CHAPTER 14 Congenital Lung Anomalies
Step 1: Surgical Anatomy
♦ Congenital malformations of the lungs in neonates and infants are uncommon. The three conditions most commonly encountered are discussed herein: congenital lobar emphysema, cystic adenomatoid malformations (CCAMs), and pulmonary sequestrations (both extralobar and intralobar).
Step 2: Preoperative Considerations
♦ Congenital lobar emphysema is the overdistention of one or more lobes of the lung. It usually results from an absence of bronchial cartilage but may occur from mucus plugging and progressive air trapping in ventilated patients. Associated anomalies of the heart and great vessels are common.
Infants may present with respiratory distress, diminished breath sounds, hyperresonance over the involved thorax, and evidence of mediastinal shift.
Chest radiographs are usually diagnostic, with hyperlucency of the involved lobe, collapse or atelectasis of the other lobes, and shift of the heart toward the opposite thorax. Fig. 14-1 is a chest radiograph demonstrating overexpanded congenital lobar emphysema of the right middle lobe and significant compression of the right upper and lower lobes.
Infants may present with respiratory distress, diminished breath sounds, hyperresonance over the involved thorax, and evidence of mediastinal shift. Chest radiographs are usually diagnostic, with hyperlucency of the involved lobe, collapse or atelectasis of the other lobes, and shift of the heart toward the opposite thorax. Fig. 14-1 is a chest radiograph demonstrating overexpanded congenital lobar emphysema of the right middle lobe and significant compression of the right upper and lower lobes.
♦ CCAMs derive from the abnormal branching of the immature bronchioles during lung development. They are commonly seen in the lower lobes and derive their blood supply from the pulmonary vessels; most have a communication with the tracheobronchial tree.
CCAMs are commonly diagnosed on prenatal ultrasound. Large lesions may result in fetal nonimmune hydrops caused by compression of the mediastinum and vena cava obstruction. Spontaneous regression may occur in 40% to 80% of prenatally detected lesions.
Figures 14-2 and 14-3 are of a neonate with a congenital cystic adenomatoid malformation of the left lower lobe. The left lung is overexpanded with multiple cystic areas present. There is significant shift of the mediastinum to the right hemithorax. The stomach bubble and nasogastric tube are situated below the diaphragm, aiding in the differential diagnosis of congenital diaphragmatic hernia.
CCAMs are commonly diagnosed on prenatal ultrasound. Large lesions may result in fetal nonimmune hydrops caused by compression of the mediastinum and vena cava obstruction. Spontaneous regression may occur in 40% to 80% of prenatally detected lesions.
Figures 14-2 and 14-3 are of a neonate with a congenital cystic adenomatoid malformation of the left lower lobe. The left lung is overexpanded with multiple cystic areas present. There is significant shift of the mediastinum to the right hemithorax. The stomach bubble and nasogastric tube are situated below the diaphragm, aiding in the differential diagnosis of congenital diaphragmatic hernia.
♦ Pulmonary sequestrations are cystic masses of nonfunctioning lung tissue with no connection to the tracheobronchial tree. They typically derive their blood supply from a systemic artery originating from the thoracic or abdominal aorta and may have systemic venous connection to the superior vena cava or azygos or hemiazygos veins. They exist in two forms: extralobar and intralobar. An extralobar sequestration is covered by separate visceral pleura, is completely discrete from the normal lung, and is most commonly seen in the left lower chest. Associated anomalies are common and include chest wall deformities, congential heart defects, and congenital diaphragmatic hernia.
Neonates may be asymptomatic or have respiratory distress, pneumonia, feeding difficulties, or congestive heart failure resulting from arteriovenous shunting. Intralobar sequestrations are found within the surrounding normal lung tissue, most commonly in the left lower lobe. These also have a systemic arterial supply but commonly drain through the pulmonary veins. The most common presenting symptom in a neonate is respiratory distress.
Neonates may be asymptomatic or have respiratory distress, pneumonia, feeding difficulties, or congestive heart failure resulting from arteriovenous shunting. Intralobar sequestrations are found within the surrounding normal lung tissue, most commonly in the left lower lobe. These also have a systemic arterial supply but commonly drain through the pulmonary veins. The most common presenting symptom in a neonate is respiratory distress.
Step 3: Operative Steps
General
♦ After the induction of general anesthesia, placement of an endotracheal tube, and obtaining adequate intravenous access, the infant is positioned for a posterolateral thoracotomy.
♦ Single lung ventilation may be accomplished by selective mainstem intubation, a bronchial blocker, or double-lumen endotracheal tube, but it is not absolutely required. Occasionally single lung ventilation is not tolerated well in infants.
♦ Posterolateral thoracotomy is the most frequently used approach and is useful for almost all pulmonary lesions requiring resection in childhood. The child is placed with the affected side up, down leg flexed at 90 degrees, a towel placed between the legs, and an axillary roll positioned to prevent stretching and vascular compromise of the dependent arm and shoulder. The ipsilateral arm is elevated toward the head and supported on blankets or pillows, taking care to avoid stretching the brachial plexus. Antiseptic preparation of the skin and preoperative antibiotic prophylaxis is used. A gently curvilinear incision is made starting at the anterior axillary line and extended posteriorly (Fig. 14-5). The fifth intercostal space is used for lower lobectomy and extrapulmonary sequestrations, and the fourth is used for upper lobectomy. To avoid the late effects of scoliosis and chest wall deformities, care is taken in performing a muscle-sparing thoracotomy and avoiding the division of the trapezius, rhomboid, and paraspinal muscles. The chest is opened along the appropriate intercostal space, and a Finochietto rib spreader is placed for visualization. Once the lesion has been identified, the procedure is continued with the correct lobectomy.
♦ The basic principles of pulmonary lobectomy involve dissection and division of the arterial supply, followed by the venous drainage, and finally the bronchus. A detailed explanation of all pulmonary resections is beyond the scope of this text; therefore we refer you to the selected references and will describe only a left lower lobectomy in detail because it is the most commonly affected lobe.
Left Lower Lobectomy
♦ The major fissure of the lung is opened by retracting the upper lobe superiorly. The pulmonary artery is located at the base of the fissure, lying in the same plane as the fissure (Fig. 14-6, A). Once the artery is located, the perivascular space is entered and the superior segmental artery and its branches and the basilar artery and its branches are dissected free. Before completion of the arterial dissection, the major fissure may need to be completely divided, a measure that is usually amenable to a stapling device. The branches of the artery are doubly ligated or suture ligated and divided.
♦ Next the lung is reflected anteriorly to expose the posterior hilum and the inferior pulmonary ligament. The ligament is divided, and the vein is exposed. In the case of a pulmonary sequestration, the systemic artery usually courses through the inferior pulmonary ligament, and this artery must be identified, doubly ligated, or suture ligated and divided before division of the inferior pulmonary ligament. The vein and its branches are doubly ligated or suture ligated and divided (Fig. 14-6, B).
♦ The upper lobe is then retracted anteriorly, and the lower lobe bronchus is exposed. The upper lobe pulmonary artery is dissected free from the underlying lower lobe bronchus, and the bronchus is dissected free. The origin of the upper lobe bronchus must be identified and preserved. The lower lobe bronchus is occluded before division, and the upper lobe is observed for adequate inflation. The lower lobe bronchus is then divided and closed in segments using monofilament sutures (Fig. 14-6, C) or using a stapling device. Once the bronchus is divided, the specimen may be removed from the chest.
♦ The chest is then filled with warm saline, and gentle positive pressure is applied to identify any air leaks from the bronchial closure. A chest tube is placed into the chest through a separate stab incision in the anterior axillary line approximately two intercostal spaces caudal to the incision. The ribs are reapproximated with interrupted absorbable suture, the chest wall muscles with running absorbable suture. The chest tube is placed to 10 to 15 cm H2O suction, and a sterile dressing is applied to the wound.
Thoracoscopic Lobectomy
♦ With advances in minimally invasive techniques and equipment, thoracoscopic pulmonary lobectomy is possible in almost any age or size of a child. Most of these procedures can be accomplished using 5-mm trocars and small, 3.5-mm, instruments. The long-term benefit of these procedures is the avoidance of late musculoskeletal complications that are seen with thoracotomy, but as of this date, definitive long-term data addressing this outcome are lacking.
Single lung ventilation, as described previously herein, is achieved, but those infants and children who do not tolerate single lung ventilation are not candidates for this procedure. The patient is positioned laterally, and the surgeon and assistant stand on the same side, facing the patient’s abdomen. There is a single video monitor placed on the opposite side of the patient. A valved 5-mm port is placed in the midaxillary line about the fifth intercostal space. A controlled pneumothorax is created by insufflating 4 torr CO2 at 1 L/min, which allows excellent visualization of the chest without the need for manual lung retraction. Two to three additional ports are placed in a triangular fashion, and 3.5-mm instruments are used (Fig. 14-7). The techniques follow those of the open procedure, mainly division of the pulmonary fissure, dissection and ligation of the arteries, veins, and the bronchus. The pulmonary vessels and the systemic vessels of a pulmonary sequestration may be sealed and divided with the Ligasure. This instrument is useful for vessels 9 mm or smaller. It is also useful in division of the fissure. Larger vessels may require endoclips, suture ligation, or an Endo-GIA stapler. The bronchus may be handled with an Endo-GIA stapler, but the chest cavity of many infants is too small to accommodate this device. In those instances, the bronchus may be divided and sutured intracorporeally with interrupted absorbable sutures. The posterolateral port incision may be enlarged to remove the specimen, or a retrieval bag may be used. A 12 French chest tube may be placed through one of the trocar sites and placed to 10 to 15 mm H2O suction.
Single lung ventilation, as described previously herein, is achieved, but those infants and children who do not tolerate single lung ventilation are not candidates for this procedure. The patient is positioned laterally, and the surgeon and assistant stand on the same side, facing the patient’s abdomen. There is a single video monitor placed on the opposite side of the patient. A valved 5-mm port is placed in the midaxillary line about the fifth intercostal space. A controlled pneumothorax is created by insufflating 4 torr CO2 at 1 L/min, which allows excellent visualization of the chest without the need for manual lung retraction. Two to three additional ports are placed in a triangular fashion, and 3.5-mm instruments are used (Fig. 14-7). The techniques follow those of the open procedure, mainly division of the pulmonary fissure, dissection and ligation of the arteries, veins, and the bronchus. The pulmonary vessels and the systemic vessels of a pulmonary sequestration may be sealed and divided with the Ligasure. This instrument is useful for vessels 9 mm or smaller. It is also useful in division of the fissure. Larger vessels may require endoclips, suture ligation, or an Endo-GIA stapler. The bronchus may be handled with an Endo-GIA stapler, but the chest cavity of many infants is too small to accommodate this device. In those instances, the bronchus may be divided and sutured intracorporeally with interrupted absorbable sutures. The posterolateral port incision may be enlarged to remove the specimen, or a retrieval bag may be used. A 12 French chest tube may be placed through one of the trocar sites and placed to 10 to 15 mm H2O suction.
Step 4: Postoperative Care
♦ The infant is allowed to feed ad libitum the following morning as long as there is no gastric distention. Antibiotics are continued until the chest tube is removed. The chest tube is maintained on 10 to 15 cm H2O suction until there is no air leak and output is minimal. At that time the tube is placed to H2O seal and a chest radiograph is obtained to ensure that no pneumothorax is present. If air does not accumulate in the chest cavity, the tube is removed and a follow-up chest radiograph is obtained to ensure that the lung remains expanded. These children are usually seen in follow-up in the clinic about 4 weeks after their procedure.
Step 5: Pearls and Pitfalls
♦ Most of these children do extremely well, and major complications such as empyema and bronchopleural fistula are rare.
Congenital Lobar Emphysema
♦ The surgeon must be prepared for immediate thoracotomy in these children because occasionally the child will acutely decompensate after the induction of anesthesia.
♦ Opening the chest will reduce the tension effects of the emphysematous lobe and allow adequate ventilation of the contralateral normal lung. In older infants and children, obstruction of the bronchus from a radiolucent foreign body leads to air trapping and a clinical picture that may mimic congenital lobar emphysema, and diagnostic bronchoscopy is helpful.
Congenital Cystic Adenomatoid Malformations
♦ This entity, especially when it occurs on the left side, may be confused with congenital diaphragmatic hernia. Noting the location of the stomach bubble and nasogastric tube beneath the diaphragm aids in the diagnosis. If the diagnosis remains in question, an upper gastrointestinal study or CT scan looking for loops of bowel in the chest may also be helpful.
Pulmonary Sequestration
♦ The most important aspect of surgical intervention for this entity is adequate and early control of the systemic arterial supply. A number of extralobar sequestrations (15%) will be found within or below the diaphragm and may be mistaken for a neuroblastoma. These lesions are amenable to laparoscopic removal, again with meticulous attention to control of the systemic arterial supply. About 10% of sequestrations may have connections to the gastrointestinal tract, and preoperative upper gastrointestinal series is helpful in defining this anatomy.
Albanese CT, Rothenberg SS. Experience with 144 consecutive pediatric thoracoscopic lobectomies. J Laparoendosc Adv Surg Tech. 2007;17:339-341.
Duncombe GJ, Dickinson JE, Kikiros CS. Prenatal diagnosis and management of congenital cystic adenomatoid malformation of the lung. Am J Obstet Gynecol. 2002;187:950-954.
Hood M. Techniques in general thoracic surgery. Philadelphia: Saunders; 1985. pp. 101-133
Laberge JM, Puligandia P, Flageole H. Asymptomatic congenital lung lesions. Semin Pediatr Surg. 2005;14:16-33.
Mei-Zahav M, Konen O, Manson D, Langer JC. Is congenital lobar emphysema a surgical disease? J Pediatr Surg. 2006;41:1058-1061. 2006
Rothenberg SS. Experience with thoracoscopic lobectomy in infants and children. J Pediatr Surg. 2003;38:102-104.
