Overview
Definition:
Congenital diaphragmatic hernia (CDH) is a birth defect characterized by an opening in the diaphragm, allowing abdominal organs to herniate into the chest cavity
This herniation can impede lung development and cause severe respiratory distress
The left posterolateral location (Bochdalek hernia) is most common (85%).
Epidemiology:
CDH occurs in approximately 1 in 2,500 to 1 in 5,000 live births
It is more common in males and on the left side
Associated anomalies occur in up to 50% of cases, including cardiac defects, chromosomal abnormalities (e.g., trisomy 18, 13), and gastrointestinal or genitourinary malformations.
Clinical Significance:
CDH is a critical surgical emergency in neonates
Prompt and appropriate preoperative stabilization, particularly regarding ventilation, is paramount to improving survival rates by optimizing cardiorespiratory function before definitive surgical repair
Inadequate management can lead to irreversible pulmonary hypoplasia and persistent pulmonary hypertension.
Clinical Presentation
Symptoms:
Severe respiratory distress shortly after birth
Tachypnea, grunting, and retractions
Cyanosis not responding to oxygen
Scaphoid abdomen
Bowel sounds heard in the chest
Hypotension and poor perfusion.
Signs:
Diminished breath sounds on the affected side
Possible palpable abdominal organs in the chest
Tachypnea (RR > 60/min)
Tachycardia
Hypotension
Paradoxical breathing
Umbilical pulse oximetry may show low saturation.
Diagnostic Criteria:
Diagnosis is typically made antenatally via ultrasound
Postnatally, it is based on clinical presentation of respiratory distress in a neonate with a scaphoid abdomen and auscultation findings suggestive of abdominal contents in the chest
Chest X-ray confirms the diagnosis, showing bowel loops or abdominal organs in the thoracic cavity and potential mediastinal shift.
Diagnostic Approach
History Taking:
Gestational age at birth
Mode of delivery
Antenatal diagnosis of CDH or other anomalies
Family history of congenital anomalies
Neonatal history of respiratory distress, cyanosis, or shock.
Physical Examination:
Assess Apgar score
Evaluate respiratory effort (retractions, grunting, nasal flaring)
Auscultate breath sounds bilaterally
note asymmetry
Palpate abdomen for organomegaly or scaphoid appearance
Assess for chest wall deformities
Evaluate peripheral perfusion and capillary refill time.
Investigations:
Immediate bedside pulse oximetry to assess oxygenation
Arterial blood gas (ABG) analysis to assess ventilation and oxygenation status (pH, pCO2, pO2, HCO3-)
Chest X-ray (AP and lateral views) to confirm herniation, mediastinal shift, and lung hypoplasia
Echocardiogram to assess for pulmonary hypertension and associated cardiac anomalies
Karyotype analysis if chromosomal abnormality is suspected.
Differential Diagnosis:
Other causes of neonatal respiratory distress: Transient tachypnea of the newborn (TTN)
Meconium aspiration syndrome
Pneumonia
Neonatal sepsis
PPHN (primary)
Congenital anomalies of the airway (e.g., tracheoesophageal fistula, laryngeal atresia)
Eventration of the diaphragm.
Management
Initial Management:
Immediate resuscitation and stabilization in the delivery room or NICU
Avoid positive pressure ventilation initially to prevent gastric distension and further mediastinal shift
Intubation is typically required for controlled ventilation
Insert an orogastric tube (OGT) to decompress the stomach, ensuring it is clamped to prevent air insufflation into the gastrointestinal tract.
Ventilation Strategy:
The primary goal is to maintain adequate oxygenation and ventilation while minimizing barotrauma and volutrauma, and avoiding worsening pulmonary hypertension
Gentle mechanical ventilation with low tidal volumes (4-6 ml/kg) and high respiratory rates (40-60 breaths/min) is often used
Peak inspiratory pressure (PIP) should be kept as low as possible (e.g., <25 cmH2O) to avoid lung injury
Target saturation 85-95% and PaO2 50-80 mmHg
Target PaCO2 45-55 mmHg
If conventional ventilation is insufficient, consider high-frequency oscillatory ventilation (HFOV)
In severe cases refractory to conventional or HFOV, extracorporeal membrane oxygenation (ECMO) may be indicated.
Medical Management:
Inotropic support (e.g., dopamine, dobutamine) for hypotension
Sedation and analgesia to reduce patient ventilator-asynchrony and oxygen consumption
Surfactant replacement therapy is generally not indicated for CDH itself but may be considered if there is coexisting surfactant deficiency
Avoid hyperoxia and hyperventilation, which can worsen pulmonary vasoconstriction.
Surgical Management:
Surgical repair is typically delayed until the infant is stabilized, usually within the first 24-72 hours of life, depending on the infant's cardiorespiratory status
Laparoscopic repair is increasingly common for smaller defects and less severe cases
Open repair is performed for larger defects or when laparoscopic approach is not feasible
The goal is to reduce the abdominal organs, close the diaphragmatic defect (often with synthetic mesh if the defect is large), and secure the abdominal contents.
Supportive Care:
Continuous cardiorespiratory monitoring
Strict fluid management to avoid overload
Nutritional support via parenteral nutrition initially, transitioning to enteral feeding once stable
Prevention of nosocomial infections.
Complications
Early Complications:
Persistent pulmonary hypertension of the newborn (PPHN), pneumothorax, lung hypoplasia, aspiration pneumonia, intraventricular hemorrhage (IVH), necrotizing enterocolitis (NEC), sepsis, gastrointestinal obstruction, wound dehiscence.
Late Complications:
Gastroesophageal reflux disease (GERD), feeding difficulties, failure to thrive, recurrent respiratory infections, restrictive lung disease, scoliosis, chronic pulmonary hypertension, developmental delay, hearing impairment.
Prevention Strategies:
Careful ventilator management to minimize lung injury
Judicious use of fluids and inotropes
Prophylactic antibiotics for sepsis prevention
Early recognition and management of GERD
Aggressive pulmonary rehabilitation.
Prognosis
Factors Affecting Prognosis:
Severity of pulmonary hypoplasia, presence and severity of associated anomalies (especially cardiac), gestational age at birth, degree of mediastinal shift, and response to initial stabilization
Survival rates vary widely, from 50-90% depending on these factors and access to specialized care.
Outcomes:
Infants who survive the neonatal period generally have improved outcomes, but may require long-term follow-up for respiratory, gastrointestinal, and developmental issues
Early and appropriate surgical intervention combined with meticulous preoperative stabilization significantly improves survival.
Follow Up:
Long-term follow-up by a multidisciplinary team including pediatric surgeons, pulmonologists, gastroenterologists, and developmental pediatricians
Regular assessment of respiratory function, growth and development, and nutritional status
Surveillance for GERD and recurrent infections.
Key Points
Exam Focus:
Key management principles in CDH include avoiding positive pressure ventilation initially, early intubation for controlled ventilation, gastric decompression via OGT, and gentle ventilation strategies
Understand the role of HFOV and ECMO
Differentiate between early and late complications.
Clinical Pearls:
A scaphoid abdomen in a neonate with respiratory distress should always raise suspicion for CDH
Remember to clamp the OGT to prevent further air insufflation into the bowel
Avoid excessive oxygenation
target saturations are lower than in non-CDH neonates to minimize the risk of PPHN exacerbation.
Common Mistakes:
Aggressive bag-mask ventilation leading to gastric distension and mediastinal shift
Over-ventilation or excessive oxygenation
Delaying surgical repair in a stable infant
Underestimating the severity of associated anomalies
Inadequate pulmonary hypertension management.