What is Tracheal Bronchus?

The tracheal bronchus is an uncommon birth defect characterized by unusual formations of the airways that stem from the trachea (the windpipe) and go towards the upper part of the lung. Generally, these formations occur within 2 cm of the carina, the area where the trachea divides into the two main bronchi (the large airways) for each lung. However, they can occur anywhere from the cricoid cartilage (a ring-shaped structure in the windpipe) to the carina. Some experts suggest that if this unusual bronchus (airway) supplies the entire upper lobe of the lung, it is referred to as bronchus suis or “pig bronchus”. This description does not include bronchi that come from the main bronchus (the large airway in each lung).

What Causes Tracheal Bronchus?

Three theories highlight different ways a tracheal bronchus might form during the early stage of development:

* The reduction theory indicates that a tracheal bronchus can result from a previously developed bronchus getting reduced in size.
* The migration theory suggests that a part of an already developed lung branch can stretch or move to a different position on the windpipe or bronchus, causing a tracheal bronchus.
* Lastly, the selection theory believes that disturbances during the formation of lung structures could cause these abnormalities. It says that if the tissue that will eventually form the bronchus comes into contact with the inner lining of the windpipe, a tracheal bronchus could develop.

Risk Factors and Frequency for Tracheal Bronchus

Tracheal bronchus is a condition that appears in about 0.9 to 3% of children, according to multiple studies. It’s often found on the right side of the body, with 0.1 to 2% of cases. The left side experiences a slightly smaller number of 0.3 to 1%. Tracheal bronchus has been linked to other birth defects. These include Down syndrome, VATER (issues with the vertebrae, anus, trachea, esophagus, and kidneys), throat and esophagus problems, spine malformations, heart defects, and underdeveloped lungs. In children, tracheal bronchus is usually found when the child is around 15 months old. It’s equally common in boys and girls. It’s often found in conjunction with other congenital conditions, with 92.3% of cases. These include heart disease (69% of cases), chromosomal abnormalities (35% of cases), and spinal fusion defects (11% of cases).

Tracheal bronchus is present in 0.9 to 3% children.
Most cases occur on the right side, with 0.1 to 2% of cases. On the left side, it’s 0.3 to 1%.
This condition can be linked to other birth defects such as Down Syndrome, VATER, esophagus problems, spine defects, heart conditions, and underdeveloped lungs.
It usually becomes apparent when the child is around 15 months old.
There’s no difference in occurrence between boys and girls.
It often comes with other congenital conditions, found in 92.3% of cases. These include heart disease in 69% of cases, chromosomal abnormalities in 35% of cases, and spinal fusion defects in 11% of cases.

Signs and Symptoms of Tracheal Bronchus

A tracheal bronchus is a condition that may not show symptoms in children, but it is often visible through signs such as wheezing, shortness of breath, a stubborn cough, frequent instances of pneumonia, or lung collapse. Adults are often asymptomatic, with the condition becoming apparent later in life. This condition should be considered in cases involving persistent pneumonia in the upper part of the lungs, lung collapse, trapped air, and chronic bronchitis.

Patients may experience chronic symptoms such as productive cough and frequent pneumonia over many years, which can sometimes lead to changes in the lung structure, as seen on a CT scan. In cases where tracheal bronchus is discovered unexpectedly—for example, during intubation or surgery—medical practitioners need to be extra mindful. There’s the danger of endotracheal tubes obstructing or accidentally entering the bronchus, leading to lung collapse, low oxygen levels, or both.

Although it’s rare for this tube to be misplaced, it’s still something that needs to be taken into account. Furthermore, the fact that a tracheal bronchus can originate anywhere along the trachea adds to the complexity. Therefore, follow-up chest X-rays are crucial. The presence of a tracheal bronchus can complicate cases where only one lung needs to be ventilated. In such scenarios, a flexible bronchoscopy should be performed to locate the tracheal bronchus and measure its distance from the carina. Subsequently, either a double-lumen tube or a regular endotracheal tube, along with bronchial blockers, can be used.

Choices between the two types of tubes are determined by normal lung anatomy as well as the nature of the tracheal bronchus. Although the left-sided double-lumen tube is most commonly used, there are exceptions where the right-sided tube is preferred. However, using the right-sided tube is not advisable in cases of a right-sided tracheal bronchus as it can block the tracheal bronchus. The tube positioning should always be confirmed using a flexible bronchoscope. Depending on which side the bronchus is on, lung isolation can be achieved either by clamping the tracheal tube or endobronchial tube.

Another more advanced tube called a ‘univent tube’ can also be used, which has two passages within a single tube and has in-built parts that can block the bronchus. Lastly, there are reports that support the use of the left-sided double-lumen tube over bronchial blockers for a tracheal bronchus.

Testing for Tracheal Bronchus

In some cases, a chest X-ray or chest CT scan can reveal a tracheal bronchus, a rare condition where an extra branch forms off the windpipe. However, this condition is most often discovered by accident during a bronchoscopy, a procedure where a doctor looks inside the respiratory system with a camera on a flexible tube.

The best test to detect congenital tracheobronchial anomalies, which are birth defects in the windpipe and bronchial tubes, is a multi-detector CT scan (MDCT) with a 3D image reconstruction. This non-invasive test builds a 3D model of the tracheobronchial system and it’s faster, covers more area, and requires less sedation than a bronchoscopy. The 3D reconstruction is especially helpful for identifying the relationship between the bronchi (air passages that connect the trachea to the lungs) and arteries. That understanding is valuable if surgery is needed.

In the past, certain conditions were hard to identify in the axial CT images, like subtle tracheal stenosis (narrowing), longitudinal extension of airway disease, and disease in airways that tilt obliquely. However, the 3D reconstructed images have helped overcome these limitations. Other noticeable conditions that can be seen in imaging for symptomatic patients include bronchiectasis (dilated bronchi), focal emphysema, and focal cystic malformations.

In a study comparing the effectiveness of MRI, MDCT, and 3D imaging in diagnosing tracheobronchial anomalies, MDCT proved to be superior to MRI. Also, 3D imaging provided specific information beneficial for surgical planning in more than half of the patients who underwent both MDCT and 3D imaging.

The role of FDG PET scans, a type of medical imaging that helps reveal how tissues and organs are functioning, is limited when it comes to differentiating between an inflammatory or malignant lesion of the tracheal bronchus. Therefore, after surgery, the extracted specimens are typically sent for a microscopic examination to determine the nature of the lesion.

Treatment Options for Tracheal Bronchus

Tracheal bronchus is a condition that can affect the airways in our lungs. The main method of handling this condition depends on whether a person is displaying symptoms. For those who aren’t experiencing any symptoms, usually all that is required is routine check-ups to monitor the situation. However, if someone has symptoms, the approach to treatment depends on how severe these symptoms are.

It’s possible for tracheal bronchus to produce a variety of symptoms. To help manage these, several medications can be used. These include bronchodilators (medicines that help open up the airways in the lungs), inhaled corticosteroids (medicines that help to reduce inflammation in the lungs), muscarinic antagonists (medicines that help to relax and widen the airways in the lungs), and antibiotics (medicines that fight infections).

If these medications aren’t successful in relieving the symptoms, surgical treatment could be considered next. There are surgical treatments known as segmentectomy and lobectomy, which involve the removal of a small part of the lung or a larger lobe of the lung respectively. These surgeries are typically done to treat recurring lung infections caused by tracheal bronchus and they have shown to be curative, meaning they aim to completely treat and get rid of the disease.

In cases where the patient needs to be put on a ventilator due to one lung being operated on (unilateral thoracotomy), bronchial blockers can be used. These are devices inserted into the airway, allowing one lung to be ventilated while the other is operated on. Alternatively, a double-lumen endotracheal tube, which is a special breathing tube, can be used. It’s important to correctly position the tube in these patients to avoid blocking the tracheal bronchus, a smaller breathing tube or adjusting the position of the tube can help. Health care providers often use a fiber optic bronchoscope, a device which provides a video image of the airways, to confirm the correct placement of the tube.

There are several medical conditions or irregularities that could potentially be causing certain symptoms. Consider the following:

Pneumonia
Tracheal stenosis
Tracheomalacia
Bronchomalacia
Inborn heart, esophagus, or larynx irregularities, as well as specific syndromes like Down syndrome or VACTERAL (which can involve vertebra defects, anal atresia, heart defects, tracheoesophageal fistula, kidney anomalies, and limb abnormalities)
Extra or supernumerary bronchus
Asthma

It’s important for healthcare professionals to take into account each of these possibilities when examining a patient and making a diagnosis.

What to expect with Tracheal Bronchus

Based on the available treatments, having a tracheal bronchus generally leads to good results. There isn’t any specific numbers we can provide to compare the results of a patient who had a surgical treatment for tracheal bronchus. But, there was a study on children that reported positive results 2 to 10 years after treatment, which was just an observation. In one case, a child who had surgery to remove their upper right lung lobe ended up needing a tracheostomy, which is a procedure that involves creating an opening in the neck to place a tube into the trachea to help breathe, but it significantly reduced how often they needed it.

Another case involved a 1-year-old patient who had an upper lobe lobectomy, which is a surgical procedure to remove one of the lobes of the lung, done through thoracoscopy, which is a minimally invasive surgical procedure where the chest cavity is inspected, and this patient had no complications one year after their surgery.

There are only two known cases of thoracoscopic upper lobe lobectomy or segmentectomy, which are types of lung surgeries, in adults with tracheal bronchus, and both had an uneventful recovery.

Possible Complications When Diagnosed with Tracheal Bronchus

Repeated instances of pneumonia
Atelectasis, a condition where the lung does not fully inflate
Acute respiratory failure, which is severe difficulty in breathing
Aspiration pneumonia, which can occur if there’s a connection with the esophagus
Congestive heart failure, which can accompany a congenital heart anomaly

Preventing Tracheal Bronchus

From the research we have, it seems there are no known genetic reasons that make some people more likely to develop abnormalities in their windpipe and lung airways. We still need to lay out how we might prevent these disorders, particularly after we pinpoint if there are any genetic factors involved. These disorders are present from birth.