Congenital Diaphragmatic Hernia

Associated Conditions Seen With Congenital Diaphragmatic Hernia

Malrotation- 90%

CNS defects (spina bifida, hydrocephalus, cerebral dysgenesis)- 30%

Cardiovascular defects (ASD, VSD, coarctation of aorta, TOF)- 20%

Chromosomal disorders (Trisomy 18 and 21)- 5 - 15%

Development of the Diaphragm and Respiratory System

Diaphragm is composed of several components:

• Septum transversum: forms the central tendon
• Pleuroperitoneal membrane: forms the dorsolateral portion
• Intercostal muscle group: forms the posterior lateral portion
• Esophageal mesentery: forms the dorsal crura

In the 7th week of gestation, peritoneal folds extend medially to fuse with the central tendon. If the fusion is incomplete, the defect is well established by 10 to 12 weeks of gestation. Size of the defect varies from 2 cm to complete agenesis of the diaphragm

Development of the Respiratory System

Normal Development

• 4 weeks: Ventral outpouching of the foregut
• 16 weeks: Successive branching of bronchi increase in alveolar air spaces
• 24 weeks to 8 years of age: development of alveolus

In CDH, there is interruption of the bronchial airway branching at 10 weeks gestation. The ipsilateral lung development is retarded at the 12th - 14th generation. Contralateral lung development is retarded at the 16th - 18th generation. Development of Type 1 alveolar epithelium is arrested.

Factors Involved in Abnormal Lung Development (Table 1)

Congenital Diaphragmatic Hernia - Incidence

SSeen in 2.6 per 10,000 births[1]. Posterolateral (Foramen of Bochdalek) hernia is more common with an incidence of almost 80% (L > R). Anteromedial (Foramen of Morgagni), Esophageal hernia and Bilateral hernias are less common. Overall mortality (with modern treatment) is 50% and morbidity remains high. most deaths occurring between 2 to 6 days of birth.[1]. Males are more affected than females, ratio being 1:0.69. [2]

Presentation

Tachypnea, cyanosis, respiratory distress

Cardiac sounds and impulse shifted to contralateral side of hernia

Absent breath sounds on the side of hernia

Scaphoid abdomen

Bowel sounds on side of hernia

Poor Prognostic Factors

• Presence of cardiac anomalies
• Underdevelopment of cardiac ventricular chambers
• Polyhydramnios
• Diagnosis before 25 weeks of gestation
• Presence of liver or stomach

Chest X Ray Findings

Management In the Delivery Room And NICU

• Intubate. Avoid ventilation with AMBU bag or mask due to risk of gastric distention, which will further compromise respiratory and cardiac function
• Positive Pressure Ventilation(see Table 2). Hyperventilation. Maintain pH >7.5. Peak inspiratory pressure <30 cm H2O (watch for pneumothorax). High frequency ventilation
• Passage of NG tube to decompress the stomach
• IV access and fluid resuscitation

Factors Contributing to Lung Injury in PPV (Table 2)

Additional Treatment Modalities

Extracorporeal Membrane Oxygenation: Current guidelines are unclear.

Aims of therapy

• To limit airway pressure and oxygen toxicity
• To eliminate shunting
• To reverse systemic hypoxemia
• To reduce pulmonary blood flow
• To allow gradual expansion of the lung

Problems with ECMO

• Technical complications in 20% of patients
• Tubing rupture or disconnection
• Clotting disorders
• Air embolism
• Oxygenator failure
• Heat exchanger malfunction
• Power failure
• Malpositioning of cannula
• Inadvertent decannulation
• 10% human error
• Open air entry port (potentially fatal)
• Blood loss due to disconnection
• Extremely labor intensive (12 to 34 ECMO specialists recommended)

Congenital Diaphragmatic Hernia - Surgery

Surgical Repair with Gore-Tex patch

Early vs Late Repair

There is no difference in survival (75% versus 72%)

Long Term Survival and Morbidity

• 10% mental retardation
• 12% seizures
• 21% requires hearing aid
• 45% have significant developmental delays (More significant in infants who underwent repairs, longer duration of ECMO)
• Chronic pulmonary insufficiency (62% of survivors)
• Pectus excavatum, scoliosis (11.4%), chest wall deformity (15.5%)[3]
• Distortion of GE angle, malrotation, reflux, GI dysmotility, failure to thrive (20 - 89% in those with repair done)
• Primary lung hypoplasia, Bronchopulmonary dysplasia, Oxygen toxicity, Barotrauma
• Chronic aspiration from GE reflux (30-80%) [4]
• Reactive airway disease
• Asthma (23.6%)[3]
• ADHD (7.3%) [3]
• Autism (1.6%) [3]
• Inguinal hernia (6.7%)
• Recurrence occurs in 2-25% patients.[5]