Congenital Diaphragmatic Hernia

• 1 in 4-5000 live births with males affected more frequently than females

• 80% are left sided through the foramen of Bochdalek.

• presentation is soon after birth with severe respiratory distress and cyanosis, and a scaphoid abdomen

• characteristic CXR showing the herniated abdominal contents into the thoracic cavity

• associated anomalies include gut malrotation (40%), cardiac anomalies (15%) and less commonly renal and neurological anomalies.

• mortality is high at 40-60%

• usually associated pulmonary hypoplasia (the degree of which is thought to be related to the stage of development at which herniation of gut occurs.)

• not all affected babies will come to surgery, as the severity of their pulmonary hypoplasia is incompatible with life

• ECMO may be a holding measure for some babies with intermediate pulmonary hypoplasia.

• essential to optimise the clinical condition prior to surgery.

• there is also impairment of pulmonary vasculature development. This causes accentuation of the normally labile tone of neonatal pulmonary vasculature predisposing infants to a transitional circulation with pulmonary hypertension and right-to-left shunting.

Management

• may be necessary to intubate the baby at birth due to severe respiratory distress. Corrective surgery to remove the abdominal contents from chest and close the defect can be performed when patient has been stable with acceptable blood gases for 24 hrs.

• during induction of anaesthesia in the un-intubated baby it is of paramount importance that the child is not "bagged" prior to intubation as this will cause gastric distension, which will further impede pulmonary ventilation. If the stomach does contain air from e.g. resuscitation at birth, then it should be aspirated via a naso-gastric tube.

• after intubation, ventilation should aim for a normal PaO2 and pH as both hypoxia and acidosis will provoke pulmonary hypertension.

• nitrous oxide should be avoided, as it will exacerbate any pre-existing bowel distension. A combination of Air/Oxygen plus a volatile agent is ideal.

• high dose fentanyl may prevent a pulmonary vasoconstrictive response to the stress of surgery. 

• pulmonary hypoplasia results in a low pulmonary compliance and may result in high intrapleural pressures if tidal volumes are increased in attempt to reach normal blood gases. Thus these children are at high risk of developing a pneumothorax secondary to barotrauma.

Monitoring

Should include:

• routine monitors

• an arterial line, ideally in right arm so that pre-ductal blood is sampled.

Post-operative care

• paralysis and ventilation with minimal handling should continue for at least 48 hours as even slight disturbances can provoke a pulmonary hypertensive crisis.

• inhaled nitric oxide may prove useful in treating these pulmonary hypertensive crises both intra-operatively and post-operatively.