A newborn male infant is born to a 23 year old G2P1 mother at 39 weeks gestation via NSVD (normal spontaneous vaginal delivery). Appropriate antenatal care and monitoring occurred throughout the pregnancy. As there were no significant antenatal problems, no prenatal ultrasonography was done. Immediately following delivery, the baby looks "normal". He cries immediately, however, at 1 minute of age, he remains very cyanotic. The neonatal resuscitation team is called to the delivery room. At 5 minutes of age, the baby remains very cyanotic, tachypneic and dyspneic, despite 100% oxygen via mask. The resuscitation team starts bag-mask positive pressure ventilation with 100% oxygen, but the baby becomes bradycardic, therefore he is intubated and ventilated. Auscultation of the lungs reveal good breath sounds in the right chest, but no breath sounds in the left. The heart sounds seemed loudest in the right chest, and the abdomen appears scaphoid. Ventilation is continued through the endotracheal tube, while an NG tube is inserted and suction is applied. A STAT chest x-ray is done, which reveals bowel (and the NG tube tip) in the left chest cavity. The baby is transferred to the NICU. This is a case of congenital diaphragmatic hernia presenting in the delivery room.
Although congenital diaphragmatic hernia (CDH) is rare (approximately 1 in 3000 births) it is associated with high mortality, morbidity, cost and suffering. Embryologically, by the end of the 12th week of gestation, fetal bowel has returned to the abdominal cavity and the formation of the diaphragm is complete, separating the intrathoracic from the intra-abdominal contents. Failure of this to occur results in a persistent pleuroperitoneal canal (foramen of Bochdalek), which allows the intra-abdominal viscera to occupy the chest cavity. This in turn prevents the lungs from developing, resulting in lung hypoplasia, worse on the side of the hernia. Although in the case above the diagnosis was not made until after delivery, with increasing use of fetal sonography, the diagnosis is commonly made prenatally, often as early as 15 weeks gestation. Unfortunately, more than 40% have associated anomalies of their brain, heart or other regions resulting in a poorer prognosis.
Classically, if undiagnosed prenatally, these infants present as a "neonatal emergency" in the delivery room. They do not respond to the typical steps of neonatal resuscitation, and usually get worse with bag-mask ventilation (BMV). With left sided CDH, breath sounds are diminished or absent in the left chest and because the mediastinum is displaced to the opposite side, the heart sounds are heard louder in the right chest. As the stomach and bowel fill with gas, (made worse by BMV), respiration and cardiac action are further compromised, and hypoxia and respiratory acidosis worsens. The neonate exhibits progressive respiratory distress, cyanosis and ultimately bradycardia. Because the abdominal contents are displaced into the chest, the abdomen often is scaphoid. Cases have been reported in which the infants remain relatively asymptomatic in the early hours and days of life. Rarely, a diaphragmatic hernia presents in an older child, as an incidental finding on physical exam or chest x-ray, or may be "acquired" as a result of traumatic rupture of the diaphragm secondary to a severe blow to the abdomen.
From the practical standpoint, 90% of congenital diaphragmatic hernias (CDH) occur on the left side. If the diagnosis is suspected clinically (but not yet confirmed), never bag-ventilate the infant. Rather, intubate, and apply "gentle" positive pressure ventilation. Secondly, pass a nasogastric catheter and apply intermittent suction to decompress the stomach (occupying the thorax and acting similar to a tension pneumothorax). These two measures alone may result in considerable clinical improvement. An emergency chest x-ray is mandatory to confirm the diagnosis. On x-ray, the air-filled bowel is seen occupying the left hemithorax, with resultant displacement of the mediastinum to the right. However, CDH has been misdiagnosed as a left tension pneumothorax, with acute respiratory distress temporarily relieved by needle aspiration. This x-ray finding of a "hyperlucent hemithorax" due to intrathoracic gastric dilatation alone is a unusual presentation of CDH in neonatal period, but can lead to a delayed diagnosis. Always look at the abdomen on x-ray, as absence of the stomach bubble in the left upper quadrant of the abdomen is an important radiologic clue to make the diagnosis.
The differential diagnosis must also include any neonatal emergency that presents with respiratory failure within minutes of birth. The clinical and radiological presentations are variable, making the diagnosis of a right-sided diaphragmatic hernia even more difficult. Careful evaluation of the clinical presentation, ultrasonography and chest films are mandatory for precise diagnosis. The liver partially blocks the pleuroperitoneal canal and limits the amount of bowel that can herniate into the chest. Symptoms in infants with right-sided hernias may be less severe, but the management is the same.
As with any form of ventilation, positive pressure can result in a pneumothorax on the contralateral side, which must be carefully observed for. If unrecognized, this can be a disastrous complication, resulting in death.
The infant born with congenital diaphragmatic hernia (CDH) remains one of the most complex patients to manage. Pulmonary hypoplasia and immaturity of the lungs remain the leading cause of death, from pulmonary hypertension (right-to-left shunting) with resultant hypoxemia. Over the last decade, there has been a constant improvement in the understanding of the pathophysiology of CDH and its management. Based on the knowledge that CDH is more of a physiological disease than a surgical disease, management strategy has shifted from immediate repair to delayed repair preceded by stabilization. However, the ideal treatment remains elusive. The old management strategy of immediate surgery is now replaced by the principle of physiologic stabilization and delayed surgery. Conventional ventilatory techniques, with high pressures and hyperventilation used to reverse ductal shunting and cause alkalinization, are now being replaced with ventilatory techniques utilizing the concepts of permissive hypercapnia and high frequency oscillation ventilation. The complications of ventilation including air leaks, barotrauma and consequent bronchopulmonary dysplasia are at least in part circumvented because of these newer techniques. Regardless of the treatment, the goal is to reverse the persistent pulmonary hypertension causing right to left shunting through the ductus arteriosus and foramen ovale.
Another recent development is the use of inhaled nitric oxide. Endogenous nitric oxide is an important modulator of vascular tone in the pulmonary circulation. Initial studies indicated that inhalation of nitric oxide results in a reduction in pulmonary hypertension, with improvement in oxygenation but no change in the systemic vascular resistance. However, no such beneficial effect has as yet been consistently reported in infants with congenital diaphragmatic hernia. Inhaled nitric oxide has side effects, although those due to nitrogen dioxide and methemoglobin formation can be minimized by using the smallest effective nitric oxide dose, continuous nitric oxide and nitrogen dioxide monitoring and frequent methemoglobin analyses. Longer term follow-up studies are needed to determine the true risk:benefit ratio of inhaled nitric oxide treatment in newborns with CDH.
Extracorporeal membrane oxygenation (ECMO) has been shown to salvage some of the most severely affected neonates. As some infants do not improve despite aggressive therapy, some centers use ECMO before hernia repair to stabilize these critically ill infants. Venovenous or venoarterial bypass is used, depending on the infant's hemodynamic stability. Bypass is continued until the pulmonary hypertension is reversed and lung function is improved, usually between 7 and 10 days of age. Approximately 60% of infants with CDH who are supported by ECMO survive. Despite this aggressive therapy, there are newborns with such severe pulmonary hypoplasia that all forms of life support are futile.
Other advanced and experimental respiratory therapies merit investigation. Further insights into the pathophysiology of CDH and the introduction of less invasive therapeutic techniques such as high frequency oscillation ventilation, inhalation nitric oxide, surfactant, and perfluorocarbon liquid ventilation may make the need for ECMO redundant.
Once medically stable, the definite treatment is surgical. The surgeon reduces the hernia gently by withdrawing the viscera from the chest. There may be enough diaphragmatic tissue to complete a direct suture repair. However, if a large portion of the diaphragm is missing, prosthetic material must be used to repair the defect. A chest tube is usually placed in the left hemithorax and brought out through an intercostal space. As the abdominal contents have been in the thorax for most of fetal development, the abdomen often does not have enough room for the "missing" contents. Forcing the contents into the abdomen will compress the vena cava and compromise respirations by pushing up on the diaphragm. The surgeon may be forced to omit total anatomic closure of the abdominal wall, and utilize skin flaps with only the skin being closed. An alternative is to create a silastic silo like those used for gastroschisis or a large omphalocele (see Gastroschisis and Omphalocele chapter). The pouch created accommodates the intra-abdominal organs, and diaphragmatic action and venous return are unimpeded. The final repair is completed after the infant has been weaned off the ventilator and is clinically stable.
Fetal surgery for congenital diaphragmatic hernia and other fetal conditions has been considered. However, at this time, open fetal surgery has proven too invasive to be justified for the treatment of diaphragmatic hernia, and progress in postnatal therapy (including ECMO) has dramatically improved the neonatal outcome in all but the most severely affected infants.
The outcome of congenital diaphragmatic hernia differs depending on the stage of the fetus or infant's life (i.e., antenatal, immediate postnatal, and postoperative). A review of the available literature on the outcome of CDH from 1985 to March 1998 (35 studies) revealed the median overall mortality was 58% for babies diagnosed in utero, 48% if born alive, and 33% postoperatively (lower mortality in this group that was stable enough to reach surgery). Although one may expect a poorer outcome with earlier intrauterine diagnosis, ultrasound, diagnosis before 25 weeks of gestation was not found to be a uniformly bad prognostic indicator (median mortality, 60%). However, outcome was worse for those fetuses with other congenital anomalies (median mortality, 93%). ECMO appears to improve survival. The median percentage mortality for all infants born alive and treated in ECMO centers was 34%, while the median percentage mortality for all ECMO-treated infants was 44%.
Unfortunately, surviving the initial repair doesn't assure future well being. Survivors of CDH usually have persistent pulmonary and nonpulmonary problems to deal with. Many of these patients require bronchodilators, oxygen, diuretics, and corticosteroids for obstructive airway disease and bronchopulmonary dysplasia. They are at high risk from respiratory syncytial virus (RSV) and should receive RSV immunoprophylaxis. Pulmonary problems continue to be the major source of morbidity for survivors of CDH long after discharge. Although the need for ECMO and the presence of a patch repair are both predictive of more significant morbidity, non-ECMO CDH survivors also require frequent attention to pulmonary issues beyond the neonatal period. There is a need for long-term follow-up of CDH patients preferably with a multidisciplinary team approach. Hopefully, future developments in medical therapy will continue to decrease the mortality and morbidity of patients with CDH.
In summary, if not diagnosed antenatally by sonography, CDH presents as a neonatal emergency in the delivery room, with a normal appearing infant not responding to resuscitation. Endotracheal intubation with gentle ventilation, followed by nasogastric suctioning is immediately indicated. Pulmonary hypoplasia and pulmonary hypertension with right-to-left shunting are common with resultant hypoxemia. The old management strategy of immediate surgery is now replaced by the principle of physiologic stabilization and delayed surgery. Other advanced and experimental respiratory therapies merit investigation. Further insights into the pathophysiology of CDH and the introduction of less invasive therapeutic techniques such as high frequency oscillation ventilation, inhalation nitric oxide, surfactant, and perfluorocarbon liquid ventilation may replace the need for ECMO. However, the ideal treatment remains elusive
1. The earliest way to diagnose a diaphragmatic hernia is:
. . . . . a. by physical exam
. . . . . b. by history
. . . . . c. by fetal ultrasound
. . . . . d. by fetal CT scan
2. The following are correct regarding diaphragmatic hernia except:
. . . . . a. is usually on the left side
. . . . . b. is frequently associated with hypoplastic lungs
. . . . . c. can present similar to a tension pneumothorax
. . . . . d. is frequently asymptomatic at birth
3. The following are true about diaphragmatic hernias:
. . . . . a. often have scaphoid abdomen on exam
. . . . . b. can be diagnosed antenatally by ultrasound
. . . . . c. at birth often have persistent cyanosis and respiratory distress
. . . . . d. all of the above
4. Treatment of diaphragmatic hernia includes:
. . . . . a. immediate surgical repair
. . . . . b. pulling the intestines back into the abdominal cavity while still in the delivery room
. . . . . c. provide immediate optimal resuscitation and stabilization first, and then surgery
. . . . . d. always do primary closure of the diaphragm
5. The true statement below is:
. . . . . a. The surgeon does not need to worry about medical problems as the neonatologist will already have treated them.
. . . . . b. There are essentially no medical problems after surgical repair.
. . . . . c. Improved ultrasound diagnosis has resulted in some women seeking termination of pregnancy.
. . . . . d. The long term outcome of survivors reveals no significant chronic pulmonary problems.
Late onset diaphragmatic hernia: Yamamoto LG. Diminished Breath Sounds and Air in the Chest. In: Yamamoto LG, Inaba AS, DiMauro R (eds). Radiology Cases In Pediatric Emergency Medicine, 1994, volume 1, case 6. Available online at: www.hawaii.edu/medicine/pediatrics/pemxray/v1c06.html
Neonatal x-rays with several congenital diaphragmatic hernias: www.hawaii.edu/medicine/pediatrics/neoxray/neoxray.html
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