Congenital diaphragmatic hernia

Congenital diaphragmatic hernia (CDH) is a common malformation characterized by a defect in the posterolateral diaphragm, the foramen of Bochdalek, through which the abdominal viscera migrate into the chest during fetal life. The incidence of CDH ranges from 1 in 2,500–5,000 births. Approximately 80% of posterolateral diaphragmatic hernias occur on the left side and 20% on the right side. Bilateral CDH is rare. The size of the defect varies from small (2 or 3 cm) to very large, involving most of the hemidiaphragm. The incidence of associated anomalies has been reported to be about 40% in most series. The most common abnormalities associated with CDH are cardiovascular anomalies, followed by skeletal, central nervous system, genitourinary, gastrointestinal, craniofacial, abdominal wall defects, and chromosomal and syndromic defects. The etiology of CDH is still unknown. Although CDH is generally considered to be sporadic, some familial cases have been reported. The onset and severity of symptoms depend on the amount of abdominal viscera in the chest and the degree of pulmonary hypoplasia. The most severely affected infants present with respiratory distress at birth. Other infants with CDH develop cyanosis, tachypnea, and grunting respirations within minutes or hours after birth. The definitive diagnosis of CDH is made postnatally by plain radiography of the chest and abdomen by demonstration of air-filled loops of the bowel in the chest and a paucity of gas in the abdomen. Despite significant advances in neonatal resuscitation and intensive care, newborn infants with CDH continue to have high mortality. Infants with associated anomalies have much lower survival rates than those with isolated CDH. The high mortality and morbidity in CDH is mainly attributed to pulmonary hypoplasia and persistent pulmonary hypertension. Infants with congenital diaphragmatic hernia are critically ill and require meticulous attention to detail in their medical care, including continuous monitoring of oxygenation, blood pressure, and perfusion. A minimal stimulation approach that reduces handling and invasive procedures, such as suctioning, has been suggested. Until recently, specialists believed that reduction of the herniated viscera and closure of the approach that enables preoperative stabilization decreases morbidity and mortality. Nowadays, management of CDH has been greatly improved by the introduction of prenatal surgical intervention with tracheal obstruction (TO) and by more appropriate postnatal care. TO appears to accelerate fetal lung growth and to increase the number of capillary vessels and alveoli. Improvement of postnatal care over the last years is mainly due to the avoidance of lung injury by applying low peak inflation pressure during ventilation. The benefits of other drugs or technical improvements such as the use of inhaled nitric oxide or extracorporeal membrane oxygenation (ECMO) are still being debated and no single strategy is accepted worldwide. Despite intensive clinical and experimental research, the treatment of the newborn with CDH remains difficult.