CONGENITAL DIAPHRAGMATIC HERNIA REPAIR

congenital diaphragmatic hernia repair - surgery - surgical care:
• Postnatal repair
o Until recently, specialists believed that reduction of the herniated viscera and closure of the diaphragmatic defect should be performed emergently following birth. More recent research demonstrates that a delayed surgical approach that enables preoperative stabilization decreases morbidity and mortality. This change is due to the recent understanding that pulmonary hypoplasia, PPHN, and surfactant deficiency are largely responsible for the outcome of CDH and that the severity of these pathophysiologies is largely predetermined in utero. The pathophysiology does not appear to be exacerbated postnatally by herniated viscera in the chest as long as bowel decompression is continuous using a nasogastric tube.
o In addition, several reports indicate that circulatory stability, respiratory mechanics, and gas exchange deteriorate after surgical repair. The ideal time to repair a CDH is unknown. Some suggest that repair 24 hours after stabilization is ideal, but delays of up to 7-10 days are often well tolerated. Many surgeons now prefer to operate on these neonates when echocardiographic evidence for normal pulmonary artery pressures is maintained for at least 24-48 hours.

• Chest tube placement
o Chest tube drainage is necessary when a tension pneumothorax is present; however, the role and mode of routine chest drainage is controversial.
o Some clinicians report improved survival when chest drainage is not used. Others think that balanced intrathoracic drainage, in which a closed gated pressure system is used to maintain intrathoracic pressure within the normal physiologic range, may minimize risk of pulmonary injury.

• Lung transplantation
o Transplantation of a single lung has been successful. Lung transplantation may allow the remaining hypoplastic lung to increase in size and recover from injury while still allowing adequate oxygenation and ventilation. The transplanted lobe may be removed after physiologic recovery in the neonatal and infantile period. ECMO support can provide for stability of gas exchange prior to transplantation.
o Auxiliary transplantation of a parental lobe to the infant with pulmonary hypoplasia has been studied in a neonatal swine model, but it has not been reported in a human infant.

congenital diaphragmatic hernia MEDICATION
Drug Category: Surfactants -- CDH may be associated with pulmonary immaturity and abnormal surfactant profiles before delivery; therefore, surfactant administration after birth may be useful. Following inhaled administration, surface tension is reduced and alveoli are stabilized, thus decreasing the work of breathing and increasing lung compliance. Many clinicians decrease the dose of surfactant by 50% because of decreased lung volume.

Drug Category: Vasoactive agents -- Judicious use of vasoactive agents may increase cardiac output without affecting systemic or pulmonary vascular resistance.

Drug Category: Opioid analgesics -- Used for deep sedation to allow adequate mechanical ventilation. They may be particularly useful in decreasing sympathetic pulmonary vasoconstriction in response to noxious stimuli such as suctioning.

Drug Category: Neuromuscular relaxing agents -- Paralysis is sometimes necessary in the infant who is unstable despite adequate sedation; however, the use of paralysis is controversial and should be reserved for unusual cases in which the infant cannot be treated with appropriate sedation.

Drug Category: Pulmonary vasodilating agents -- Recently approved as a therapeutic modality for infants with PPHN, nitric oxide is an important mediator of vascular tone. It is delivered as an inhaled gas. At least 2 multicenter studies did not show that inhaled nitric oxide decreases mortality or the need for extracorporeal support in infants with CDH; however, it may be useful in stabilizing an infant while evaluating or transferring for ECMO.

congenital diaphragmatic hernia Further Inpatient Care:
• Pulmonary care
o Some severely affected infants have chronic lung disease. These infants may require prolonged therapy with supplemental oxygen and diuretics, an approach similar to that for bronchopulmonary dysplasia.
o The use of steroids, particularly high doses for prolonged periods, is controversial and may actually hinder appropriate lung and brain development.

• Neurologic evaluation
o Following recovery, a neurologist or developmental pediatrician should examine the patient, including an evaluation for CNS injury by head CT scanning.
o Because the incidence of hearing loss is high, perform an automated hearing test prior to discharge.

• Feeding: Incidence of significant gastroesophageal reflux is very high. While most infants can be managed medically, surgical intervention with Nissen or Thal procedures is sometimes required.

congenital diaphragmatic hernia Further Outpatient Care:
• Growth: Failure to thrive is common in a significant percentage of survivors and is most common in severely affected infants. Possible causes include increased caloric requirements because of chronic lung disease, poor oral feeding because of neurologic delays, and gastroesophageal reflux.

• Developmental follow-up
o Because of the risk for CNS insult and sensorineural hearing loss, infants should be closely monitored for the first 3 years of life, preferably in a specialty follow-up clinic.
o Reassess hearing at 6 months of life (and later if indicated) because late sensorineural hearing loss occurs in a high percentage of patients.
o Evaluate the patient prior to entering school to determine if any subtle deficits may predispose the patient to learning disabilities.