Definition of tracheal stenosis

Tracheal stenosis is defined as the constriction of the trachea, or windpipe, which makes breathing more difficult. The trachea is a cartilage tube made of soft tissue. Air moving from your mouth and nose to your lungs passes through your trachea. It becomes more difficult for air to pass through your trachea when you have tracheal stenosis because of inflammation, damage, or scar tissue.¹ The medical term for the abnormal narrowing of a bodily channel is "stenosis." It may appear in various areas of your throat. For instance, laryngotracheal stenosis, a similar disorder, causes narrowing of the larynx (voice box) and trachea. Narrowing the region beneath your voice cords and above your trachea is known as subglottic stenosis.¹

Iatrogenic causes

Tracheal stenosis can arise due to various local factors, such as damage from airway tube contact, Inability to manage cuff pressure, infections, or technical errors during procedures. Systemic contributors, like cardiovascular issues and metabolic diseases, may also weaken the tracheal wall and lead to narrowing. Additionally, less common causes include congenital abnormalities, autoimmune disorders, tumours, and physical trauma.²

This condition often causes difficulty breathing, which can severely impact daily life and become life-threatening if left untreated. Identifying high-risk individuals and diagnosing the condition early are essential for implementing preventive and therapeutic measures. However, the exact causes of tracheal stenosis remain unclear, as prior research has shown inconsistent results. To address this uncertainty, this article focuses on identifying potential risk factors to enhance prevention and management strategies for this condition.²

Normal anatomy of the trachea

The trachea is positioned along the midline of the neck and upper chest, beginning at the lower edge of the larynx, specifically at the cricoid cartilage. It extends into the thoracic cavity and measures approximately 10–12 centimetres in length and 2–2.5 centimetres in diameter in adults. It spans from the C6 vertebra to the T4/T5 vertebrae, terminating at the carina, where it branches into the left and right main bronchi.³

The trachea is supported by 16–20 C-shaped hyaline cartilage rings, which are evenly spaced along its length. These cartilage rings help maintain the trachea’s structure and keep the airway open. The posterior side of the rings is incomplete, facing the esophagus, allowing flexibility during swallowing.³

Blood supply to the trachea is provided by the inferior thyroid arteries and bronchial arteries. It receives nerve signals from the autonomic and sensory nervous systems, including parasympathetic fibres from the vagus nerve (cranial nerve X), sympathetic fibres from the thoracic sympathetic ganglia, and sensory fibres from the vagus nerve. Lymphatic drainage occurs through the pretracheal and paratracheal lymph nodes, eventually flowing into the bronchomediastinal lymphatic trunks.³

Functions

The trachea is a primary airway that connects the upper respiratory system to the lungs. It helps warm and humidify the air before it reaches the lungs. It is essential in keeping the airway open and protecting the lower respiratory system by filtering the air. The trachea's cilia move mucus and trapped particles upward, where they can be cleared by swallowing or coughing. This process is called mucociliary clearance. The trachea is highly responsive to irritants and foreign particles, helping to trigger the cough reflex to remove harmful substances. It also aids in regulating airflow into and out of the lungs. Furthermore, the trachea provides flexibility for swallowing and supports the structure of the left and right main bronchi.³

Pathophysiology of tracheal stenosis 

Tracheal stenosis is often acquired after intubation or tracheostomy, and it can also be part of a broader condition called tracheobronchial stenosis. It happens when inflammation, trauma, or infection causes scarring and fibrosis in the trachea, which leads to a narrowing of the airway. This narrowing is usually caused by abnormal healing processes, such as the growth of granulation tissue, thickening of the tracheal walls, and damage to the cartilage rings. Inflammation and tissue death (necrosis) of the tracheal lining are most common at the site of the tracheostomy stoma or where the tube balloon is placed. Acute stenosis that occurs after intubation is typically due to swelling (oedema) or granulation tissue. This type of stenosis can extend over several centimetres and usually affects the trachea above the level of the chest opening. In cases of chronic strictures, tracheomalacia (weakening of the tracheal cartilage) can develop, which may cause difficulty breathing (dyspnea).⁴

Risk factors

Tracheal stenosis has several risk factors, These include having a tracheotomy as mentioned above, diabetes, prolonged intubation and mechanical ventilation, respiratory infections, a high incision, and a ratio of the intratracheal tube cuff diameter (C) to the transverse diameter at the clavicle (T) greater than 150%. To reduce the risk of tracheal stenosis, it's important to shorten the duration of mechanical ventilation and intubation, avoid unnecessary tracheotomies after long periods of intubation, and consider early tracheotomy for obese patients who need prolonged mechanical ventilation. Additionally, choosing the correct incision location and catheter, maintaining an appropriate C/T ratio, preventing respiratory infections, and managing diabetes can help minimise the risk of developing tracheal stenosis.²

Diagnosis

Idiopathic tracheal stenosis is typically diagnosed after other potential causes have been excluded. This diagnosis is often made alongside a medical history review and physical examination. Confirmation is achieved through various diagnostic tests such as chest X-rays, CT scans, pulmonary function tests, and bronchoscopy.⁵

ENT specialists use several tests to diagnose tracheal stenosis and determine the appropriate treatment. These may include:

• Endoscopic Procedures: Bronchoscopy is the main procedure used to diagnose tracheal stenosis, and sometimes a laryngoscopy may also be performed¹
• Imaging Procedures: A CT scan of the chest and neck is the most commonly used imaging technique for detecting tracheal stenosis. In some cases, an MRI may be recommended to help guide treatment planning¹
• Pulmonary Function Tests: Breathing tests are often required to assess lung function¹
• Additional Tests: Blood tests may be used to check for signs of infection or inflammation, and a biopsy may be conducted to determine if any abnormal growths in the airway are cancerous¹

Management and treatment

There are multiple strategies for managing tracheal stenosis. While physical examination, flow-volume studies, and CT scans play an important role in diagnosis, bronchoscopy is essential for visual confirmation to assess the severity and nature of the stenosis.⁵

The most common treatments for tracheal stenosis focus on procedures designed to expand the trachea. These options include:

• Tracheal Dilation: A balloon or dilator is inserted into the trachea to stretch it, improving airflow and making breathing easier¹
• Laser Bronchoscopy: A laser is used to remove scar tissue from the trachea, which helps open up the airway¹
• Tracheal Stent: A small stent, made from plastic or metal, is placed in the trachea to keep it open. However, this may not be suitable for all cases, depending on the location of the stenosis¹
• Tracheal Resection and Reconstruction: In this surgical procedure, the tissue causing the narrowing is removed, and the two ends of the trachea are reconnected, restoring a clear airway¹

The most appropriate treatment depends on the location and severity of the stenosis. Your healthcare provider will guide you in selecting the best approach for your condition.

Prognosis

Treatment for tracheal stenosis typically involves surgery or a nonsurgical procedure. Each option has different recovery times and outcomes. Surgical options like tracheal resection and reconstruction are more invasive but offer long-term relief by removing the narrowing. Nonsurgical procedures like tracheal dilation are less invasive and may provide sufficient relief or need to be repeated. Regardless of the procedure, your healthcare provider will closely monitor your recovery to detect any recurrence, as new scar tissue can develop. They will discuss the likelihood of the condition returning and the necessary follow-up care.¹

Conclusion

Tracheal stenosis, caused by the narrowing of the trachea due to trauma, inflammation, or scarring, is a serious condition that can affect breathing. Timely diagnosis and the right treatment, whether surgical or nonsurgical, are crucial for restoring airflow and improving the quality of life. Though treatments are generally effective, recurrence is possible, which makes continuous monitoring and follow-up care important for long-term management.