Airway Complications After Lung Transplant

Introduction:

Lung transplantation is an effective therapeutic option for people with end-stage lung disease that offers long-term survival and improved quality of life. Lung transplantation is usually performed in patients whose condition does not improve with medications or any other treatments. Like any other surgery, complications are associated with lung transplantation. Despite the advancements in surgical techniques, airway complications following lung transplantation remain a source of morbidity. However, recent advancements in organ preservation and medical management of the patient have resulted in a significant decrease in the airway complications that occur after lung transplantation.

What Is a Lung Transplant?

A lung transplant is a type of surgical procedure that is used to remove one or both damaged lungs and replace them with a healthy lung from the donor. Most of the replaced lungs are taken from a deceased person. Lung transplantation is associated with complications like infections and rejections. However, most people return to normal life within three to six months. The two main types of lung transplants are as follows:

• Cadaveric Transplants: The lungs required for replacement are obtained from deceased organ donors.

• Living Transplant: The lungs to be replaced are taken from non-smoking healthy adults who are a good match and can donate a portion of one of their lungs. People who donate a portion of their lungs can lead a healthy life with the remaining lung tissue.

What Are the Complications Associated With Lung Transplants?

The risks associated with a lung transplant are as follows:

• Surgical Risks: Like any other surgical procedure, lung transplantation also has associated risks like blood clots, unfavorable scarring, bleeding, and infections.

• Risk of Rejection: The immune system protects the body by defending against foreign substances that harm the body. In patients who undergo lung transplantation, the body’s immune system interprets the lungs as a foreign object and attacks them. As a result, the body’s immune system rejects the new lungs. The chances of transplant rejection are high in the initial months (first 12 months) following the surgery and decrease over time. Hence, immunosuppressive drugs are given to the patient to prevent transplant rejection. In most cases, patients are advised to take these drugs for the rest of their life.

• Risk of Infection: Immunosuppressive drugs are often given to people who undergo lung transplantation to stop or slow down the immune system from rejecting the new lung. A suppressed immune system has a reduced ability to fight infections, and the patient is prone to developing infections like skin, blood, respiratory, and fungal infections.

What Are the Airway Complications After a Lung Transplant?

The airway complications following a lung transplant are as follows:

• Bronchial Stenosis: Bronchial stenosis refers to the narrowing of the bronchial tubes that branch off the trachea into the lungs. It is one of the most common airway complications after a lung transplant. It is usually seen within the first two to nine months after the surgery, but can also occur a year after the transplantation. Some patients with bronchial stenosis may be asymptomatic while others may experience symptoms like cough, wheezing, shortness of breath (dyspnea), or post-obstructive pneumonia. In very few patients, a severe form of bronchial stenosis called vanishing bronchus intermedius syndrome (VBIS) is seen. VBIS is the narrowing or degeneration of the bronchus intermedius associated with increased morbidity and mortality. It is usually seen six months after the transplant.

• Dehiscence: Dehiscence occurs due to severe airway necrosis and occurs within one to five weeks of transplantation. It may be of two types namely partial or complete. The morbidity and mortality rates vary depending on the severity of the infection. The commonly observed features are the inability to wean from mechanical ventilation, pneumothorax or collapsed lung (a condition in which air from the lungs leaks into the space between the chest wall and the lung), subcutaneous emphysema (a condition in which the presence of air is seen under the skin), lung collapse, or persistent leakage of air after transplant. It can lead to further infections or peribronchial abscess (a swollen area near the bronchus that is filled with pus mostly due to bacterial infection). Complete dehiscence often succumbs to sepsis (a life-threatening condition in which the body responds extremely to an infection).

• Tracheobronchomalacia: Tracheobronchomalacia is the weakening or collapsing of the trachea (airway) and bronchial tubes leading to difficulty in breathing. It is usually seen within four months after the transplantation procedure. The symptoms include the inability to clear secretions, wheezing, dyspnea, recurrent infections, stridor (an abnormal high-pitched sound caused while breathing due to disrupted airflow), and a ‘barking’ cough.

• Bronchial Fistulae: The bronchial fistula is a communicating tract between the bronchus (airway in the lungs) and the pleural surface of the lungs or surface of the thoracic wall. Fistulas involving the endobronchial tree are the most severe complication that occurs after lung transplantation. It often presents as a life-threatening condition characterized by hypotension, tension pneumothorax (a life-threatening situation in which air gets accumulated in the space between the lungs and the chest wall resulting in compression of the lungs, heart, and other structures in the chest), subcutaneous emphysema, or persistent air leak.

• Exophytic Granulation Tissue: Benign endobronchial granulation tissue results in airway obstruction in some patients within a few months after the surgery. Infection with Aspergillus intensifies the condition. The symptoms are cough, hypoxia, progressive dyspnea, or post-obstructive pneumonia.

• Anastomotic Infections: The use of steroids and immunosuppressives increases the risk of endobronchial infections involving opportunistic pathogens. Bacterial infections caused by Pseudomonas and Staphylococcus aureus include bronchitis, tracheitis, or pneumonia. Fungal infection caused by Aspergillus mainly involves airway complications like bronchial stenosis.

How to Diagnose Airway Complications After a Lung Transplant?

The methods to diagnose the various airway complications after a lung transplant are as follows:

• Flexible bronchoscopy.

• CT (computed tomography) scan of the chest.

• Chest X-ray.

• Spirometry.

• Helical CT (computed tomography).

• Dynamic magnetic resonance imaging.

• Virtual bronchoscopy.

How to Treat Airway Complications After a Lung Transplant?

The treatment options for various airway complications after a lung transplant are as follows:

• The treatment options for bronchial stenosis are as follows:

  1. Neodymium-yttrium-aluminum-garnet (Nd: YAG) laser is used for sudden clearing of blocked airways.

  2. Cryotherapy (a procedure that uses an extremely cold instrument or liquid to freeze and destroy abnormal tissues).

  3. Endobronchial electrocautery knife (a tool with diagnostic and therapeutic purposes in managing conditions that cause airway obstruction).

  4. Balloon bronchoplasty (a minimally invasive method to dilate a blocked airway and restore sufficient airflow).

  5. Endobronchial stent (a tube that is placed to open the narrowed airway and help in breathing).

  6. Argon plasma coagulation (a procedure that uses argon gas to control bleeding from the lesions of the gastrointestinal tract).

  7. Balloon dilation (often done along with endobronchial stent placement).

  8. Silicone stents and self-expanding metallic stents in severe cases.

  9. Surgical options are lobectomy (a surgical procedure to remove one of the lobes of the lungs), retransplantation (a treatment option for lung transplant recipients with severe graft dysfunction), and wedge bronchoplasty (a wedge-shaped reconstruction or repair of the bronchus following lung procedures).

• The treatment options for dehiscence are as follows:

  1. Mild cases are treated with surveillance bronchoscopy and antibiotic treatment.

  2. Placing self-expanding metallic stents.

  3. Surgical options include flap bronchoplasty (a procedure which is used to improve the narrowing of the bronchial tube and lung function), reanastomosis (a surgical procedure that is used to reconnect two body structures by reversing the surgery that was used to disconnect these structures), or retransplantation.

• The treatment options for tracheobronchomalacia are as follows:

  1. Asymptomatic patients mostly do not require any treatment.

  2. Airway clearance techniques like percussion vests or oscillatory devices.

  3. Conservative medical management.

  4. Airway stenting.

  5. Maintenance of airway hydration with mucolytics (medicines that are used for the thinning and loosening of the mucus in the airways to clear it easily through coughing), saline nebulizer treatments, and noninvasive positive-pressure ventilation.

  6. Severe cases may require nocturnal noninvasive positive-pressure ventilation or silicone stent insertion.

  7. Surgical methods like tracheoplasty (a surgical procedure to improve airflow by widening the obstructed airway), reconstruction, resection, and retransplantation are rarely used.

• The treatment options for bronchial fistulae are as follows:

  1. Antibiotics.

  2. Thoracostomy (a procedure in which a tube is inserted into the space between the lungs and the chest wall to remove air or fluids and also to deliver medications).

  3. Surgical options include direct closure with flap reinforcement, trans-sternal bronchial closure, chronic open drainage, or thoracoplasty.

  4. Endoscopic closure techniques using methyl-2-cyanoacrylate, tissue glues, and fibrinogen plus thrombin are useful in patients who cannot tolerate highly invasive procedures.

  5. Covered metallic stents are used to occlude airway fistulas.

  6. Endobronchial valves are used to prevent persistent air leaks.

• The treatment options for exophytic granulation tissue are as follows:

  1. Debridement using cryotherapy or neodymium: yttrium-aluminum-garnet (Nd: YAG) laser.

  2. Forceps resection is used in exercising localized mild granulation tissue.

  3. Argon plasma coagulation.

  4. Electrocautery (a procedure in which abnormal tissue is removed using heat from an electric current).

• The treatment options for anastomotic infections are as follows:

  1. Combination of systemic antibiotics and bronchoscopic debridement or drainage.

  2. Aerosolized Tobramycin or Colistin is often used as an adjunct treatment for multidrug-resistant bacterial infections.

  3. Anti-fungal prophylactic agents like inhaled Amphotericin-B, Itraconazole, or Voriconazole are used.

  4. Frequent bronchoscopy surveillance.

  5. Aggressive early empiric therapy (a therapy that is given only based on experience without any knowledge about the nature or cause of the disease).

Conclusion:

Although the chances of airway complications after a lung transplant are low, it is associated with significant mortality rates despite the advancements in surgical techniques. However, early recognition of airway complications using interventional bronchoscopy procedures and advanced medical management helps prevent them. Hence, based on its potential to save the lives of people who have end-stage lung disease, a lung transplant is considered a boon by many people despite the complications.