Congenital Diaphragmatic Hernia (CDH)

Timing - Repair waits until the neonate is medically optimized, and delaying improves outcomes. The emergency was the physiology at birth, not the operation.

Preoperative picture - CBC, metabolic panel, lactate, coagulation studies, arterial blood gas, chest x-ray, echocardiogram, and head ultrasound. The echo is the one that changes your plan: LV hypoplasia, shunt direction, and pulmonary artery pressure.

Airway - Most arrive from the NICU already intubated. If you have to intubate in the room, rapid-sequence with propofol and skip mask ventilation - gastric insufflation expands the herniated viscera and squeezes what lung there is.

Neuromuscular blockers - Generally avoided. Lung function deteriorates after administration without demonstrated benefit, and losing spontaneous ventilation costs compliance.

Decompress the stomach - Oro- or nasogastric tube to low continuous suction, placed before you start and left in.

Access - Right radial arterial line for preductal sampling and beat-to-beat pressure. Put venous access in the upper extremities, because reducing the viscera raises abdominal compartment pressure and can cut inferior vena cava return. A central line earns its keep postoperatively for vasoactives.

Monitoring - Pre- and postductal pulse oximetry alongside arterial line, EKG, NIBP, temperature, and end-tidal CO2. A widening gap between preductal and postductal saturation means pulmonary pressure is climbing and the right-to-left ductal shunt is opening. Follow hemoglobin, glucose, and serial ABGs, and keep looking at the non-operative lung field for pneumothorax.

No nitrous - N2O expands gas trapped in the thorax and in herniated bowel.

Maintenance - High-dose IV opioid is the backbone, with volatile agent as a cautious supplement - enough to blunt stimulation, not enough to drop cardiac output.

Ventilation - Permissive hypercapnia, close attention to peak inspiratory pressure, and high-frequency oscillatory ventilation when conventional ventilation fails. Hyperventilating to alkalosis would lower pulmonary pressure and shrink the ductal shunt, but the barotrauma is not worth it; excess pressure buys a contralateral pneumothorax.

Thoracoscopic versus open - Survival is comparable, but thoracoscopic repair runs higher PaCO2 and more acidosis from CO2 insufflation, which are exactly the two things that raise pulmonary vascular resistance.

Hypotension - Target blood pressure to gestational age. Most CDH neonates have adrenal insufficiency on random cortisol and their hypotension responds well to stress-dose hydrocortisone; give 10 to 20 mL/kg boluses if hypovolemic. Dextrose-containing maintenance fluid covers caloric needs, but do not volume-load a marginal ventricle.

Pulmonary hypertension therapy - Reserve pulmonary vasodilators for poor organ perfusion with preductal SpO2 below 85% or a pre- to postductal saturation difference greater than 10%. Inhaled nitric oxide when the LV works, milrinone when there is LV diastolic dysfunction, where it also acts as a lusitrope and improves LV filling. Prostacyclin or a phosphodiesterase inhibitor is second line.

Postoperative - Back to the NICU intubated and ventilated, weaning support as tolerated. Watch the lung fields for pneumothorax, hemorrhage, and atelectasis. Multimodal analgesia - opioid, epidural, and acetaminophen if liver function tests are normal.

Congenital diaphragmatic hernia (CDH) is incomplete closure of the developing diaphragm - most often the posterolateral Bochdalek defect - letting abdominal viscera into the chest during lung development. The crowded thorax interferes with branching of both airways and pulmonary vessels, so the lung is hypoplastic: thickened alveolar walls, acinar hypoplasia, fewer terminal bronchioles, and dysfunctional surfactant production.

The pulmonary vasculature is hypertrophied and hyperreactive, and pulmonary hypertension worsens with every rise in PaCO2 and fall in PaO2. Compression deforms the heart too - left ventricular hypoplasia from poor filling, right ventricular hypertrophy from chronic afterload, and right-to-left shunting across a PDA and a rotated foramen ovale. Push that far enough and you have persistent pulmonary hypertension of the newborn (PPHN) with hypoxemia refractory to conventional therapy. Intestinal malrotation and congenital heart disease commonly travel with it.