TOPIC No.3: Congenital anomalies which are accompanied by respiratory insufficiency.

 

Plan:

1.                Esophageal atresia.

2.                Diaphragmatic Hernias.

3.                Pulmonary Hypoplasia.

4.                Congenital Lobar Emphysema.

5.                Congenital Cystic Adenomatoid Malformation.

6.                Bronchogenic Cyst.

 

1. Esophageal Atresia/Tracheoesophageal Fistula

EA is a condition in which the proximal and distal portions of the esophagus do not communicate. The upper segment of the esophagus is a dilated blind-ending pouch with a hypertrophied muscular wall. This pouch typically extends to the level of the second to fourth thoracic vertebra. In contrast, the distal esophageal portion is an atretic pouch with a small diameter and a thin muscular wall; it extends a variable distance above the diaphragm.

TEF is an abnormal communication between the trachea and esophagus. When associated with EA, the fistula most commonly occurs between the distal esophageal segment and the trachea. The distal esophageal segment communicates with the trachea just above the carina. An H-type TEF represents a TEF without EA. It can occur at any level from the cricoid cartilage to the carina, although it usually courses obliquely (with the tracheal end proximal) at or above the level of the second thoracic vertebra.

Background, types of EA and TEF

Five types of EA and TEF have been described. The most common abnormality is EA with a distal TEF (84%). Isolated atresia with no fistula is the next most common finding (8%), followed by TEF with no atresia (so-called H type) (4%). EA with proximal and distal fistulas (3%) and EA with a proximal fistula (1%) are less common.

Diagram depicting the five variations of oesophageal atresia. (a) Atresia no fistula (510%).

(b) Oesophageal atresia with high fistula only (1%). (c) Oesophageal atresia with low fistula only (8090%).

(d) Oesophageal fistula with low and high fistula (23%). (e) H-fistula with no atresia (58%). o = oesophagus;

s = stomach.

 

Etiologies and factors. The etiologies of these anomalies are still largely unknown, but many theories concerning their origins have been proposed. The trachea and esophagus are foregut derivatives. Lateral mesodermal ridges form in the proximal esophagus during the fourth gestational week, and the fusion of these grooves in the midline separates the esophagus from the trachea around the 26th day of gestation.

Notochord abnormalities, desynchronous esophageal mesenchymal and epithelial growth rates, neural crest cell involvement, and incomplete tracheoesophageal separation resulting from a lack of apoptosis are mentioned in some of the theories that have been proposed for EA embryogenesis. Similarly, incomplete tracheoesophageal septation, lateral ridge fusion failure, and tracheal and esophageal proximity have been suggested in explanations of the origin of TEF. In addition, vascular insufficiencies; genetic factors; vitamin deficiencies; drug and alcohol exposures; and viral, chemical, and physical external events may contribute to the development of EA and/or TEF.

Pathophysiology. Because of the discontinuous esophagus, infants with EA cannot clear their secretions. This defect leads to persistent drooling and aspiration or regurgitation of food after attempted feedings. TEF causes additional complications because of the tracheoesophageal communication. When infants with this anomaly strain, cough, or cry, air enters the stomach through the fistula. As a result, the stomach and small intestine become dilated, elevating the diaphragm and making respiration more difficult. The reflux of food and gastric secretions may also occur up the esophagus and through the fistula into the tracheobronchial tree; this reflux can contribute to pneumonia and atelectasis. Therefore, pneumonia and respiratory distress are common complications.

Abnormal esophageal motility has been observed in children with EA and/or TEF. Controversy often exists as to whether the abnormality was inherently present in the child's esophagus or if the dysfunction was a result of the surgical treatment. Manometric studies have shown that the motility disorder is present before surgical treatment. Animal studies have also shown that esophageal transection followed by repair does not precipitate disturbances in motility. Discoordinated peristalsis has been reported from the level of the fistula to the stomach in patients with isolated TEF.

Frequency. The international occurrence varies, with estimates ranging from 0.4 to 3.6 cases per 10,000 live births in different regions of the world.

Mortality/Morbidity. Despite an increased number of patients with severe anomalies, survival rates as high as 95% have been reported. In uncomplicated cases, survival rates approach 100%.

Clinical signs. The first clinical sign of an infant with EA is maternal polyhydramnios resulting from the infant's inability to swallow and absorb amniotic fluid through the gut. Polyhydramnios is seen in infants with many diagnoses; only 1 in 12 infants with polyhydramnios have EA. Polyhydramnios is seen in 95% of infants with EA and no fistula and in 35% of patients who have EA with a distal fistula. Increased pressure due to the amniotic fluid accumulation results in a greater number of premature births and neonates with low birth. One third of infants with EA weigh less than 2250 g.

Most infants with EA become symptomatic within the first few hours of life, unlike children with an isolated fistula, who have more subtle symptoms that may not be recognized initially. Excess salivation and fine, frothy bubbles in the mouth and sometimes nose result from an inability to swallow. Any attempts at feeding result in choking, coughing, cyanotic episodes, and food regurgitation. The presence of a fistula increases respiratory complications due to aspiration of food and secretions in the trachea and lungs. Pneumonitis and atelectasis develop quickly in the affected neonate, and rattles heard during respirations are common. Fistulas also allow air to enter the stomach and intestines, leading to abdominal distension. With atresia alone, the abdomen appears scaphoid.

Many anomalies are associated with EA, and 50-70% of children with EA have some other defect.

Diagnosis. Once the EA is considered, appropriate diagnostic procedures are necessary. The simplest and quickest diagnostic procedure is the passage of a 10 to 12 French oral tube into the esophagus. If an obstruction encountered (usually in 9 to 13 cm), EA is likely. If the tube passes belong this point, atresia is unlikely. In either case, a radiograph of the chest must be obtained to confirm the position of the tube.

Ultrasound. Although ultrasonography has no role in the routine postnatal evaluation of EA and/or TEF, prenatal sonography is a valuable screening tool for EA and/or TEF. The diagnostic accuracy is increased if an anechoic area is present in the middle of the fetal neck; this sign differentiates EA from diseases with possible swallowing impairments.

Plain radiographs provide much information, including findings for EA confirmation and depiction of the side of the aortic arch side, presence of any vertebral or other associated anomalies, and others. Barium studies performed after the surgical placement of a gastrostomy may be used to evaluate the gap length and associated GI abnormalities such as duodenal atresia or malrotation. However, radiographs may not always demonstrate the presence of a fistula.

Findings on posteroanterior and lateral chest images confirm a diagnosis of EA by displaying a coiled nasogastric tube (placed for determination of EA) in the proximal esophageal pouch of a child with EA.

Any vertebral anomalies may be visualized, and some cardiac anomalies may be suggested. Aspiration pneumonia, especially in the right upper lobe, and patchy atelectasis are frequently present.

Aside from these general findings, the radiographic observations in children with EA and/or TEF vary depending on the type of anomaly present.

H-type of tracheooesophageal atresia.

Oesophageal atresia. Total absence of gas in the bowel.

 

The anatomy should be clarified bronchoscopically at the time of the first anesthetic.

Treatment.

Preoperative management.

                  Confirming the diagnosis and type of anomaly;

                  Evaluating the pulmonary status, treating existing pulmonary problems, and preventing further tracheal contamination;

                  Searching for, and treating other major associated problems.

To prevent further aspiration, the pharynx is frequently suctioned. The patient is cared far in a head-elevated position, with a catheter insert into the upper esophageal pouch and connected to continuous sump suction.

All patients are given antibiotic.

If there is clinical or radiological evidence of significant atelectasis or pneumonia, a decompression Stamm gastrostomy is performed using general anesthesia. Patients usually respond well within 24 to 72 hours, at which time the anomaly is repaired.

Gastrostomy decompression, upper pouch suction, and central venous nutritional support allow for the stabilization of the patient, the search for other disease, and the treatment of both medical or surgical problems.

Operative management.

Surgical repair is performed under general anaesthesia with endotracheal intubation. The endotracheal tube is advanced close to the tracheal bifurcation, and the infant is ventilated manually with rather low inspiration pressures and small tidal volumes. These measures serve to avoid overinflation of the stomach as well as to stabilize the trachea throughout the intervention. The Replogle tube is initially kept in place to easily identify the upper pouch intra-operatively. Broad-spectrum antibiotic prophylaxis is administered on induction. We routinely start with a tracheo-bronchoscopy using a rigid 3.5 mm endoscope. Trachea and main bronchi are briefly inspected, and the fistula to the oesophagus is localized, which is usually approximately 57 mm above the carina. Exceptionally, it may be found at the carina or even in the right main bronchus, indicating a short lower segment, and most likely with a long oesophageal gap. The next step is to look for an upper fistula. The dorsal membranous region of the tracheal wall is inspected carefully up to the cricoid cartilage. Small upper fistulas are easily missed. To avoid this pitfall, irregularities of the dorsal wall are gently probed with the tip of a 3F ureteric catheter passed through the bronchoscope. If a fistula is present, the ureteric catheter will glide into it.

 

The standard approach for repair of an oesophageal atresia is a right latero-dorsal thoracotomy. If a right aortic arch is diagnosed pre-operatively, a left-sided thoracotomy is recommended.However, if an unsuspected right descending aorta is encountered during surgery, the procedure can be continued in most cases, establishing the anastomosis on the right of the aortic arch.

The baby is positioned on the left side, stabilized with sandbags and fixed to the table with adhesive bands.The right arm is abducted without undue tension. Mild anteversion helps to reduce the risk of traction injury to the brachial plexus. The elbow is flexed to 90, and the forearm is best tied to a transverse bar mounted over the head of the child with soft slings. Care must be taken that no part of the body is submitted to pressure during the procedure. Exposed sites must be well padded. Soft pillars may be placed between the knees and underneath the feet, or the limbs wrapped with cotton wool, which protects against heat loss at the same time. A folded towel under the left side of the chest improves exposure and facilitates access in particular to the deeper structures.

A slightly curved skin incision is placed 1 cm below the tip of the scapula from the midaxillary line to the angle of the scapula. Some surgeons prefer a vertical skin incision in the midaxillary line for cosmetic reasons.A major advantage in neonates is the possibility of employing a muscle sparing technique due to their soft and mobile tissue layers. Only small flaps of skin and subcutaneous tissue are raised around the incision. The latissimus dorsi muscle is mobilized by cutting through the anterior fascial attachment. It is then lifted off the thoracic wall and retracted posteriorly together with the thoracodorsal nerve, which runs on its deep surface following the posterior axillary line.When the latissimus muscle is rectracted, the border of the serratus anterior muscle is mobilized along its origin from the tip of the scapula to the sixth rib and retracted up and forwards simultaneously with the scapula.

 

The intercostals muscles are divided along the upper border of the fifth rib.When the parietal pleura is exposed in one spot, a tiny moist cotton swab mounted on an artery forceps is used to sweep it off the thoracic wall for an extrapleural approach.As soon as possible, a rib spreader is inserted and opened stepwise with care. For continuation of the pleural stripping towards the dorsal mediastinum, the use of two soft pledgets is recommended, one to hold the already reflected pleura under mild tension by pressing it towards the dorsal mediastinum, the other to proceed with the dissection. An inadvertent tear in the pleura can be closed with a fine (6/0) monofilament absorbable suture.

The azygos vein is mobilized with right-angled forceps and divided in between two ligatures (4/0 Vicryl). The right vagus nerve is identified, which runs along the lateral border to the upper pouch and accompanies the tracheo-oesophageal fistula towards the lower oesophagus. The lower oesophagus is usually rather thin and hypoplastic. Extreme care must be taken to avoid any trauma to the delicate tissue. Handling and squeezing the oesophageal wall with forceps should be restricted to an absolute minimum. Preservation of all vagal fibres supplying the lower oesophagus is also aimed for. Denudation invariably entails a significant motility disorder and may cause severe gastro-oesophageal reflux.

 

Right-angled forceps are passed behind the distal oesophagus and a vascular sling is placed around it in order to pull it away from the trachea. This facilitates identification of tracheo-esophageal fistula, which is now freed from surrounding tissue. Traction sutures are then placed at the tracheal and oesophageal ends of the fistula, and one additional stay suture nearby holds the lower oesophagus.

 

At this stage, the fistula is divided and closed with a continuous absorbable monofilament 6/0 suture. Some authors prefer interrupted stitches, others apply transfixation stitches. The level of division must be as close to the trachea as possible without risking a narrowing of the airway. Since most fistulas run obliquely upwards, a small residual pouch frequently remains in the trachea. The fistula closure is tested for an air leak by watching out for air bubbles during forceful ventilation after filling warm saline solution into the chest. At this stage it is advisable to temporarily relieve the lung from the continuous retraction and achieve through careful ventilation cycles a full expansion of all collapsed areas.

 

The upper pouch is often retracted into the neck. Asking the anaesthetist to push on the Replogle tube serves to advance the upper pouch into the operative field.Traction sutures are placed on either side of the pouch to assist mobilization. Dissection of the oesophagus from the trachea is most challenging because they are adherent to each other by an intervening firm connective tissue layer. Sharp scissor dissection is required taking extreme care to avoid any accidental penetration into either organ. Anterior and lateral aspects of the upper pouch are easily freed using pledgets. If an upper fistula is encountered, it is transected close to the oesophagus and closed on both sides with interrupted monofilament absorbable 6/0 sutures. Contrary to the lower oesophagus, the upper pouch has an excellent blood supply and can be dissected up to the thoracic inlet if necessary. Thus, if a large gap exists, further dissection of the upper oesophagus is preferable to extensive mobilization of the lower segment which involves the risks of ischaemia and subsequent dysmotility.

After the upper oesophageal pouch is mobilized, both segments are approximated to see whether an end-to-end anastomosis is possible.

 

Opening of the upper pouch for the anastomosis should be well centred at its lowermost point. This is best achieved by incising the pouch exactly over the tip of the fully advanced Replogle tube.An asymmetric opening results in an uncentred anastomosis, potentially leading to lateral pre-anastomotic outpouching. The upper pouch is opened by a horizontal incision, which results in a fish-mouth-shaped aperture, adapted to the diameter of the lower oesophagus.

 

The end-to-end anastomosis is fashioned with interrupted absorbable 6/0 sutures. The first two stitches are placed on either side. The posterior wall needs two or three additional sutures.Meticulous care must be given to take sufficiently large bites of muscular tissue together with the mucosal layer. The latter tends to retract upwards in the upper pouch as soon as it is opened. Once all posterior wall sutures are placed, the oesophageal segments are gently pulled together, and the sutures are tied on the mucosal surface.

Thereafter, a 5F silastic feeding tube the connection hub of which has been cut off is sutured with the cut end to the tip of the Replogle tube,which is then withdrawn by the anaesthetist until the feeding tube appears outside the mouth. The distal end of the feeding tube is passed into the stomach. The tubeserves for postoperative gastrointestinal decompression and early feeding, and also functions as transanastomotic splint for drainage of saliva.

The anterior aspect of the anastomosis is completed in a similar way as described above with three or four stitches, this time tying the knots on the outside of the oesophageal wall.

 

The goal of a tension-free end-to-end anastomosis can be achieved with this technique in most cases of oesophageal atresia with a distal fistula. If the tension appears to be too much despite mobilization of the upper pouch up to the thoracic inlet, further length may be gained with a circular myotomy in the upper pouch according to Livaditis. This is achieved by introduction of a 8F balloon catheter into the upper pouch transorally, which is transfixed at the lower end of the pouch with a 4/0 monofilament traction suture and the balloon is blown up until it fills the pouch. The muscle layer is then divided above the balloon approximately 1 cm cranial to the future anastomotic line, either in a circular or in a spiral fashion. The mucosal layer of the upper pouch is rather thick so that mucosal tears can usually be avoided with careful dissection.The upper pouch can be lengthened by 510 mm by this method, which may suffice to create an anastomosis without undue tension. Development of a pseudodiverticulum (outpouching of the mucosa through the established gap in the muscle layer) after circular myotomy has been described.

 

Another way to reduce inappropriate tension on the anastomosis is to fashion a mucosal-muscular flap from a larger upper oesophagus. A right-angled incision is made in one half of the upper pouch. The flap thus created is turned by 90 so that the vertical cut surface faces downwards. It is then rolled into a tube.However, the gain in length results in a reduction in diameter.

If a satisfactory dorsal wall anastomosis can be established, but undue tension arises in the anterior half, a right-angled flap in the corresponding part of the upper pouch without tubularization may bridge the gap and result in a safe anastomosis. The thoracic cavity is irrigated with normal saline. A soft drain is introduced via a separate intercostals stab incision and the tip placed near the anastomosis. Before closure, the lungs are fully expanded by forced ventilation until all collapsed regions are well aerated again.

The ribs are approximated with two or three pericostal sutures. Latissimus dorsi and serratus anterior muscles are allowed to fall back into their original positions and are sutured to their fascial insertion sites with one or two 3/0 absorbable sutures each. The subcutaneous fat is readapted with 5/0 absorbable sutures including the corium.This technique approximates the skin perfectly in most cases so that separate skin sutures are not necessary. The incision is simply approximated with adhesive strips. In those cases in whom wound margin adaptation remains unsatisfactory, a continuous subcuticular monofilament 5/0 suture is applied,which is pulled after a few days.

 

Postoperative Care

The patient is managed by a team approach that includes surgeon, neonatologist, nurses, and respiratory therapists. In a near-term baby with an uncomplicated anastomosis, the anesthetic effects are allowed to wear off and extubation is achieved within 24 h. Fentanyl is used for postoperative pain, either by bolus or continuous drip. Some prefer to keep the child heavily sedated or even paralyzed for a few days, especially when the anastomosis has been done under a lot of tension, in which case extubation may be delayed for up to 6 or 7 days. Neck flexion has also been advocated to decrease tension on the anastomosis. We keep the tip of the Replogle tube above the anastomosis as marked intraoperatively and under continuous suction. Some remove the Replogle after a few days if there is minimal drainage, indicating passage of saliva through the anastomosis. Parenteral nutrition is started as soon as possible and enteral feedings are initiated through the silastic feeding tube.

The extrapleural chest tube is kept on underwater seal drainage and gentle (10 cm H2O) suction added for the first 24 h. Usually only a minimal amount of serous drainage is noted. In a stable extubated baby, we obtain a contrast esophagram and UGI series under fluoroscopy 57 days postoperatively. After removing the Replogle, we usually start this study with a non-ionic isoosmolar water-soluble agent, then switch to dilute barium if there is no aspiration or anastomotic leak. We observe the swallowing reflex, esophageal motility, anastomotic site and distal esophagus. Then, if the baby is tolerating the procedure well, we fill the stomach enough to look for GER and assess gastric emptying and the position of the ligament of Treitz. It is normal for the esophageal anastomosis to appear narrowed and for the upper esophagus to appear dilated, but there should be no stasis.

As long as there is no leak and good swallowing, feedings are initiated after this study and will help to gradually dilate the anastomosis and lower esophagus. The chest tube is removed the next day and antibiotics are stopped if this is not already done. Oral feedings often progress slowly because of poor sucking or swallowing reflexes. The silastic nasogastric tube is used to complete each feeding, after the child has

been offered the bottle.

The infant may be discharged when feeding well and gaining weight, occasionally with the feeding tube still in place to ensure adequate intake. Parents are warned about the signs of complications such as reflux, tracheomalacia, anastomotic stricture, and recurrent fistula. We discharge all babies on H2-blockers until a pH probe is done at 6 months of age. Patients are followed up frequently in the first year of life, and then once or twice a year at least until school age and preferably until adulthood. It is very important to explain to the parents that there will be some permanent scarring at the anastomosis, which prevents normal distensibility of the esophagus at this site. We therefore recommend pureed food up to 1218 months, and then only minced food until 5 years of age when the child has learned to chew well before swallowing, and has adequate teeth to do so. All those caring for such children have seen patients admitted with an impacted foreign body at the anastomotic site despite a normal appearance of the anastomosis on contrast studies. This might be food, often a piece of meat or popcorn, or a foreign body.

Complications

Although most term babies do very well after esophageal atresia repair, some even going home by 1 week of age, the potential complications are numerous. These can be related to associated problems such as prematurity and cardiac defects, to the malformation itself, or to its treatment. Our discussion will focus on the latter. These may be divided roughly into early (<30 days), intermediate (13 months) and late complications (Table 29.2).

Anastomotic leaks occur in 510% and can be suspected by the presence of frothy saliva in the chest tube drainage. Small extrapleural leaks that are well drained by the tube are treated with continued upper pouch suctioning and antibiotics and usually seal spontaneously. Some surgeons even start feedings despite a leak, but we prefer to wait until radiological resolution. Beware of anastomotic stenoses, which often develop within a few weeks after a leak. A complete hemithorax white-out or a massive pneumothorax is usually caused by a major leak or a total anastomotic disruption. Breakdown of the tracheal suture line should also be considered. The child can rapidly deteriorate and necessitate more chest tubes and emergency thoracotomy. If the baby is not

acutely sick, we would perform a contrast study; extravasation of most of the contrast agent indicates the need for thoracotomy, while a smaller leak can be treated non-operatively.

When thoracotomy is required, it is sometimes possible to simply repair the dehiscence if the tissues appear healthy and the repair can be performed under minimal tension. Otherwise, it is wiser to ligate the distal end, create a cervical esophagostomy and a gastrostomy, with repair delayed for some months. However, as the trend has been to avoid cervical esophagostomy in recent years, some would elect to close the upper pouch and leave it decompressed with a Replogle tube, returning later for a delayed reanastomosis.

Patients who develop recurrent coughing, choking, apneic episodes, pneumonia and vomiting or regurgitation, present a diagnostic challenge. These are symptoms common to several of the complications. Choking during feedings may indicate a recurrent or missed fistula, tracheomalacia, esophageal stenosis, or swallowing incoordination with aspiration. Choking after feedings, with or without vomiting, is usually a manifestation of GER. The contrast esophagram with videofluoroscopy is the first and most important investigation. It is crucial for the surgeon and radiologist to cooperate on this study in order to evaluate swallowing coordination and esophageal motility. The patient is bottle-fed initially to study the full progression of the contrast medium.

Tracheal narrowing may occur at the tracheal suture line or with tracheomalacia, most often at the level of the upper pouch. This can often be diagnosed on the lateral views during video fluoroscopy. The tracheal diameter is evaluated during inspiration and expiration and with a bolus of swallowed contrast material. With severe tracheomalacia, the trachea lumen may appear completely obliterated between the aortic arch and the distended esophagus, especially during expiration or crying.

A distal congenital stenosis might be difficult to differentiate from an acquired one due to reflux. If seen early and not responding to balloon dilations, it is more likely to be congenital and is very likely to require resection. However, this associated anomaly is more often diagnosed after a few months, when the child starts taking solids. In order to evaluate the presence of GER, the rate of gastric emptying and the position of the ligament of Treitz, more contrast may be required. If the baby is unable to swallow enough contrast material, the existing nasogastric feeding tube is used, or one can be inserted gently under fluoroscopic control. A recurrent TEF can be difficult to demonstrate. This study is best done with the patient in the prone position, injecting the contrast through a feeding tube under pressure as it is gradually withdrawn from the lower esophagus. Depending on the results of radiological investigations, the precise symptoms and their severity, further tests may be required. Bronchoscopy is the best procedure to evaluate fistula recurrence and the presence of a tracheal diverticulum at the fistula site. The bronchoscopy can be done simply as a diagnostic procedure or as part of the definitive operation if the problem has been identified by the contrast study. When tracheomalacia is severe and is associated with dying spells (apnea and cyanosis during feeding or following a crying spell), aortopexy is indicated. Bronchoscopy is useful before, during and after this procedure to assess the tracheal lumen. To confirm tracheomalacia, the tracheoscopy is done with the patient breathing spontaneously under light general anesthesia, since the collapsed lumen is most obvious during expiration. Rare patients with diffuse tracheobronchomalacia may require more than a simple aortopexy.

The incidence of severe tracheomalacia requiring aortopexy varies from 2.5 to more than 10% in some series. This wide variation is explained in part by the fact that some patients in the past died without a diagnosis, or were treated by prolonged intubation or tracheostomy awaiting spontaneous improvement. Surgeons are now more aggressive in doing an aortopexy, which has proven to be safe and effective. It is interesting to note that tracheomalacia is unusual in cases of pure esophageal atresia, but there is no clear explanation to this observation. Another important point is that tracheomalacia may manifest itself early by the inability to extubate and CO2 retention as the child starts to breathe spontaneously, or it may become symptomatic much later, even a few weeks after discharge with the typical dying spell described above. Fistula recurrence is a serious complication that can lead to death, therefore aggressive investigation with fluoroscopy and bronchoscopy are essential. The identification and the surgical repair of a recurrent fistula can be facilitated by the insertion of a ureteral catheter at bronchoscopy. The classic approach is a repeat right thoracotomy, transpleural division of the fistula, and interposition of healthy tissue such as an intercostal pedicle or a pericardial flap. Some surgeons have approached this problem through a left thoracotomy or by means of a transtracheal repair. Less invasive ways to obliterate the fistula by bronchoscopy with laser, electrocoagulation or synthetic glue and sclerosing agents were initially associated with a higher recurrence rate. However, the use of fibrin glue has gained in popularity and may be an acceptable first line of treatment in a stable patient, but one must be careful not to use excessive pressure when applying the glue since an excess amount could spill over into the trachea with disastrous consequences.

GER might present with vomiting, recurrent pneumonia and asthma, failure-to-thrive, or stenosis of the lower esophagus or at the site of anastomosis. Since nearly all EA patients have some degree of GER, we make a liberal use of drugs to inhibit acid production. In patients presenting with symptoms while on H2-blockers, we optimize the dose, use proton pump inhibitors, and use motility agents in some patients. Evaluation should include an extended pH probe study, preferably done with the tip in the mid-esophagus to pick up only the more significant refluxes.

Fundoplication is required in 1025% of patients after esophageal atresia repair. The indications are life-threatening symptoms, recurrent esophageal stenosis refractory to dilations, and failure of medical treatment. Fundoplication is more complicated in these patients. The esophagus is often short, the gastroesophageal junction having been pulled up into the chest at the time of esophageal repair. Because of abnormal esophageal peristalsis, the wrap has more risk of causing a mechanical obstruction. Despite these complicating factors, and the fact that the long-term failure rate has been high in some series, the increased use of fundoplication combined with better techniques for esophageal anastomosis (single layer, end-to-end) has led to a marked reduction in the need for secondary esophageal surgery.

Symptomatic anastomotic stenosis often results from a leak. It can also be related to reflux or to an anastomosis constructed under tension. Most stenoses can be treated with balloon dilations, which is now the method preferred by most pediatric surgeons, gastroenterologists, and radiologists. It is thought to be safer than bougienage. It can performed under fluoroscopy in the radiology suite, without general anesthesia, or in the operating room, under endoscopic and fluoroscopic control. After one or two dilatations, the addition of triamcinolone injected into the stricture or mitomycin C applied topically might reduce subsequent stricture formation, increasing the success rate and decreasing the number of dilatations required. Failure to respond to repeated dilations over a period of several weeks or months despite appropriate treatment of an associated reflux indicates the need for excision of the area. With proven GER, we would usually perform a fundoplication first, then resect the anastomotic stricture if it keeps recurring after a few more dilatations.

Often several complications coexist and the treatment sequence is based upon a judgment of which is most lifethreatening to the baby. Most infants after esophageal atresia repair have abnormal esophageal peristalsis, some degree of GER and tracheomalacia. When life-threatening symptoms are present, a careful history and appropriate investigation will help decide what should be addressed first. Faced with a child with severe hypoxic spells associated with feeding or crying and radiographic evidence of both GER and tracheomalacia, we would perform a bronchoscopy to exclude a recurrent or missed fistula and be prepared to perform an aortopexy during the same anesthesia if severe tracheomalacia was confirmed (apposition of the posterior and anterior tracheal walls during expiration).

Patients who are discharged from the hospital after successful restoration of esophageal continuity should not be considered cured. There is a general impression that feeding and respiratory problems completely disappear after a few years. Although it is true that most patients tend not to complain and are reluctant to return for yearly follow-ups, one must be aware of the potential problems. Late mortality can occur from associated anomalies and from complications of the disease or its treatment. In infants with a smooth initial course, unexpected death has resulted from tracheomalacia or food impaction in the esophagus. A surprisingly high incidence (>1%) of sudden infant death syndrome is noted in several large series, which gives some support to the theory of an immaturity of vagal reflexes in these patients. Tracheomalacia and GER may also contribute to these deaths.

Late morbidity can be related to the esophageal anastomosis, to abnormal esophageal motility, to GER and to respiratory problems. GER is probably the most troublesome since it can result in anastomotic or lower esophageal strictures and may be accompanied by Barretts esophagus. Esophageal carcinoma has now been reported in six patients, 2046 years after esophageal atresia repair. Because most children grow up with symptoms from an abnormally-functioning esophagus, they tend not to realize that they have a problem. It was formerly thought that reflux improved with time, but several studies have now shown that GER and esophagitis persist in a significant number of older children and adults, even when they are asymptomatic. Closer follow-up and more aggressive treatment of GER are therefore required. Since reflux and esophagitis do not necessarily correlate with symptoms, surveillance esophagoscopy every 35 years has been recommended. The development of Barretts esophagus calls for an antireflux procedure. Reflux has also been linked to respiratory problems such as recurrent pneumonia, bronchitis and asthma. The anastomotic scar and abnormal esophageal motility contribute to long-term dysphagia in about half the patients, although most do not complain about it. This often leads to swallowing difficulties and to food impaction requiring esophagoscopy for its removal. Patients are counseled to eat slowly, take small bites and drink a lot while eating.

Respiratory problems in the first year might be related to recurrent fistula, GER, tracheomalacia or associated anomalies such as LTEC. Any of these may lead to serious morbidity and even mortality if not promptly recognized and treated. Later in life, the respiratory symptoms tend to improve. In contrast to classical teachings, however, one study found that 40% of adults still had the typical barking cough of tracheomalacia and 24% had intermittent respiratory problems such as asthma, pneumonia and bronchitis. This finding was more common in patients who had these problems in early childhood. A daily cough was associated with symptoms of reflux and dysphagia.

Long-term growth and development have been considered within the normal range in most reviews, but in a large series of patients operated at Great Ormond Street between 1980 and 1984, one-third of patients were below the third percentile for their age when assessed at 6 months to 5 years of age, including 21% of patients in the good risk category.

Scoliosis may be secondary to vertebral or rib anomalies, anastomotic leak with pleural scarring, or an unnecessary long thoracotomy with rib excision. One must follow all the patients and actively look for any deformity. Overall, most adults who survive esophageal atresia repair seem to enjoy a normal life and do not perceive their symptoms as significant. Several large series confirm the gradual improvement in survival in the last half century, despite the fact that smaller newborns with a higher frequency of associated anomalies are being treated. All authors agree that associated anomalies are the most significant factor affecting the prognosis, but a small number of infants who should survive continue to die of complications even in experienced centers. Waterstons classification has lost all its usefulness in the past two decades. The classification we have proposed (Table 29.3) highlights the fact that children with life-threatening anomalies and those with major anomalies combined with preoperative ventilator dependence, for example extreme prematures with severe hyaline membrane disease, are in a high-risk category, with an expected mortality of 40% or more, depending on the anomalies. The remainder have a good prognosis, with an expected survival of well over 90%. Other recent classifications put the emphasis on cardiac anomalies as making patients high-risk.

 

 

2. Congenital diaphragmatic hernia

Congenital diaphragmatic hernia (CDH) is an abnormal opening in the diaphragm that allows part of the abdominal organs to migrate into the chest cavity, occurring before birth.

Congenital diaphragmatic hernia is seen in 1/2200 to 1/5000 live births with the vast majority (80 to 90%) occurring on the left side. There is a 2% recurrence rate in first degree relatives of a patient with the disease.

Diaphragmatic hernia is usually a sporadic abnormality. However, in about 50% of affected fetuses there are associated chromosomal abnormalities (mainly trisomy 18, trisomy 13 and PallisterKillian syndrome mosaicism for tetrasomy 12p), other defects (mainly craniospinal defects, including spina bifida, hydrocephaly and the otherwise rare iniencephaly, and cardiac abnormalities) and genetic syndromes (such as Marfan syndrome).

Anatomy of the diaphragm. The diaphragm is the fibromuscular sheet that that separates the thoracic and abdominal cavities; it is the principal muscle of inspiration. The fibrosus portion of the diaphragm, the central tendon, accounts for about 35 % of its total surface. The muscular portion arises from whole of the internal circumference of the thorax, being attached:

1.               In front, by fleshy fibres to the xiphoid process,

2.               To the internal surface of the 6 to 7 inferior ribs,

3.               Behind, to two aponeurotic arches, named the ligamentum arcuatum externum and internum,

4.               By the crura, to the to the lumbar vertedrae. The right and left crus arise from the anterior surface of the bodies and intervertebral substances of 4 upper lumbar vertebrae, on each side of the aorta.

In 80 % of bodies, there is the gap between the muscles arising from the ligamentum arcuatum externum and those of the costal origin as they traverse to the central tendon, which is called the lumbo-costal triangle. Bochdalec postulated that congenital posterolateral diaphragmatic hernia was caused by a weakness in the area of the lumbo-costal triangle.

Normally, there are 3 significant openings in the diaphragm:

1.               The vena cava transverses the central tendon to the right of the midline;

2.               The esophageal hiatus is just to the left of the midline and slightly posterior to the plane of the vena cava;

3.               The aorta lies on the verterbral bodies.

Herniation of the viscera through the opening of the aorta or vena cava has not been described. However, herniation of the stomach through the esophageal hiatus is common and incidence increases with aging.

Five defects might develop in the diaphragm to create intraabdominal viscera herniation.

1.     The esophageal hiatus is the most frequent area, whrein the stomach pralapses into the mediastinum.

2.     A congenital posterolateral defect occurs from maldevelopment of the diaphragm. The Bochdalek CDH accounts for approximately 70% of cases and occurs in a posteriolateral region of the diaphragm.

3.     Anomalous attachment of the diaphragm to the sternum and adjacent ribs results in a foramen, which allows the bowel to extend into the anterior mediastinum.

4.     The assotiation of an epigastric omphalocele and a retrosternal defect in the diaphragm and pericardium (pentalogy of Cantrell) results in herniation within the pericardium.

5.     Attenuation of the tendinous or muscular portion of the diaphragm produces eventration.

Simile to eventration, paralysis of the muscles of the diaphragm either from trauma to the phrenic nerve or a congenital defect in the anterior horn cells of the cervical spine cord (C 3, 4) as in Werdnig-Hoffmann disease, results in herniation of the intraabdominal contents into the thoracis cavity.

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Embriogenesis of posterolateral diaphragmatic hernia and pulmonary hypoplasia. The septum transversum grows posteriorly to meet the dorsal mesentery of the foregut, forming the central portion of the diaphragm during the fourth to eighth weeks of fetal life. The lateral folds of peritoneum and pleura develop simultaneously, completing the separation between the thorax and the abdomen. Disruption of this process results in a posterolateral defect in the diaphragm (foramen of Bochdalek). This closure of the pleuroperitoneal canal is completed on the right side before the left, which may explain why 90 % of the diaphragmatic defects present on the left side.

As the diaphragm is developing, the midgut undergoes elongation and development outside the coelom. The midgut normally returns to the abdominal cavity and undergoes rotation and fixation at about the tenth week of fetal life. If closure of the diaphragm is incomplete, the intestine herniates into the chest as it returns to the coelom, inhibiting development of the lung and preventing the normal process of intestinal rotation and fixation. The spleen, stomach, and left lobe of the liver as well as the bulk of the intestine often reside within the thoracic cavity.

Herniation of the abdominal viscera into the thoracic cavity seriously impairs development of the ipsilateral, and to some extent the contralateral, lung. This hypoplasia of the pulmonary parenchyma accounts for the major physiological problems encountered in these infants.

The degree of hypoplasia of the pulmonary vessels correlates with the adequacy of ventilation. If the pulmonary parenchyma is inadequate, mechanical ventilation will not prevent severe hypoxia, hypercarbia, and acidosis in these infants. Occasionally, adequate ventilation can be achieved initially, indicating that enough pulmonary parenchyma is present to sustain life. Later, arterial blood gas balance deteriorates, with the development of pulmonary hypertension and right to left shunting through the patent ductus arteriosus (persistent fetal circulation). In this situation pulmonary circulation with progressive vasoconstriction and pulmonary hypertension decreases perfusion of the lung and results in clinical deterioration. Vasodilating agents do not alter this pattern of persistent fetal circulation. They dilate the systemic as well as the pulmonary circulation, causing systemic hypotension; this creates a need for additional fluid administration, which in turn results in further pulmonary oedema and deterioration.

After birth air entering the gastrointestinal tract distends the herniated bowel, shifting the mediastinum toward the contralateral side and compressing the contralateral lung. This process can be largely prevented by sump catheter decompression of the stomach.

 

Clinical manifestations. Most infants develop respiratory symptoms in the first 24 h after birth. Although a spectrum of respiratory distress exists, many children immediately become severely cyanotic. Physical examination discloses a scaphoid abdomen, displacement of the cardiac apex away from the side with the defect, and decreased or absent breath sounds on the affected side. Rarely, bowel sounds can be heard in the chest. The occasional infants who become symptomatic weeks to months after birth respond well to surgical treatment.

Diagnosis. Prenatally, the diaphragm is imaged by ultrasonography as an echo-free space between the thorax and abdomen. Diaphragmatic hernia can be diagnosed by the ultrasonographic demonstration of stomach and intestines (90% of the cases) or liver (50%) in the thorax and the associated mediastinal shift to the opposite side. Herniated abdominal contents, associated with a left-sided diaphragmatic hernia, are easy to demonstrate because the echo-free fluid-filled stomach and small bowel contrast dramatically with the more echogenic fetal lung. In contrast, a right-sided hernia is more difficult to identify because the echogenicity of the fetal liver is similar to that of the lung, and visualization of the gall bladder in the right side of the fetal chest may be the only way of making the diagnosis.

Antenatal Diagnosis

CDH is increasingly identified by antenatal ultrasound. The images reveal a heterogeneous intrathoracic mass with peristalsis and the stomach bubble is sometimes seen in the chest. For left-sided lesions, which account for 8590% of cases, the finding that liver has herniated up in the chest is associated with a poor prognosis (more complications, more likely to need ECMO, decreased survival: 40% vs. 90+%). Other clinical features that appear to correlate with a poor prognosis include early gestational age at diagnosis, polyhydramnios, cardiac hypoplasia, and diminished total lung volume. Rightsided defects are also associated with a higher morbidity and mortality. In infants with left-sided defects, lung area-tohead circumference ratio (LHR) can be used as measure of severity and is predictive of mortality; however, as treatment continues to improve, it is less predictive of morbidity than in the past. The ratio is obtained, usually at 2426 weeks gestation, by measuring the cross-sectional area of the right lung at the level of the atria (in square millimeters) and dividing it by the head circumference (in millimeters). In general, an LHR £1.0 is associated with low survival while a ratio of >1.4 is associated with improved outcome. Fetal lung volumes calculated by ultrafast fetal MRI also correlate with morbidity and survival. At this time, the best predictor of poor outcome in infants with left-sided CDH is liver herniation (liver up). In those without liver herniation (liver down), LHR and lung volumes continue to have some predictive value but this is evolving as treatments improve.

Figure . Fetal ultrasound image at the level of the fourchamber heart (dotted arrow). Gastric bubble (solid arrow) at the level of the four-chamber heart suggests CDH. This is the level used to calculate the lung-head ratio.

 

There was once hope that in utero surgical repair of fetuses with CDH could help to reduce mortality, but this has not been the case. After several well-designed controlled studies, it is clear that the fetuses who do well with prepartum repair are the ones who are likely to have done well with standard therapy and the survival of high-risk fetuses is not improved by repair before birth. Another fetal intervention that holds some promise is tracheal occlusion. Occluding the trachea early in gestation leads to the accumulation of lung fluid and a dramatic increase in lung size. This has been shown in a fetal sheep model and in limited human studies to be a potentially useful technique, presumably by minimizing the herniation of bowel and allowing the lungs to grow more than they might have otherwise. The techniques available to occlude the trachea have evolved from surgical application of a metal clip that is removed at birth to a fetoscopically placed endotracheal balloon that is ruptured at birth. This technique is being studied in ongoing human trials and awaits approval for use in the US.

 

Figure. Fetal MR image of a left-sided CDH at 28 weeks gestation. A large CDH with herniation of the small bowel and stomach is found within the left hemithorax (solid arrow). There is dextroposition of the fetal heart (dotted arrow). There is no evidence of liver herniation.

 

Although fetal surgical intervention is currently not feasible, antenatal diagnosis of CDH is a relatively common indication for referral to a fetal treatment center. Early referral is helpful for prospective parents as they can be provided counseling, prognostic information that helps them decide whether to continue the pregnancy, and help with the considerable preparation required for the safe delivery and postnatal care of these infants. Because of the small but significant risk of associated anomalies and chromosomal abnormalities, we recommend fetal echocardiography and karyotype analysis, which is most safely and accurately performed by amniocentesis. Ultrafast fetal MRI is performed to help identify associated anomalies and liver herniation, and to measure lung volumes. Genetic counseling is offered as well; specifically array comparative genomic hybridization (aCGH) is recommended under some circumstances as a useful tool for the identification subtle chromosomal abnormalities. Fetal US is repeated at 2-week intervals t assess fetal growth and amniotic fluid volume, and to rule out complications such as bowel ischemia, ascites, hydrops, or particulate matter (meconium) in the amniotic fluid. Nonstress testing is performed twice per week starting at 33 weeks and corticosteroids are administered for preterm labor as indicated per standard protocol.

The best timing and mode of delivery of infants with CDH is not known with certainty. There is no advantage to scheduled cesarean delivery though, based on retrospective reviews, some believe that there might be an advantage to early term delivery (3738 weeks). Nevertheless, we recommend scheduled induction of labor at 3839 weeks, preferably at a center where proper monitoring and all aspects of advanced care, including ECMO, are available. Delivery by cesarean section is performed when indicated by standard criteria. The Special Delivery Unit of The Childrens Hospital of Philadelphia is unique in that infants are delivered at a free-standing tertiarycare childrens medical center, where neonatal and surgical specialists are immediately available, obviating the need for transportation to another facility.

Polyhydramnios (usually after 25 weeks) is found in about 75% of cases and this may be the consequence of impaired fetal swallowing due to compression of the esophagus by the herniated abdominal organs.

After birth, a chest radiograph should be obtained, preferably after an orogastric tube has been passed into the stomach. If the radiograph is taken before air enters the bowel, the affected chest is radiopaque, but the trachea and heart are shifted to the contrlateral side, and the aerated lung is diminished. An upright thoracic radiograph shows multiple loops of intestine in the thoracic cavity and no diaphragmatic outline.

 

 

Figure A, Anteroposterior chest radiograph in a neonate with a CDH demonstrating air-filled loops of bowel within the left chest. The heart and mediastinum are shifted to the right, and the hypoplastic left lung can be seen medially. B, Postoperative radiograph demonstrating hyperexpansion of the right lung with shift of the mediastinum to the left. The edge of the severely hypoplastic left lung is again easily visualized (arrow).

 

 

Figure. This infant presented with respiratory distress and a right CDH.

 

Differential diagnoses include cystic adenomatoid malformation, eventration of the diaphragm, pneumatoceles from staphylococcal pneumonia, and pulmonary agenesis or hypoplasia. The radiographic appearances of all of these entities include presence of the diaphragm and a normal intra-abdominal bowel gas pattern.

Treatment.

Preoperative care. Initial resuscitation is mandatory if these infants are to survive. Intubation for respiratory distress is often required before a radiograph is available. A nasogastric tube should be inserted and placed on suction to prevent further distention of the intestine. Because the hypoplastic lungs are susceptible to barotrauma, ventilation with high pressure must be avoided. A tension pneumothorax on the contralateral side often proves fatal. Rapid ventilation with short inspiratory times, low pressure, and 100 % oxygen is most effective. Alkalosis, hypocarbia, and oxygenation all decrease pulmonary artery pressures and the right to left shunt seen in persistent fetal circulation. Sedation seems to benefit those with very reactive pulmonary vasculature, but it does not help those with inadequate pulmonary tissue, who develop early pulmonary hypertension and acidosis. The infant must be kept warm during transport to avoid peripheral vasoconstriction and acidosis: the latter can elevate pulmonary artery pressure.

Although surgical repair was traditionally performed urgently, recent studies have shown that ventilatory compliance decreases appreciably in infants after surgery, producing a decline in the arterial gases. The current practice is to stabilize these infants with ventilation, sedation, and intestinal decompression, deferring repair of the defect until 36 to 72 h after birth. Delay may avoid the development of pulmonary hypertension and persistent fetal circulation due to surgical stress.

Some infants are placed on ECMO (extracorporeal membrane oxygenation) which is a heart/lung bypass machine which gives the lungs a chance to recover and expand after surgery.

Surgical repair.

General anaesthesia with muscle relaxation is used. The baby is positioned supine on a warm blanket. The most commonly preferred approach is abdominal. This offers good exposure, easy reduction of the abdominal viscera and recognition and correction of associated gastrointestinal anomalies. A subcostal transverse muscle cutting incision is made on the side of the hernia.

The contents of the hernia are gently reduced in the abdomen. On the right side, the small intestine and colon are first reduced and the liver is withdrawn last. After the hernia is reduced, an attempt is made to visualize the ipsilateral lung. This is usually done by retracting the anterior rim of the diaphragm. Often, a hypoplastic lung can be observed at the apex. A hernial sac, composed of pleura and peritoneum, is present in about 20% of patients. The sac, if present, is excised to avoid leaving a loculated spaceoccupying lesion in the chest.

Most diaphragmatic defects can be sutured by direct sutures of the edges of the defect. Usually the anterior rim of the diaphragm is quite evident. However, the posterior rim may not be immediately apparent and may require dissection for delineation. The posterior rim of the diaphragm is mobilized by incising the overlying peritoneum.

The defect is closed by interrupted non-absorbable sutures. Occasionally, the posterior rim is absent altogether, in which case the anterior rim of the diaphragm is sutured to the lower ribs with either periostial or pericostal sutures.

If the defect is large, it may not be possible to repair it by direct suture. Various techniques have been described and include the use of prerenal fascia, rib structures, the latissimus dorsi muscle, rotational muscle flaps from the thoraco-abdominal wall and prosthetic patches. The operations involving muscle flaps are too long and complex for critically ill patients and can lead to unsightly chest deformities. Prosthetic materials, including Marlex mesh, reinforced silicone elastomer, preserved pericardial heterografts, preserved dura and the polytetrafluoroethylene patch (PTFE),have been advocated. The most commonly used prosthetic material presently is Surgisis soft tissue graft, which is incorporated into adjacent tissue, and this tends to lessen the risk, extension or displacement, with a decreased risk of infection. Abdomen is closed in layers. If the abdominal cavity is small, gentle stretching of the abdominal wall will enable safe closure in most of the patients. Chest drain should be avoided. The argument against the use of a chest drain is in avoidance of barotraumas as it increases the transpulmonary pressure gradient.

Plication of the diaphragm has been used for many years to treat eventration. Plication increases both tidal volume and maximal breathing capacity and has been successful in many clinical series. An abdominal approach through a subcostal incision is preferred for left-sided eventration but a thoracic approach through a posterolateral incision via the sixth space may be used for right-sided lesions. The transabdominal approach allows good visualization of the entire diaphragm from front to back and easier mobilization of abdominal contents.

Postoperative care.

Although the diaphragmatic hernia can usually be repaired, if both lungs are markedly hypoplastic, adequate oxygenation will never be achieved. Survival may be compromised in babies with relatively good lungs if pulmonary artery hypertension occurs. Extracorporeal membrane oxygenation can decrease the degree of pulmonary artery hypertension by producing adequate oxygenation, alkalosis, and hypocarbia. All three factors will lower pulmonary artery pressures, and this technique may save some infants who previously have succumbed to persistent fetal circulation.

Ventilatory support is nearly always needed following repair. It must be regulated to limit inspiratory pressures and minimize barotrauma to the lungs. The hypoplastic lung bud should not be distended artificially. Close monitoring of arterial blood gases is essential: deterioration often indicates rising pulmonary artery pressures and additional sedation with fentanyl should be instituted. Deliberate hyperventilation to produce alkalosis and hypocarbia will decrease pulmonary artery resistance and hence pressures. Comparisons of preductal (right radial artery) and postductal (umbilical artery or posterior tibial artery) gases will define the extent of shunting at the ductal level.

Complication. Acute deterioration may be due to a pneumothorax on the contralateral side: this should be confirmed radiographically and treated with intercostal tube drainage.

Further inpatient care. Babies may require several weeks of hospitalization after surgery depending on how long breathing needs to be supported with a machine. Feeding is begun after the first bowel movement is passed. Feeding is usually done through a tube into the stomach or small intestines until the breathing tube is removed.

Prognosis. Isolated diaphragmatic hernia is an anatomically simple defect, which is easily correctable, the mortality rate is about 50%. The main cause of death is hypoxemia due to pulmonary hypertension, resulting from the abnormal development of the pulmonary vascular bed.

Retrosternal hernias.

There are two forms of retrosternal hernia. In Cantrells pentalogy, there is a congenital developmental defect in the retrosternal diaphragm and pericardium, which is associated with epigastric diastasis or omphalocele. Oftentimes, there is the shor or splir distal sternum, as well as cardiac defect that usually consists of a ventricular septal defect, tetralogy of Fallot, or diverticulum of the myocardium from the left ventricle.

The second forn of retrosternal hernia is a parasternal hernia or hernia through the foramen of Morgagni (Morgagni hernia). This is far less common than the foramen of Bochdalek hernia (1 2 %) and has less physiological significance. These retrosternal hernias usually have a true sac and cause few respiratory symptoms: intestinal obstruction is a more common mode of presentation.

The diagnosis is suggested by the presence of air or fluid levels in the retrosternal region on an upright thoracic radiograph. Barium contrast studies may demonstrate the presence of intestine in the sac, but are rarely necessary. The hernia is best repaired through a transabdominal approach, with excision of the sac and primary closure of the defect in the diaphragm. Because there is little compression of the lungs during fetal development, pulmonary hypoplasia or respiratory compromise after repair are rare.

Eventration of the diaphragm.

Eventration of the diaphragm may be congenital, resulting from failure of normal ingrowth of muscle into the developing diaphragm or it may be acquired, resulting from phrenic nerve injury. Whatever the cause there is an abnormally redundant and attenuated diaphragm which has little or no ability to contract. Ninety per cent of these lesions are on the left side. Symptoms vary greatly: some patients suffer severe respiratory compromise, while in others it is an asymptomatic incidental finding. The diagnosis is best confirmed by fluoroscopy, which demonstrates paradoxical motion of the diaphragm. Flexibility of the mediastinum in infants permits transmission of the paradoxical motion of the diaphragm to the contralateral side.

The need for repair is determined primarily by the symptoms produced by the eventration, and not by the radiographic findings. A small eventration can be repaired easily through a limited, low thoracotomy, the defect being reefed up by plication with non-absorbable sutures until the diaphragm is taut. A large eventration has similar radiographical appearances to a Bochdalek hernia, the thorax being filled with abdominal viscera. This is best repaired through an abdominal incision.

3. Pulmonary Aplasia and Hypoplasia

Pulmonary aplasia results from the interrupted development of the normal bronchial tree with either absence of. or reduction in, the number of normal alveoli. Pulmonary hypoplasia refers to the reduction in size of an entire lung and its individual components. Although these lesions generally arise for different reasons, the former as a primary defect in organogenesis and the latter secondary to extrinsic compression from an intrathoracic mass lesion, they are physiologically similar and are therefore presented jointly here. Although primary pulmonary hypoplasia does occur spontaneously, this problem is more often the result of lesions such as congenital diaphragmatic hernia or CCAM, which limit alveolar development in utero. These children present with newborn pulmonary hypertension, persistent fetal circulation, and respiratory failure.

Several forms of congenital thoracic dystrophy produce acute or chronic asphyxiation related to pulmonary hypoplasia. All are rare, but Jejune thoracic dystrophy is the least rare. The physiologic problem, pulmonary hypoplasia, results from in utero restriction of lung development by an abnormal chest wall. Most affected infants have many other problems and do not survive. The only circumstance in which surgical intervention appears rational is in potentially nonlethal forms of the disease. In this circumstance, procedures designed to enlarge the thorax have been attempted. Median sternotomy and several individualized forms of thoracoplasty have been described. Insufficient data are available for meaningful clinical analysis of these approaches.

 

4.Congenital Lobar Emphysema

Congenital lobar emphysema, or congenital lobar overinflation. refers to the abnormal postnatal collection of air within a lobe of the lung that is otherwise anatomically normal. This condition is characterized by expiratory air-trapping within the affected lobe, resulting in lobar parenchymal distention. Compression of adjacent normal lung and mediastinal structures is expected, and physiologic impairment of gas exchange is common. The process is classically the result of developmental deficiency of the cartilage that supports the bronchus to the involved lobe, resulting in focal bronchial collapse and obstruction to expiratory air flow. This specific defect, however, is demonstrable in only one-third to two-thirds of surgically resected emphysematous lobes (8). The remainder of these infants and children have a variety of partially obstructing bronchial lesions. Some are endobronchial in origin and potentially reversible (e.g.. viscid secretions, mucous plugs, or granulation tissue). Some are the result of extrinsic compression of the bronchus with partial obstruction. Causes include mediastinal lymphadenopathy; adjacent vascular structures, such as an aberrant or enlarged pulmonary artery or ductus arteriosus; mediastinal cysts or tumors that are bronchogenic in origin; or other congenital or acquired mediastinal lesions with an intimate hilar relation. For these reasons, preresection bronchoscope evaluation is recommended with the expectation that reversible bronchial obstruction be corrected before sacrificing a lung lobe that is otherwise normal.

In addition, developmental abnormalities of the alveoli or the terminal airways may be associated with the clinical findings of congenital lobar emphysema. Of note in this regard is the finding of polyalveolar morphology, a descriptive histologic term that refers to a substantial and abnormal increase in the number of alveoli present. In this circumstance, postnatal air-trapping occurs within these many alveoli.

Congenital lobar emphysema is a rare lesion, with a 2:1 or 3:1 male predominance. It is most common in the white population. Unilobar involvement is the rule, with affected sites distributed in the following manner: left upper lobe, 40% to 50%; right middle lobe. 30% to 40%; right upper lobe, 20%; lower lobes, 1%; and multiple sites the remainder (7,8) (Fig. 61-2). Congenital lobar emphysema is associated with congenital heart disease or abnormalities of the great vessels in about 15% of infants (9,10,11). Indeed, extrinsic bronchial compression from vascular structures appears to be a common etiologic problem in this circumstance. For this reason, screening echocardiography is appropriate in all infants with congenital lobar emphysema.

Affected infants usually do not have symptoms at birth. With the onset of extrauterine life and spontaneous respiration, air-trapping and progressive lobar distention develop. Initial clinical symptoms are generally tachypnea and dyspnea, followed by cyanosis if oxygenation is sufficiently impaired. A cough or wheezing may also be present, but this is of little specificity. About one-half of affected infants develop symptoms in the first few days of life; the remainder develop symptoms within the first 6 months. Older infants and children may have few or no symptoms. Infants may have rapidly progressive respiratory failure, with up to 10% to 15% of patients requiring emergency thoracotomy. Generally, the clinical progression is slower, and some patients remain without symptoms. The clinical presentation may be one of progressive respiratory distress; therefore, an affected infant may become increasingly agitated, anxious, and tachypneic. These normal responses to hypoxemia exacerbate the air-trapping phenomenon as the peak inspiratory and expiratory pressures escalate. In particular, focal bronchial collapse occurs with excessive expiratory effort; as this develops, the lobar emphysema worsens, and further compromise in gas exchange results. Likewise, positive-pressure ventilation can induce acute lobar distention with potentially catastrophic respiratory decompensation or mediastinal displacement. The physiologic derangements may be indistinguishable from those of tension pneumothorax. This is an important consideration during endoscopic evaluation of the endobronchial tree. Particularly in infants with preoperative symptoms, the surgeon must be prepared to decompress the thorax by emergent thoracotomy and then to proceed with definitive lobectomy.

Congenital lobar emphysema is typically found in term infants, but acquired emphysematous disease in preterm infants is common. The cause of this latter problem is multifactorial, including barotrauma from positive-pressure ventilation, oxygen toxicity, and lung immaturity. It is often seen in conjunction with, and as a complication of. bronchopulmonary dysplasia. Unlike congenital lobar emphysema, multiple areas of focal hyperinflation and interstitial emphysema are often present. Unilobar right lower lobe involvement is also common, probably as a consequence of endotracheal tube positioning, which selectively ventilates the right mainstem bronchus. These characteristics help differentiate congenital and acquired disease.

Physical findings of congenital lobar emphysema may include an asymmetric thorax, a shift in the apical cardiac impulse to the contralateral side, and focal hyperresonance and diminished breath sounds over the affected lobe. None of these findings, however, has the necessary sensitivity and specificity to demonstrate the precise nature of the problem.

The diagnosis is best established by plain chest radiograph (Fig. 61-2). Typical findings include lobar hyperinflation, contralateral shift of the mediastinum and trachea, compression or even lobar atelectasis of adjacent lung, and flattening of the ipsilateral hemidiaphragm. If these

findings are all present, there is no need for additional imaging studies. Differentiating this presentation from tension pneumothorax is essential. The latter is characterized by collapse of the entire affected lung into the hilum. In contrast, although lobar emphysema can be dramatic in its radiographic appearance, adjacent compressed lung can almost always be discerned, most often the lower lobe at the base of the thorax. In addition, the occasional congenital cystic adenomatoid malformation (CCAM) with a single large cystic component can be mistaken for lobar emphysema. Because lobar emphysema rarely involves the lower lobes, this is an important differentiating feature. Nonetheless, the surgical management of these latter two lesions is similar so preoperative differentiation is less important than for tension pneumothorax, for which the treatment is different. As with most mass lesions in the chest, computed tomography (CT) and magnetic resonance (MR) imaging provide excellent anatomic information for infants with congenital lobar emphysema. These procedures are most helpful in elective situations when the diagnosis is in doubt. In addition, ventilationB"b"perfusion scans have been employed to evaluate infants with lobar emphysema, particularly when the areas of involvement are multiple or the disease acquired (12). In this setting, specific areas of nonfunctional lung can be identified and resected if they appear to compromise adjacent normal lung.

FIGURE 61-2. Congenital lobar emphysema involving the right middle lobe. (A) Herniation of the affected lobe across the midline has occurred (arrow), with compression of the adjacent right upper and right lower lobes. Mediastinal shift into the contralateral thorax is also apparent. (B) Similar abnormalities in a 4-month-old girl with involvement of the left upper lobe, the most common site of congenital lobar emphysema.

 

Because the natural history of congenital lobar emphysema is often progressive and includes potentially life-threatening respiratory insufficiency, prompt surgical lobectomy is the treatment of choice for infants and young children. Because the underlying lesion is structural, medical treatment can be considered only a supportive adjunct in patients with symptoms. In patients without symptoms, particularly older children, this approach may be tempered reasonably because the likelihood of sudden decompensation in this circumstance is low. The rationale for routine endoscopic evaluation of the affected bronchus has been noted. The purpose is to identify and eliminate reversible endobronchial obstructions from secretions, mucous plugging, or granulation tissue. Clearly reversible endobronchial problems should be corrected without parenchymal lung resection.

Extrinsic bronchial compression is associated generally with a focal cartilaginous defect of the affected bronchus that is not adequately relieved by simple decompression.

Although congenital lobar emphysema results from a specific anatomic defect, reconstructive procedures, such as bronchoplasty or segmental bronchial resection and anastomosis, are generally inappropriate. The diminutive size of the infant bronchus and the possibility of nonfocal cartilaginous tracheobronchial defects present important technical obstacles to successful local reconstructive procedures. In addition, there is little reason to select this approach because the clinical results of lobectomy are generally excellent for this lesion (9,10,11,13).

Acquired emphysema is often seen in preterm infants with a multitude of other problems. Treatment is generally medical and supportive, with the natural history being one of slow resolution over a number of months. In the acute phase, selective ventilation of nonemphysematous areas of lung or the use of alternative strategies such as high-frequency oscillatory or jet ventilation can minimize the peak airway pressure, which is directly correlated to the formation of emphysema. These approaches can also help infants with congenital lobar emphysema if prolonged transport is necessary or there is delay in reaching the operating suite. Lobectomy may be beneficial in occasional selected patients with severe regional emphysematous disease; however, late death may result from associated bronchopulmonary dysplasia in these patients.

As noted, infants and children have an excellent response to lobectomy for congenital lobar emphysema (9,10,11,13). Even in those who are critically ill and require emergency thoracotomy, the physiologic response is a predictably prompt and dramatic return to normal after resection of the affected lobe. Mortality for this specific lesion is rare in a modern pediatric surgical environment. The general risks of thoracotomy and lung resection include morbidity related to anesthesia, empyema, pneumothorax, infection, bleeding, and bronchopleural fistula. These are not different than for any other neonatal thoracotomy and lobectomy, and are presented in detail in the section that deals with outcomes after lung resection. The cumulative incidence of these types of complications is about 5% to 10% in most modern pediatric surgical practices, although it has been as high as 20% to 40% in recent decades (7.9.10.11). Long-term pulmonary function is also predictably excellent after lobar resection, and this is discussed separately later. For infants with coexisting congenital heart disease, acquired pulmonary emphysema, or additional medical problems, the outcome is generally dictated by these other conditions.

In follow-up studies by Frenckner and Freyschuss. (14) actual lung volumesB"b'residual volume, vital capacity, total lung capacity, and forced expiratory volume in 1 second (FEV,)B"B"in patients who had undergone neonatal lobectomy for congenital lobar

emphysema were 90% of predicted values, and no long-term functional impairment was reported. Infants who had undergone neonatal lobectomy for congenital lobar emphysema were evaluated as adults by McBride and colleagues in 1980 (13). Ipsilateral and contralateral lung volumes were found to be equal, despite the previous lobectomy. This appeared to be the result of compensatory tissue growth, not simply distention of residual lung parenchyma. In this latter study, perfusion was found to be equally distributed between the operated and nonoperated lungs. These patients demonstrated diminished expiratory flow rates compared with expected values (FEV,, 72% of predicted; maximal midexpiratory flow, 45% of predicted). These findings appear to result from disproportional

growth between the conducting and the terminal airways during infancy. This concept does not diminish the excellent clinical prognosis for these infants, and is presented in detail at the end of this chapter.

 

5. Congenital Cystic Adenomatoid Malformation

Congenital cystic adenomatoid malformation (CCAM) is a term applied to a spectrum of lobar hamartomatous abnormalities of the lung. The pathologic definition requires an increase in terminal respiratory structures, usually bronchioles, in a glandular or adenomatoid pattern that is normally seen during organogenesis. It is suggested that developmental control of the lobar lung bud and the surrounding mediastinal mesenchyme is lost between 16 and 20 weeks' gestation, giving rise to a lesion that is composed of multiple interconnected cysts that are disorganized and variably sized. Involvement is generally unilobar, and communication with the tracheobronchial tree is usually present. Three types of CCAM lesions were described by Stocker and colleagues (15) in 1977 and are illustrated in Fig. 61-3. Subsequently, others used the terms cystic, intermediate, and solid to categorize the different lesions observed with this malformation. More recently. Adzick and colleagues (16) defined these lesions as either macrocystic (greater than 5-mm cyst diameter) or microcystic (solid or less than 5-mm cyst diameter), by use of prenatal ultrasound examination to differentiate between the two. Because the natural history is dependent on morphologic type, the distinctions have more than semantic import. Clinical treatment and outcomes are presented later.

Both before and after parturition, the important physiologic consequences of CCAM result from mediastinal or normal lung compression by the mass lesion. Lesions of great size, particularly those that are microcystic or solid in composition, are potentially associated with in utero mediastinal displacement, hydrops fetalis, and fetal death. As many as one-third of all newborns with CCAM have evidence of fetal hydrops at delivery. It is now routine to establish the diagnosis of CCAM by prenatal ultrasound. The data for the fetus diagnosed with CCAM are more limited and controversial, but as many as 40% of fetuses with CCAM lesions will progress to hydrops and fetal demise, whereas 15% will spontaneously regress (17). Adzick and colleagues (18) suggested that the appearance of anasarca or hydrops in fetuses with microcystic CCAM is an indication of impending fetal demise; they have reported neonatal survival after fetal lobectomy in a small number of highly selected patients (19). Macrocystic lesions appear less threatening in utero, and although some have been managed with prenatal thoracoamniotic shunting or aspiration, most of these infants can be successfully treated after delivery at term. In addition, it appears that a substantial number of macrocystic lesions, perhaps one-third, diminish in size during fetal development (20.21). This is an important area of active investigation. Appropriate selection of patients for prenatal therapy depends on accurate information defining the natural history of CCAM.

Postpartum physiologic problems related to CCAM generally result from either pulmonary hypoplasia in newborns or inadequate tracheobronchial drainage with secondary infection in older infants and children. The former problem appears related to in utero compression and developmental arrest of the ipsilateral lung by the CCAM mass. In addition, some degree of contralateral pulmonary hypoplasia resulting from the shifted mediastinum is common. Pulmonary parenchymal hypoplasia and persistent pulmonary hypertension can result in acute respiratory failure in newborns. Severely affected infants with CCAM may have all the ventilatory instability of infants with congenital diaphragmatic hernias. This includes the potential need for conventional mechanical ventilation, high-frequency or jet ventilation, or extracorporeal life support. These issues are discussed in detail in Chapters 11 and 58. Although the spectrum of physiologic derangement includes both acute life-threatening respiratory failure and progressive newborn respiratory insufficiency, only about 30% of live-born infants with CCAM present in these ways. Many present with infectious pulmonary problems related to the persistent communication of the CCAM with the tracheobronchial tree. The abnormal lung parenchyma is exposed to environmental organisms, but lacks normal clearance mechanisms. This leads to a variety of infectious problems, such as recurrent pneumonia or lung abscess, or to more subtle chronic problems, such as failure to thrive. In contemporary practice, prenatal diagnosis yields a number of asymptomatic infants referred for treatment. In general, these infants should undergo elective lobectomy.

CCAM lesions are uncommon, representing about 30% to 40% of developmental lung bud anomalies in most reports. There is a slight male predominance and no apparent racial or geographic predilection. CCAM lesions are equally distributed between the left and right lobes, with bilateral disease being rare. Unilobar involvement is most common, with any lobe at risk, although there appears to be slight predilection for the lower lobes in most reports. Fortunately, multilobar disease when it occurs tends to be unilateral so surgical resection can be achieved by pneumonectomy, if necessary. A maternal history of polyhydramnios is common, and preterm delivery occurs in as many as one-half of these infants. Therefore, the many problems of preterm delivery may be superimposed.

Depending on the institutional environment, one-half or more of these lesions are detected and referred based on prenatal ultrasonography findings. As outlined earlier, about one-third of newborns with CCAM develop symptoms of tachypnea, dyspnea, cyanosis, or overt respiratory insufficiency in the first month of life. The remainder present with the consequences of pulmonary infectionB"Btone-half of these within the first year of life and the remainder at periods up to and including adulthood. Later presentations include recurrent or persistent pneumonia, lung abscess, pneumothorax, reactive airway disease, and failure to thrive, but not usually progressive respiratory insufficiency in older patients. Associated anomalies, including congenital heart disease, pectus excavatum. renal agenesis, skeletal anomalies, jejunal atresia, and others, have been reported, but the incidence is variable and may be no more than for the normal population (6,7).

The issues related to prenatal diagnosis have been discussed. The postnatal evaluation of infants with nonspecific respiratory symptoms is best begun with a plain chest radiograph. In infants with CCAM, however, the radiographic findings are variable. Images obtained shortly after birth may show retained fetal lung fluid within the lesion, and if it is a microcystic or solid lesion, this may not change with time. Macrocystic lesions tend to become aerated with ventilation, and the chest radiograph then has an area of air-filled cysts within the thorax. In infants, this appearance must be distinguished from congenital diaphragmatic hernia, particularly when the left side is involved. Although plain films alone are generally adequate, passage of a nasogastric tube into the stomach or an upper or lower gastrointestinal tract contrast study showing intrathoracic intestine may be helpful in distinguishing the two. Because the surgical approach is generally different for these two lesions, prospective distinction is important. Mediastinal displacement, compression of adjacent normal lung, and flattening of the intact ipsilateral diaphragm are also typical plain chest radiograph findings for CCAM. In older children with infectious complications, the findings are often less clear, and either CT with intravenous contrast or MR evaluation is necessary to provide definitive anatomic detail of the lesion (Fig. 61-4). Angiography has little or no role in the diagnosis of CCAM and other thoracic mass lesions in the modern environment because it has demonstrable risks and the information derived is available by less invasive means.

FIGURE 61-4. (A) Plain chest radiograph of a 9-year-old child who presented with fever, pleuritic chest pain, and cough. The lesion is an infected cystic adenomatoid malformation of the right lower lobe. (B) The lesion in A is shown on chest computed tomography scan after treatment with antibiotics and before surgical resection of the right lower lobe. (From Coran AG. Oldham KT. The pediatric thorax. In: Greenfield LJ, Mulholland MW, Oldham KT. et al. Surgery: scientific principles and practice. Philadelphia: JB Lippincott, 1993:813, with permission.)

 

The principal goal of treatment for CCAM is to resect the area of abnormal lung promptly. Some carefully selected fetuses may benefit from prenatal intervention; however, concerns remain about the natural history of the lesions, appropriate patient selection, and the risk of preterm labor. Experience with this approach is limited and is insufficient to be definitive. Generally, an in utero diagnosis and macrocystic disease are indications for sequential observation and delivery in a tertiary care environment where prompt thoracotomy and state-of-the-art critical care support are available. For the infant, treatment most often requires a thoracotomy with lobectomy. This can be life saving in critically ill newborns with mediastinal shift and normal lung compression from a ventilated and expanding CCAM. Fig. 61-5 demonstrates the relative size of a right lower lobe CCAM deliberately delivered from the thorax of an infant in extremis. The normal adjacent lung was allowed to ventilate, providing immediate physiologic relief before lobar resection. Because of the long-term risk of infectious complications, surgical resection is considered standard in older patients and in patients without symptoms. It is appropriate in the setting of an acute infectious process to treat a child preoperatively with systemic antibiotics to reduce acute inflammation. Long-term medical management, however, is not appropriate. Approximately 8% of primary lung malignant tumors and 4% of benign tumors are associated with cystic malformation of the lung, including CCAMs (22). To date, at least 24 reports of malignancy occurring within these and other congenital cystic lung lesions add further rationale for surgical resection (22.23.24.25). Pulmonary blastoma and rhabdomyosarcoma are the most common of these malignancies.

FIGURE 61-5. Right lower lobe cystic adenomatoid malformation that led to acute respiratory distress in a neonate. The size of the lobe after delivery from the thorax is much larger than the volume of the infant thoracic cavity. Delivery of such a space-occupying mass lesion from the thorax can lead to profound and immediate physiologic relief.

 

Pneumonectomy is required in as many as 15% to 20% of affected patients to achieve complete resection of a complex or multilobar CCAM (6,7,10). For the limited and well-demarcated CCAM, segmental resection has been reported, but data suggest that operative morbidity may be greater with this approach, and there is little or no apparent long-term benefit.

Outcome after surgical resection of CCAM is generally good. Adzick and colleagues (18) reported survival in four of six selected fetuses with microcystic CCAM after in utero thoracotomy and lobectomy between 24 and 32 weeks' gestation. For infants who are found at birth to have CCAM, the survival probability with resection is between 80% and 100% in most reports (6,7,10). When it occurs, death is usually the result of respiratory failure in newborns. In older children with infectious presentations, death is rare. The potential complications of neonatal lobectomy for CCAM are not different than for other similar lesions. Although many complications are possible, the overall incidence is less than 10%, and most can be readily managed. Most children have excellent long-term pulmonary function after lobectomy for CCAM. The experience after pneumonectomy is more limited and perhaps less optimistic given the larger extent of the resected lung (see discussion of outcomes after lung resection at the end of this chapter).

 

6. Bronchogenic Cysts and Lung Cysts

A developmental cyst arising from the trachea or a bronchus is referred to as a bronchogenic cyst. These account for about 20% to 30% of congenital bronchopulmonary-foregut cystic malformations (9.10). Potential locations include the cervical or thoracic trachea, the hilar bronchi, or the more distal intraparenchymal bronchi. It has been reported that about 70% of thoracic bronchogenic cysts are located within the lung parenchyma, and the remainder are in the mediastinum, but this distribution varies considerably among different reports (5.6.7,10). Ectopic bronchogenic cysts, including those in paravertebral, paraesophageal, pericardial, subcarinal, and subcutaneous locations, have been reported.

Bronchogenic cysts are typically unilocular mucus-filled lesions arising from the posterior membranous portion of the airway. They do not usually communicate with the functional tracheobronchial tree. Many anatomic variations, however, have been described. By definition, the cyst has structural elements of the airway, including cartilage, smooth muscle, mucous glands, and respiratory epithelium. Likewise, these lesions have a normal bronchial arterial blood supply. The character of the epithelium depends on the site of origin; ciliated columnar, cuboidal. and squamous epithelium are all found within the tracheobronchial tree, and therefore, within these cysts (Fig. 61-9).

This section also considers cystic lung lesions that result from abnormal development of the more distal airways, alveoli, or pleural or lymphatic tissue. Even collectively, these true lung cysts are rare congenital lesions. They constitute a heterogeneous group of lung parenchymal cystic lesions with histologic features representative of their sites of origin. The spectrum is varied and can overlap with cysts that are bronchogenic in origin. Differentiation of the tissue of origin for simple lung cysts is principally of pathologic interest because the presentations are similar, and clinical management is generally straightforward with a good outcome. One important exception is when the developmental abnormality is lymphatic in origin. The result then may be pulmonary lymphangiectasis. This is typically characterized by diffuse bilateral pulmonary cystic disease, and the outcome is often lethal because resection is not feasible.

The discussion of bronchogenic and other lung cysts is consolidated because of the overlap in their clinical presentations and the similarity in their embryologic origins. As with other congenital cystic lung lesions, physiologic injury from bronchogenic and lung cysts generally results from either compression of adjacent hollow viscera, such as the airway or esophagus (Fig. 61-10), or inadequate drainage of secretions with secondary infection. Malignancies have also been reported within these lesions, and rhabdomyosarcoma, bronchogenic carcinoma, and adenocarcinoma have been described (22.23.24.25.32). In newborns with cysts adjacent to the trachea or proximal airways, respiratory distress or air-trapping with lobar emphysema are important and potentially life-threatening problems. More distal lesions may be asymptomatic or may present with evidence of infection. The latter usually occur in older children because time is necessary for the development of infection. Clinical presentations range from no symptoms to life-threatening respiratory distress, although the latter is rare. Infection and nonspecific respiratory symptoms. such as cough, dyspnea, tachypnea, wheezing, or chest pain, are typical. The usual chest radiographic appearance of a bronchogenic cyst is that of a smooth, roughly spherical, paratracheal. or hilar solid mass without calcification. Displacement of the adjacent airway and distal air-trapping are relatively frequent, even in patients without symptoms. Air-fluid levels suggest communication with the tracheobronchial tree or foregut. and this is a particularly likely finding in the presence of acute infection.

FIGURE 61-9. Bronchogenic cyst. The wall of this bronchogenic cyst consists of dense fibrous tissue (asterisks). Cartilage and seromucinous glands were also present (not shown). (Masson trichrome, l~52.) (Courtesy of Kay Washington, MD. Duke University Medical Center, Durham, NC.)

 

FIGURE 61-10. Esophogram demonstrating extrinsic compression [arrows) from a foregut-derived cystic lesion that caused symptomatic tracheal obstruction in an infant. At time of excision, this lesion had both esophageal and tracheal elements, consistent with a shared embryologic origin. Simple excision relieved the symptoms.

 

True lung cysts can occur anywhere. They are typically single, unilocular lesions. These can be large or small and difficult to distinguish from a lung abscess or macrocytic CCAM on chest radiograph. Discovery of a bronchogenic or true lung cyst after slow or incomplete radiographic resolution of acute pneumonia has also been well described. As with other thoracic mass lesions. CT and MR imaging provide both diagnostic accuracy and excellent definition of the anatomic relations of these lesions. In the patient with dysphagia and a paraesophageal bronchogenic cyst, a contrast esophagogram may demonstrate extrinsic compression at the site of the lesion. Likewise, endoscopic examination of the tracheobronchial tree or esophagus may show extrinsic compression.

Resection of the cystic abnormality is standard treatment for virtually all bronchogenic and lung cysts, even if asymptomatic. The risk of infection appears to be high, although no prospective data exist. Generally, simple local resection is easily accomplished and definitive. Occasionally, however, limited parenchymal lung resection or even lobectomy may be required. Preoperative treatment of pneumonia is helpful in diminishing perioperative morbidity and in minimizing the magnitude of parenchymal resection. Preservation of adjacent normal parenchyma is an important operative principle. Wedge resection, segmentectomy. and lobectomy have all been reported for individual circumstances. As with many other thoracic lesions, thoracoscopic resection of bronchogenic and lung cysts is feasible for selected patients. It is essential to establish precise anatomic relations preoperatively if a

thoracoscopic approach is planned because bronchogenic cysts are often beneath the mediastinal pleura, and therefore, require pleural incision and mediastinal exploration to localize the lesion. Mediastinal exploration is important for infants with lobar emphysema because an occult bronchogenic cyst may be responsible, and relief is occasionally possible without lobar lung resection.

The long-term outcome for infants and children with bronchogenic and true lung cysts is excellent because they generally do not require sacrifice of significant normal lung parenchyma. Likewise, perioperative morbidity is low and mortality rare, particularly for mediastinal lesions without tracheobronchial communication. If lung resection is required, outcome is not different than for patients with other lung lesions, such as lobar emphysema or CCAM. and these outcomes are presented later in detail.