Congenital TS may manifest in neonates or pediatric patients, and the age of symptom onset largely depends on the severity of developmental defects. Acquired TS may affect patients of any age, a significant share of whom presents with a medical history of endotracheal intubation, tracheostomy or other procedures involving the windpipe. Other patients develop TS due to as yet undiagnosed space-occupying lesions and may not be able to provide conclusive anamnestic data.
In general, TS is related to respiratory problems. Patients generally suffer from dyspnea. In mild cases, dyspnea may only be experienced during exercise. In severe cases, dyspnea is observable at rest and associated with cyanosis. TS patients tend to wheeze and cough. Due to the negative intra-thoracic pressure stimulating air flow during inspiration, a less stable trachea tends to collapse in this breathing phase. This process is often accompanied by respiratory sounds. However, additional respiratory sounds that are perceptible during expiration do not rule out TS. TS predisposes to respiratory infections and some patients may present with recurrent bronchitis and pneumonia.
Neither of the aforementioned symptoms is pathognomonic for TS. Indeed, TS patients have repeatedly been misdiagnosed with lower airway disease and asthma. Thus, non-responders need to be carefully re-evaluated for possible TS and underlying pathologies . This is of utmost importance in cases where neoplasms cause TS. An early diagnosis of cancerous disease may significantly improve the prognosis of the patient.
Of note, congenital TS may be associated with additional malformations, e.g., congenital heart diseases like atrial septal defect, ventricular septal defect, double aortic arch, patent ductus arteriosus, and Tetralogy of Fallot, among others . Patients diagnosed with either of those entities should be thoroughly examined for the presence of TS and vice versa.
Severe TS may be diagnosed after clinical examination. Chronic, less severe cases are more difficult to identify. It may be particularly challenging to distinguish TS from other, more common lower respiratory tract diseases such as bronchitis and asthma. In this context, an examination with a laryngoscope or fiberoptic nasopharyngoscope should allow for a reliable assessment of the upper respiratory tract. An endoscopic examination may be required to confirm a tentative diagnosis of TS and to ascertain the presence of intra-tracheal obstructions. Endoscopy is considered the gold standard for TS diagnosis . Tracheoscopy and bronchoscopy may be realized in a single procedure. If necessary, biopsy samples may be taken under endoscopic guidance. Their histopathological analysis may be of great importance for therapeutic decisions. Of note, some patients may react with tachycardia and cardiac arrhythmias during endoscopic examination. Patients with cardiovascular problems should be monitored accordingly.
Other techniques may be employed to depict those tissues surrounding the trachea. Extra-tracheal pathologies like space-occupying lesions may be recognized in images obtained by means of computed tomography or magnetic resonance imaging. Cardiovascular malformations may be diagnosed similarly, but echocardiography is of greater importance to this end .
Spirometric evaluation of lung function may be very helpful but requires an active participation of the patient. The expiration of air through stenotic airways takes abnormally long and patients suffering from TS usually require more than a second to exhale 70% of the tidal volume. The corresponding test may be repeated after the administration of bronchodilators. In the case of asthmatic patients, test results typically improve, but this does not apply to individuals suffering from TS.
Treatment of tracheal stenosis depends on the disease etiology. In general, surgical interventions should be kept to a minimum since they may promote the growth of fibrous tissue that may aggravate the patient's initial condition. As has been mentioned above, tracheostomy is associated with a considerable high rate of post-operative TS. Therefore, minimally invasive techniques are to be preferred to remove scar tissue and to widen the tracheal lumen. Laser surgery and balloon catheter dilation are often carried out, but relapses are frequent in moderate to severe cases of TS. Intraluminal stents may provide short-term relief, but a resection of narrowed sections of the trachea with subsequent reconstruction of the windpipe is often unavoidable. In this context, tracheal end-to-end anastomosis and side-slide tracheoplasty have been used successfully , but may not be feasible if an extensive tracheal resection is necessary. Alternatively, pericardial or aortic patches or tracheal autografts may be used to reconstruct the trachea. This is of major importance in congenital TS since this condition often comprises large segments of the windpipe. If extra-tracheal, space-occupying lesions like a vascular ring, goiter, or tumor account for TS, therapy should aim at a decompression of the trachea and may comprise drug therapy or surgical resection of the mass lesion.
Overall prognosis will depend on the grade of stenosis and on the underlying disease. While short-term prognosis is good, long-term prognosis is doubtful. Intraluminal stents may momentarily resolve the respiratory problem, but the restoration of complete tracheal function may not be possible. Balloon catheter dilation is associated with a high risk of recurrence. Prognosis improves with early diagnosis and initiation of treatment .
Congenital TS is a rare condition. It is most frequently associated with complete tracheal rings of cartilage and may involve either short or extended portion of the windpipe. Furthermore, the precise location, as well as the degree of luminal narrowing may vary . Additionally, vascular malformations may lead to tracheomalacia and TS in neonates .
Acquired TS is usually related to internal or external trauma, tracheomalacia or neoplasms, among others.
The overall incidence of congenital TS has been estimated to be <2 per 100,000 live births. Only about a fourth of affected neonates present with isolated TS, while the majority of patients are diagnosed with comorbidities like cardiovascular malformations .
The most common cause of acquired TS is prolonged endotracheal intubation, wherein TS is primarily developed by patients who have been intubated for prolonged periods of time. Anesthetists have been using the technique of endotracheal intubation for more than a hundred years. A possible causal relation between intubation and tracheal disease was first reported about fifty years ago . Since then, the quality of endotracheal tubes has improved considerably. The incidence rate of tracheal injury per intubation has concomitantly been decreasing. However, the overall number of patients who receive respiratory support has been increasing, which might explain why TS can still be observed rather frequently. Moreover, the vast majority of patients who undergo tracheostomy show certain degrees of tracheal narrowing and 3-12% of these people develop clinically relevant TS .
As has been indicated above, congenital TS may be the result of distinct developmental defects. On the one hand, complete cartilage rings may impede tracheal growth. On the other hand, so-called vascular rings may encircle the trachea and hinder its development.
With regards to post-intubation TS, this condition ultimately results from mucosal damage due to the pressure exerted by inflated cuffs. Therefore, many patients feel somewhat sore after an endotracheal intubation. The part of the tracheal wall that has been under pressure becomes edematous but usually heals within a short period of time. This may, however, not be the case if high pressure provokes mucosal ischemia and subsequent ulceration. The ulcer may also heal, but the healing process may involve the formation of granulation tissue as well as fibrous remodeling of the tracheal wall. Finally, the fibrous tissue contracts and the trachea loses elasticity. TS may manifest several weeks after the intubation.
The location of TS may reveal important clues as to the cause of post-intubation TS:
Today, high pressure-low volume cuffed tubes have largely been replaced by low pressure-high volume ones. The latter distribute pressure along an extended part of the trachea, minimize point loads, and thus allow for prolonged endotracheal intubation without increasing the risk of TS. Moreover, some materials used for the fabrication of endotracheal tubes have been found to cause mucosal damage and subsequent stenosis. These materials are no longer used. These technical advances have significantly contributed to a decreasing incidence of TS per intubation.
Few recommendations can be given to prevent TS. Endotracheal intubation should be performed only when strictly necessary, particularly in patients with a known history of tracheal problems. However, the possible consequences of not having a patient intubated usually by far outweigh the risks of tracheal lesions due to intubation. Low-grade stenosis after tracheal surgery is often unavoidable.
Because early detection of TS significantly improves the outlook, close monitoring after prolonged intubation, tracheostomy or tracheal surgery may help to prevent more severe sequelae.
The trachea is a part of the upper respiratory tract and connects the larynx and the bronchial tubes. There are several organs in close proximity to the trachea, e.g. esophagus, thyroid gland, salivary glands and lymph nodes.
Any obstruction of the trachea may be deemed tracheal stenosis (TS). Here, TS is used as a general term that merely refers to the mechanical narrowing of the trachea. It may be congenital or acquired and may be the result of intra-tracheal or extra-tracheal processes. With regards to intra-tracheal pathologies, mucosal irritation and inflammation after prolonged intubation may lead to TS. Despite the continuous improvement of materials and methods, endotracheal intubation continues to be the most common trigger of TS. Furthermore, tracheitis may be provoked by infectious agents, autoimmune reactions or prolonged exposure to noxious gasses such as tobacco smoke. Distinct pathologies may affect adjacent organs and if mass lesions occur outside of the trachea, they may compress the trachea leading to TS.
Trachea is the Latin name of the windpipe. The trachea forms part of the upper respiratory tract and connects the larynx with the bronchial tubes. It is composed of a series of C-shaped cartilage rings that confer considerable stability to this organ. If the tracheal lumen is narrowed due to any reason, physicians will diagnose the condition as tracheal stenosis (TS).
Since TS is a general term, there are many possible causes. TS may be present at birth, e.g. if a newborn has O-shaped, complete cartilage rings that hinder tracheal growth. However, the most common trigger of TS is prolonged endotracheal intubation. If someone is intubated, the tube will be arrested in their trachea by inflating an endotracheal cuff. It will exert some pressure on the tracheal mucosa, but it will maintain the tube in place and allow inhalation anesthesia or respiratory support. If the tracheal mucosa has to support high pressure or pressure for prolonged periods of time, an ulcer may develop. These ulcers will eventually heal, but during the healing process fibrous tissue may form and narrow down the tracheal lumen. Other causes for TS are external trauma as well as space-occupying processes in close proximity, e.g., goiter and tumors.
The single most important symptom of TS is difficulty in breathing. This may manifest during exercise or even at rest. Patients may perceive respiratory sounds when inhaling or exhaling. Wheezing and coughing is common. Because patients suffering from TS are more susceptible to respiratory infections, recurrent bronchitis or pneumonia may also indicate tracheal narrowing. Reduced supply of oxygen to the body's tissues may be noted as the skin takes on a bluish tone. This condition is referred to as cyanosis and is most easily seen around the mouth and the nose.
Visualization of the tracheal lumen and surrounding tissues is the mainstay of diagnosing TS. The former is best examined by means of laryngoscopy and bronchoscopy. A small camera is introduced into the patient's upper airway and the condition of the trachea may be assessed directly. Computed tomography scans may be required to assess the general condition of the head and neck region.
Lung function tests may be carried out if the patient is able to actively participate in the examination.
Treatment depends on the degree of tracheal narrowing and the underlying disease. Laser surgery is a minimally invasive technique that may be applied to remove scar tissue. Also, a balloon may be used to dilate the trachea. However, these methods are associated with frequent relapses, particularly in more severe cases of TS. Open surgery is associated with the risk of formation of scar tissue and further narrowing of the windpipe. In severe cases, the constricted part of the trachea has to be removed and the upper airways have to be reconstructed using different techniques.