Congenital Lung Malformations Treatment & Management

Nonsurgical therapy is limited to the treatment of complications and associated respiratory failure. Antenatal prevention of preterm delivery (tocolytics) is important to avoid adding the complications of prematurity to any respiratory compromise that might be associated with the congenital lung malformation. If preterm delivery seems likely, maternal steroid administration may improve newborn surfactant and decrease hyaline membrane disease.

After birth, antibiotics are indicated for infection. Supplemental oxygen and mechanical ventilation are used for respiratory failure. In pulmonary sequestration and arteriovenous malformation (AVM), systemic arterial blood supply can be embolized, although thoracotomy and resection is usually just as rapid and more definitive than embolization.

In congenital lobar emphysema (CLE), the infant is placed in a decubitus position with the involved side dependent, and the noninvolved side is selectively intubated. Gentle ventilation and respiratory monitoring are required.

Most lesions can be approached by means of a posterior lateral thoracotomy through the fifth intercostal space without resecting a rib. If thoracoscopy is performed, collapsing the lung with a double-lumen bifurcated endotracheal tube is usually not possible. For this reason, the authors use ports so that carbon dioxide can be introduced to gently depress the lung. In most cases, 5-7 mm Hg suffices and does not cause hemodynamic compromise. A balloon catheter can be passed through the endotracheal tube to serve as a bronchial blocker.^{[4, 5]}

If pulmonary hypoplasia is diagnosed antenatally and judged to be incompatible with extrauterine life, some have suggested in utero intervention. This is done by occluding the fetal trachea with a balloon or clip. The accumulating fetal lung fluid seems to induce growth of the lung beyond normal. Because the lesion is rare and because the outcome is difficult to predict, this technique has not become popular. Some have tried to accomplish the same objective postnatally when a patient is receiving extracorporeal membrane oxygenation (ECMO). One can then instill a perfluorocarbon for liquid ventilation under pressure and expect some lung growth and development. Serial amnioinfusions have been helpful in certain cases of oligohydramnios.

In the extrauterine intrapartum (EXIT) procedure, the fetal head, neck, and shoulders are delivered through a uterine opening to allow for an assessment of the airway while the fetus is still attached to placental circulation. This technique has been used as a primary procedure to treat tracheal occlusion, to manage neck masses, and to facilitate the safe delivery of conjoined twins. For respiratory management, ECMO may be required after delivery.

Procedures to enlarge the thorax have been tried when an abnormal chest wall causes lung hypoplasia. These procedures include thoracoplasty and median sternotomy. In congenital lobar emphysema, cystic adenomatoid malformation (CAM) and sequestration resection of the abnormal lung, whether a lobe or a segment, is indicated.

Bronchogenic cyst

Posterolateral thoracotomy is performed to excise a bronchogenic cyst. The skin is incised from an inframammary point to a point about 5 cm below the scapula to a point midway between the scapula and the spine. Next, the latissimus dorsi is incised, and the intercostals space entered. The pleura is opened. Bronchogenic cysts are easy to dissect and can be removed intact. Fluid aspiration is unnecessary and may hinder dissection. Any remaining mucosa may cause recurrence of the cyst.

Pulmonary hypoplasia

Surgical intervention may be necessary to manage airway narrowing. This narrowing can also be managed by placing a spacer on the contralateral side of the chest so that the airway does not become kinked and so that the lung does not hyperexpand. Tissue expanders have been used for this purpose. They offer the advantage that they can be slowly expanded over time by injecting saline through a subcutaneous port.

The authors have been disappointed with the longevity of tissue expanders. Leaks frequently occur, and the tissue expander must be replaced. The authors prefer to use the old but stable technique of placing ping-pong balls. This method creates a stable and long-lasting mass. As the patient grows, repeat operation to place more ping-pong balls is occasionally required, but this is unusual. The authors have had one patient who had to undergo repeat operation to remove one ball because overcorrection had occurred.

Placing a spacer on the contralateral side of the chest may also prevent the scoliosis that many of these children develop.

Pulmonary sequestration

Lobectomy is required to manage intrapulmonary lesions. Segmentectomy can be done in a few patients. The extrapulmonary sequestration can be resected without the loss of normal lung tissue.

Most children can be extubated in the recovery room. If this is not possible, supplemental oxygen or mechanical ventilation is provided as needed. Meticulous pain management increases the likelihood of extubation, including thoracic epidural or intrapleural infusion or even just local infiltration of intercostals nerves.

The authors then administer intravenous morphine 0.05 mg/kg/h in children younger than 6 months or 0.1 mg/kg/h in older children. In children school age, patient-controlled analgesia is best.

Full expansion of the lung should be achieved to seal air leaks. The chest tube is changed from suction to an underwater seal when no air leak is present. When chest output is more than 2 mL/kg/d, the chest tube can be removed.

Maintenance fluids are provided intravenously to keep the patient a little dry and oral liquids are started the next day.

The authors encourage early ambulation. Many patients can be discharged in 3-5 days.

The prognosis is usually excellent after resection of congenital lung lesions when indicated. Attention is focused on any associated anomalies. If pneumonectomy was required, mediastinal shift may lead to cardiorespiratory compromise. This can be managed by placing an intrathoracic balloon prosthesis or by performing a tracheal-suspension procedure to relieve tracheal kinking.

Infants with limited remaining lung (eg, those with hypoplasia or extensive cystic adenomatoid malformation) may be at risk for chronic lung disease. These infants may benefit from home oxygen therapy and prophylaxis against respiratory syncytial virus. Yearly influenza vaccines may also be considered in these patients after the age of 6 months. Scoliosis and chronic lung insufficiency may develop.

General risks of thoracotomy and lung resection include empyema, pneumothorax, bleeding, and bronchopleural fistula. With respiratory insufficiency due to insufficient pulmonary tissue, pulmonary-artery hypertension and gastroesophageal reflux may occur and cause further deterioration. Failure to thrive can occur just as it does in congenital heart disease. Patients with failure to thrive may require supplemental feeding, even by means of a gastrostomy. Scoliosis can be a late complication when lung tissue is decreased in one thoracic cavity. Orthopedic intervention with bracing or open surgery may be necessary.

The incidence of complications after lung resection has decreased from 20-40% to 5-10% with modern care. Long-term pulmonary function after lobar resection is excellent.

Bronchogenic cyst

Because the normal lung parenchyma is not removed, the prognosis after surgical resection of bronchogenic cyst is excellent.

Pulmonary hypoplasia

The prognosis of patients with pulmonary hypoplasia depends on several factors, as follows:

• Associated anomalies
• Pulmonary hypertension
• Severe oligohydramnios, which increases the mortality rate
• Preterm delivery or rupture of the membranes earlier than 28 weeks' gestation
• Sidedness (Because the right lung is normally larger than the left, hypoplasia of the right lung is associated with a worsened outcome.)

Pulmonary sequestration

If the pulmonary sequestration is resected before repeated infections occur, morbidity can be prevented. In addition, the patient's prognosis depends on associated anomalies. The survival rate approaches 100% in the absence of other medical problems. Extralobar resection does not involve the removal of normal lung, and postoperative pulmonary function is excellent.

Congenital lobar emphysema

Frenckner and Freyschuss and then McBride showed that the lung volumes were 90-100% of predicted values in patients who underwent lobectomy for congenital lobar emphysema (CLE) as neonates.^{[6, 7]} This change results from compensatory growth of lung tissue and not from residual lung distention. However, the flow rates were low compared with predicted values (FEV₁ at 72% of expected). These findings may have resulted from the fact that alveoli continue to form, whereas airway formation ceases after birth.

Cystic adenomatoid malformation

The overall probability of survival is 80-100% in most studies.^[8] Most children have excellent long-term pulmonary function after lobectomy.

Factors in the natural history that may modify the patient's prognosis include the type (type 3 has the worst prognosis), size (large lesions produce respiratory compromise and mediastinal shift), timing of surgery (early surgical resection may improve outcomes), hydrops fetalis (this worsens the prognosis), and bilateral involvement (this results in a poor outcome).

Advancements in obstetric care, early detection of anomalies, noninvasive diagnostic modalities, early definitive surgery, and intensive care have improved the outcome of patients with congenital lung malformations. In minimally invasive thoracoscopic surgery, tiny holes are drilled in the chest to provide surgical access to internal structures. This technique is as effective as open thoracotomy in selected cases.

Fetal surgery

Preterm labor is one of the greatest challenges in fetal surgery. Fetal endoscopic surgery (ie, fetendo) obviates a large uterine incision and may reduce the overall risks of fetal surgery by reducing uterine trauma and, thence, preterm labor. Fetal endoscopic surgery, the extrauterine intrapartum (EXIT) procedure, and the plug (ie, tracheal occlusion) procedure have improved the outlook in numerous cases of congenital lung malformation. However, fetal surgery is still limited to relatively few tertiary care centers. Extracorporeal membrane oxygenation (ECMO) must be available should persistent pulmonary hypertension is detected.

A randomized controlled trial of 24 fetuses with congenital diaphragmatic hernia failed to show an appreciable effect on 90-day survival rates after tracheal occlusion to induce lung growth.^[9] Tracheal occlusion was compared with standard care (planned delivery and intensive postnatal care at a tertiary care center) in this study.

Total or partial lobectomy may be performed in patients with cystic adenomatoid malformation (CAM). When an entire lung is involved, the option of total pneumonectomy is controversial. Thoracentesis is helpful in hydrops associated with cystic adenomatoid malformation. Thoracoamniotic shunts may be placed. Placement of shunts before 20 weeks' gestation may be associated with postnatal chest wall abnormalities. In hydrops associated with cystic adenomatoid malformation in fetuses older than 32 weeks, babies should be delivered via the EXIT procedure rather than via fetal surgery.