6.2 Pulmonary Hypertension

Pulmonary Hypertension in the Pediatric ICU

Pulmonary hypertension (PH) is sustained elevation of pulmonary artery pressure that increases pulmonary vascular resistance (PVR) and afterloads the right ventricle (RV). In children, PH may be idiopathic, heritable, or secondary to congenital heart disease (especially left-to-right shunt lesions with pulmonary overcirculation), chronic lung disease of prematurity, congenital diaphragmatic hernia, obstructive sleep apnea, or thromboembolic disease. Whatever the cause, the CCRN Pediatric nurse must prevent acute rises in PVR, support RV function, and manage inhaled pulmonary vasodilators without causing rebound crisis.

Pediatric Triggers That Raise PVR

The pulmonary vascular bed is exquisitely reactive in infants and children. Common PICU triggers that precipitate or worsen PH include:

• Alveolar hypoxia and hypoxemia — the strongest reversible stimulus for pulmonary vasoconstriction
• Acidosis (respiratory or metabolic) — further increases PVR
• Hypercarbia when it produces acidosis
• Pain, agitation, suctioning, and cold stress — catecholamine surges and desaturation events
• High mean airway pressure / excessive PEEP — overdistention compresses alveolar capillaries and may raise PVR
• Abrupt withdrawal of inhaled nitric oxide, prostacyclin analogs, or other pulmonary vasodilators

Conversely, strategies that lower PVR include optimized oxygenation, mild alkalosis when ordered for crisis, adequate sedation and analgesia, lung recruitment without overdistention, and continuous delivery of prescribed pulmonary vasodilators.

Recognizing Right-Heart Failure

When PVR remains high, the RV dilates, septum bows leftward, left-ventricular filling falls, and cardiac output drops. Pediatric signs of RV failure / PH crisis include:

• Sudden desaturation with systemic hypotension
• Tachycardia progressing to bradycardia if untreated
• Rising central venous pressure (CVP) or jugular venous distention
• Hepatomegaly, peripheral edema, and ascites in subacute failure
• Oliguria from low cardiac output
• Clear or near-clear lung fields when left heart function is relatively preserved (contrast with left-sided cardiogenic pulmonary edema)
• In children with intracardiac communications, right-to-left shunting worsens cyanosis

Near-infrared spectroscopy (NIRS), lactate trends, mixed or central venous saturation, and echocardiography (when available) help confirm inadequate systemic oxygen delivery. Do not wait for a perfect echo report if the child is crashing — treat reversible triggers immediately while calling the intensivist and cardiology/PH team.

Inhaled Nitric Oxide: Nursing Essentials

Inhaled nitric oxide (iNO) is a selective pulmonary vasodilator delivered with the ventilator (or specialized nasal systems). Because it reaches ventilated alveoli, it improves V/Q matching and lowers PVR with less systemic hypotension than many IV vasodilators. Key nursing points:

1. Closed delivery — iNO must remain in the inspired limb continuously. Circuit changes, transport, and bagging require a plan so the child is never without nitric oxide if dependent.
2. Dose — typical starting ranges are ordered by the team (often mid-single-digit to 20 ppm in many PICU protocols); the nurse verifies the set ppm matches the order and documents response (SpO2, PaO2, hemodynamics).
3. Toxicity monitoring — watch nitrogen dioxide (NO2) levels on the delivery system and methemoglobin per protocol. Rising methemoglobin impairs oxygen carrying capacity.
4. Weaning — decrease gradually. Rebound pulmonary hypertension after abrupt cessation can cause precipitous hypoxemia and RV failure. If rebound occurs, resume the prior effective dose and re-attempt a slower wean.
5. Adjuncts — children may also receive IV/SQ prostacyclin analogs, endothelin receptor antagonists, PDE-5 inhibitors, or milrinone for RV support; know which agents are continuous infusions that cannot be interrupted casually.

Crisis Avoidance Bundle

Think of PH care as a prevention checklist every shift:

• Oxygenation first: treat atelectasis, pneumothorax, tube obstruction, and low FiO2 errors before adding more vasoactive drugs.
• Maintain ordered pH/PaCO2 targets; avoid permissive hypercapnia strategies used in asthma when the child has reactive PH unless the team explicitly accepts that trade-off.
• Sedate and analge before invasive care; preoxygenate and limit suction passes.
• Keep iNO and PH infusions running during imaging and transport with battery/tank checks.
• Have a crisis algorithm ready: 100% oxygen, hand ventilation as ordered, deepen sedation, correct acidosis, resume interrupted vasodilators, support blood pressure without excessive systemic vasoconstriction that worsens RV afterload imbalance, and prepare for ECMO consultation in refractory cases at capable centers.

Connecting Assessment to Action

A toddler with repaired congenital diaphragmatic hernia who desaturates and becomes hypotensive during unplanned suction without preoxygenation is demonstrating a classic PH crisis pathway. The correct sequence is not "draw labs first" — it is restore oxygen delivery, stop the noxious stimulus, ensure pulmonary vasodilator continuity, and support the RV while calling for help. Exam questions often test whether you recognize that clear lungs plus systemic hypoperfusion still equal a cardiac output emergency driven by the right heart, not left-sided failure.

Synergy Model Angle

PH nursing exemplifies clinical judgment under the AACN Synergy Model: matching nurse competencies (vigilance, collaboration, systems thinking) to a child whose resiliency is low and whose response to therapy can reverse within minutes. Document triggers, vasodilator doses, methemoglobin results, and hemodynamic responses so the next nurse inherits a usable PH "passport," not a fragmented flow sheet.