Overview
Definition:
Congenital Diaphragmatic Hernia (CDH) is a birth defect characterized by an opening in the diaphragm, the muscle separating the abdomen from the chest, allowing abdominal organs to herniate into the chest cavity
This herniation often impedes lung development (pulmonary hypoplasia) and causes severe respiratory distress.
Epidemiology:
The incidence of CDH is approximately 1 in 2,500 to 5,000 live births
It is more common on the left side (80-85%) than the right
Associations with chromosomal abnormalities and other congenital anomalies are present in up to 40-50% of cases
Early diagnosis and management are critical for survival.
Clinical Significance:
CDH represents a life-threatening condition in neonates due to pulmonary hypoplasia and persistent pulmonary hypertension
Prompt surgical repair is essential to decompress the chest cavity, allow for lung expansion, and improve hemodynamic stability, thereby increasing the chances of survival and reducing long-term morbidity.
Indications
Surgical Indication:
Surgical repair of CDH is indicated in all neonates diagnosed with this condition
The timing of surgery, however, is debated and depends on the patient's respiratory status and hemodynamic stability
Options include early repair in stable infants versus delayed repair after stabilization with mechanical ventilation and/or extracorporeal membrane oxygenation (ECMO) in unstable infants.
Timing Considerations:
Early repair (within the first 24-72 hours of life) is favored by some for stable infants to prevent further organ herniation and potential complications
Delayed repair is often necessary for severely compromised infants requiring ventilatory support, extracorporeal membrane oxygenation (ECMO), or nitric oxide therapy to improve pulmonary compliance and reduce pulmonary hypertension before surgery.
Contraindications:
Absolute contraindications are rare, but extremely severe, unmanageable pulmonary hypoplasia with evidence of non-viability may preclude aggressive surgical intervention
Other coexisting severe anomalies incompatible with life may also influence the decision-making process regarding the extent of surgical intervention.
Preoperative Preparation
Resuscitation And Stabilization:
Immediate resuscitation involves intubation and mechanical ventilation to manage respiratory distress
Hyperventilation is often avoided to prevent barotrauma to hypoplastic lungs
Oxygenation is carefully managed to maintain adequate saturation without causing pulmonary vasoconstriction
Gastric decompression via an orogastric tube is crucial to prevent abdominal distension.
Pharmacological Management:
Inotropic support (e.g., dopamine, milrinone) may be required for hemodynamic instability
Vasodilators like inhaled nitric oxide (iNO) are used to treat persistent pulmonary hypertension of the newborn (PPHN), aiming to reduce pulmonary vascular resistance and improve oxygenation.
Diagnostic Imaging:
Antenatal ultrasound is the primary diagnostic tool
Postnatal diagnosis is confirmed by chest X-ray, which typically shows abdominal contents in the chest and a mediastinal shift
Other imaging like abdominal ultrasound or CT scan may be used to fully delineate the defect and associated anomalies, but are often deferred until after initial stabilization and repair.
Nutritional Support:
Parenteral nutrition is usually initiated early due to the inability to feed orally
Enteral feeding is cautiously introduced after successful surgical repair and stabilization of respiratory status.
Procedure Steps
Surgical Approach:
The repair can be performed via an open approach (abdominal or thoracic) or laparoscopically
The abdominal approach is more common and involves a subcostal or upper abdominal incision
The thoracic approach may be used if the hernia sac extends significantly into the chest
Laparoscopic repair is increasingly utilized in select centers for less severe cases.
Hernia Sac Management:
If a hernia sac is present (more common in Bochdalek hernias on the right), it is carefully dissected from the lung and pleura
In most cases, the sac is excised, although some surgeons may close it if intact and not causing significant compression
For Morgagni hernias, the sac is usually anterior and easily excised.
Diaphragmatic Defect Closure:
The primary goal is to repair the diaphragmatic defect
Small defects can be closed primarily with sutures
Larger defects often require prosthetic patch repair using materials like Gore-Tex or Marlex mesh, which are durable and well-tolerated
The repair aims to restore diaphragmatic integrity.
Abdominal Closure:
After repair, the abdominal organs are returned to the abdominal cavity
If the abdominal wall is tight, temporary abdominal silo placement may be necessary to allow for gradual abdominal expansion
The abdominal incision is then closed.
Postoperative Care
Ventilatory Management:
Postoperative ventilatory support is critical
Strategies include permissive hypercapnia, low tidal volumes, and controlled pressures to minimize lung injury
Gradual weaning from mechanical ventilation is based on improving pulmonary function and oxygenation.
Hemodynamic Monitoring:
Continuous monitoring of heart rate, blood pressure, and oxygen saturation is essential
Inotropic and vasoactive medications are managed to maintain adequate perfusion and manage residual pulmonary hypertension
Fluid balance is meticulously monitored.
Pain Management:
Adequate analgesia is crucial to facilitate ventilation and recovery
Epidural anesthesia, patient-controlled analgesia (PCA) with opioids, or scheduled multimodal analgesia are commonly employed.
Nutritional Support Postop:
Enteral feeding is gradually advanced as tolerated once bowel function returns and respiratory status is stable
Parenteral nutrition is continued if necessary
Growth and development are monitored closely.
Complications
Early Complications:
Persistent pulmonary hypertension of the newborn (PPHN), respiratory failure, pneumothorax, atelectasis, wound infection, intra-abdominal hypertension, bowel obstruction due to adhesions, and re-herniation
Sepsis is also a risk.
Late Complications:
Gastroesophageal reflux disease (GERD), failure to thrive, recurrent pneumonias, chronic lung disease, scoliosis, abdominal wall defects, and neurodevelopmental delays
Residual diaphragmatic weakness or hernia recurrence can occur.
Prevention Strategies:
Meticulous surgical technique, appropriate preoperative stabilization, careful postoperative ventilatory management, prompt recognition and treatment of PPHN, effective pain control, and vigilant monitoring for signs of complications are key preventive measures
Early identification and management of GERD are also important.
Prognosis
Factors Affecting Prognosis:
Survival rates have improved significantly, ranging from 70-90%
Key prognostic factors include the severity of pulmonary hypoplasia, the presence and severity of associated anomalies, the degree of lung hypoplasia, the timing of diagnosis and repair, and the need for ECMO
Left-sided CDH generally has a better prognosis than right-sided.
Outcomes:
Most survivors achieve significant improvement in respiratory function
However, a substantial proportion may experience long-term respiratory morbidities, feeding difficulties, and developmental issues
Long-term follow-up is essential to manage these sequelae.
Follow Up:
Long-term follow-up is multidisciplinary, involving pediatric surgeons, pulmonologists, gastroenterologists, and developmental pediatricians
This includes regular pulmonary function tests, evaluations for GERD, nutritional assessments, and developmental surveillance
Serial imaging may be performed to monitor for recurrence.
Key Points
Exam Focus:
Understand the pathophysiology of pulmonary hypoplasia and PPHN
Differentiate between early and delayed repair indications
Recognize key features on CXR
Know the common surgical approaches and prosthetic materials used
Be aware of immediate and long-term complications.
Clinical Pearls:
Always consider gastric decompression in suspected CDH to prevent mediastinal shift
Hyperventilation is usually detrimental in neonates with CDH
ECMO is a bridge to surgical repair or recovery for critically ill infants
Monitor for signs of bowel ischemia postoperatively due to abdominal compartment syndrome.
Common Mistakes:
Delaying surgical consultation for neonates with respiratory distress where CDH is suspected
Aggressive ventilation strategies that worsen barotrauma
Inadequate management of PPHN
Premature discontinuation of ventilatory support
Neglecting long-term sequelae like GERD and developmental issues.