessary painful or stressful stimulation. Especially when you already know the infant becomes hypoxemic or unstable with handling.

• Be meticulous with oxygen: Titrate FiO₂ to the prescribed saturation range rather than accepting prolonged hypoxemia or unnecessary hyperoxia. In an extremely preterm infant, both sides matter.

• Protect lung recruitment: Watch for changes in respiratory support, chest movement, ETT position, secretions, CO₂/pH, and oxygen requirement. Inadequate recruitment and abnormal lung volumes can worsen pulmonary vascular physiology.

• Pay attention to patterns around care: Does the infant repeatedly desaturate with handling and recover slowly? Is the oxygen requirement progressively increasing? Are episodes becoming harder to recover from? Those trends are worth communicating.

• Don't assume every oxygen problem is RDS: If oxygenation is disproportionately poor, unusually labile, or not improving as expected despite reasonable lung recruitment, pulmonary vascular physiology belongs on the differential and echocardiography may help clarify what is happening.

• Know why iNO was started (if it is started): In a 25-weeker, “because they're hypoxic” and “because echo/clinical findings suggest PH physiology” are not equivalent rationales.

Speaking of iNO... Inhaled nitric oxide is an established pulmonary vasodilator for appropriately selected term and near-term infants with hypoxemic respiratory failure and PPHN. Routine or rescue iNO use solely for respiratory failure in premature infants has not shown the same benefit. The American Academy of Pediatrics, in a clinical report most recently reaffirmed in 2025, states that the available evidence does not support using iNO in early routine, early rescue, or later rescue regimens for infants born before 34 weeks (Kumar & Committee on Fetus and Newborn, 2014/2025). There may, however, be selected premature infants with documented PH physiology in whom the medical team considers pulmonary vasodilator therapy.

BPD-associated pulmonary hypertension: a different problem again

Now imagine a baby born at 24 weeks who is several months into their NICU stay with established BPD.

Pulmonary hypertension here has a different story: Normal alveolar development and pulmonary vascular development happen together. When lung development is disrupted, pulmonary vascular growth can be disrupted too.

The baby may have fewer pulmonary vessels, abnormal vascular remodeling, and increased muscularization of the pulmonary arteries. Chronic and intermittent hypoxemia can further contribute to pulmonary vasoconstriction and remodeling. Over time, the right ventricle has to pump against this increased resistance.

BPD-PH isn't one problem either

BPD-PH itself splits into different types depending on what's actually driving the pressure. Singh et al. (2026) recently proposed a physiology-based framework for thinking about this:

Type 1 is what most of us picture first: elevated resistance from the vascular changes we just described. This is the classic phenotype, and it's the one most likely to respond to oxygen and pulmonary vasodilators.

Type 2 is flow-dependent. A shunt, whether that's a PDA, an ASD, or something similar, is sending too much blood flow through the lungs. In this phenotype, a vasodilator can actually make things worse by increasing that flow further.

Type 3 is post-capillary, meaning the problem is backpressure coming from behind the lungs. This can come from left ventricular dysfunction, or from pulmonary vein stenosis, a narrowing that develops in some babies with BPD-PH and is often under-recognized. Vasodilators are cautioned against here too, since they can worsen pulmonary edema.

This is exactly why a vasodilator that helps one baby with BPD-PH can hurt another.

What should the nurse be paying attention to?

With BPD-associated PH, think about trends. Is the baby's oxygen requirement creeping up? Are desaturation episodes becoming more frequent or taking longer to recover from? Does the baby become particularly unstable with feeding, stooling, agitation, or routine care? Are they struggling to grow despite adequate nutritional support? Has their respiratory support stopped progressing or their requirements increased? What does their echocardiogram show?

These bedside findings alone do not diagnose pulmonary hypertension. But experienced NICU nurses are often the people spending 12 hours watching these patterns evolve. Your assessment matters.

When you know the physiology, your interventions look different

We can memorize that hypoxemia is bad. But understanding that hypoxemia can increase pulmonary vasoconstriction gives you the why.

We can memorize that the baby needs an echocardiogram. But understanding that echocardiography helps identify shunt direction, pulmonary pressure, ventricular function, and underlying hemodynamics gives you the why, and helps you advocate for making that study as physiologically gentle as possible. Things like warming the gel, dimming the lights when appropriate providing containment, covering the baby's eyes and providing pain management and sedation if it's needed.

A baby with pulmonary hypertension shouldn't have to prove how sick they are by becoming profoundly unstable during every intervention.

Pulmonary vasodilators: don't just memorize the drug

The same thinking applies when pulmonary vasodilators are started.

Don't stop at "This baby is on nitric oxide." Ask yourself why it was selected, what pathway it acts on, and whether the baby is actually responding.

Most of the medications we use for pulmonary hypertension work through a few main pathways, and knowing which pathway a drug acts on tells you what to expect and what to watch for.

The nitric oxide pathway: Inhaled nitric oxide diffuses into the smooth muscle of the pulmonary vasculature and raises a molecule called cGMP, which relaxes the vessel. It produces relatively selective pulmonary vasodilation because it reaches ventilated lung units directly and is rapidly inactivated once it enters the bloodstream, which limits systemic effects without eliminating them entirely. That's why it's the first-line choice for an acute PH crisis in a term or near-term infant with hypoxemic respiratory failure associated with PPHN, after lung recruitment has been optimized. Sildenafil works on the same pathway from a different angle, blocking the enzyme that breaks cGMP down. That's why you'll often see it used to help wean a baby off iNO, or as a longer term therapy once the acute crisis has passed.

Worth knowing: the neonatal evidence behind sildenafil is weaker than it is for iNO. Cochrane reviews rate the existing trial data as low to very low quality, so its widespread use reflects clinical experience and physiologic reasoning more than strong randomized evidence.

The endothelin pathway: Endothelin is a hormone that constricts pulmonary vessels and promotes the kind of vascular remodeling we see in chronic disease like BPD-PH. Bosentan blocks that receptor. It's typically reserved for chronic management rather than acute crises, and it requires monitoring liver function, since hepatotoxicity is a known risk.

The cAMP pathway: This one covers two different medications that reach a similar destination by different routes. Milrinone inhibits an enzyme called PDE3, which raises intracellular cAMP. That combination improves how well the heart squeezes while also lowering pulmonary vascular resistance, making milrinone a physiologically attractive choice when a baby has both PH and ventricular dysfunction, though it can drop systemic blood pressure and needs to be used carefully. When used for PH specifically, milrinone is off-label, and its use is based largely on physiologic rationale and clinical experience rather than robust neonatal randomized trials.

Prostacyclin analogs like epoprostenol and treprostinil raise cAMP through an entirely different route, acting directly on prostacyclin receptors rather than inhibiting PDE3. They tend to be reserved for severe or refractory disease, since neonatal experience with them is more limited and delivery can be complex.

Knowing the pathway also helps you understand why a medication might not be the right choice for every baby. A vasodilator that works beautifully for a term baby with classic PPHN could make things worse for a baby whose pressure is actually coming from too much blood flow through a big PDA. That's the whole point of asking why the pressure is elevated before asking which drug to give.

And this still isn't every type of neonatal pulmonary hypertension

Pulmonary hypertension can also occur in babies with pulmonary hypoplasia, congenital diaphragmatic hernia, congenital heart disease, pulmonary vein stenosis, alveolar capillary dysplasia, and other conditions.

That's exactly the point. "Pulmonary hypertension" describes important physiology. It doesn't tell you the entire disease process.

In Summary

The next time you're caring for a baby with pulmonary hypertension, don't stop at the diagnosis.

Ask yourself: Why is the pressure elevated in this baby?

Then connect that answer to what you're seeing. That's how we move beyond task-oriented care and develop the clinical reasoning that helps us anticipate what our patients need.

That's how we become nurses who anticipate what our patients need, recognize subtle changes, and advocate confidently at the bedside.

Want to understand the WHY behind neonatal care?

Pulmonary hypertension is just one example of why memorizing diagnoses, medications, and normal values isn’t enough. When you understand the physiology, you can recognize subtle changes, anticipate what your patient may need, and communicate your concerns more confidently.

That’s how I teach inside my Neonatal Certification Review Course. We don’t just review what you need to know for the RNC-NIC or CCRN-Neonatal exam... we connect the concepts to what you’re actually seeing and doing at the bedside.

With more than 20 hours of instruction, 500+ practice questions, flashcards, bonus lessons, and lifetime access, the course is designed to help you prepare for certification while becoming a more confident NICU nurse.

LEARN MORE ABOUT THE NEONATAL CERTIFICATION REVIEW COURSE

References

Ball, M. K., Seabrook, R., Bonachea, E., et al. (2021). Evidence-based guidelines for acute stabilization and management of neonates with persistent pulmonary hypertension of the newborn. American Journal of Perinatology, 40, 1495–1508. https://doi.org/10.1055/a-1711-0778

Barrington, K. J., Finer, N., & Pennaforte, T. (2017). Inhaled nitric oxide for respiratory failure in preterm infants. Cochrane Database of Systematic Reviews, 1(1), CD000509. https://doi.org/10.1002/14651858.CD000509.pub5

Bassler, D., Kreutzer, K., McNamara, P., & Kirpalani, H. (2010). Milrinone for persistent pulmonary hypertension of the newborn. Cochrane Database of Systematic Reviews, (11), CD007802.

Chan, S., Brugha, R., Quyam, S., & Moledina, S. (2022). Diagnosis and management of pulmonary hypertension in infants with bronchopulmonary dysplasia: A guide for paediatric respiratory specialists. Breathe, 18(4), 220209. https://doi.org/10.1183/20734735.0209-2022

Jain, A., Giesinger, R. E., Dakshinamurti, S., et al. (2022). Care of the critically ill neonate with hypoxemic respiratory failure and acute pulmonary hypertension: Framework for practice based on consensus opinion of Neonatal Hemodynamics Working Group. Journal of Perinatology, 42(1), 3–13. https://doi.org/10.1038/s41372-021-01296-z

Kelly, L. E., Ohlsson, A., & Shah, P. S. (2017). Sildenafil for pulmonary hypertension in neonates. Cochrane Database of Systematic Reviews, 8(8), CD005494. https://doi.org/10.1002/14651858.CD005494.pub4

Kumar, P., & Committee on Fetus and Newborn. (2014, reaffirmed 2025). Use of inhaled nitric oxide in preterm infants. Pediatrics, 133(1), 164–170. https://doi.org/10.1542/peds.2013-3444

Mandell, E. W., Kinsella, J. P., & Abman, S. H. (2021). Persistent pulmonary hypertension of the newborn. Pediatric Pulmonology, 56(3), 661–669. https://doi.org/10.1002/ppul.25073

Mani, S., Mirza, H., Ziegler, J., & Chandrasekharan, P. (2024). Early pulmonary hypertension in preterm infants. Clinics in Perinatology, 51(1), 171–193. https://doi.org/10.1016/j.clp.2023.11.005

Mirza, H., Mandell, E. W., Kinsella, J. P., McNamara, P. J., & Abman, S. H. (2023). Pulmonary vascular phenotypes of prematurity: The path to precision medicine. The Journal of Pediatrics, 259, 113444. https://doi.org/10.1016/j.jpeds.2023.113444

Singh, Y., Nath, S., Gahlaut, S., & Chan, B. (2026). Physiology-based diagnosis and management of bronchopulmonary dysplasia associated pulmonary hypertension (BPD-PH). Children, 13(2), 272. https://doi.org/10.3390/children13020272

Singh, Y., & Lakshminrusimha, S. (2021). Pathophysiology and management of persistent pulmonary hypertension of the newborn. Clinics in Perinatology, 48(3), 595–618. https://doi.org/10.1016/j.clp.2021.05.009