Cardiovascular System

In the fetal circulation, arterial blood from the placenta bypasses the lungs through the patent foramen ovale and ductus arteriosus. After first breath, the foramen ovale closes, along with a precipitous drop in pulmonary arterial pressure caused by decreases in pulmonary vascular resistance, thereby promoting pulmonary blood flow. Decreased blood flow along with a higher oxygen content also promote closure of the ductus arteriosus. Many factors can contribute to persistent pulmonary hypertension (PPHN) with right-to-left shunt. Hypoxemia, acidosis, and sepsis all contribute to PPHN. Prematurity is also a significant risk factor for persistent ductus arteriosus. Nonsteroidal anti-inflammatory drugs (NSAIDs), such as indomethacin, have been used to close a patent ductus arteriosus in premature infants pharmacologically. If unsuccessful, surgical ligation may be necessary. An infant heart has a limited capacity to increase the stroke volume and, therefore, cardiac output is largely rate-dependent. Cardiac output is significantly affected by bradycardic episodes. Capillary refill is an ideal clinical indicator of adequate cardiac perfusion. A prolonged capillary refill longer than 1 to 2 seconds may represent significant shunting of blood from the peripheral tissues to the central organs, as may occur with cardiogenic and/or hypovolemic shock.

Pulmonary System

The lungs are not fully matured at birth and continue to form new terminal bronchioles and alveoli until about 8 years of age. In premature infants, lung immaturity is one of the greatest contributors to morbidity and mortality. Immature lungs have fewer type II pneumocytes and a lower production of surfactant, which is critical for reducing alveolar surface tension and thereby increasing functional residual capacity. Hence, premature infants are at significant risks for alveolar collapse, hyaline membrane formation, and barotrauma. Surfactant is a lipoprotein mixture of phospholipid, protein, and neutral fats. Lecithin, the most predominant phospholipid, can be measured in amniotic fluid, and the lecithin-to-sphingomyelin ratio is used to determine fetal lung maturity. In addition to pulmonary parenchymal issues, the airway of the newborn is small (tracheal diameter = 2.5 to 4 mm) and easily plugged with secretions. The respiratory rate for a normal newborn may range from 40 to 60 breaths/min, with a tidal volume of 6 to 10 mL/kg. Nasal flaring, grunting, intercostal and substernal retractions, and cyanosis constitute symptoms of respiratory distress. Infants are obligate nasal and diaphragmatic breathers and any condition that obstructs the nasal passages (including the nasogastric tube) or interferes with diaphragmatic function may result in severe respiratory compromise. A major contributor to the treatment of premature infants, therefore, has been the ability to provide exogenous surfactant. This has resulted in improved survival and decreased incidence of bronchopulmonary dysplasia, a condition characterized by oxygen dependence, radiologic abnormality, and chronic respiratory symptoms beyond the first 28 days of life. The administration of inhaled nitric oxide, a potent inducer of vascular smooth muscle relaxant, has also proven useful in neonates with PPHN.

Thermoregulation

Newborn infants are at great risk for cold stress and must be maintained in a neutral thermal environment to reduce oxygen consumption and metabolic demands. The major risk factors for the development of hypothermia in infants include their relatively large body surface area, lack of hair and subcutaneous tissue, and increased insensible losses. Also, a neonate responds to cold ambient temperature by a mechanism of nonshivering thermogenesis, in which increases in metabolic rate and oxygen consumption by the mobilization of brown fat deposits occur. Continued cold exposure ultimately can lead to decreased perfusion and metabolic acidosis. To avoid radiant and evaporative heat loss, the use of overhead radiant heaters and warming lights is a common practice, but a caution for significant insensible water losses should be made. All fluids should be warmed, especially when transfusing cold stored blood products.

Immunologic Function

Neonates are immunodeficient with reduced levels of immunoglobulins (IgA, IgG, IgM) and of the C3b component of complement. As such, premature infants are at increased risk for severe infection. The evaluation of sepsis in neonates requires an extensive workup of surveillance cultures of blood, urine, and cerebrospinal fluid as well as a complete blood count with platelet count, differential smear, and plain radiography. Sepsis may result from various invasive devices that are essential to the care of premature infants, such as prolonged endotracheal intubation, umbilical catheters, and bladder catheterization. Based on subtle clinical changes (e.g., reduced tolerance of enteral feeding, temperature instability, reduced capillary refill, tachypnea, irritability), implementation of empirical antibiotic therapy targeted at common bacterial pathogens such as group B beta-hemolytic streptococci, methicillin-resistant Staphylococcus aureus, and Escherichia coli may be lifesaving.

Fluid Requirements

Fluid and electrolyte therapy in pediatrics requires careful assessment of fluid intake, fluid losses, and electrolyte abnormalities prior to initiating fluid management. It also requires frequent monitoring during the course of therapy to assess the adequacy of treatment. Accurate estimation of IV fluid and electrolytes is critical, especially in small infants with a narrow margin of error. Because of increased insensible water losses through thinner immature skin, fluid requirements for premature infants are substantial. Insensible water losses are directly related to gestational age, ranging from 45 to 60 mL/kg/day for premature infants weighing less than 1500 g to 30 to 35 mL/kg/day for term infants. Other factors, such as radiant heat warmers, phototherapy for hyperbilirubinemia, and respiratory distress, further increase losses. In the first 3 to 5 days of life, there is a physiologic water loss of up to 10% of the body weight of the infant. As such, fluid replacement volumes are less over the first several days of life. These fluid volumes are regarded as estimates and may change according to differing patient factors.

Fluid requirements are calculated according to body weight (Table 67-1). During the first few days of life, the fluid recommendations are conservative; however, most neonates require 100 to 130 mL/kg/day for maintenance fluids by the fourth day of life. Neonates with conditions that are associated with excessive fluid losses (e.g., gastroschisis) can require as much as 1.5 times maintenance volume. The two best indicators of sufficient fluid intake are urine output and osmolarity. The minimum urine output in a newborn and young child is 1 to 2 mL/kg/day. Although adults can concentrate urine in the range of 1200 mOsm/kg, an infant responding to water deprivation is only able to concentrate urine to a maximum of 700 mOsm/kg. Clinically, this indicates that greater fluid intake and urine output are necessary to excrete the solute load presented to the kidney during normal metabolism. In general, the daily requirements for sodium and potassium are 2 to 4 and 1 to 2 mEq/kg, respectively. These requirements are usually met with a solution of 5% dextrose in 0.45% normal saline with 20 mEq KCl/liter at the calculated maintenance rate. Fluid losses from gastric drainage, ostomy output, or diarrhea should also be carefully assessed and replaced with an appropriate solution. Gastric losses should be replaced in equal volumes with 0.45% NS with 20 mEq KCl/liter. Diarrheal, pancreatic, and biliary losses are replaced with isotonic lactated Ringer’s solution. Acutely hypovolemic patients requiring rapid volume expansion should be treated with an IV bolus of 10 to 20 mL/kg body weight of whole blood, plasma, or 5% albumin. Transfusions of packed red blood cells are given in increments of 5 to 10 mL/kg.

Table 67-1 Daily Fluid Requirements for Neonates and Infants

Nutrition

Cervical Lymphadenopathy

Enlarged lymph nodes is one of the most common pediatric conditions, resulting in frequent referral to a surgeon for biopsy and/or resection. They occur usually along the sternocleidomastoid muscle border, often presenting in clusters. The cause is multifocal but often thought to be infectious. A careful history and physical examination are typically sufficient to determine surgical indications; however, the use of diagnostic ultrasound has significantly increased in recent years. In most healthy children, cervical lymphadenopathy presents as a small, mobile, rubbery, palpable mass in the anterior cervical triangle. However, relatively fixed, nontender, progressively enlarging nodes in the supraclavicular region should raise suspicion for more serious underlying conditions. Other associated symptoms, such as night sweats and a history of weight loss, should also be thoroughly investigated. Chest radiography is often performed as a screening method to detect mediastinal adenopathy. If enlarged anterior mediastinal nodes are seen, a computed tomography (CT) scan of the chest is obtained to assess nodes better and identify potential airway compression. Patients with acute, bilateral cervical lymphadenitis are usually managed nonoperatively because respiratory viral infectious causes (e.g., adenovirus, influenza virus, respiratory syncytial virus) are common. S. aureus and group A streptococci are responsible for most cases of acute pyogenic lymphadenitis. When nodes become fluctuant because of a central area of liquefying necrosis, needle aspiration or incision and drainage should be performed.

Cat scratch disease is a self-limiting infectious condition characterized by painful regional lymphadenopathy. Bartonella henselae, a gram-negative bacillus, is responsible for most cases. A history of exposure to cats is helpful, but not always present. Indirect immunofluorescent antibody testing has only moderate specificity and, therefore, the use of the polymerase chain reaction assay from a lymph node biopsy is more useful for diagnosis. There is no specific treatment for cat scratch disease because it is usually self-limited. A less common infectious cause for cervical lymphadenitis is nontuberculous mycobacterial infection.¹ In general, the nodes are fluctuant, with a violaceous appearance of the overlying skin. The diagnosis is typically made by positive cultures for nontuberculous acid-fast bacilli, along with a tuberculin skin test. Surgical excision is usually indicated because most nontuberculous mycobacteria are resistant to conventional chemotherapy.

Cystic Hygroma

Cystic hygromas are multiloculated cystic spaces lined by endothelial cells; they occur as a result of lymphatic malformation. Most cystic hygromas involve the lymphatic jugular sacs and present in the posterior neck region. The other common sites are the axillary, mediastinum, inguinal, and retroperitoneal regions, and approximately 50% of them present at birth. Cystic hygromas usually present as soft cystic masses that distort the surrounding anatomy, including the airway, which can result in acute airway obstruction. Prenatal recognition of a large cystic mass of the neck is associated with a significant risk to the airway, greater association with chromosomal abnormalities, and higher mortality rates. Advanced prenatal imaging modalities allow for careful coordination of surgical intervention at the time of delivery.

Aside from distorting adjacent normal structures, cystic hygromas are prone to infection and hemorrhage within the mass. Imaging studies, such as magnetic resonance imaging (MRI), can play a crucial role in preoperative planning. In general, complete surgical excision is the preferred treatment. However, this may be difficult because of the intimate involvement with surrounding vital structures. Resections are generally tedious, requiring careful isolation and ligation of lymphatic branches. Aggressive blunt and electrocautery dissections can lead to inadequate control of lymphatics, often resulting in recurrence and/or infection caused by accumulation of the lymphatic leak. Radical resection with sacrifice of vital structures is not advocated. Injection of sclerosing agents such as bleomycin or OK-432, derived from Streptococcus pyogenes, has been reported to be effective in the nonoperative management of cystic hygromas.²

Thyroglossal Duct Cyst

A thyroglossal duct cyst is a midline neck lesion that originates at the base of the tongue at foramen cecum and descends through the central portion of the hyoid bone. It is one of the most common midline neck lesions presenting in preschool-aged children (Fig. 67-1A). Although thyroglossal duct cysts may occur anywhere from the base of the tongue to the thyroid gland, most are found at or just below the hyoid bone. The standard operation for thyroglossal duct cysts has remained unchanged since it was described by Sistrunk in 1928. It involves complete excision of the cyst in continuity with its tract, the central portion of the hyoid bone, and the tissue above the hyoid bone, extending to the base of the tongue (see Fig. 67-1B). Failure to remove these tissues will result in a high risk for recurrence because multiple sinuses have been histologically identified in these locations. Embryologically, a thyroid diverticulum develops as a median endodermal thickening at the foramen cecum. As the embryo develops, the thyroid diverticulum descends in the neck and remains attached to the base of tongue by the thyroglossal duct. Also, as the thyroid gland descends to its normal pretracheal position, the ventral cartilages of the second and third branchial arches form the hyoid bone—hence, the intimate anatomic relationship of the thyroglossal duct remnant with the central portion of the hyoid bone. Normally, the thyroglossal duct regresses by the time the thyroid gland reaches its final position. When the elements of the duct persist despite complete thyroid descent, a thyroglossal duct cyst may develop. Failure of normal caudal migration of thyroid gland results in a lingual thyroid, in which no other thyroid tissue is present in the neck. Ultrasound or radionuclide imaging may provide useful information to identify the presence of a normal thyroid gland within the neck.

FIGURE 67-1 A, Thyroglossal duct cyst presents as a midline neck mass. B, Sistrunk procedure consists of excision of the thyroglossal duct cyst up to its origin at the foramen cecum, including the central portion of hyoid bone.

(From Josephs MD: Thyroglossal duct cyst. In Chung. DH, Chen MK [eds]: Atlas of pediatric surgical techniques, Philadelphia, 2010, Elsevier Saunders, pp 28–33.)

Branchial Cleft Remnants

The branchial cleft remnants typically present as a lateral neck mass on a toddler. The structures of the head and neck are derived from six pairs of branchial arches, their intervening clefts, and pouches. Congenital cysts, sinuses, or fistulas result from failure of these structures to regress, persisting in an aberrant location. The location of these remnants generally dictates their embryologic origin and guides the subsequent operative approach. Failure to understand the embryology may result in incomplete resection or injury to adjacent structures. All branchial remnants are present at the time of birth; however, they are often not recognized until later in life. These lesions may present as sinuses, fistulas, or cartilaginous rests in infants. However, they occur more commonly as cysts in older children and adolescents. The clinical presentation may range from a continuous mucoid drainage from a fistula or sinus to the development of a cystic mass that may become infected. Branchial remnants may also be palpable as cartilaginous lumps or cords corresponding with a fistulous tract. Dermal pits or skin tags may also be evident.

First branchial remnants are typically located in the front or back of the ear or in the upper neck near the mandible. Fistulas typically course through the parotid gland, deep or through branches of the facial nerve, and end in the external auditory canal. Remnants from the second branchial cleft are the most common. The external ostium of these remnants is located along the anterior border of the sternocleidomastoid muscle, usually in the vicinity of the upper half to lower third of the muscle. The course of the fistula must be anticipated preoperatively because stepladder counterincisions are often necessary to excise the fistula completely. Typically, the fistula penetrates the platysma, ascends along the carotid sheath to the level of the hyoid bone, and turns medially to extend between the carotid artery bifurcation. The fistula then courses behind the posterior belly of the digastric and stylohyoid muscles to end in the tonsillar fossa. Third branchial cleft remnants usually do not have associated sinuses or fistulas and are located in the suprasternal notch or clavicular region. These most often contain cartilage and present clinically as a firm mass or subcutaneous abscess.

Torticollis

Torticollis is a state of abnormal muscle tone in the neck, resulting in the head to twist and turn to one side. It may be congenital or acquired and can occur at any age. In infants with congenital torticollis, the head is typically tilted toward the side of the affected muscle and rotated in the opposite direction. Although the true cause is unknown, birth trauma is most frequently considered. Congenital torticollis presents within a few weeks after birth as an isolated condition. However, acquired torticollis may be associated with a range of conditions, including acute myositis, brainstem tumors, atlantoaxial subluxation, and infectious causes, such as retropharyngeal abscess, cervical adenitis, or tonsillitis. The diagnosis is typically based solely on the clinical history and examination findings. Treatment of congenital torticollis is largely nonoperative, with passive range-of-motion stretching of the affected muscle for several months. Surgical resection or division of the involved muscle is rarely indicated.

Indications

The major indications for neonatal ECLS include meconium aspiration, respiratory distress syndrome, PPHN, sepsis, and congenital diaphragmatic hernia (CDH). Neonates with complex congenital cardiac defects may be supported with ECLS perioperatively. Meconium aspiration is the most common indication for neonatal ECLS and is associated with the highest survival rate (>90%). Selection criteria for the initiation of neonatal ECLS vary slightly among institutions. Generally, an infant must have at least an 80% predicted mortality with continued conventional medical treatment to justify ECLS therapy. Two guidelines have been historically used as a means to predict survival without ECLS. The alveolar-arterial difference in the partial pressure of oxygen (PAO₂ − PaO₂ [also known as AaDO₂]) is calculated as follows:

AaDO₂ more than 610 for longer than 8 to 12 hours, and AaDO₂ more than 620 for 6 hours associated with extensive barotrauma and severe hypotension requiring inotropic support, are considered to be criteria for ECLS. The oxygen index (OI) is calculated as the fraction of inspired oxygen (usually 1.0) multiplied by the mean airway pressure ×100 divided by PaO₂. An 80% mortality is noted with an OI more than 40. Exclusion criteria include gestational age less than 34 weeks, birth weight less than 2 kg, and a nonreversible pulmonary pathology. Additional exclusion criteria include the presence of cyanotic congenital heart disease or another major congenital anomaly that precludes survival, intractable coagulopathy or hemorrhage, sonographic evidence of a significant intracranial hemorrhage (higher than a grade I intraventricular hemorrhage), and more than 10 to 14 days of high-pressure mechanical ventilatory support. Before the initiation of ECLS, all infants must undergo echocardiography to rule out congenital heart disease and cranial ultrasound to exclude the presence of significant intracranial hemorrhage.

Physiologic Considerations

The basic concept of ECLS is to drain venous blood, remove carbon dioxide, add oxygen through the artificial membrane lung, and then return warmed blood back into the circulation. Venoarterial bypass provides cardiac and respiratory support, whereas venovenous bypass provides only respiratory support. Venoarterial bypass is used most commonly; the right internal jugular vein and common carotid artery are typically chosen for cannulation because of their vessel sizes, accessibility, and adequate collateral circulation. The ECLS circuit is composed of a silicone rubber bladder, which collapses when venous return is diminished, roller pump, membrane oxygenator, heat exchanger, tubing, and connectors. Venous blood from the right atrium drains through the venous cannula to the bladder and is pumped to the membrane oxygenator, where carbon dioxide is removed and oxygen is added (Fig. 67-2). The oxygenated blood then passes through the heat exchanger and is returned to the patient through the arterial cannula. The patient is systemically anticoagulated to prevent clotting of the ECLS circuit; hence, patients are at risk for bleeding complications. As such, hematocrit values, platelet counts, and fibrinogen levels must be closely monitored and maintained at acceptable ranges. Cranial ultrasound is performed for the first few days of ECLS to monitor for hemorrhage and then done on an as-needed basis. Extracorporeal flow is gradually weaned as native cardiac or pulmonary function improves. Indicators of lung recovery include an increasing PaO₂, improved lung compliance, and clearing of the chest x-ray. Once the extracorporeal flow rate reaches minimal levels, the patient is trialed off bypass by temporarily clamping cannulas. If tolerated, the patient is taken off ECLS support on moderate conventional ventilatory settings.

FIGURE 67-2 Extracorporeal life support circuit. A venoarterial circuit is shown here .

(From Shanley CJ, Bartlett RH: Extracorporeal life support: Techniques, indications, and results. In Cameron JL [ed]: Current surgical therapy, ed 4, St. Louis, 1992, Mosby Year Book, pp 1062–1066.)

Complications

Bleeding is the most common complication of ECLS and may result in medical (e.g., intracranial) or surgical (e.g., neck cannulation site, intrathoracic, GI) problems. Birth weight and gestational age are the most significant correlates of intracranial hemorrhage on ECLS; infants weighing less than 2.2 kg and younger than 35 weeks gestational age are at highest risk. Other significant complications associated with ECLS include seizures, neurologic impairment, renal failure requiring hemofiltration or hemodialysis, hypertension, infection, and mechanical malfunction (e.g., failure of the membrane oxygenator, pump, and heat exchanger). Other potential complications include mechanical failure of the circuit.

Pathogenesis

The specific cause for CDH is unknown, but it is thought to result from failure of closure of the pleuroperitoneal canal in the developing fetus. Normally, the pleuroperitoneal cavities become separated by the developing membrane in weeks 8 to10 of gestation. When this process fails, closure of the pleuroperitoneal canal is incomplete and a posterolateral diaphragmatic defect results. The posterolateral location of this hernia is known as Bochdalek’s hernia; it is distinguished from a CDH of the anteromedial location known as Morgagni’s hernia. As a result of the defect, abdominal contents herniate through the resultant defect in the posterolateral aspect and compress the ipsilateral developing lung. These lungs have smaller bronchi, with less bronchial branching and less alveolar surface area than lungs in normal infants. The ipsilateral lung is affected more severely; however, lungs from both sides are affected by pulmonary hypoplasia. In addition to the abnormal airway development, the pulmonary vasculature is also significantly affected by increased thickness of arteriolar smooth muscle. Also, arteriolar vasculature is extremely sensitive to the multiple local and systemic vasoactive factors. Hence, the severity of pulmonary hypoplasia and pulmonary hypertension significantly affect the overall morbidity and mortality in CDH infants.

Clinical Presentation

The most frequent clinical presentation of CDH is respiratory distress caused by severe hypoxemia. The initial symptoms and signs include grunting respiration, chest retractions, dyspnea, and cyanosis with scaphoid abdomen. Breath sounds are decreased and bowel sounds may be heard in the chest. The shifting of heart sounds to the right (for left CDH) is common. A significant differential between preductal and postductal pulse oximetry indicates the presence of right-to-left shunting as a result of PPHN. The diagnosis of CDH is frequently made prenatally as early as 15 weeks of gestation by ultrasonography during an otherwise unremarkable pregnancy. Infants who have a late onset of CDH (after 25 weeks of gestation) have been reported to have better overall survival rates. The herniation of the stomach and liver, along with polyhydramnios, has all been associated with poor outcome. The presence of associated anomalies also significantly decreases the overall survival. With prenatal diagnosis, delivery of a fetus with CDH should take place at an institution capable of providing advanced neonatal critical care, including extracorporeal membrane oxygenation (ECMO) support.

Diagnosis

At birth, CDH infants demonstrate symptoms of respiratory distress with a classic chest radiographic appearance of multiple bowel loops in the thoracic cavity, along with mediastinal shift (Fig. 67-3). An orogastric tube may appear to coil in the chest. The differential diagnosis of CDH includes congenital cystic adenomatoid malformation, bronchogenic cyst, diaphragmatic eventration, and cystic teratoma. In Morgagni’s hernia, the diagnosis is often delayed until childhood because most infants are asymptomatic. Chest radiographs may reveal an air-fluid level immediately posterior to the sternum. Usually, the infant does well for several hours after delivery during the so-called honeymoon period and then begins to demonstrate worsening respiratory function. Therapeutic interventions are targeted to reduce PPHN. In approximately 10% to 20% of cases, CDH is diagnosed beyond the first 24 hours of life, at which time infants present with various symptoms of feeding difficulties, respiratory distress, and pneumonia.

FIGURE 67-3 Congenital diaphragmatic hernia. Multiple gas-filled bowel loops are located in the left hemithorax and the mediastinum is shifted to the right.

Treatment

The open fetal surgery for CDH has failed to show significant overall survival advantage. Occlusion of the fetal trachea, resulting in accumulation of lung fluid to stimulate lung growth, has garnered significant recent interest. A laparoscopic approach has also been used to apply external clips or place balloons and sponges to occlude the fetal trachea. However, the fetal occlusion technique has not significantly influenced the overall survival rate with CDH, and fetal interventions for CDH remain limited to a few centers. The postnatal management of CDH is directed toward stabilization of the cardiorespiratory status while minimizing iatrogenic injury from therapeutic interventions. Immediate securing of the airway with endotracheal intubation is critical. Excessive mean airway pressure ventilation can result in pneumothorax and compromised venous blood return to the heart. An orogastric tube is placed to prevent gastric distention, which may worsen the lung compression, mediastinal shift, and ability to ventilate. The use of tolazoline, a nonselective α-adrenergic blocking agent, as a pharmacologic pulmonary vasodilator has not produced clinically significant results. Inhaled nitric oxide is used by most centers as a pulmonary vasodilator. Surfactant administration and high-frequency ventilation have also resulted in variable overall outcome for CDH infants. However, the recent use of gentle ventilation with permissive hypercapnia and stable hypoxemia has resulted in a significantly higher survival rate (≈75%) for CDH infants.

Outcomes

Beyond the immediate postoperative period, many infants with CDH experience significant morbidity because of PPHN and respiratory dysfunction. Many children who survive aggressive management of severe respiratory failure manifest neurologic problems, such as abnormalities in motor and cognitive skills, developmental delay, seizures, and hearing loss. Other problems include a high incidence of gastroesophageal reflux (GER) and foregut dysmotility. Other morbidities associated with CDH survivors include chronic lung disease, scoliosis, growth retardation, and pectus excavatum deformities.

Bronchogenic Cyst

Bronchogenic cyst is the most common cystic lesion of the mediastinum. The cyst wall consists of fibroelastic tissue, smooth muscle, and cartilage, whereas the cyst itself is lined with respiratory tract epithelia (ciliated columnar cells). It can also contain mucus-producing cuboidal cells, which contribute to enlargement of the cyst with mucus. They may occur anywhere along the tracheobronchial tree but are usually found around the carina and right hilum. Less frequently, they present in the neck, lung, pleura, pericardium, or below the diaphragm. When the cysts are large, they can compress surrounding vital structures, including the airway. Infants are particularly at risk because of their narrow, easily compressible airway. Bronchogenic cysts can also cause dysphagia, pneumothorax, cough, and hemoptysis or become infected, which is how older children present. Often picked up on postnatal chest x-ray, the diagnosis is confirmed by CT as a spherical nonenhancing mass. It is fluid- or mucus-filled, although an air-fluid level is apparent if the cyst communicates with the airway. Cysts within the pulmonary parenchyma typically communicate with a bronchus, whereas those in the mediastinum usually do not. Bronchogenic cysts are routinely resected even if asymptomatic, although recently there have been debates on observation alone for this condition.⁴ Rare cases of malignant transformation have been reported. Resection is performed by video-assisted thoracic surgery (VATS) or thoracotomy.

Congenital Pulmonary Airway Malformation

CPAMs have been controversially described as hamartomatous lesions in which a multicystic mass replaces normal lung tissue. They are connected to the tracheobronchial tree and its blood supply is pulmonary. Although they are usually unilateral and unilobar, they can present in the immediate perinatal period with life-threatening respiratory distress. If asymptomatic during this time, infants and older children can go on to present with fevers, persistent cough, and recurrent pneumonia. CPAMs can undergo malignant transformation; rhabdomyosarcoma has been reported. They are classified based on their appearance on imaging and confirmation is made by pathologic examination. According to the Stocker classification, type I lesions account for almost 75% of all cases and consist of a small number of large, 2- to 10-cm cysts that can compress normal lung parenchyma. Type II lesions have numerous cysts, usually measuring less than 1 cm in diameter. Type III lesions are rare and appear to be only a few millimeters in diameter.⁵ However, they are associated with mediastinal shift, hydrops, and a poor prognosis.

Ultrasound and, less commonly, MRI, are used to locate the lesion, characterize its appearance, determine its blood supply and venous drainage, and evaluate whether there is any displacement of other thoracic structures. Also, when there is any uncertainty, prenatal MRI has been used to differentiate CPAM from other congenital thoracic abnormalities. Postnatally, a chest radiograph is usually diagnostic, revealing a mass with a possible mediastinal shift and air-fluid levels, but a chest CT is frequently obtained for confirmation. When fetal distress occurs in utero, options include fetal thoracotomy and thoracoamniotic shunting (if the fetus is <32 weeks). Most fetuses with a prenatally diagnosed CPAM experience partial regression in the third trimester and can be treated with expectant management. They can then undergo postnatal resection at 5 to 8 weeks of life.⁴ Postnatal management of the symptomatic patient necessitates resection via a thoracotomy or VATS. The treatment of asymptomatic patients is more controversial but it is generally agreed that they should be resected, given the risk of infection and malignancy.

Pulmonary Sequestration

Bronchopulmonary sequestrations (BPSs) are nonfunctional nests of microcystic pulmonary tissue that have no connection to the tracheobronchial tree but are fed by an aberrant systemic artery. There are two types, intralobar (IL) and extralobar (EL); the former is contained within normal lung parenchyma and the latter is separate and encased by its own pleura.⁴ ELSs occur predominantly in males and, in 40% of cases, other congenital anomalies, such as posterolateral diaphragmatic hernia, pectus excavatum and carinatum, and enteric duplication cysts, can be found.

Lacking a communication to the airway, sequestrations do not form enlarged cysts or cause spontaneous pneumothoraces. They can, however, infarct, become infected, and cause hemoptysis. It has been reported that ELSs can undergo torsion as well. Because of their aberrant systemic vascular supply (Fig. 67-4), BPSs can result in significant left-to-right shunting in infants, who are then susceptible to high-output cardiac failure.⁶ For an initial evaluation, Doppler ultrasound may reveal a systemic arterial supply from the infradiaphragmatic or thoracic aorta. The lesion itself may appear solid, but can also be cystic. CT or MRI can aid in further defining the vascular anatomy. Accounting for 75% of all BPSs, intralobar sequestrations (ILSs) are found within the medial or posterior segments of the lower lobes, more on the left side. Most ELSs are found posteromedially in the left lower chest but can occur within or below the diaphragm. Air within an ILS usually signifies infection, whereas the same finding in an ELS suggests the presence of a fistulous connection with the esophagus.⁴

FIGURE 67-4 Anomalous arterial vascular pedicle to extralobar pulmonary sequestration. The arterial branch comes directly off the thoracic aorta.

If a BPS is identified on prenatal ultrasound, the fetus is followed with serial ultrasound, looking for mass enlargement and the development of complications such as hydrops, pleural effusion, or polyhydramnios.⁶ BPS has been reported to spontaneously regress. In fact, it is estimated that 68% of BPSs undergo spontaneous regression before birth as they become isodense with the surrounding lung. The involution may occur as the lesion outgrows its blood supply. Because of the risk for infection and bleeding, ILSs are usually resected by segmentectomy or lobectomy. ELSs are usually asymptomatic and, because there is generally no tracheobronchial communication, the risk of infection is low. As such, many of these lesions can be observed.

Congenital Lobar Emphysema

CLE describes a progressively distended, hyperlucent lobe caused by abnormal bronchopulmonary development. Air trapping in the emphysematous lobes occurs with intrinsic or extrinsic obstruction, which includes endobronchial obstruction from mucosal proliferation and extrinsic compression from vascular anomalies. In over 90% of cases, it involves the left upper or right middle lobe. CLE is rarely diagnosed prenatally, but its prevalence is 1 in every 20,000 to 30,000 deliveries.⁴ It tends to present in the first few days of life and as late as 6 months after birth. On ultrasound, CLE appears as an echogenic homogenous lung mass. When CLE is discovered in an asymptomatic patient, observation is recommended because these lesions have a tendency to regress. A chest radiograph is customarily diagnostic because it reveals overdistention of the involved lobe. Importantly, the lucency should not be mistaken for a pneumothorax, and positive-pressure ventilation should be used with caution because of the propensity of these patients to undergo auto-PEEP (positive end-expiratory pressure; auto-PEEP is defined as the end-expiratory intrapulmonary pressure that develops as a result of dynamic airflow resistance during mechanical ventilation). When the CLE progresses to the point that it causes mediastinal shift and worsening symptoms, an open thoracotomy with lobectomy is indicated.

Esophageal Atresia and Tracheoesophageal Fistula

Esophageal atresia is a congenital condition of esophageal discontinuity that results in proximal esophageal obstruction. A tracheoesophageal fistula (TEF) is an abnormal fistula communication between the esophagus and trachea. Esophageal atresia and TEF can occur alone or in combination. The incidence of this anomaly is 1 in 1500 to 3000 live births, with a slight male predominance. Approximately one third of infants with esophageal atresia or TEF have a low birth weight, and 60% to 70% have associated anomalies. During the fourth week of gestation, the esophagotracheal diverticulum of the foregut fails to divide completely to form the esophagus and trachea. In 10% of patients, there is a nonrandom, nonhereditary association of anomalies referred to by the acronym VATER (vertebral, anorectal, tracheal, esophageal, renal or radial limb); an alternative acronym is VACTERL (vertebral, anorectal, cardiac, tracheal, esophageal, renal, and limb). Five anatomic variants of esophageal atresia are depicted in Figure 67-5. In the most common type (C lesion) of esophageal atresia with TEF, the proximal blind pouch ends approximately the distance of one to two vertebral bodies from the distal TEF. The distal TEF is typically located 1 cm above the carina in the membranous portion of the trachea.

FIGURE 67-5 Anatomic variants and incidence of esophageal atresia with tracheoesophageal fistula.

Clinical Presentation and Diagnosis

The diagnosis of esophageal atresia is considered in an infant with excessive salivation along with coughing or choking during the first oral feeding. A maternal history of polyhydramnios is often present, more often in isolated proximal atresia (86%). In an infant with esophageal atresia and TEF, acute gastric distention may occur as a result of air entering the distal esophagus and stomach with each inspired breath. Reflux of gastric contents into the distal esophagus will traverse the TEF and spill into the trachea, resulting in cough, tachypnea, apnea, and/or cyanosis. The presentation of isolated TEF without esophageal atresia may be more subtle, often beyond the newborn period. In general, these infants have choking and coughing associated with oral feeding. The inability to pass a nasogastric tube into the stomach of the neonate is a cardinal feature for the diagnosis of esophageal atresia. If gas is present in the GI tract below the diaphragm, an associated TEF is confirmed (Fig. 67-6A). Conversely, the inability to pass a nasogastric tube in an infant with absent radiographic evidence of GI gas is almost diagnostic of an isolated esophageal atresia. The use of isotonic contrast by mouth to demonstrate the presence and/or level of the proximal esophageal atresia is strongly discouraged because of risk for aspiration. The diagnostic evaluation includes screening for other associated anomalies. Echocardiography and renal ultrasound are performed to evaluate for congenital heart defects (including aortic arch anomaly) and genitourinary malformations.

FIGURE 67-6 A, Plain chest radiograph of infant with proximal esophageal atresia with distal TEF. The distal tip of the orogastric tube is noted, with a surrounding gas-filled proximal esophagus (arrows). The TEF is also indicated by the presence of gastric air. B, Rigid bronchoscopy inspection of distal tracheoesophageal fistula. The luminal size of the fistula (arrowhead) is equal to that of either main bronchus (arrows).

Treatment

Preoperative Management

Initial treatment includes decompression of the proximal esophageal pouch with a sump tube (e.g., Replogle tube) placed on continuous suction. The infant is positioned in an upright prone position to minimize GER and prevent aspiration. Broad-spectrum IV antibiotic coverage should be started empirically. Routine endotracheal intubation is avoided because positive-pressure ventilation may be inadequate to inflate the lungs because air is directed into the TEF through the path of least resistance. Ventilation may be compounded further by the resultant gastric distention. Gastrostomy to decompress the distended stomach should be avoided because it may abruptly worsen the ability to ventilate the patient. In these circumstances, manipulation of the endotracheal tube to be positioned distal to the TEF (e.g., right mainstem intubation) may minimize the leak and permit adequate ventilation. Furthermore, placement of an occlusive balloon catheter (Fogarty) into the fistula through a bronchoscope may be useful, but this maneuver can be risky. As a last resort, emergent thoracotomy with ligation of the fistula alone may be required. A preoperative chest radiograph and echocardiogram provide sufficient information to determine the side of the aortic arch. A right thoracotomy is performed for the operative repair in patients with a normal left-sided aortic arch. However, for infants with a right-sided arch, a left thoracotomy would be preferred. A higher incidence of aortic arch anomalies (e.g., vascular rings) and postoperative complications has been reported with right-sided aortic arch.⁷

Surgical Management

The typical surgical approach for the most common esophageal atresia with TEF involves an open thoracotomy, with an extrapleural approach through the fourth intercostal space. Bronchoscopy is routinely performed to determine the relative site of the fistula and exclude the presence of a second fistula (see Fig. 67-6B). After extrapleural dissection to expose the posterior mediastinum, the azygos vein is divided to reveal the underlying TEF. The TEF is dissected circumferentially and its attachment to the membranous portion of trachea is taken down. The tracheal opening is approximated using interrupted nonabsorbable sutures. The proximal esophageal pouch is then mobilized as high as possible to afford a tension-free esophageal anastomosis. The blood supply to the upper esophageal pouch is generally robust and is based on arteries derived from the thyrocervical trunk. However, the blood supply to the lower esophagus is more tenuous and segmental, originating from intercostal vessels. As such, significant mobilization of the lower esophagus is avoided to prevent ischemia at the esophageal anastomosis. The anastomosis is performed using a single- or double-layer technique (Fig. 67-7A). The rates of anastomotic leak are slightly higher with the single-layer anastomosis, whereas the rates of esophageal stricture are higher with the double-layer technique.

FIGURE 67-7 A, A single-layer end-to-end anastomosis is performed using nonabsorbable sutures. Two corner stitches are placed and a back row anastomosis is completed first. Just prior to completing the anterior row of the anastomosis, a nasogastric tube is placed across it. B, Thoracoscopic esophageal anastomosis.

(A from Ricketts R: Esophageal atresia with tracheoesophageal fistula. In Chung DH, Chen MK [eds]: Atlas of pediatric surgical techniques, Philadelphia, 2010, Elsevier Saunders, pp 44–53; B from Wulkan ML: Thoracoscopic repair of esophageal atresia with tracheoesophageal fistula. In Chung DH, Chen MK [eds]: Atlas of pediatric surgical techniques, Philadelphia, 2010, Elsevier Saunders, pp 59–65.)

In case of a long gap between the two ends of the esophagus, there are several options. The first option is to suture the divided end of the distal esophagus to the prevertebral fascia, mark its location with a metal clip, and close the thoracotomy. Over a 2- to 3-month period, the proximal esophageal pouch may grow so that a subsequent primary esophageal anastomosis may be possible. Second, a circular or spiral esophagomyotomy of the upper pouch may be performed to gain esophageal length and facilitate a primary anastomosis. Another technique involves the placement of traction sutures through the proximal and distal ends of the esophagus, brought out through the chest. These sutures are then progressively tightened and a primary esophageal anastomosis is performed after several days.⁸ Alternatively, a cervical esophagostomy may be constructed and a formal esophageal replacement performed at a later date.

In patients with pure esophageal atresia, primary anastomosis in the newborn period is not feasible because of a long gap between the two esophageal ends. Initially, a cervical esophagostomy for drainage of oral secretions and gastrostomy for enteral feeding access are performed. An esophageal replacement using the stomach, small intestine, or colon is then carried out at approximately 1 year of age. In some cases, the two ends of the esophagus may spontaneously grow so that a primary anastomosis may be accomplished by 4 months of age. The swallowing of saliva may actually promote elongation of the upper pouch, and an esophagostomy is therefore avoided. In patients with pure TEF, without esophageal atresia, the site of the TEF is usually in the region of the thoracic inlet. In this case, the surgical approach is through a cervical incision. At the time of surgical repair, it is often helpful to perform rigid bronchoscopy and cannulate the TEF with a guidewire to facilitate its identification. Recently, thoracoscopic repair has been described by several pediatric surgical centers (see Fig. 67-7B).⁹

The mortality rate of esophageal atresia or TEF is directly related to associated anomalies, particularly cardiac defects and chromosomal abnormalities. In the absence of these factors, survival of more than 95% of patients is expected. Postoperative complications unique to esophageal atresia or TEF include esophageal motility disorders, GER (25% to 50%), anastomotic stricture (15% to 30%), anastomotic leak (10% to 20%), and tracheomalacia (8% to 15%).

Gastroesophageal Reflux

GER is a common problem in infants and children. During the first year of life, infants normally experience some degree of vomiting, thought to be the result of an incompetent lower esophageal sphincter mechanism. This physiologic vomiting usually resolves spontaneously after 6 to 12 months. Pathologic GER can present with a spectrum of clinical symptoms. Although diagnostic studies can determine the presence of significant reflux, the patient’s symptoms remain as the most important factor in determining the surgical treatment of GER. Neurologically impaired children who are in need of enteral feeding access also have to be evaluated for concomitant reflux prior to gastrostomy placement. Today, a laparoscopic approach has become a standard for fundoplication with gastrostomy in pediatric patients.

Hypertrophic Pyloric Stenosis

Hypertrophic pyloric stenosis (HPS) is a disease of newborns, with an incidence of 1 in 300 to 900 live births. It is one of the most common GI surgical disorders in early infancy; it is most common between the ages of 2 and 8 weeks. Boys are affected four times as often as girls, with first-born male infants being at highest risk. Hypertrophy of the circular muscle of the pylorus results in constriction and obstruction of the gastric outlet, leading to nonbilious, projectile emesis, loss of hydrochloric acid with the onset of hypokalemic hypochloremic metabolic alkalosis, and dehydration. Although the exact cause for HPS remains unknown, a lack of nitric oxide synthase in pyloric tissue has been implicated.

Treatment: Surgical Management

The treatment of HPS is pyloromyotomy, consisting of incising through thickened pyloric musculature while preserving the underlying mucosa. This can be performed through a right upper quadrant or periumbilical incision. Recently, laparoscopic pyloromyotomy (Fig. 67-8) has gained popularity because of better cosmesis, with similar outcomes to those of the open technique.¹² Before surgery, it is important that the infant be fully rehydrated with IV fluids to establish an adequate urine output and correct electrolyte disturbances such as metabolic alkalosis. Because the infant with underlying metabolic alkalosis will compensate with respiratory acidosis, postoperative apnea may occur. Thus, the serum HCO₃⁻ level needs to be normalized before surgery. Postoperatively, infants are usually allowed to resume enteral feedings. Vomiting after surgery occurs frequently but is generally self-limited. Potential complications include incomplete myotomy, mucosal perforation, and wound infection.

FIGURE 67-8 A, Laparoscopic pyloromyotomy is started using a retractable blade. B, A spreader with grooves on the outer surface is used to complete the pyloromyotomy. Intact mucosal bulging along with independent muscular wall motion is confirmed.

(From St. Peter SD, Ostlie DJ: Laparoscopic and open pyloromyotomy. In Chung DH, Chen MK [eds]: Atlas of pediatric surgical techniques, Philadelphia, 2010, Elsevier Saunders, pp 253–265.)

Duodenal Atresia

Duodenal atresia is thought to occur as a result of failure of vacuolization of the duodenum from its solid cord stage. The range of anatomic variants includes duodenal stenosis, mucosal web with intact muscular wall (so-called windsock deformity), two ends separated by a fibrous cord, and complete separation, with a gap within the duodenum. It is associated with several conditions, including prematurity, Down syndrome, maternal polyhydramnios, malrotation, annular pancreas, and biliary atresia (BA). Other anomalies, such as cardiac, renal, esophageal, and anorectal anomalies, are also common. In most cases, the duodenal obstruction is distal to the ampulla of Vater (85%), and therefore infants present with bilious emesis. In patients with a mucosal web, the symptoms of postprandial emesis may occur later in life.

Clinical Presentation and Diagnosis

Infants with duodenal obstruction are generally first detected during a prenatal ultrasound evaluation. Immediately after birth, a plain abdominal radiograph shows a typical double-bubble sign, if obtained before orogastric tube decompression of swallowed gastric air (Fig. 67-9A). If distal air is present, an upper GI contrast study should be obtained rapidly, not only to confirm the diagnosis of duodenal stenosis or atresia but also to exclude midgut volvulus, which would constitute a surgical emergency.

FIGURE 67-9 A, Plain abdominal radiograph shows double-bubble appearance of duodenal atresia. B, Proximal transverse to distal longitudinal (diamond-shaped) or side-to-side duodenoduodenostomy is performed for congenital duodenal obstruction.

(From Duodenal obstruction. In O’Neill JA Jr, Grosfeld JL, Fonkaksrud EW, et al [eds]: Principles of pediatric surgery, ed 2, St. Louis, 2003, Mosby, p 474.)

Jejunoileal Atresia

Jejunoileal atresia is the most common GI atresia; it occurs in approximately 1 in 2000 live births. It is thought to occur as a result of an intrauterine mesenteric vascular occlusion. Atresias occur slightly more frequently in the jejunum than in the ileum. Jejunoileal atresias are classified as type I, a mucosal web or diaphragm (Fig. 67-10A), type II, with an atretic cord between two blind ends of bowel with intact mesentery, type IIIa, a complete separation of the blind ends of the bowel by a V-shaped mesenteric gap, and type IIIb, an apple peel or Christmas tree deformity with a large mesenteric gap (see Fig. 67-10B), in which the distal bowel receives a retrograde blood supply from the ileocolic or right colic artery. This tenuous blood supply has implications for reanastomosis and the potential for ischemic necrosis caused by an antenatal volvulus. Thus, many of these infants with this type of atresia are born with reduced intestinal length. Finally, in type IV, there are multiple atresias, with a string of sausage appearance.

FIGURE 67-10 Jejunoileal atresia. A, Massively dilated jejunum with narrow distal bowel segment. B, Apple peel type of atresia with a large mesenteric gap.

Intestinal Malrotation and Midgut Volvulus

The actual incidence of rotational anomalies of the midgut is difficult to determine, but is estimated to occur in 1 in 6000 live births. The midgut normally herniates out of the coelomic cavity through the umbilical ring at approximately the fourth week of fetal development. By week 10 of gestation, the intestine begins to migrate back into the abdominal cavity in a counterclockwise rotation around the axis of the superior mesenteric artery (SMA) for 270 degrees. The duodenojejunal segment returns first and rotates beneath and to the right of the SMA to fix in the left upper quadrant at the ligament of Treitz. The cecocolic segment also rotates counterclockwise around the SMA to rest in its final position in the right lower quadrant. By the week 12, this process of intestinal rotation is complete and the colon becomes fixed to the retroperitoneum. An interruption or reversal of any of these coordinated movements implies an embryologic explanation for the range of anomalies seen.

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