Overview
Definition:
Congenital diaphragmatic hernia (CDH) is a birth defect characterized by a hole in the diaphragm, the muscle separating the abdomen and chest
This allows abdominal organs to herniate into the chest cavity, leading to pulmonary hypoplasia and severe respiratory compromise.
Epidemiology:
CDH occurs in approximately 1 in 2,000 to 5,000 live births
It is more common on the left side (80-85% of cases) compared to the right
Incidence varies geographically and is associated with other congenital anomalies in up to 50% of cases.
Clinical Significance:
CDH presents a significant challenge in neonatal care due to severe pulmonary hypoplasia and persistent pulmonary hypertension
Optimal management, including appropriate sedation and ventilation strategies, is critical to improve survival rates and reduce morbidity in affected infants, making it a high-yield topic for DNB and NEET SS preparation.
Clinical Presentation
Symptoms:
Severe respiratory distress at birth
Tachypnea
Cyanosis refractory to oxygen
Grunting respirations
Nasal flaring
Retractions
Scaphoid abdomen
Bowel sounds may be heard in the chest.
Signs:
Hypoxia with oxygen saturation < 90%
Tachycardia
Hypotension
Decreased breath sounds on affected side
Dullness to percussion over chest
Palpable abdominal contents in chest
Scaphoid or empty abdomen.
Diagnostic Criteria:
Diagnosis is typically made antenatally via ultrasound
Postnatally, diagnosis is based on clinical presentation and confirmed by chest X-ray demonstrating abdominal contents in the thoracic cavity and absence of lung markings on the affected side.
Diagnostic Approach
History Taking:
Detailed antenatal history (ultrasound findings)
Maternal medical history (e.g., diabetes, infections)
Family history of congenital anomalies
Gestational age at birth
Birth weight
Perinatal events.
Physical Examination:
Thorough cardiopulmonary examination
Palpation of the abdomen to assess for organ herniation
Auscultation of bowel sounds in the chest
Assessment of vital signs including O2 saturation, heart rate, respiratory rate, and blood pressure.
Investigations:
Chest X-ray: demonstrates herniated organs and hypoplastic lung
Abdominal ultrasound: confirms absence of abdominal organs
Echocardiogram: to assess for pulmonary hypertension and associated cardiac defects
Arterial blood gases (ABGs): to assess for hypoxemia and hypercapnia
Blood tests: complete blood count (CBC), electrolytes, renal function tests, and blood glucose.
Differential Diagnosis:
Other causes of neonatal respiratory distress: transient tachypnea of the newborn (TTN), meconium aspiration syndrome, pneumonia, sepsis, pneumothorax, choanal atresia, diaphragmatic paralysis, esophageal atresia with tracheoesophageal fistula (TEF).
Management
Initial Management:
Immediate stabilization includes intubation and initiation of mechanical ventilation
Avoid bag-mask ventilation to prevent barotrauma and further organ herniation
Nasogastric tube insertion to decompress the stomach
Fluid resuscitation and inotropic support if hypotensive.
Sedation And Analgesia:
Crucial for patient comfort, reducing metabolic demand, and facilitating mechanical ventilation
Agents: Fentanyl (opioid analgesic) for pain and procedural sedation
Midazolam (benzodiazepine) for anxiolysis and sedation
Titrate doses based on patient response and vital signs
Target: adequate sedation to prevent distress and ventilator dyssynchrony, aiming for RASS score of -3 to -5
Continuous infusion may be necessary
Monitor for respiratory depression and hypotension.
Gentle Ventilation Strategy:
Goal is to minimize ventilator-induced lung injury (VILI) and avoid barotrauma and volutrauma, given the severely hypoplastic lungs
Initial settings: Low tidal volumes (4-6 mL/kg)
Respiratory rate (RR) 30-60 breaths/min
Peak inspiratory pressure (PIP) < 25-30 cm H2O
Positive end-expiratory pressure (PEEP) 4-5 cm H2O
FiO2 as needed to maintain oxygen saturation (target 88-95%)
Permissive hypercapnia is often accepted (pH > 7.20, PaCO2 < 60-80 mmHg) to avoid high PIPs
Maintain adequate PEEP to keep alveoli open
ECMO may be considered if conventional ventilation fails.
Surgical Management:
Surgical repair is typically delayed until the infant is stabilized and lungs are adequately ventilated, usually within 3-7 days of birth, but can be earlier if indicated
Laparoscopic or open repair techniques are used to reduce the herniated organs back into the abdomen and close the defect
Prosthetic patch may be used for larger defects.
Supportive Care:
Continuous cardiopulmonary monitoring
Strict fluid management
Nutritional support via parenteral nutrition initially, transitioning to enteral feeding as tolerated
Management of associated anomalies
Minimizing handling and stimuli to reduce oxygen consumption.
Complications
Early Complications:
Persistent pulmonary hypertension of infancy (PPHN)
Pneumothorax
Barotrauma/Volutrauma
Respiratory failure
Sepsis
Gastrointestinal obstruction/dysmotility
Cardiac arrhythmias
Renal failure.
Late Complications:
Chronic lung disease
Recurrent hernias
Gastroesophageal reflux disease (GERD)
Failure to thrive
Neurodevelopmental delays
Scoliosis.
Prevention Strategies:
Careful patient selection for ventilation settings
Minimizing ventilator pressures and volumes
Early decompression of stomach
Judicious use of sedation and analgesia
Prompt surgical intervention when stable
Aggressive management of PPHN with inhaled nitric oxide (iNO) or ECMO if necessary.
Prognosis
Factors Affecting Prognosis:
Severity of pulmonary hypoplasia
Presence and severity of PPHN
Gestational age at birth
Presence of other congenital anomalies
Effectiveness of initial stabilization and ventilation
Timing and success of surgical repair.
Outcomes:
Survival rates have improved significantly with advances in neonatal care and surgical techniques, ranging from 60-90% in centers of excellence
Infants with less severe lung hypoplasia and no major associated anomalies tend to have better outcomes.
Follow Up:
Lifelong follow-up is essential, focusing on pulmonary function, neurodevelopmental assessment, nutritional status, and management of complications such as GERD and recurrent hernias
Regular review by pediatric pulmonologists, surgeons, and developmental pediatricians.
Key Points
Exam Focus:
Remember that the primary goal of ventilation in CDH is to avoid barotrauma and support gas exchange without worsening lung injury
Permissive hypercapnia is a key concept
Sedation is essential for patient comfort and ventilator synchrony
Avoid bag-mask ventilation.
Clinical Pearls:
Always suspect CDH in a neonate with severe unexplained respiratory distress and scaphoid abdomen
Initiate gentle ventilation and decompress the stomach immediately
Echocardiogram is vital for assessing pulmonary hypertension
Delayed repair is often preferred for stability.
Common Mistakes:
Aggressive ventilation leading to barotrauma
Using high tidal volumes or pressures
Delayed surgical intervention in unstable patients
Inadequate sedation leading to ventilator dyssynchrony
Neglecting to rule out associated anomalies
Forgetting about the risk of PPHN.