Anesthesiology APPLIED Exam › Pediatric and neonatal

Congenital diaphragmatic hernia

Pediatric and neonatal·~4 min read· Physician-reviewed✓ Sourced · 3

Stem

A 4-day-old boy, 3.1 kg, born at 38 weeks with a prenatally diagnosed left congenital diaphragmatic hernia, was intubated at birth and is on conventional ventilation in the NICU: peak pressure 23 cm H2O, PEEP 4, rate 50, FiO2 0.4. Preductal SpO2 is 92% and postductal 84%. Lactate is 1.6 mmol/L, urine output 1.5 mL/kg/h, and echo shows moderate pulmonary hypertension with preserved function. The surgeons want to repair it today through the abdomen.

Question

Is he ready for surgery, and how will you conduct the anesthetic?

Ideal answer

HeadlineReady, not an emergency: preductal 85 to 95% on less than 50% oxygen, lactate under 3, urine output over 1 mL/kg/h.¹

Keep NICU ventilation; never hand-bag aggressively. Hypoplastic, hypertensive lungs: peak under 25, PEEP 3 to 5, rate 40 to 60, PaCO2 50 to 70 with pH at least 7.25, preductal saturation 80 to 95%.²
Pre- and postductal oximetry, arterial line, decompressed stomach, because the gap shows ductal shunting; 15 to 20 mL/kg crossmatched blood ready.¹^,3
Opioid and relaxant, no nitrous oxide, low-dose volatile only. Volatile if tolerated;² nothing that raises pulmonary vascular resistance and risks a hypertensive crisis.
Mean pressure at least gestational age, about 38, keeping systemic above pulmonary pressure, limiting right-to-left shunt; inhaled nitric oxide and milrinone ready.¹

Watch for: the saturation gap, airway pressures, pneumothorax, and the abdomen as bowel returns.

Breaking down the answer

Stabilize first, operate second — the old emergency repair has been abandoned. Changes if: rising FiO2 or pressors, and I tell the surgeon he is not ready.¹
Why gentle ventilation — the hypoplastic lungs tear easily; barotrauma causes contralateral pneumothorax and kills more babies than CO2 does.² Changes if: he cannot be ventilated at a peak of 30 and rate 60, then high-frequency oscillation.¹
Why two oximeters — a widening gradient shows right-to-left ductal shunting from rising pulmonary pressure before the preductal number falls.
No mask ventilation, gastric tube on drainage — gas in herniated bowel compresses the lung and shifts the mediastinum.³^,2
Plan for the ventricle as well as the lung — left-sided hernias can come with left ventricular dysfunction, and adrenal insufficiency appears when pressors fail.¹
What raises PVR — hypoxia, hypercapnia beyond target, acidosis, hypothermia and light anesthesia; I avoid every one.
He stays intubated — back to the NICU ventilated, on opioid analgesia and sedation.¹

Follow-up question

As the surgeon reduces the bowel and closes the abdomen, the preductal saturation falls from 92 to 74%, the postductal to 55%, peak pressure rises to 32 and blood pressure drops. What do you do?

Follow-up answer

HeadlineThree possibilities, said aloud: tight closure compressing lungs and cava, contralateral pneumothorax, or pulmonary hypertensive crisis. The surgeon stops closing and releases the fascia.

100% oxygen and gentle hand-ventilation to feel compliance. I listen for asymmetric breath sounds and ask for a transilluminator or needle decompression on the right, because aggressive ventilation causes a contralateral pneumothorax.² For pulmonary hypertension: deeper opioid, acidosis and CO2 corrected toward the low end of target, inhaled nitric oxide, and milrinone 0.5 or epinephrine 0.05 mcg/kg/min for the ventricle.¹ A gas and the pre- and postductal gap again; ECMO team if preductal saturation stays below 80% despite maximal support.²

Pitfalls that cost points

Hyperventilating to a normal PaCO2 with high pressures.
Mask-ventilating vigorously before the tube is in, or forgetting the gastric tube.
Missing the contralateral pneumothorax as the cause of sudden deterioration.

Rapid-fire

Q: Which side is most common? A: The left, about 85%, through a posterolateral Bochdalek defect.²

Q: How common is it? A: About 2 to 3 per 10,000 live births.²

Q: What other anomalies matter? A: Nonisolated cases carry cardiac, chromosomal and other anomalies in roughly 30 to 50%, so I want an echo.²

Q: Why the postductal probe on a leg? A: Lower-body blood comes across the ductus, so a falling postductal number signals right-to-left ductal shunting.

Q: What is the target MAP? A: At least the gestational age in weeks for a newborn.¹

Numbers to know

Item	Value
Peak inspiratory pressure	<25 cm H2O²
PEEP and rate	3–5 cm H2O, 40–60/min¹
Permissive hypercapnia	PaCO2 50–70 mmHg, pH ≥7.25²
Preductal SpO2 target	80–95%²
Ready for repair	Preductal 85–95% on FiO2 <0.5, lactate <3, urine >1 mL/kg/h¹
Oscillator trigger	Cannot ventilate at PIP 30 and rate 60¹
ECMO trigger	Preductal SpO2 persistently <80% on maximal support²

Sources

1.Congenital Diaphragmatic Hernia (SPA Case Guide) · Society for Pediatric Anesthesia, 2023 · www2.pedsanesthesia.orgRepair-readiness criteria (CDH EURO), ventilation targets, MAP goal and vasoactive doses.
2.Congenital diaphragmatic hernia · OpenAnesthesia · openanesthesia.org
3.Congenital diaphragmatic hernia · NYSORA · nysora.com

Facts on this page were checked against these sources on Oct 15, 2026. Guidelines change; confirm doses against current institutional protocols.