Diaphragmatic Hernias Treatment & Management

In contrast to historic management patterns, which focused on the actual repair of the diaphragmatic hernia, the contemporary management of congenital diaphragmatic hernia (CDH) places emphasis on the management of pulmonary hypoplasia and persistent pulmonary hypertension. Current management uses various gentle alveolar recruitment strategies and a nonurgent approach to the operative treatment of congenital diaphragmatic hernia.^{[15, 1]}

Immediately following delivery, the infant is intubated (bag and mask ventilation is avoided). A nasogastric tube is passed to decompress the stomach and to avoid visceral distention.

Adequate assessment involves continuous cardiac monitoring, ABG and systemic pressure measurements, urinary catheterization to monitor fluid resuscitation, and both preductal (radial artery) and postductal (umbilical artery) oximetry.

Pressure limited ventilation should be used, allowing the lowest airway pressures compatible with staying on the steep side of the pressure volume loop and preductal oxygen saturations greater than 90%. Peak inspiratory pressures (PIP) should be less than 30 cm H₂ O. Hypercarbia is allowed as long as the pH can be buffered.^[16]

Alternative means of support (eg, high-frequency oscillatory ventilation [HFOV], extracorporeal membrane oxygenation (ECMO), and inhaled nitric oxide [iNO]) should be considered for patients who fail to stabilize on conventional ventilation.

HFOV is recommended for infants with hypercarbia and hypoxemia resistant to conventional ventilation or requiring high PIP (>30 cm H₂ O).^[17] HFOV uses an oscillating diaphragm to create a sinusoidal column of air within the airways. The diaphragm oscillates at a high frequency and improves gas exchange without increased ventilatory pressures. Increased gas exchange leads to elimination of carbon dioxide, which decreases the stimulus for pulmonary vasoconstriction and decreases pulmonary hypertension. At some institutions, HFOV is chosen as the primary means of ventilation.^[18]

Surfactant rescue or prophylactic therapy is associated with an improvement in oxygenation in some neonates with congenital diaphragmatic hernia.^{[19, 20]} Surfactant used as rescue therapy is administered within 24 hours of birth in neonates with congenital diaphragmatic hernia and a poor prognosis. As prophylactic therapy, surfactant (50-100 mg/kg of Infasurf R) is administered prior to the first breath in neonates with congenital diaphragmatic hernia who were given a poor prognosis antenatally. Prophylactic surfactant therapy and natural surfactants are thought to be more efficacious. No definitive evidence of a surfactant deficiency in human neonates has been identified, and surfactant as rescue therapy has not been shown to improve outcome.^[21]

iNO has proven to be a highly selective pulmonary vasodilator and has been used as rescue therapy in infants with persistent pulmonary hypertension of newborn (PPHN). iNO produces pulmonary vasodilatation, decreases the ventilation-perfusion mismatch, and reverses the ductal shunting observed in PPHN. Limited success has been gained in the use of iNO in patients with congenital diaphragmatic hernia, but efficacy of iNO improves following surfactant therapy.^[22]

The selection criteria for ECMO eligibility in congenital diaphragmatic hernia are the standard criteria used for other neonates with respiratory failure, as follows: a pH less than 7.15, oxygenation index greater than 40, and failure to respond to maximal medical treatment. ECMO should be reserved for patients who fail to respond to the alternative therapies if the extent of pulmonary hypoplasia is not considered to be lethal and when acute deterioration occurs in the postoperative period. ECMO in these cases provides respiratory support without additional barotrauma or oxygen toxicity. It allows time for the transition from fetal circulation, as well as the maturation of the pulmonary parenchyma (see image below).

No ideal time for repair of congenital diaphragmatic hernia is recognized, but the authors suggest that the window of opportunity is 24-48 hours after birth to achieve normal pulmonary arterial pressures and satisfactory oxygenation and ventilation with minimal ventilator settings. However, surgical repair can be safely delayed in stable patients, and the operation can be scheduled on a semi-elective basis. Urgent surgical repair is almost never necessary and may worsen the pulmonary hypertension.

The priority of the preoperative care is focused on the ventilatory management of the newborn and determining if the patient has any other associated congenital anomalies, particularly cardiac abnormalities. Echocardiography should always be performed prior to surgical repair.

A subcostal incision is made. The abdominal viscera are examined, and the hernia is reduced by gentle traction. A hernia sac is sought and excised if found. Following careful dissection of the posterior leaf of the diaphragm, primary repair can be accomplished in a single layer using nonabsorbable sutures. If the diaphragmatic defect is large enough to preclude primary closure, a prosthetic patch, or rotational muscle flaps^[23] or fascial flaps^{[24, 25]} can be used. If the patient is stable, the malrotation is corrected and Ladd bands are lysed. The open transthoracic repair of a left-sided and right-sided diaphragmatic hernia has been reported. However, this approach is not commonly used.

Thoracoscopic or laparoscopic repair was established earlier on for late presenters and neonates requiring minimal ventilator support. Thoracoscopic repair is now being performed on neonates on HFOV and nitric oxide. Exclusion criteria are not clearly defined however intrathoracic liver or stomach, inability to tolerate a period of manual ventilation, and large or anterolateral defects have been cited as reasons for initial open repair or conversion to open repair. Thoracoscopic repair provides improved visibility, less need for postoperative opioids, and decreased duration of ventilation (which may related to the patient group selected). The recurrence rate as high as 23% among infants undergoing thoracoscopic repair in the newborn period.^{[26, 27]}

If abdominal closure may interfere with chest wall or diaphragmatic compliance or lead to abdominal compartment syndrome, then a temporary silo with delayed primary closure of the fascia or skin can be safely accomplished.

The use of chest tubes is controversial, as is the use of suction. The authors prefer to use a chest tube but limit suction to 5 cm H₂ O. Most authors in North America suggest avoiding the use of suction to minimize mediastinal shift.

The patient with a right-sided defect and an intrathoracic liver presents unique problems to the surgeon. The neonatal liver is extremely friable, and kinking of the hepatic veins and the inferior vena cava can accompany the return of the liver to the abdomen. Careful manipulation of the liver into the abdomen must be accompanied by hemodynamic monitoring. Occasionally, a 2-cavity (right chest and abdomen) approach may be necessary to reduce the viscera. Another well-described technique is to repair the diaphragmatic hernia using thoracotomy. Such approach typically allows for reduction of the liver and viscera back into the abdomen with excellent exposure of the diaphragm.

Surgical repair while the patient is on ECMO was initially associated with an increased mortality rate, surgical site hemorrhage, and intracranial hemorrhage.^[28] To decrease the hemostatic complications, associated ECMO platelet counts are now maintained above 150,000/μL, and the activated clotting times (ACT) are decreased to 160-180 seconds.

Use of aminocaproic acid in the perioperative period decreases the fibrinolysis associated with use of the ECMO circuit and leads to decreased hemorrhagic complications. Intraoperative and postoperative blood loss is decreased with the following:

• Use of electrocautery for skin incision
• No dissection of the posterior leaf if primary repair is unlikely
• Use of prosthetic patch repair
• Limited blunt and sharp dissection
• Judicious use of electrocautery
• Application of topical thrombin to the suture line

Repairing the diaphragmatic hernia after decannulation from ECMO avoids the hemostatic complications associated with ECMO. This leads to recurrent pulmonary hypertension in some patients. The authors prefer repair on ECMO when the patient is ready for decannulation. Therefore, the patient tolerates decannulation if bleeding occurs.

Continued care is provided for survivors of congenital diaphragmatic hernia by a multidisciplinary team consisting of a social worker, nutritionist, physiotherapist, pediatrician/neonatologist, neurologist, and pediatric surgeon.

The following screening tests could be performed prior to discharge:

• Chest radiography
• ABG
• Brain stem auditory evoked potentials
• Head CT scanning or head ultrasonography
• Developmental evaluation.

In the outpatient clinic, chest radiography, pulmonary function tests, nutritional and developmental assessments, and repeated auditory, ophthalmology, and neurology evaluations are performed.

Complications observed in the early postoperative period include recurrent pulmonary hypertension and deterioration in respiratory mechanics and gaseous exchange. Less commonly observed complications include recurrence of the congenital diaphragmatic hernia (CDH), which is more common with patch repair;^[29] leakage of peritoneal fluid and blood into the thorax; and development of an ipsilateral hydrothorax. Small-bowel obstruction may occur secondary to adhesions or volvulus.

Long-term outcomes and prognosis are as follows:

• Long-term pulmonary disease depends on the degree of pulmonary hypoplasia, barotrauma, and volutrauma sustained in the neonatal period. Bronchopulmonary dysplasia and restrictive and/or obstructive lung disease may be observed.
• Failure to thrive is often observed in the presence of optimal feeding regimes.
• Functional and anatomic esophageal abnormalities are associated with significant gastroesophageal reflux in 40% of survivors.^[9] Prophylactic fundoplication at the time of primary repair for infants requiring a patch repair is advocated by some team as a means of preventing growth disorders or failure to thrive in this subset of patients. Other patients who may go on to require fundoplication include the neurologically impaired and those with chronic lung disease. Most other infants outgrow gastroesophageal reflux.^{[30, 31]}
• The use of extracorporeal membrane oxygenation (ECMO), hyperventilation treatment, and ototoxic medication places this population at a higher risk for sensorineural hearing loss as well as neurodevelopmental abnormalities (ie, cognitive and developmental delay, cerebral palsy, seizure disorders, impaired vision).
• Altered musculoskeletal development results in thoracic scoliosis, pectus deformities, and a decreased thoracic cavity on the affected side.
• In late childhood and adolescence learning disability, developmental disability and attention deficit hyperactivity disorder are noted in approximately 50% of patients. In addition to cognitive and attention deficits behavioral problems are seen. Only a third of these children require placement in a special educational class.^[32]

For excellent patient education resources, visit eMedicine's Esophagus, Stomach, and Intestine Center. Also, see eMedicine's patient education article Hiatal Hernia.

Experimental fetal surgery has been expanding rapidly over the last 3 decades. The fetus with congenital diaphragmatic hernia most likely to benefit from in utero intervention has lethal pulmonary hypoplasia and no coexisting other lethal congenital anomalies. To date, no prenatal parameter has been able to reliably predict the occurrence of lethal pulmonary hypoplasia. Hence, selection criteria for in utero intervention remain controversial. Current trends in fetal surgery for severe congenital diaphragmatic hernia focus on the manipulation of lung growth by temporary occlusion of the fetal trachea using minimal access surgery (see image below).

The immature lung in fetuses with congenital diaphragmatic hernia should benefit from antenatally administered corticosteroids. In the fetal lamb model, corticosteroid administration at 24 and 48 hours prior to delivery was associated with significant increases in lung compliance. Clinical trials using late prenatal steroids have failed to demonstrate improved survival, length of stay, and duration of ventilation.^[33]

Recent clinical studies point to an alteration in vitamin A metabolism in fetuses with congenital diaphragmatic hernia which is independent of maternal vitamin A levels.^{[34, 35]} In addition, ongoing experimental work is looking at the positive impact of antenatal vitamin A on lung development in animal models of congenital diaphragmatic hernia. In the nitrofen rat model, a decrease in the incidence of diaphragmatic hernias and pulmonary hypoplasia has been noted. In the lamb model, improvement in ventilation and a decrease in ventilation induced lung injury has been observed.^{[36, 37, 38]}