Pediatric Surgery: Congenital Diaphragmatic Hernia

Basics

• Congenital Defect of the Diaphragm Allowing Abdominal Viscera Herniation into the Chest
• Most Common Side: Left (80%)
• Most Occur Before Embryologic Closure of the Pleuroperitoneal Canal
  • Has No Hernia Sac but 20% Have a Parietal Pleural or Peritoneal Membrane
• Survival: 60-90%
  • Previously Worse but Improving with Better Medical Managements

Physiologic Effects

• Pulmonary Hypoplasia
  • Both Lungs are Affected but Ipsilateral Lung is Worse
  • Retains Normal Number of Bronchial Buds
  • May Have Decreased Numbers of Bronchial Branches & Alveoli
• Arterial Muscular Hyperplasia with Fewer Branches
  • Increased Risk of Pulmonary Hypertension

Factors Associated with Poor Prognosis

• Polyhydramnios
• Bilateral Defects
• US Diagnosis Before 24 Weeks Gestation
• Prenatal US with Low Lung-Head Ratio

Presentation

• Most Present within 24 Hours of Birth
• Majority Have Chronic Pulmonary Disease
  • May See Significant Improvement in First 2 Years
  • Hypoplastic Lungs Never Fully Recover
• Respiratory Distress
• Pulmonary Hypertension
• Asymmetric Barrel Chest
• Scaphoid Abdomen
• Absent Ipsilateral Breath Sounds

Associations

• One-Third Have Major Associated Anomalies
• Cardiac Malformations (24%)
• Vascular Hypoplasia of Internal Jugular Vein & Carotid Artery
  • Can Make ECMO Challenging
• Cantrell Pentalogy
  • Cardiac Defects
  • Pericardial Defects
  • Cleft Sternum
  • Diaphragmatic Hernia
  • Omphalocele

Types

• Bochdalek’s Hernia: Posterolateral (Most Common) Mn
• Morgagni’s Hernia: Anteromedial
  • Through the Foramina of Morgagni (Sternocostal Hiatus or Space of Larrey)

Diagnosis

• Many are Found on Prenatal US Screening
• Postnatal Dx: Chest XR
• After Diagnosis Additional Abnormalities Should be Sought: Echocardiogram, Renal US & Cranial US

Treatment

• General Treatment: Initial Medical Stabilization with Delayed Surgical Repair
• Medical Stabilization:
  • Intubate & Mechanically Ventilate
    • Avoid Mask Ventilation as it Will Distend Intrathoracic Stomach/Intestine
    • Pressure-Limited Goal-Directed Ventilation with Permissive Hypercapnia
    • Initial Goals: PaO2 > 60 and PaCO2 < 60
  • Consider Surfactant or Inhaled Nitric Oxide
  • Manage Pulmonary Hypotension
  • Avoid Hypotension – Increases Risk of Right-to-Left Shunt & Hypoxia
  • May Need Extracorporeal Membrane Oxygenation (ECMO)
• Surgical Repair:
  • Timing of Surgery Not Well Defined
  • Incision: Left Subcostal (Some Prefer Thoracotomy)
  • Primary Repair
    • Should Be Tension Free (May Be Difficult)
    • Consider a Diaphragm Patch or Muscle (Latissimus Dorsi) Flap if Needed
  • May Be Unable to Close Abdominal Fascia Due to Loss of Domain