CHAPTER 29: Surgery

NEONATAL SURGERY

CONGENITAL DIAPHRAGMATIC HERNIA

Disorder characterized by pulmonary hypoplasia due to intrauterine compression of the developing lungs by herniated viscera.

EPIDEMIOLOGY

• Incidence is 1000 per year (1:2000–1:5000 live births); female:male 2:1

• 7–10% gestations end in fetal demise

• Defects more common on left side (about 80%)

• Associated with anomalies (10–35%) including: Central nervous system (CNS) lesions, tracheobronchial abnormalities, omphalocele, cardiovascular (CV) lesions, skeletal and syndromes (trisomy 13, 18, 21, Beckwith–Weidemann, Brachmann–de Lange, and Pallister–Killian, among others)

ETIOLOGY

• Unknown currently, though several pharmacologic and environmental factors have been implicated, including a possible role for vitamin A deficiency and/or retinoid regulated gene defects

• Embryologic theory: Lack of closure of the posterolateral pleuroperitoneal canals in the 8th week of gestation fails to separate the thoracic and abdominal cavities

• Portions of the diaphragm and pulmonary parenchyma arise from thoracic mesenchyme and if disrupted may lead to absence of part of hemidiaphragm and pulmonary hypoplasia

• Most cases are sporadic; familial cases occur (2%)

DIFFERENTIAL DIAGNOSIS

• Cystic adenomatoid malformation, cystic teratoma, pulmonary sequestration, bronchogenic cyst, neurogenic tumors, primary lung sarcoma, diaphragmatic eventration

PATHOPHYSIOLOGY

• Herniation of abdominal contents into thoracic cavity through posterolateral foramen of Bochdalek

• Diaphragmatic defect may be small or may include entire hemidiaphragm

• Pulmonary vasculature has increased muscularization of pulmonary arterioles and decreased branching of vessels resulting in pulmonary hypertension

• Lungs are hypoplastic due to chronic compression, with decreased numbers of bronchial branches on both ipsilateral and contralateral sides

CLINICAL MANIFESTATIONS

• Most patients present with respiratory distress within the first hours of life secondary to severe pulmonary hypoplasia and associated pulmonary hypertension

• 10–20% may have delayed presentation characterized by less severe pulmonary hypoplasia and pulmonary hypertension, as well as gastrointestinal (GI) symptoms (e.g., vomiting, abdominal pain, constipation)

• Pneumothorax

• On exam: Absence of breath sounds; bowel sounds in chest; scaphoid abdomen; increased anterior-posterior diameter of chest; shifted heart sounds

DIAGNOSTICS

• Prenatal ultrasound able to detect defect as early as 11th week, mean gestational age (GA) at diagnosis is 24 weeks; accuracy has been reported to be between 40 and 90%

• Antenatal diagnosis is associated with more severe defects and a worse prognosis; if diagnosed by ultrasound, fetal MRI should be performed

• During fetal period, a lung-head ratio (LHR, area of contralateral lung to fetal head circumference by ultrasound) of <1 indicates severe disease

• Observed-to-expected LHR (O/E LHR) accounts for changes in LHR with GA, and O/E LHR <25% suggests severe CDH

• Echocardiography and amniocentesis to detect other anomalies

• Chest x-ray

MANAGEMENT

Initial Medical Management

• Initial resuscitation includes correction of hypoxia, hypercarbia, acidosis, and hypothermia as they increase pulmonary vascular resistance and worsen pulmonary hypertension

• Intubate early to avoid inflation of the stomach with bag-mask ventilation

• Nasogastric decompression to decrease ...