Congenital Diaphragmatic HerniaVideo: Thoracoscopic Congenital Diaphragmatic Hernia Repair in an Infant  The incidence of congenital diaphragmatic hernia (CDH) is 1 in 2000 to 1 in 5000 live births with a 2% incidence among siblings or parents who have had CDH. CDH occurs on the left side 80% of the time. Bilateral diaphragmatic hernias are rare. The incidence of other abnormalities in newborns with CDH is approximately 28-50%. The connection between the abdomen and chest closes with formation of a membrane between weeks 2 and 8 of gestation. The etiology of a CDH remains unknown. However, certain drugs such as thalidomide and nitrofen have been associated with the development of CDH. Failure of the posterolateral, or outer and back aspect, of the diaphragm to close appears to result in the formation of the diaphragmatic hernia. Once the diaphragm has failed to close, the abdominal contents herniate or remain in the chest. This results in the development of lungs which are small on both sides, although this is most prominent on the side of the diaphragmatic hernia. A left CDH typically consists of a 1-2 inch opening in the diaphragm into which the abdominal contents; including part of the liver, the spleen, the stomach, and most of the intestines; have moved. If the stomach is in the chest the chances of survival are decreased. The intestines are usually completely free in the chest, although occasionally a membrane will cover them restricting them partially to the abdomen. The liver is usually in the chest on a right sided congenital diaphragmatic hernia. The problem with CDH is the small lungs. This probably results from compression of the lungs by the organs in the chest. The lungs are both small and immature. Some have suggested that the primary problem is with the lungs and not the diaphragm. The number of airway branches (bronchioles) and air sacs (alveoli) are markedly reduced. In addition, the lung blood vessels are abnormal. Fewer blood vessels are present and those that are present have more muscle in the blood vessel wall and are prone to spasming. When a baby is in the uterus blood flow through the lungs is limited, typically between 10-20% of the total. However, once born, the newborn physiology must alter such that all blood now travels through the lungs. Since there are fewer blood vessels and the blood vessels that are present are prone to constricting and spasming, blood tends to continue to follow a path between the two atria of the heart or between the pulmonary artery and the aorta so that the lung is bypassed by the flowing blood. As such, oxygen cannot be delivered into nor carbon dioxide removed from the blood effectively. This is made worse by the small lungs which make adding oxygen and removing carbon dioxide from the blood more difficult.  At our center, the in-utero diagnosis of a diaphragmatic hernia is made in approximately 44% of patients who present with CDH. Sixty percent of patients who ultimately present with a diaphragmatic hernia have a "normal" ultrasound. The usual findings on ultrasound which suggest the diagnosis of CDH is a shift of the heart away from the side of the CDH and the presence of the stomach in the left chest. A newborn will typically present with low oxygen levels, blue discoloration, and difficulty with breathing at birth, although some newborns with CDH will remain without any symptoms. A chest x-ray will demonstrate the presence of the intestines and possibly the stomach in the chest. Placement of a tube into the stomach allows identification of the stomach location. Only if necessary, contrast dye can be placed into the stomach in order to identify the presence of the intestines in the chest to discern a diaphragmatic hernia from cyst-type abnormalities of the lung. A search for other abnormalities, especially those involving the heart, should be performed. Patients with diaphragmatic hernia typically have a small heart which may contribute to problems with blood pressure and blood flow to the tissues. The heart can he evaluated by ultrasound echocardiograms. On physical examination, the abdomen is often flat because of the lack of abdominal contents. The severity of diaphragmatic hernia spans a great spectrum from those patients who remain completely symptom-free to those who have essentially no capability of absorbing oxygen or removing carbon dioxide via the lungs. A number of factors have been considered as predictors of the outcome of newborns with diaphragmatic hernia and include a diagnosis before 20 weeks gestation, the presence of extra amniotic fluid, and the presence of the stomach in the chest. However, studies have shown that their predictive capabilities are fairly poor. The presence of heart abnormalities, other than those described previously that are related to the shunting or passage of blood from the right side to the left side of the heart does indicate an especially poor outcome. The presence of the liver in the chest is associated with a reduced survival rate. Recently identified good predictors of survival at birth are the gestational age and the Apgar, (color, cry, work of breathing, muscle tone, and heart rate). Blood which is directly draining from the lungs into the heart may be sampled from the artery in the right arm (pre-ductal blood). The presence of a high carbon dioxide level (PaCO2 >50 mmHg) or low oxygen levels indicates a poor prognosis.  A diagnosis in-utero should be followed by a search for heart, brain, and spinal cord abnormalities. It is preferable that the fetus and mother be born at a center which can apply newer techniques of newborn respiratory support. Recent studies have suggested that in-utero surgery for repair of diaphragmatic hernia is not associated with an improvement in survival. However, there may be a role for obstructing the trachea, or windpipe with a clip in those fetuses with diaphragmatic hernia who have part of the liver in the chest. Obstruction of the trachea results in lung growth and is being explored as a possible means for treating such fetuses with CDH in-utero. Once born, a tube is placed in the trachea in order that oxygen may be delivered and carbon dioxide removed as the lungs are ventilated with a breathing machine, or ventilator. A tube is also placed into the stomach to maintain the stomach and intestines as free of air as possible. Appropriate tubes are also placed into the arteries and veins in order to administer medications and to draw blood to evaluate oxygen and carbon dioxide levels. Most infants can be managed with a routine ventilator, although other interventions with high frequency ventilators, which deliver small breaths at a very rapid rate, may be effective at distending the lungs to improve oxygen levels. Although not proven, administration of surfactant may enhance lung function. Nitric oxide, which by theory, should reduce the spasm in the lung blood vessels in patients with CDH, has been proven to be of little use in CDH infants except as a temporizing means until other interventions such as ECMO can be initiated. In the past it was felt that the operation to repair a diaphragmatic hernia should be performed immediately in order to remove the intestines from the chest and to allow lung expansion. However, recent data have suggested that immediate operation may actually make the function of the lungs worse. For that reason, many centers have now chosen a strategy wherein the operation to repair the diaphragm and to remove the abdominal contents from the chest are only performed once the lung status has improved. We currently apply a protocol in which the operation for the diaphragmatic hernia is performed when the patient is ready to be taken off the ventilator or if a number of days go by in which progress cannot be made in reducing the oxygen levels on the ventilator. For those patients who require ECMO immediately, we make every attempt to wean them from ECMO and to lower the ventilator pressure and oxygen levels once off ECMO before performing the operation. If after 14 days on ECMO, no improvement is observed, then the operation is performed. Likewise, at any point when improvement stalls over a period of 3-5 days, the operation is performed. It is not unusual for days or weeks to go by before repair of the diaphragmatic hernia is performed. However, our experience suggests that the need for ECMO is markedly reduced by this strategy. The approach to repair of the diaphragm may be via either the chest or the abdomen. In most cases, an incision is made just under the ribs. The intestines, stomach, spleen, and part of the liver are removed from the chest. Because of their abnormal location, the intestines will be in an unusual configuration which requires some separation of the intestines so they do not twist upon themselves. In some cases, the appendix may be removed because of its ultimate abnormal location. In many cases, the muscle of the diaphragm can be brought together and closed. If not, then a piece of Gore-tex plastic material is used to make a diaphragm. Once the intestines have been brought down into the abdomen, the muscles of the abdomen may be tight upon closure. If necessary, an additional piece of plastic Gore-tex may be used to form the muscles of the abdomen. At completion of the operation, attempts at lowering the levels of the ventilator pressures and oxygen are continued. Once these are at an appropriate low level, the breathing tube, or endotracheal tube, will typically be removed.  ECMO is applied in instances where adequate oxygen is not being provided and/or carbon dioxide removed from a baby with CDH. Typically, the level of oxygen in the blood, the amount of oxygen being administered, and the level of ventilator pressures required to provide that oxygen level are used in calculating an index which determines the need for ECMO. Most patients with CDH are candidates for ECMO. Only those who have evidence of very poor lung function as indicated by low right arm artery oxygen levels or high carbon dioxide levels; are of very low birthweight, who have a number of birth defects so that they are unlikely to have a good quality of life, or who have problems which preclude ECMO, as outlined on the ECMO website, are excluded from this treatment. Occasionally, patients will require operation while on ECMO. This may result in potential bleeding complications because of the need to administer heparin to prevent clotting in the ECMO circuit. As such, operations on ECMO are only performed when all other options have failed. The average time on ECMO for a patient with CDH is 7 days. The current survival rate for patients with CDH treated at ECMO centers is approximately 65-69%, but ranges from 39-99% at individual centers. Some patients with CDH progress well and are in the hospital for only a few weeks. On the other hand, those who survive with especially severe effects of CDH may be in the hospital for a number of months and have chronic problems. Chronic lung disease occurs in 50-60% of patients, although most patients by age 5 lead normal lives. Developmental delay may be present in 45% of high-risk infants, although catch-up in growth and neurologic development frequently occurs over time. Many patients with CDH will develop gastroesophageal reflux in which stomach contents tend to come back up the esophagus which may lead to vomiting, aspiration of stomach contents into the lungs, or injury or scarring of the esophagus due to acid. Many of these patients will be treated with medications for this problem, although some will require operation. Other abnormalities include the development of beast bone or sternal abnormalities such as pectus excavatum, or sunken chest. In addition, curvature of the spine or scoliosis may occasionally occur. New therapies which are being explored include the in-utero operation with tracheal ligation. This is being performed with a fetoscopic, or scope type technique, which is minimally invasive and hopefully will reduce the otherwise high incidence of premature labor. Steroid therapy and administration of thyroid related hormones may increase lung growth and maturation prior to birth. Finally, the use of perfluorocarbon agents to provide distention of the lungs may be associated with lung growth and improvement in lung function and the ability to improve oxygen transfer and carbon dioxide removal. Suggested readings authored by the University of Michigan, Section of Pediatric Surgery
This information is provided by the University of Michigan Department of Surgery, Section of Pediatric Surgery and is not intended to replace the medical advice of your doctor or health care provider. Please consult your health care provider for advice about a specific medical condition. For additional health information, please contact your health care provider or our offices. |
