Congenital Tracheal Stenosis
Annie Lapointe, M.D.
May 22, 2003

Here is the plan of today’s presentation. We will start with the case presentation and then we will review the definition of congenital tracheal stenosis, its history, its classification, the associated anomalies, the embryology of the trachea and bronchus, the clinical presentation of congenital tracheal stenosis, its diagnosis, its management and we will finally conclude.

FP is a 3- week-old male with Down syndrome and PDA ligation hospitalized at Driscoll Children’s Hospital. There, he had been intubated soon after birth for respiratory distress secondary to meconium aspiration. After multiple unsuccessful intubation attempts in the NICU, a bronchoscopy with intubation in the OR had been required. This exam showed a narrowed mid-trachea. A chest CT scan suggested complete congenital tracheal rings.

He was then transferred to TCH, where his initial examination showed decreased breath sounds bilaterally and high-pressure volumes. The arterial blood gas (ABG) confirmed severe respiratory acidosis. Upon our initial examination, we performed a flexible bronchoscopy at the bedside through the 3.5 ETT. We could see tracheal narrowing with circumferential granulations at the tip of the ETT along with blood and mucus. We successfully improved the ventilation by reintubating the patient with a 3.0 ETT that passed the narrowed area. A bronchoscopy performed in the OR a few days later confirmed a mild narrowing at the level of the junction of the mid and distal thirds of the trachea with probable complete tracheal rings. The granulations were removed endoscopically. Given the mild form of stenosis, discussion with the primary team led to conservative management as the preferred approach.

The patient was successfully extubated 5 days later. However, after 10 days, the patient developed increased work of breathing, tachypnea, and mild biphasic stridor. An ABG showed increased PCO2 to 89. Bronchoscopy showed severe circumferential scarring at the site of the stenosis. The bronchoscope dilated the scar and the patient was reintubated with a 3.0 ETT.

Cardiovascular surgery was consulted for surgical management of the tracheal stenosis. A tracheal resection with an end-to-end anastomosis under ECMO was performed the same day. Histologic exam of the specimen showed a 2 cm segment with near complete tracheal rings. A bronchoscopy performed 1 week later showed normal healing at the anastomosis site without residual stenosis. The patient was successfully extubated 4 days later.

Another bronchoscopy done one month later showed mild stenosis at the anastomosis site with some granulations. A pH-probe evaluation showed severe GERD. The patient successfully underwent a fundoplication and G-tube placement. Bronchoscopies performed one and 6 months later showed a stable mild stenosis of the distal trachea without airway compromise, and mild tracheomalacia. The patient is currently at home without oxygen requirement, and growing well.

Congenital tracheal stenosis is defined as an intrinsic narrowing of the tracheal lumen arising the novo in the trachea. It may affect part or the entire trachea and may also extend into the bronchi. This narrowing may or may not be associated with other abnormalities of the trachea, such as complete tracheal rings. A complete tracheal ring is an anomaly where the normal C-shaped tracheal cartilage is fused posteriorly, replacing the normal posterior membranous portion of the trachea. This anomaly is often found in congenital tracheal stenosis.

Congenital tracheal stenosis is a rare disorder with an estimated incidence of 0.6% to 2.9% of patients presenting with various respiratory symptoms. With advances in neonatal medicine, this incidence is, however. expected to increase.

The first known case of congenital tracheal stenosis was that of autopsy findings, back in 1832. However, it was not until 1941 that it was described in the literature when Wolman did a review of 11 cases. Based on autopsy findings, he already advanced the concept that some children could outgrow their stenosis and have a good prognosis. Cantrell and Guild introduced the first classification of congenital tracheal stenosis in 1964 and also reported the first successful attempt at surgical correction. It was only with Kimura et al., in 1982, that a successful surgical option for long-segment tracheal stenosis was introduced, decreasing substantially the mortality for children in that subgroup. Tsang in 1989, and then Grillo in 1994, introduced the slide-tracheoplasty as another successful option for long-segment stenosis.

Tracheal stenoses were first classified, as mentioned before, by Cantrell and Guild in 1964. This system, though useful for classification and publication, does not encompass the wide variety of patterns of tracheal and bronchial stenosis and some authors prefer not to use any. Cantrell and Guild’s system consists of three types. The first type includes generalized tracheal hypoplasia, which is the most severe form and has the highest associated mortality. The second one, the “funnel-like” stenosis, is characterized by progressive proximal to distal tracheal stenosis. The third type is the “hourglass” or segmental stenosis and it is the most frequent type of tracheal stenosis.

Another classification has been introduced more recently by Hoeffer et al in 1994 to facilitate the management of congenital tracheal stenosis by taking prognosis in account. Class 1 consists of small segmental stenotic areas and few associated anomalies. It is associated with an 8% mortality rate and often responds to conservative therapy. Class 2 is characterized by extensive stenosis and one or many associated anomalies, except significant heart or lung disease. This condition carries a 45% mortality rate. Finally, Class 3 includes any stenotic lesion with significant pulmonary or cardiac disease and carries the highest mortality: 79%. Class 2 and 3 demand more definitive airway management procedures. These estimated mortality prognoses are likely to change with advances in surgical techniques.

Let’s review some embryology basics of the respiratory system to better understand the origins of congenital tracheal stenosis. When the embryo is about 4 weeks old, an outgrowth from the ventral wall of the foregut is formed. It is called the respiratory diverticulum. The hepatic primordium migrates from this outgrowth a few days later. The trachea will extend caudally, ventrally and roughly parallel to the esophagus. The lung buds, which are at the distal end of this outgrowth, will give rise to the bronchus and the lungs, starting around the fifth week.

By week 8, the splanchnic mesoderm surrounds the developing respiratory diverticulum and by week 10, the cartilage rings and the tracheal smooth muscles will already be clearly defined.

Though the clear etiology of congenital tracheal stenosis is not known, two hypotheses have been advanced to explain it. The first one is in the case of a disorder happening during the fourth week of gestation that would affect both the respiratory and hepatic primordia. This would give the most severe form of stenosis and a high prevalence of associated anomalies. On the other hand, if a disorder occured between the 8th and 10th weeks of gestation, impaired development would be limited to the cartilages and their supporting tissue. A less severe stenosis would then occur, with only few associated anomalies.

The diagnosis of congenital tracheal stenosis must be considered from birth to adulthood, though most cases will present between birth and 3 months of age. It is accepted that, in general, the younger the age at presentation, the worse the outcome, but this is not always true. Symptoms can be persistent from birth, as is usually the case in severe forms, or may be periodic, with exacerbations from respiratory infections. It can also be unmasked with intubation for an elective surgery for one of the associated congenital anomalies. In that case, difficult intubation, failure to extubate or requirements for high pressure ventilatory support should raise our suspicion.

Congenital tracheal stenosis presents itself with various and non-specific symptoms. The two most frequent symptoms are biphasic or expiratory stridor, depending on the location of the stenosis within the trachea, and respiratory distress. Other symptoms to look for are recurrent pneumonia, wheezing, cyanotic episodes, atypical bronchiolitis and failure to thrive.

Symptom severity is variable and depends on the patient’s age, the presence or absence of associated anomalies and on the degree of stenosis. It is important to realize that degree of stenosis is more important than length of stenosis, as airway resistance is linearly proportional to the length of stenosis, whereas it increases fourfold with a radius decrease of the tracheal lumen. Because of the rarity of this disorder and this variable and non-specific presentation, the initial diagnosis is rarely right.

Patients with congenital tracheal stenosis often have associated congenital anomalies and their presence should raise the level of suspicion for its diagnosis. Most frequently, those anomalies are from heart or vascular origin. Pulmonary artery sling is the most frequent associated anomaly, occurring in 30% of the cases. Other airway anomalies, like bronchial stenosis, tracheal bronchus or lung hypoplasia, are also frequent. Tracheoesophageal fistula, skeletal abnormalities and genetic disorders are also frequent findings.

The most frequent genetic disorder associated with congenital tracheal stenosis is Down syndrome, like for our little patient. As we know, airway obstruction is common in patients with Down syndrome and is often multifocal. Though the true incidence of congenital tracheal stenosis in those patients is not known, its association is now well recognized in the literature. It is not surprising since 40% of Down syndrome patients have a congenital heart disease, which is, in turn, associated with a 1.2% incidence of congenital tracheal stenosis, as we just saw. The defect is most often of the segmental type, with complete tracheal rings.

Diagnosis and management of congenital tracheal stenosis in Down syndrome patients is the same as in patients without genetic disorder, with careful attention to associated anomalies. Given this higher incidence of congenital tracheal stenosis and the 6% incidence of subglottic stenosis, a Down syndrome patient should always be intubated with an endotracheal tube 0.5-1.0 mm smaller than the standard age-appropriate tube size to avoid iatrogenic complication.

The diagnostic evaluation of congenital tracheal stenosis should include radiologic as well as endoscopic modalities. Precise evaluation of the length and degree of stenosis is essential to choose the appropriate treatment.

The initial study should be a chest X-ray using magnification and high kilovoltage. The air in the trachea will outline the tracheal lumen and show a stenosis if present. The exam should be done during inspiration and expiration to exclude air-trapping and impaired deflation of the lung. Though this exam is simple and easy, the quality of the image is not good enough for adequate surgical planning.

Tracheobronchography was once seen as an essential tool to adequately evaluate the length and severity of the stenosis and make appropriate surgical plans. This exam was not without consequences as airway inflammation and subsequent obstruction not uncommonly occurred. Introduction of non-ionic contrast has much improved this shortcoming, but this exam is now out of favor given the newest noninvasive techniques such as CT scan.

CT scan is now considered the best imaging modality for evaluation of the trachea and the major bronchi. It is especially useful to evaluate the full length of a stenosis too severe for a bronchoscope to go through or to rule out external compression of the trachea by a mass or an aberrant vessel. It has in fact pretty much replaced tracheobronchography in recent years since it is considered to be safer and less invasive. Spiral CT shortens the duration of the exam and allows 3D reconstruction and an excellent visualization of the airway beyond the site of stenosis.

A final and positive diagnosis can only be made with endoscopic evaluation. Endoscopy is also useful to plan the appropriate treatment, to evaluate for the presence of other associated anomalies and to assist in the assessment of the prognosis. This exam should only be performed in the presence of a skilled endoscopist and an experienced anesthesiology team since only minimal trauma to the stenotic segment can lead to edema and acute airway obstruction. For the same reasons, passage of the bronchoscope through the stenosis should be avoided unless the surgical team is present and prepared to perform a definitive repair at that time.

Finally, barium swallow study, echocardiography with Doppler imaging and MRI of the mediastinum are all very useful exams to exclude associated cardio-vascular anomalies.

The treatment of congenital tracheal stenosis is directed at providing a safe airway and at managing any associated anomalies. The choice of intervention will depend on the extent and severity of the lesion.
                                               
In patients with minimal disease and tolerating prolonged periods of time without hospitalization, conservative management is warranted. With time and optimal treatment, as the patient grows, the stenosis may become less significant and less symptomatic. Many cases of patient outgrowing their stenosis have actually been described in the literature to support this. Optimal conservative management consists of chest physiotherapy, humidification of inspired air, aggressive early intervention with medical therapy and antibiotics for upper respiratory tract infections, and avoidance of endotracheal intubation. Should it be necessary, endotracheal intubation should be performed so that the tip of the tube is positioned at least 1 cm above the stenosis and suctioning should be kept to an absolute minimum.

In children with severe or prolonged airway symptomatology, surgical intervention is recommended. Various surgical options exist depending on the severity of the stenosis.

Tracheotomy provides a safe airway for individuals with minimal but symptomatic disease who might have trouble at times of vigorous activities or upper respiratory tract infections. Gradual increases in the size of the tracheotomy tube can dilate the stenosis progressively and stent the airway open. This method of management avoids more involved surgery in these patients with slightly more advanced disease and gives them the chance to outgrow their disease.

Serial dilatations of tracheal stenosis can be performed with a balloon-tipped angioplasty catheter. This procedure is done through a bronchoscope or an endotracheal tube under general anesthesia. When needed, adjuvant techniques like electrocautery removal of granulations, steroids injections or intraluminal stents are used.

Hebra et al did a 15-year review in 1991 of 37 patients who had undergone balloon dilatation of their stenosis, 48.6% of whom had previously undergone an open procedure for their stenosis. The patients had four procedures on average. Fifty-four percent of them achieved long-term improvement and half of the tracheotomized patients were decannulated. They had four deaths, but only one was related to the procedure.

Other case series also emphasize the necessity of serial incremental procedures to maintain long-term cure. Because of this limitation in its effectiveness, balloon dilatation is only recommended to be used in recurrences of stenosis after an open procedure, in acquired tracheal stenosis or in cases were associated anomalies preclude major surgery.

Resection and primary anastomosis is the treatment of choice for strictures up to 50% of the length of the trachea. This is equivalent to about 8 rings. This can safely be performed even in neonates through a median sternotomy. This procedure is usually performed with cardiopulmonary bypass or extracorporeal membrane oxygenation. The surgeon can enhance tracheal mobility with suprahyoid release and a hilar mobilization. Prolene sutures through and through mucosa are currently favored in the literature. The head should be kept flexed for 2 to 4 weeks. Bronchoscopy and extubation are done in the OR 48 hours to 7 days later, depending on the surgeon’s preference. If some granulations are seen, they are removed at that time.

For patients with a stenosis of more than 50% of the length of the trachea, a tracheoplasty must be considered. Two options exist: the enlargement tracheoplasty or the slide tracheoplasty. The enlargement tracheoplasty consists of a longitudinal tracheal incision made the whole length of the stenosis. The surgeon then passes down the trachea an endotracheal tube appropriate for the patient’s size and a graft is finally placed to cover the secondary deficit in the tracheal wall. Postoperative intubation is required for 7 to 12 days. Different grafts have been used with variable success, including anterior esophagus wall, free tibial periosteal graft, pericardium or rib cartilage graft. The last two are most widely used.

The results of this procedure are variable, with mortality ranging from 0% to 77% in the literature. Recurrent tracheal granulations, restenosis and graft protrusion with lumen obstruction are frequently encountered whatever the graft type used.

Andrews, Cotton et a. did a review of 18 patients with long-segment stenosis treated with enlargement tracheoplasty and pericardial graft. Morbidity due to granulation tissue was common and required multiple endoscopic procedures. Tracheomalacia was also common, occurring in 6 patients. Thirteen percent of the patients continued to require tracheotomy tubes. They had an overall mortality of 47%, which is comparable to the results of other case-series.

Slide-tracheoplasty is the other surgical option for long-segment stenosis. It is performed by first transecting the mid-portion of the trachea. The mid-anterior wall of the proximal trachea and the mid-posterior wall of the distal trachea are then incised longitudinally. The two halves of the trachea are then overlapped and sutured together. The end result is a shorter but wider trachea.

Lang et al did a review of 11 cases treated by slide-tracheoplasty in 1999. All survivors had a dramatic improvement in their symptoms. The procedure allowed early extubation given the excellent tracheal stability obtained with the repair. Because there is only normal tracheal mucosa and no graft to mucosalize, granulation formation was only a minimal problem. The overall mortality in this series was 27%, which compares favorably with that for enlargement tracheoplasty. To maximize success, simultaneous treatment of all associated cardiovascular anomalies must be done, which implies performance of a complete preoperative diagnosis. With this high success rate and the low incidence of morbidity and complications, slide-tracheoplasty is slowly becoming the standard of care over enlargement tracheoplasty for long-segment tracheal stenosis.

Case Presentation

FP is a 3-week-old male with Down syndrome and PDA ligation hospitalized at Driscoll Children’s Hospital. There, he had been intubated soon after birth for respiratory distress secondary to meconium aspiration. After multiple unsuccessful intubation attempts in the NICU, a bronchoscopy with intubation in the OR had been required. This exam showed a narrowed mid-trachea. A chest CT scan suggested complete congenital tracheal rings.

He was then transferred to TCH, where his initial examination showed decreased breath sounds bilaterally and high-pressure volumes. The arterial blood gas (ABG) confirmed severe respiratory acidosis. Upon our initial examination, we performed a flexible bronchoscopy at the bedside through the 3.5 ETT. We could see tracheal narrowing with circumferential granulations at the tip of the ETT along with blood and mucus. We successfully improved the ventilation by reintubating the patient with a 3.0 ETT that passed the narrowed area. A bronchoscopy performed in the OR a few days later confirmed a mild narrowing at the level of the junction of the mid and distal thirds of the trachea with probable complete tracheal rings. The granulations were removed endoscopically. Given the mild form of stenosis, discussion with the primary team led to conservative management as the preferred approach.

The patient was successfully extubated 5 days later. However, after 10 days, the patient developed increased work of breathing, tachypnea, and mild biphasic stridor. An ABG showed increased PCO2 to 89. Bronchoscopy showed severe circumferential scarring at the site of the stenosis. The bronchoscope dilated the scar and the patient was reintubated with a 3.0 ETT. Cardiovascular surgery was consulted for surgical management of the tracheal stenosis. A tracheal resection with an end-to-end anastomosis under ECMO was performed the same day. Histologic exam of the specimen showed a 2 cm segment with near complete tracheal rings. A bronchoscopy performed 1 week later showed normal healing at the anastomosis site without residual stenosis. The patient was successfully extubated 4 days later.

Another bronchoscopy done one month later showed mild stenosis at the anastomosis site with some granulations. A pH-probe evaluation showed severe GERD. The patient successfully underwent a fundoplication and G-tube placement. Bronchoscopies performed one and 6 months later showed a stable mild stenosis of the distal trachea without airway compromise, and mild tracheomalacia. The patient is currently at home without oxygen requirement, and growing well.

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