Diaphragmatic Hernia (Congenital), Pediatric
Defect in the diaphragm allowing herniation of abdominal contents into the thoracic cavity, causing varying degrees of pulmonary hypoplasia
There are 4 types of congenital diaphragmatic hernia (CDH):
Bochdalek hernia (posterolateral location)
Morgagni hernia (lateral retrosternal location)
Pars sternalis (medial retrosternal)
Anterolateral
Epidemiology
1:2,000-5,000 live births
Left sided in 85-90%
Right-sided and bilateral defects less common
Familial recurrence 2%
Pathophysiology
Diaphragm arises from 4 elements and is complete by 8 weeks' gestation.
Septum transversum, which becomes the central tendon of the diaphragm
Pleuroperiotoneal membranes, which extend from the lateral body wall and fuse with the septum transversum and esophageal mesentery
Mesentery of the esophagus, which becomes the crura of the diaphragm
Lateral body wall from which myocytes migrate to muscularize the diaphragm
Posterolateral (Bochdalek defect) in 70%, anterior (Morgagni) in 25-30%, central in 2-5%
Main problem concerns pulmonary hypoplasia, which results in pulmonary hypertension.
Smaller lungs with fewer airway branches, fewer alveoli per terminal lung unit, and decreased surfactant production
Decreased pulmonary vascular surface area and smaller muscular arterioles with abnormal vasoreactivity results in pulmonary hypertension.
Both ipsilateral and contralateral lungs are hypoplastic, worse on ipsilateral side.
Degree of pulmonary hypoplasia and pulmonary hypertension determines illness severity both in acute and chronic settings.
Etiology
Unknown
Experimental rat models suggest role of vitamin A deficiency in pathogenesis.
Commonly Associated Conditions
40-50% of cases associated with another type of congenital malformation
Cardiac: 10-35%
Genitourinary: 23%
Gastrointestinal malformations: 14%
Central nervous system abnormalities: 10%
Estimated that 10% of patients with associated congenital anomalies have a syndrome
Associated syndromes include Beckwith-Wiedemann and trisomies 13, 18, and 21.
Diagnosis
History
Prenatal imaging and follow-up testing:
CDH detected by prenatal ultrasound in >70% cases
Larger defects easier to detect by ultrasound. Thus, prognosis is poorer in those CDH cases detected antenatally.
Magnetic resonance imaging (MRI) can be used to confirm the diagnosis and may predict degree of pulmonary hypoplasia by estimation of lung volume.
Amniocentesis and genetic consultation to screen for chromosomal anomalies advised
Important to evaluate for associated congenital abnormalities to guide management
During the prenatal period, the degree of pulmonary hypoplasia and thus prognosis may be determined by the following:
Observed/expected lung-to-head ratio as determined by ultrasound
Observed/expected fetal lung volume ratio by fetal MRI
Presence of liver in thorax implies worse prognosis.
Fetal surgery is a possibility for large lesions; however, results have been disappointing.
Postnatal history
Large defects present at birth with respiratory distress.
May be easily identified on chest radiograph; however, CT scan may be required to confirm the diagnosis.
Smaller defects may be undetected until late childhood/adolescence or even adulthood.
Symptoms may include the following:
Recurrent cough
Recurrent chest infections
Intestinal obstruction
Feeding intolerance
Physical Exam
Scaphoid abdomen (abdominal contents in thoracic cavity) and asymmetry of chest wall
Decreased breath sounds with dullness to percussion on the affected side
Bowel sounds heard in the chest
Heart sounds shifted to the contralateral chest
Diagnostic Tests & Interpretation
Imaging
Chest radiograph (CXR)
Opacified hemithorax with contralateral shift of mediastinum
Decreased lung volumes
Esophageal portion of nasogastric tube deviated toward opposite side
May see loops of bowel in the thoracic cavity
Bowel remaining in the abdomen usually gasless
Echocardiogram
Right ventricular function is an important determinant of illness severity.
Can estimate degree of pulmonary hypertension
Determine presence of associated congenital cardiac defects
Alert
CXR findings in the newborn period may be subtle. In addition, small CDH defects may present outside of newborn period.
Lab
Arterial blood gas
Po2 low: reflects significant hypoxemia
Po2 high: reflects inadequate ventilation
pH, bicarbonate, lactate: acid-base balance
Karyotype: to assess for associated syndromes and chromosomal abnormalities
Differential Diagnosis
Pulmonary
Pulmonary sequestration
Congenital pulmonary airway malformation (CCAM)
Pneumatocele
Pulmonary cyst
Diaphragmatic eventration
Hiatal hernia
Congenital lobar emphysema
Pulmonary agenesis
Anterior mediastinal mass
Pneumonia
Atelectasis
Pleural effusion
Pneumothorax
Cardiac
Dextrocardia
Congenital heart disease
Treatment
Acute
General Measures
Aim for delivery of infant in the hospital where defect is to be repaired as this situation is associated with better outcomes.
Insertion of a nasogastric tube to decompress herniated contents and allow venting
Mechanical ventilation
Avoid bag and mask ventilation.
Goal is to limit barotrauma, maintain peak pressures ≤25 mm Hg and positive end-expiratory pressure (PEEP) of at least 5 mm Hg
Permissive hypercapnia: tolerate Paco2 up to 60 mm Hg
Aim for preductal oxygen saturation >85%
Consider high-frequency oscillatory ventilation and extracorporeal membrane oxygenation (ECMO) when earlier measures are not effective (e.g., pH <7.25, Paco2 >60 mm Hg, preductal saturation <85% on FiO2 0.6)
Cardiovascular support
In setting of pulmonary hypertension, aim for higher mean arterial blood pressure.
Pulmonary hypertension
Severity predicts outcome.
50% of patients are responsive to inspired nitric oxide (iNO), but the effect may be temporary. iNO has no influence on overall outcome.
Sildenafil: Phosphodiesterase 5 inhibitor may be used as an adjunct to iNO to prevent rebound hypertension when weaning iNO or in management of chronic pulmonary hypertension.
In setting of left ventricular dysfunction with a right ventricle-dependent systemic circulation, milrinone and prostaglandin may be used to decrease afterload and maintain ductal patency.
Alert
It is important to assess and treat pulmonary hypertension.
Avoid aggressive ventilation. It is important to minimize barotrauma.
Surgical Correction
Delaying surgery until infant is stabilized has been associated with better outcome.
Primary repair versus prosthetic patch
Minimally invasive thoracoscopic approach now possible, although is associated with an increased recurrence rate compared with the open approach
Up to 50% will require patch repair of diaphragmatic defect.
Recurrence of hernia occurs in up to 50% of patch closures.
Patch closure of abdomen or creation of surgical silo may be required with very large defects.
Ongoing Care
Follow-up Recommendations
Long-term multidisciplinary follow-up required to monitor for complications and recurrence of hernia
Pulmonary
Chronic lung disease: Up to 50% require supplemental oxygen at 28 days and 16% at the time of discharge from hospital.
Prevalence of long-term pulmonary morbidity unclear-some series report chronic pulmonary symptoms in up to 50% of survivors.
Spirometry shows obstructive pattern of lung disease.
Scoliosis and chest wall defects may cause restrictive lung disease.
Gastrointestinal/nutrition
Growth failure secondary to chronic lung disease, increased work of breathing, gastroesophageal reflux, and oral aversion
Failure to thrive is common-up to 1/3 require gastrostomy tube
Gastroesophageal reflux (45-90%): may lead to recurrent bronchitis, worsening bronchopulmonary dysplasia, aspiration pneumonia. Persists into adulthood. Consider an H2 blocker in all patients
Cardiac
Pulmonary hypertension may persist in up to 30%.
Neurodevelopmental
Behavioral, cognitive, and motor problems common
Greater risk in those with large defects or those requiring ECMO
Sensorineural hearing loss
Incidence varies: up to 40% described by some
Underlying cause unknown
Deficit is progressive, so regular long-term follow-up is recommended.
Surgical
Orthopedic: pectus deformity and scoliosis
Recurrence of hernia (in up to 50%): risk greater in those who required patch closure
May present with vomiting, bowel obstruction, pulmonary symptoms, or may be asymptomatic
Serial CXR recommended for screening
Alert
Recurrence of CDH is common and typically presents with vague gastrointestinal symptoms (in contrast to a dramatic presentation of the newborn period).
Hearing impairment may be progressive. Therefore, serial screening through childhood is essential.
Prognosis
Depends on the degree of pulmonary hypoplasia and pulmonary hypertension
70% postnatal survival, with up to 90% survival described by some centers
50% survival in those requiring ECMO
Prematurity associated with worse prognosis
Additional Reading
American Academy of Pediatrics Section on Surgery; American Academy of Pediatrics Committee on Fetus and Newborn, Lally пїЅKP, Engle пїЅW. Post discharge of infants with congenital diaphragmatic hernia. Pediatrics. 2008;121(3):627-632. пїЅ[View Abstract]
Bohn пїЅD. Congenital diaphragmatic hernia. Am J Respir Crit Care Med. 2002;166(7):911-915. пїЅ[View Abstract]
Danzer пїЅE, Gerdes пїЅM, D'Agostino пїЅJA, et al. Longitudinal neurodevelopmental and neuromotor outcome in congenital diaphragmatic hernia patients in the first 3 years of life. J Perinatol. 2013;33(11):893-898. пїЅ[View Abstract]
Kotecha пїЅS, Barbato пїЅA, Bush пїЅA, et al. Congenital diaphragmatic hernia. Eur Respir J. 2012;39(4):820-829. пїЅ[View Abstract]
Van Den пїЅL, Sluiter пїЅI, Gischler пїЅS, et al. Can we improve outcome of congenital diaphragmatic hernia? Pediatr Surg Int. 2009;25(9):733-743. пїЅ[View Abstract]
A: Reported rates of recurrence vary from 10 to 50%. Serial screening with CXR and a high index of suspicion is necessary. The typical presentation includes emesis, gastrointestinal obstruction, or respiratory symptoms.
Q: Is pulmonary impairment lifelong?
A: Although pulmonary function improves with growth, studies (spirometry, plethysmography, ventilation-perfusion [V/Q] scanning) show persisting deficits. Most patients report decreased pulmonary morbidity/symptoms with increasing age.
Q: What follow-up is necessary?
A: Long-term multidisciplinary follow-up is essential. Complications involving multiple organ systems are common.
Q: Why is long-term gastrointestinal follow-up necessary?
A: Although complications such as failure to thrive and oral aversion are less common with increasing age, the risk of reflux is lifelong. Treatment into adulthood may be required to control reflux and prevent Barrett esophagus.