Sandbox: diaphragmatic hernia
Historical perspective
Historical perspective:
In 1679, the first case of congenital diaphragmatic hernia was reported by Riverius. In 1888, the first procedure to repair congenital diaphragmatic hernia in an adult was done and in 1889, the first procedure on an infant was done. In 1905, the first successful operation was done but the success rate was only about 60% in 1925. In 1940, A set of diagnostic criteria for diaphragmatic hernia were suggested. In 1950, the transthoracic approach was suggested instead of the transabdominal approach.
Epidemiology
Incidence
The incidence of congenital diaphragmatic hernia ranges from 50 to 150 per 100.000 live births.[1]
Prevalence
The prevalence of congenital diaphragmatic hernia ranges from 10 to 40 per live births.[2]
Sex
Congenital diaphragmatic hernia has no sex predilection.[2]
Age
90% of the congenital diaphragmatic hernias present in the neonatal period.
Classification
Congenital diaphragmatic hernia can be classified into three types according to the site of herniation.
Posterolateral (Bochdalek) diaphragmatic hernia It is the most common subtype. Most commonly occurs on the left side and rarely occurs bilaterally.
Anterior (Morgagni) diaphragmatic hernia In anterior diaphragmatic hernia, the intestine bulges into the thorax through the anterior midline. Most of the cases of anterior diaphragmatic hernia occur on the right side.
Hiatal hernia The intestine finds its way to the thorax through the esophageal hiatus. More common in the adults than in the neonates.
Pathophysiology
The herniated viscera decrease the area needed by the lung to develop appropriately. According to the degree of herniation, the degree of pulmonary hypoplasia is determined. The development of the pulmonary artery tree is halted too resulting in excessive masculinization of the arteries. As most of the cases of diaphragmatic hernia is unilateral, the pulmonary hypoplasia is also usually unilateral, but it can be bilateral if the mediastinum is pushed by a massive unilateral hernia. The abnormal alveolar development can lead to hypoxemia leading to pulmonary vasoconstriction which aggravates the condition.
Natural history, complications and prognosis
Natural history 90% of the cases of congenital diaphragmatic hernia presents in the neonatal period. If left untreated, congenital diaphragmatic hernia can be fatal due to pulmonary hypoplasia and severe pulmonary hypertension. Complications GI complications Pulmonary hypoplasia Abnormal developmental rotation of the midgut Midgut volvulus Gastric volvulus Cardiopulmonary complications Pulmonary hypoplasia Pulmonary artery hypertension In severe cases, ventricular hypoplasia
Prognosis The prognosis is mainly dependent on the size of the defect and the degree of the herniation. The presence or absence of liver herniation on fetal MRI is the most reliable prediction of the postnatal survival. The estimation of fetal lung volume and lung area to head circumference is a useful indicator for the prognosis of the disease in the absence of liver herniation. The mortality ranges from 25-60% of the cases.
Natural history, complications and prognosis
Natural history
90% of the cases of congenital diaphragmatic hernia presents in the neonatal period. If left untreated, congenital diaphragmatic hernia can be fatal due to pulmonary hypoplasia and severe pulmonary hypertension.
Complications
GI complications Pulmonary hypoplasia Abnormal developmental rotation of the midgut Midgut volvulus Gastric volvulus Cardiopulmonary complications Pulmonary hypoplasia Pulmonary artery hypertension In severe cases, ventricular hypoplasia
Prognosis
The prognosis is mainly dependent on the size of the defect and the degree of the herniation. The presence or absence of liver herniation on fetal MRI is the most reliable prediction of the postnatal survival. The estimation of fetal lung volume and lung area to head circumference is a useful indicator for the prognosis of the disease in the absence of liver herniation. The mortality ranges from 25-60% of the cases.
Symptoms
CDH most often presents in the neonatal period as:
Respiratory distress: The neonate may show cyanosis, tachycardia, lethargy, intolerance to feeding due to inadequate oxygenation. Adrenal insufficiency: it is a common association with congenital diaphragmatic hernia.
Physical exam
General appearance
A neonate with CDH usually appears cyanotic and in acute distress.
Vital signs
Heart rate: tachycardia Respiratory rate: tachypnea
Lungs
The chest may have a barrel shape. Absent breath sounds at the side of the hernia Peristaltic sounds in the chest
Heart
The heart sounds may be displaced to the other side of the chest. The heart sounds may reveal the murmurs of associated cardiac anomalies.
Abdomen
The abdomen is scaphoid due to herniation of the abdominal content into the thoracic cavity.
Laboratory tests
Arterial blood gas
ABG may show hypoxemia, metabolic acidosis, and hypercapnia. The embryo should be investigated for the presence of associated chromosomal abnormalities.
Radiological tests
Antenatal ultrasound
CDH can be diagnosed in the 24th week In addition to the hernia, ultrasound can show polyhydramnios and absence of the gastric air bubble Left sided CDH is far more common than right sided CDH, while bilateral CDH is rare. The presence of liver herniation is associated with worse prognosis and survival. The estimation of lung area to head circumference ratio can give an idea about the prognosis (especially if there is no liver herniation). The lower the ratio, the worse the prognosis.
Chest x-ray
Bowel loops in the thoracic cavity (can be further demonstrated through placement of a feeding tube) Shifting of the mediastinum to the contralateral side
Echocardiography
Echocardiography must be done to exclude associated cardiac anomalies and to exclude the presence of an associated ventricular strain from the pressure.
Medical treatment
Antenatal glucocorticoids
Antenatal glucocorticoids improve the survival by increasing the secretion of surfactant and thus stimulating lung maturation and preventing severe pulmonary hypoplasia.
Surgical
Preoperative stabilization of the patient is important as performing the operation in an unstable infant is associated with higher morbidity and mortality rates. Preoperative stabilization measures include: Mechanical ventilation: The aim is to ensure proper oxygenation without causing any barotrauma to the lung. Peak inspiratory pressure should be always less than 30 cm H2O Nasogastric tube insertion: The aim is to decompress the bowel and to give more space for the lung Blood pressure support: using vasopressors or isotonic fluid: The aim is to keep the mean blood pressure above 50 mmHg. High-frequency oscillatory ventilation: It is useful in improving the oxygenation without increasing the pressure in the airways or the alveoli. Extracorporeal membrane oxygenation: It is used as the last resort in patients resistant to all the conventional methods of ventilation. Inhaled nitric oxide: The hypoxemia resulting from lung compression can cause hypoxemia that may result in pulmonary vasoconstriction and hypertension.
Surgical procedures The procedure must not be done unless the infant is stable. Most of the operations are done through a subcostal incision. The repair can be done in one of two ways depending on its size: Primary closure: it involves repairing the defect using non-absorbable sutures. It is used if the defect is relatively small. Patch closure: using a prosthetic or fascial patch to close the defect. It is useful especially with large defects but increases the risk of infection. Endoscopic procedures through the thorax or the abdomen have been reported to have lower mortality rates but have higher recurrence rates. If CDH repair is associated with an abdominal wall defect, silo closure may be tried temporarily until the CDH is stabilized.
References
- ↑ Fisher JC, Haley MJ, Ruiz-Elizalde A, Stolar CJ, Arkovitz MS (2009). "Multivariate model for predicting recurrence in congenital diaphragmatic hernia". J. Pediatr. Surg. 44 (6): 1173–9, discussion 1179–80. doi:10.1016/j.jpedsurg.2009.02.043. PMC 3072822. PMID 19524735.
- ↑ 2.0 2.1 McGivern MR, Best KE, Rankin J, Wellesley D, Greenlees R, Addor MC, Arriola L, de Walle H, Barisic I, Beres J, Bianchi F, Calzolari E, Doray B, Draper ES, Garne E, Gatt M, Haeusler M, Khoshnood B, Klungsoyr K, Latos-Bielenska A, O'Mahony M, Braz P, McDonnell B, Mullaney C, Nelen V, Queisser-Luft A, Randrianaivo H, Rissmann A, Rounding C, Sipek A, Thompson R, Tucker D, Wertelecki W, Martos C (2015). "Epidemiology of congenital diaphragmatic hernia in Europe: a register-based study". Arch. Dis. Child. Fetal Neonatal Ed. 100 (2): F137–44. doi:10.1136/archdischild-2014-306174. PMID 25411443.