Tracheal anomalies in children represent one of the greater challenges in pediatric otolaryngology. In addition to the compromised airway, there is a high prevalence of associated anomalies. Despite surgical and technologic advances, significant morbidity and mortality remain.
Recent advances in molecular biology and development of novel animal models have challenged older theories of foregut development and have allowed increased understanding of the pathophysiology of congenital airway anomalies.
Bronchoscopy should be performed with the patient spontaneously ventilating; no attempt should be made to force a scope through a critical stenosis.
Imaging using advanced radiologic techniques is an important tool in the workup of these children to precisely characterize airway anomalies, with acceptable sensitivity and specificity. However, bronchoscopy remains the gold standard in the assessment of the pediatric airway.
Tracheomalacia is classified as either primary (intrinsic) or secondary (to compression); the majority of patients with primary tracheomalacia have mild to moderate severity and can be managed expectantly until spontaneous resolution occurs.
Endoscopic procedures have become very effective in management of short, acquired tracheal stenoses, although their application in longer segment stenoses is limited.
Tube stents are useful for short-term support of the pediatric airway in several situations. Although initially effective at maintaining patency of the airway, wire stents have a high rate of associated complications and should be used only in salvage situations and when all other surgical options have been exhausted.
Slide tracheoplasty is the preferred surgical treatment for long-segment congenital tracheal stenosis with complete rings. For short stenoses, segmental resection and reanastomosis is preferred.
Advances in tissue engineering and transplant medicine have opened a new array of possibilities for tracheal reconstruction.
Esophageal atresia, with or without tracheoesophageal fistula, is the most common congenital anomaly of the esophagus. Of the five variations, esophageal atresia with distal tracheoesophageal fistula (85%) is most commonly encountered.
Congenital tracheal anomalies present a compromised distal airway and associated comorbidities, which may challenge the most experienced pediatric otolaryngologists. Over the last two decades, management has evolved with development of new surgical techniques. However, significant morbidity and mortality remain, and continued integration of new information is required to meet the unique set of challenges.
The symptoms of congenital tracheal anomalies are generally related to the size of the airway. Mild obstruction can often be treated expectantly, whereas more significant lesions may require airway splinting, repair of associated anomalies, tracheal reconstruction, or novel bioengineered solutions. Airway size may be decreased secondary to collapse, congenital narrowing, intraluminal tissue ingrowth, or extrinsic compression. The etiology and degree of narrowing guide the treatment algorithm.
At 4 weeks’ gestation, the foregut develops a laryngotracheal groove, which extends from the ventral aspect of the primordial pharynx caudal to the fourth branchial arches to produce a laryngotracheal bud. The laryngotracheal bud is circumferentially invested with splanchnic mesenchyme. The endoderm develops into respiratory epithelium and glands, and the splanchnic tissue will differentiate to the cartilage, connective tissue, and muscles of the airway.
A long-held hypothesis is that the foregut develops bilateral indentations called tracheoesophageal folds or lateral ridges, which migrate medially in a pinching motion to fuse and create the tracheoesophageal septum, which ultimately separates the trachea from the esophagus. This process begins caudally and extends cranially under the controlled balance of epithelial proliferation and apoptosis, with the caudal end giving rise to the respiratory buds. However, data to substantiate the process of septation of the foregut are lacking, and these lateral ridges have not been identified in animal studies. Alternate theories have been developed based on molecular biology as well as results from directed mutagens (doxorubicin), which produce a variety of foregut malformations. Laryngotracheal clefts also arise secondary to abnormal development of the tracheoesophageal septum (see Chapter 30 ).
In summary, no consensus has been reached regarding the process of airway development (see the Suggested Readings).
Endoscopic visualization of the airway is essential for correct diagnosis and characterization of tracheal pathology. Intravenous (IV) dexamethasone is administered to the patient at a dose of 0.5 mg/kg prior to instrumenting the airway. The patient is initially mask ventilated, and then the vocal folds are topically anesthetized with lidocaine. It is essential to maintain spontaneous ventilation to allow true assessment of any dynamic collapse of the airway. A laryngoscope is positioned in the valleculae, and insufflation of oxygen and inhalational agents is provided either via the side port of the laryngoscope or with an endotracheal tube (ETT) placed in the pharynx. A 2.7-mm or smaller rigid, zero-degree telescope connected to a monitor with videorecording is used to assess the airway. Observations during bronchoscopy should include subglottic diameter; presence of complete tracheal rings ( Fig. 27-1 ); length and position of stenosis ( Fig. 27-2 ); scar formation; malacia of any segments of the airway, because the position and shape of the airway can often help determine which vascular structure might be the cause; presence of fistula on the posterior wall, often above the carina; presence of a tracheal bronchus ( bronchus suis ), seen in 50% of cases of congenital tracheal stenosis (CTS); carinal findings; and the presence of mainstem bronchomalacia.
Complications may include mucosal trauma, laryngospasm, bradycardia, pneumothorax, bleeding, and edema, any of which may contribute to the loss of the ability to oxygenate or ventilate the patient. A telescope or bronchoscope should never be forced through a stenotic or edematous area because even minor mucosal trauma may precipitate complete airway obstruction.
The rigid bronchoscope allows more control over the airway at the expense of a larger diameter (generally at least 1 mm larger than the telescope alone). Flexible bronchoscopy may also be useful; the bronchoscope can be placed through a ventilating mask, suspension laryngoscope or nasal passage, or a ventilating bronchoscope can be placed above the stenotic portion of the airway. Ultrathin flexible bronchoscopes (diameter 1.8 mm) allow similar visualization compared with the telescope; however, these scopes do not have a suction channel or side port and do not support ventilation, and resolution is reduced compared with the telescope. Hayashi and colleagues have recently described use of a stereovision flexible bronchoscope (outer diameter 2.2 mm).
Multiple radiographic modalities can provide unique information about tracheal anomalies and their commonly associated findings. Plain film radiography provides limited diagnostic information for many tracheal anomalies but may show postobstructive hyperinflation, postobstructive pneumonia, or narrowing of the tracheal air column. Airway fluoroscopy, when available, may be helpful for dynamic assessment of tracheomalacia (TM), tracheal stenosis, or vascular compression in children who are unable to tolerate bronchoscopy. However, fluoroscopy is a less sensitive method for detection of mild airway compression. Indentation of the esophagus visualized during a barium swallow can suggest incomplete or complete vascular rings. Contrast bronchography is of historic interest only.
Advances in computed tomography (CT) allow three-dimensional multiplanar reconstructions and virtual bronchoscopy. Axial CT remains the radiographic study of choice for evaluating the pediatric airway. Use of inspiratory and expiratory imaging allows some assessment of dynamic changes in the airway. However, CT uses ionizing radiation and may require IV contrast to show vascular structures well.
Virtual bronchoscopy is produced by postprocessing CT data, most commonly obtained in a single breath hold at end inspiration. Internal rendering of CT data produces a virtual luminal view that imitates bronchoscopy, whereas external rendering produces CT bronchography, which illustrates the airway’s dimensions and its relationship to adjacent structures. The advantage of virtual bronchoscopy is the ability to provide information about the poststenotic portion of an airway that is too narrow to allow even small bronchoscopes to safely pass. Several studies have demonstrated good accuracy of this modality in assessing tracheobronchial stenosis, but it may not be as effective for malacia, and it can occasionally be misleading for the finer anatomic details required for surgical planning. As this technology improves over time, it has the potential for better utility in diagnosing and characterizing various tracheal anomalies.
Magnetic resonance imaging (MRI) and magnetic resonance angiography (MRA) provide good detail of cardiovascular anatomy, accuracy in assessing the larger airways, and multiplanar capability. In many centers, MRI/MRA has replaced conventional angiography for assessment of vascular rings. Conventional MRI is unable to provide dynamic information on the airway throughout the respiratory cycle. In contrast, cine MRI uses real-time continuous acquisition of the airway to demonstrate dynamic collapse or stenosis, and it samples images at different phases of the respiratory cycle. Disadvantages of MRI include a longer acquisition time (30 to 60 minutes) and the potential need for sedation, which are particularly problematic in children who already have a tenuous airway.
Many centers utilize echocardiography to delineate congenital heart anomalies, given the high frequency of cardiac comorbidities with tracheal anomalies. In experienced hands, echocardiography may be sufficient to diagnose vascular rings, the most commonly encountered cardiovascular comorbidity; however, some centers may prefer to utilize CT or MRI/MRA. Echocardiography does not allow identification of the atretic segments of aortic branches involved in vascular rings and is limited in evaluating airway compression.
In summary, radiographic studies may complement endoscopy but they cannot supplant it. With further technical advances in imaging, the diagnostic algorithm to evaluate tracheal lesions will continue to evolve.
Tracheal Agenesis, Atresia, and Webs
Tracheal agenesis is a rare congenital anomaly with nearly universal mortality. Approximately 100 cases have been described. At birth, patients have an aphonic cry, respiratory distress, increasing cyanosis, and falling Apgar scores. If a tracheoesophageal fistula (TEF) is present, bag mask ventilation or esophageal intubation—accidental or purposeful—may temporize for the inability to adequately ventilate. Laryngoscopy may demonstrate absence of vocal folds, and tracheal rings are not palpable in the neck. A nasogastric tube may not pass to the stomach if esophageal atresia (EA) is present.
The most commonly used classification system for tracheal agenesis was proposed by Floyd. In type I, the proximal trachea is absent, and the airway connects to a distal TEF. In type II, which is most common, the carina arises from the lower esophagus. In type III, the mainstem bronchi originate from two separate anastomoses with the esophagus.
Patients with tracheal agenesis most commonly manifest other features of VACTERL association ( v ertebral defects, a nal atresia, c ardiovascular defects, t racheoesophageal fistula or e sophageal atresia, r enal defects, and l imb defects). However, multiple congenital anomalies have been described with associated tracheal agenesis, and there is no predominant molecular etiology.
Surgical correction, if undertaken, involves using the esophagus and fistula as a neotrachea, with a double-barrel proximal esophagostomy (the superior end for salivary fistula and the inferior end for the stoma of a neotrachea). The esophagogastric junction is divided, and if EA is not present, the stump is oversewn. A gastrostomy is placed for alimentation. Only two survivors beyond 10 months have been reported. Watanabe and colleagues described survival of a child for over 4 years with normal neurodevelopment by using the above strategy with the addition of an external esophageal splint, in which the collapsible esophageal walls are retracted by permanent sutures to the splint to hold it open as a neotrachea. Tissue engineering may offer hope for these patients in the future.
Tracheal webs are less common than laryngeal glottic webs and most commonly occur at the level of the cricoid. They are typically amenable to endoscopic management, although resection and reanastomosis is an option.
Esophageal atresia (EA), with or without tracheoesophageal fistula (TEF), is the most common congenital anomaly of the esophagus (1 in 3500), and survival has improved dramatically over the past 20 years. Five types of anomalies are encountered: EA with distal TEF (85%), isolated EA without TEF (8%), H-type TEF (4%), EA with proximal TEF (3%), and EA with proximal and distal TEF (<1%). These entities can occur in isolation or as part of a spectrum of associated anomalies, such as VACTERL and CHARGE ( c oloboma of the eye, h eart defects, a tresia of the anal choanae, r etardation of growth and/or development, g enital and/or urinary abnormalities, and e ar abnormalities and deafness) associations. Up to 50% of patients will have other congenital anomalies, most commonly cardiovascular anomalies.
Most of these patients will be diagnosed shortly after birth, either by the inability to pass a 10F catheter beyond 10 cm, excessive drooling, respiratory distress, or cyanotic episodes during nursing. A chest radiograph may show a gastric bubble if a distal TEF is present, along with air in the proximal pouch. Endoscopy can be useful for the diagnosis, particularly as an alternative to contrast studies with their associated risk in this setting.
Surgical treatment options include placement of an immediate gastrostomy followed by attempted primary anastomosis at 3 months, or the Foker technique, which attempts to elongate the esophagus with external traction sutures prior to anastomosis. The procedure begins with closure of the fistula at the trachea, followed by the EA repair via thoracotomy. Long-gap EA, defined as greater than 3 cm or the height of two vertebrae, is more challenging and sometimes requires rotation of a pedicled colonic or gastric interposition flap or a free jejunal graft. Complications include anastomotic leaks, esophageal strictures, and esophageal dysmotility, and TM and gastroesophageal reflux disease (GERD) are both common. In a long-term study of the Helsinki experience, Sistonen and colleagues found that only 20% of patients with repaired EA had normal pulmonary function.
Complete Vascular Rings
Double aortic arch is the most common type of complete vascular ring, followed by right aortic arch with aberrant left subclavian artery and left ligamentum arteriosum. Taken together, these two entities comprise over 95% of complete rings. Surgical treatment for symptomatic patients entails division of the vascular ring, usually via a limited left thoracotomy or video-assisted thoracic surgery.
A double aortic arch develops when the distal right fourth branchial arch fails to involute, which leads to development of paired aortas. The right arch is typically larger and more cephalad and passes behind the esophagus before joining the left arch to form a left-sided descending aorta ( Fig. 27-3, A ). Double aortic arch typically produces severe TM with onset of symptoms usually before 1 year of age. High success rates in the immediate postoperative period are reported. However, mild respiratory symptoms may persist for months to years in 30% to 50% of surgical patients.
In cases of right aortic arch with aberrant left subclavian artery and left ligamentum arteriosum, the mid-left fourth arch involutes, rather than the distal right fourth arch, as in normal development. As a result, the left subclavian artery and ligamentum arise from an outpouching known as Kommerell diverticulum, a remnant of the distal left fourth arch within the descending aorta (see Fig. 27-3, B ). These patients generally have milder symptoms.
Incomplete Vascular Rings
In incomplete vascular rings, it is debated whether the aberrant vessel actually compresses the airway or whether increased compliance of the adjacent tracheal rings produces the malacic segment. In a dynamic study by Cheung and colleagues that combined bronchography and angiography, all patients with abnormal anatomy on CT or MRI were found to have primary airway malacia rather than actual vascular compression. However, some children will clearly benefit from arteriopexy, which may improve airway patency by both removing compression as well as distracting the airway, helping to splint it open.
An aberrant innominate artery arises from an abnormally distal takeoff from the aortic arch and ascends over the anterior trachea about 1 to 2 cm above the carina (see Fig. 27-3, C ). A history of apparent life-threatening events (ALTEs) or reflex apnea is an indication for aortopexy, which resolves respiratory symptoms in approximately 80% of patients, although mild residual malacia may take some months to resolve. Alternatively, the aberrant innominate artery may be reimplanted into the aorta more proximally, such that it lies to the right of the trachea and does not cross it, although this approach does not have the potential additional benefit of splinting open the airway from the suspension.
A left pulmonary artery sling develops when the left pulmonary artery arises from the right pulmonary artery and passes between the trachea and esophagus to cause compression of the right mainstem bronchus and distal trachea (see Fig. 27-3, D ). Complete tracheal rings and long-segment tracheal stenosis are seen in 50% of patients.
Tracheomalacia (TM) may be primary or secondary and is manifested by increased compliance and flaccidity of the supportive anterolateral cartilaginous framework. A normal framework resists collapse of the airway on expiration, when intrathoracic pressure exceeds intraluminal pressure. TM may occur secondary to weakness, absence, or deformity of the cartilage segments and/or hypotonia or reduction of the longitudinal myoelastic segments, most commonly in the distal third of the trachea. Concurrent bronchomalacia is common and occurs in approximately 30% of cases of TM. Disorders associated with TM include cardiovascular malformations (20% to 58%), bronchopulmonary dysplasia (52%), and gastroesophageal reflux (50%, rising to 78% in severe TM).
Symptoms of TM may range from mild to severe, depending on the location, length, and degree of collapse. Symptoms may include expiratory (or biphasic) stridor, wheezing, barking or brassy cough, retractions, and recurrent pulmonary infections because of impaired mucociliary clearance. In more severe cases, symptoms include cyanotic episodes, neck hyperextension, feeding difficulties, failure to thrive, apnea, or ALTEs. Exacerbation of symptoms is seen with crying, feeding, coughing, and respiratory infections and when Valsalva maneuvers are done.
The diagnosis of TM is established by bronchoscopy in a spontaneously ventilating patient. A decrease in luminal diameter greater than 50% at end expiration is considered diagnostic, and many patients with symptomatic TM show a greater than 75% collapse. Most cases of TM are mild, with symptoms that begin at 5 to 6 months of age as crouplike symptoms or with difficulty clearing secretions. Moderate cases will have frequent episodes of wheezing or stridor exacerbated by exertion or upper respiratory tract infection. Patients with mild to moderate TM will usually demonstrate clinical improvement in 6 to 12 months with resolution by 2 years of age as the cartilage matures. Patients with severe disease will have a greater tendency toward cyanotic episodes and possible reflex apnea, which may lead to ALTEs. The morbidity and mortality rates from severe TM remain high if the disorder is not treated.
Primary tracheomalacia arises from intrinsic weakness in the trachea itself; the incidence is higher in premature infants. In a normal trachea, the cross-sectional view displays a ratio of cartilaginous ring/posterior musculomembranous wall of 4.5 : 1. In contrast, this ratio may be closer to 2 : 1 in cases of primary TM manifested as a narrow anteroposterior diameter and a widened posterior membranous wall on bronchoscopy. Patients with primary TM typically have mild to moderate symptoms, and the natural course for most healthy and even premature patients is spontaneous resolution with time.
TM is a consistent feature of EA with TEF, which may be considered primary because of a congenital histologic deficiency of the cartilage and abnormal structure at the fistula site. Not surprisingly, a high rate of symptomatic TM persists after repair of the TEF.
Secondary tracheomalacia is a segmental collapse of a portion of the airway. Secondary TM may arise secondary to localized inflammation or breakdown of the tracheal wall, as seen with prolonged intubation or tracheotomy, or it may result from extrinsic compression as a result of complete or incomplete vascular rings, mediastinal masses (bronchogenic cysts, lymphatic malformations), or cardiac enlargement (left atrial hypertrophy).
Treatment of Tracheomalacia
Patients with TM and mild to moderate symptoms may be managed expectantly with antibiotic therapy for recurring respiratory infections, humidified oxygen, intermittent steroids, and pulmonary physiotherapy. Frequent hospitalizations may be required until growth results in clinical resolution of the malacia. In moderate to severe cases, parents should be familiar with basic cardiopulmonary resuscitation techniques and should have home oxygen available. Continuous positive-airway pressure may be a temporizing option, particularly for associated bronchomalacia, but it is less practical as a long-term management strategy. Tracheostomy is a long-standing option for severe TM, and longer trach tubes may be used to attempt to stent open the distal trachea. Approximately 12% to 62% of infants/children still require tracheostomy for TM.
Aortopexy involves approximation of the aorta to the posterior sternum by placement of permanent sutures in the wall of the ascending aorta, typically near the takeoff of the right innominate artery. The aorta is thus pulled anteriorly, which, by virtue of its fascial attachments to the trachea, pulls the tracheal lumen open in the anterior-posterior dimension. The most common indication for aortopexy is one or more ALTEs. It is most commonly utilized in TM associated with EA or vascular compression, although it has been described in cases of severe primary TM. It may provide a good secondary procedure for residual malacia following repair of vascular rings, tracheal stenosis, or TEF. In a recent review of 40 papers encompassing 581 aortopexy procedures, Torre and colleagues showed a pooled success rate of 80% with significant improvement, whereas 12% had no change or worsened, and 6% died. Intraoperative bronchoscopy to assess the positioning and optimal tension of the sutures is recommended. Airway improvement after aortopexy appears to persist over the long term. Aggressive treatment of GERD that includes fundoplication prior to or during aortopexy has been advocated because of a higher rate of aortopexy failure in patients with untreated reflux.
Stents counteract collapse of the airway during expiration, making them useful as primary treatment for tracheobronchial stenosis or severe TM, as secondary salvage treatment for refractory collapse or stenosis after previous surgery, or as adjunctive treatment to support a grafted or transplanted segment of the airway. Application of airway stents began with the introduction of the silicone Montgomery T-tube in 1965. Over the past 20 years, there has been an increasing number of stent types, which are classified as tube stents, wire mesh stents, and hybrid stents (both tube and wire components).
Tube stents are typically made of silicone (e.g., Montgomery, Hood, and Dumon stents) and are placed via rigid bronchoscopy. The advantages of this type of stent are ease of removal and good tissue compatibility with less granuloma formation than with metallic stents, although granulation and mucus plugging can still be problematic. Disadvantages of these tubes include a negative effect on mucociliary clearance in the stented segment of the airway, a higher tendency to migrate, an inability to conform to tortuous airways, and a greater wall thickness. These drawbacks may make tube stents impractical for use in the airways of infants and small children. In particular, it is difficult to achieve the necessary degree of coaptation between a tube stent and the tracheal wall to treat TM or pathology resulting after repair of TEF. Tube stent insertion is considered the best option in the presence of inflammation or if early removal is anticipated, such as to provide stability for a reconstructed segment of the trachea. Tube stents are more resistant to microbial colonization than wire stents and may stimulate less granulation.
Metallic mesh stents come in a compressed state, which allows placement via the side channel of a flexible bronchoscope with relative ease of insertion. They are either balloon expandable (e.g., Palmaz stent) or self-expanding (e.g., Ultraflex stent) and may be reexpanded as the airway grows. Metallic stents have a thinner wall and thus provide an increased airway lumen and are able to conform to various geometries. They may possibly preserve mucociliary clearance. In addition, if the stent overlies a branch in the airway, the pores allow preservation of ventilation. Disadvantages include a high rate of granulation tissue formation and difficulty in removing or repositioning the stent. After 6 to 8 weeks, epithelialization is complete and the stent is incorporated into the tracheal wall, making removal risky or impossible. Erosion into adjacent vascular structures has also been reported.
Nicolai reviewed the literature for published series of all types of pediatric airway stents and found an initial success rate of 92.6% (112/121) in relieving airway obstruction, while also noting a stent-related mortality of 11.6% to 12.9%. Based on this review, he concluded the following: 1) stents should not be used when other surgical options are available; 2) airways compressed by a vessel should not receive a stent as primary therapy, only for severe refractory malacia after vascular repair; 3) airway stents are acceptable for short-term postoperative support of the tracheal lumen; and 4) tracheotomy with a long distal cannula may be a better alternative than stenting for TM unresponsive to aortopexy. Of note, in 2005, the Food and Drug Administration issued an advisory against metallic airway stents in benign airway disorders because of high complication rates.
Bioabsorbable stents represent an emerging area of therapy for pediatric airway disorders. Vondrys and colleagues reported on their initial experience with new bioabsorbable polydioxanone stents in children, placing 11 stents in four patients. These stents are very compatible with tracheal mucosa, maintain rigid strength for 6 weeks, and dissolve completely by 15 weeks. Early success with this type of stent in adult patients has been reported. The authors report that the stent relieved obstruction without complication, but insertion was technically more difficult to perform compared with other stents.
Zhu and colleagues reported on a novel mitomycin C drug-eluting bioabsorbable stent, which showed decreased granulation and rate of restenosis in a rabbit model. Patients treated with immunosuppressive drugs after lung transplantation have been incidentally noted to have a decreased tendency to form granulation tissue and stenosis at the anastomotic site compared with patients who are not receiving an immunosuppressive regimen. The concept of drug-eluting bioabsorbable stents delivering various adjunctive topical medications to modulate the tissue response and combat restenosis and the development of granulation tissue holds significant promise for the future.
In contrast to intraluminal stents, extraluminal splints do not disrupt the mucosa. External splinting of the airway with cartilage or a Marlex splint has been described. However, results with this procedure have been mixed, and it may be less effective for distal TM. Bugmann and colleagues recently described use of a bioabsorbable Y-shaped splint sewn to the posterior membranous trachea. However, TM persisted after aortic arch repair, and aortopexy was still required to open the airway. Recently, Zopf and colleagues reported use of a novel bioresorbable splint created with a three-dimensional printer which was successfully used to treat life-threatening bronchomalacia. This splint was specifically designed to resist external compression while allowing for growth.
Tracheal stenosis may be congenital or acquired. In congenital tracheal stenosis (CTS), the usual U-shaped tracheal cartilage is replaced by O-shaped complete cartilaginous tracheal rings. Acquired tracheal stenosis results from endoluminal scarring or collapse, usually secondary to prolonged intubation, tracheotomy, or previous surgery. It may also develop secondary to an inhalational chemical burn injury, trauma or infection or as a manifestation of systemic inflammatory diseases such as polychondritis or Wegener granulomatosis. Patients with tracheal stenosis present with varying symptoms, often correlated to the diameter of the most obstructive segment. At the severe end of the spectrum, a neonate may present with respiratory distress, stridor, cyanosis, barking cough, and ALTEs, whereas at the mild end of the spectrum, older children may manifest minor symptoms such as intermittent wheezing, stridor, or exercise intolerance. Symptoms may progress as respiratory demand increases with age of the child if the stenotic area does not grow. Patients with long-segment CTS are more likely to have early respiratory distress and associated anomalies. The most common associated anomaly, present in 50% of patients, is a pulmonary artery sling. Cardiac defects, lower airway arborization, and other vascular anomalies are also common.
The 1964 classification of Cantrell and Guild is still widely used; it divides CTS into three types: 1) generalized hypoplasia with narrowing of the entire trachea as a result of complete tracheal rings (limited to the trachea with normal bronchi); 2) funnel-like stenosis with a normal-diameter proximal trachea with progressive narrowing distally because of complete rings; and 3) segmental stenosis ( Box 27-1 ). Alternate classification systems have been described ( Table 27-1 ).
Type 1: Generalized hypoplasia of the entire trachea
Type 2: Funnel stenosis: normal proximal trachea with distal narrowing to carina
Type 3: Segmental stenosis with up to three rings involved
|Mild||Occasional or no symptoms|
|Moderate||Respiratory symptoms without respiratory compromise|
|Subtype A||No other associated malformations|
|Subtype B||Associated malformations|
As the worldwide experience with CTS has grown, innovative surgical methods have been introduced and refined. Treatment principles are based on the length and degree of stenosis, location of stenosis, presence of previous scarring or cartilage loss, and comorbidities. CTS has historically been associated with high mortality rates when managed by medical therapy alone. However, not all patients with tracheal stenosis will require surgery.
Serial bronchoscopies or high-resolution imaging may be used to follow children who demonstrate minor symptoms. Rutter and colleagues reported on a group of 10 patients with complete tracheal rings with mild symptoms of respiratory distress, who were managed medically. Five patients remained minimally symptomatic and had demonstrated growth of their airway, two children became more symptomatic and underwent slide tracheoplasty, and three were still being followed. Cheng and colleagues noted a phenomenon of “catch-up” growth of six nonoperated patients with complete tracheal rings who were followed with serial CT scans, such that the stenotic areas had reached a normal diameter by the age of 9 years. Both of these series were included in a review of 310 patients with CTS, of whom 39 were initially managed conservatively. Of those 39, 6 eventually underwent surgical management, 2 died, and none required tracheostomy over a mean follow-up period of 6.5 years. These data suggest that approximately 10% can be successfully managed conservatively. The true prevalence of CTS is likely underestimated because many patients with minimal symptoms in infancy will ultimately experience growth of the airway and will not come to the attention of the airway surgeon.
Endoscopic procedures are valuable for controlling acquired tracheal stenosis, including scarring that occurs because of stent placement, but they have a more limited role in the treatment of complete tracheal rings. Often, these procedures are used in combination; for example, laser incisions of a stenotic segment may be followed by dilatation and stenting or application of topical therapy.
The principles of laser management of airway stenosis are well established. Comanagement of the airway with anesthesia colleagues during laser procedures is critical to avoid complications such as airway fire. The laser is often used in the vaporization of postoperative granulation tissue of the subglottis or trachea and has also been utilized to create radial incisions in more mature stenotic lesions, leaving intervening islands of intact mucosa to prevent the tendency toward cicatricial scarring, as described by Shapshay ( Fig. 27-4 ). The troughs created by the laser remucosalize and increase the luminal cross-sectional area, although several procedures may be necessary to achieve a satisfactory result. Often, the laser radial incisions are followed by dilatation of the segment. An alternative use of the laser is to create a microtrapdoor, in which the laser is used to make a transverse superior incision; then an inferiorly based flap is elevated after making the lateral cuts with a sickle knife or microscissors ( Fig. 27-5 ). The laser is used to ablate the underlying posterior fibrotic scar before laying the mucosal flap back into place.