Congenital diaphragmatic hernia (CDH) is a congenital malformation (birth defect) of the diaphragm. The most common type of CDH is a Bochdalek hernia; other types include Morgagni hernia, diaphragm eventration and central tendon defects of the diaphragm. Malformation of the diaphragm allows the abdominal organs to push into the chest cavity, hindering proper lung formation.
CDH is a life-threatening pathology in infants, and a major cause of death due to two complications: pulmonary hypoplasia and pulmonary hypertension. Experts disagree on the relative importance of these two conditions, with some focusing on hypoplasia, others on hypertension. Newborns with CDH often have severe respiratory distress which can be life-threatening unless treated appropriately.
The list of signs and symptoms mentioned in various sources for Congenital diaphragmatic hernia includes the 11 symptoms listed below:
- Respiratory distress
- Breathing difficulty
- Rapid breathing
- Severe retraction
- Increased chest diameter
- Bowel sounds upon chest auscultation
- Pleuroperitoneal fold defect
- Abnormal lung development
- Respiratory acidosis
- Metabolic acidosis
This condition can often be diagnosed before birth and fetal intervention can sometimes help, depending on the severity of the condition. Infants born with diaphragmatic hernia experience respiratory failure due to both pulmonary hypertension and pulmonary hypoplasia. The first condition is a restriction of blood flow through the lungs thought to be caused by defects in the lung. Pulmonary hypoplasia or decreased lung volume is directly related to the abdominal organs presence in the chest cavity which causes the lungs to be severely undersized, especially on the side of the hernia.
Survival rates for infants with this condition vary, but have generally been increasing through advances in neonatal medicine. Work has been done to correlate survival rates to ultrasound measurements of the lung volume as compared to the baby's head circumference. This figure known as the lung to head ratio (LHR).
A small percentage of cases go unrecognized into adulthood.
First step in management is orogastric tube placement and securing the airway (intubation). The baby will usually be immediately placed on a ventilator. Extracorporeal membrane oxygenation (ECMO) has been used as part of the treatment strategy at some hospitals. ECMO acts as a baby heart-lung bypass (though it can be used for older children as well). A cannula is inserted into the carotid artery, allowing the blood to exit the body and begin its trek through the ECMO circuit, it is then scrubbed, oxygenated, and passes through a filter before being returned to the body via a second cannula into the baby's own circulatory system where it makes its rounds before returning to the ECMO circuit to be oxygenated again. In essence, the ECMO circuit acts as the baby's lungs. Babies require extra blood volume and hefty doses of blood thinners in order to keep the circuit running without clot formation, which could be potentially fatal. Even though the baby is not using her lungs, an ocillating ventilator maybe still be used to keep some air in the lungs so that they do not fully collapse while not being used. During ECMO the pulmonary artery has a chance to rest, as it were, thus hopefully reducing the presence of pulmonary hypertension, one of the biggest complication of CDH cases. CDH repair can be done while the baby is on ECMO, although blood thinners increase the risk of bleeding complications. Usually surgeons prefer to perform CDH repairs off ECMO. Once the baby is taken off ECMO the carotid artery is sealed and can no longer be used. When repairing the hernia an incision is made in the abdomen. The hernia can sometimes be simply stitched closed but in more complicated cases a patch may be required. A synthetic patch can be used but will usually require replacement later as the child grows. A more natural patch can be created by slicing and folding over a section of abdominal muscle and securing it to the exsiting piece of diaphragm. Any organ displacement is corrected during surgery. Though the heart and lungs will usually move back into position on their own, once displaced organs such as bowel, liver, or stomach, are out of the way. The incision is then closed. Sometimes, the incision site will be left open to allow the body to adjust to newly moved organs and the pressure associated with that, and then closed later once swelling and drainage has decreased.
Diaphragm eventration is typically repaired thoracoscopically, by a technique called plication of the diaphragm. Plication basically involves a folding of the eventrated diaphragm which is then sutured in order to "take up the slack" of the excess diaphragm tissue.