Bronchiolitis Obliterans Following Lung Transplantation

Introduction

Lung transplantation (a surgical procedure where the diseased lung is replaced with a healthy one) is one such step taken in cases where lung damage has occurred. After the lung transplantation, protection and attention to the recipient's body are important to see if the lung transplant is stable and acceptable to the patient's body. Unfortunately, sometimes these lung transplants can cause a condition in the lung called bronchiolitis obliterans. Bronchiolitis obliterans and its associated risk factors, symptoms, diagnosis, and treatment steps taken to prevent bronchiolitis obliterans are further discussed below.

What Are Bronchiolitis Obliterans?

Bronchiolitis obliterans is also termed popcorn lungs. It is a condition where the lungs' bronchioles (small branched air tubes present in the lungs) get affected due to infection and inflammation (swelling). The bronchioles in the lungs have the smallest air passages, and these passages get blocked when they are subjected to infections. Further, these obstructive airways cause a decline in lung function. Bronchiolitis obliterans usually develops after lung transplantation or hematopoietic stem cell transplantation (intravenous transplantation of hematopoietic stem cells, which are immature blood cells that further develop into blood parameters like red blood cells, white blood cells, and platelets). Although it is not an infection, it relates to an infection. Therefore, the main reason for developing bronchiolitis obliterans is the scarring of the airways, specifically of the transplanted lung.

What Are the Risk Factors of Bronchiolitis Obliterans?

There are many cases in which lung transplantation patients progress to bronchiolitis obliterans conditions. But some patients develop bronchiolitis obliterans earlier than other people. It is due to some risk factors that initiate the process earlier, and they are:

• Primary Graft Dysfunction: This condition occurs when the lung being transplanted has got injured while retrieving it from the donor's body. If the injured lung is transplanted, then it requires more attention and support after transplantation.

• Lung Rejection: In some cases, lung rejection can occur by the recipient's body as the antigens and antibodies are formed against the transplanted donor's lung.

• Gastroesophageal Reflux Disease (GERD): Gastroesophageal reflux disease is formed when stomach acid flows in a backward direction entering directly into the tube that connects the mouth to the stomach (esophagus). In this backflow process, there is fluid reflux into the airways in the lungs while reaching the throat. It is commonly seen in patients dealing with lung transplantation and lung injury.

• Infections: There are certain types of infections that can increase the chances of bronchiolitis obliterans. Some of the common microbes that are associated with bronchiolitis are Pseudomonas aeruginosa (bacteria), Cytomegalovirus (virus), Aspergillus (fungus), respiratory syncytial virus (RSV), parainfluenza virus, and influenza virus (flu-virus).

What Are the Associated Symptoms of Bronchiolitis Obliterans?

Sometimes, people after getting affected by bronchiolitis obliterans, express no related symptoms. So the recipient patient with a transplanted lung needs to have regular follow-ups after getting transplanted. It is a very important step to prevent the patient from bronchiolitis obliterans. Although some people do show symptoms and they are:

• Shortness of breath (dyspnea).

• Decrease in exercise and physical activity.

• Fatigue.

• Cough.

• Sometimes, cough with mucus production.

• Fever.

• Chills.

How Bronchiolitis Obliterans Is Diagnosed?

After the patient has undergone lung transplantation, the doctor recommends the patient for regular follow-up visits to check the functioning of the lung. This follow-up is scheduled to check the stability and ensure no infection develops after transplantation. For diagnostic and safety purposes, the doctor recommends undergoing a few tests mentioned below:

• Checking Lung Function: Lung function tests are performed by doctors to diagnose bronchiolitis obliterans. It is done by using the forced expiratory volume (FEV1), which can measure the amount of air blown out in a second of forced expiration. It can be measured by another method of FEV of 25 to 75 percent, called spirometry. In the initial months of transplantation, the spirometry method is used to measure the values of the lungs, like FEV1. If any such values change or decrease, it gets noticed by the doctor as it can increase the chances of bronchiolitis obliterans.

• Imaging Studies: The patient is recommended to undergo chest X-rays or CT (computerized tomography) scans to determine if there are any infections or abnormalities. Sometimes air entrapment and new infiltrates can cause chances of rejection of the lung that is transplanted and to figure them out, imaging studies are recommended.

• Bronchoscopy: Bronchoscopy is a type of endoscopic technique used to view the inner part of the lungs. Also, other procedures like lung biopsy are performed by checking samples of the lung tissue to diagnose any infections. Bronchoalveolar lavage is another technique used to test the lung fluid through the tiny tubes and then suction it out for testing. These tests mainly diagnose any kind of infection that can lead to bronchiolitis obliterans.

How Is Bronchiolitis Obliterans Treated and Prevented?

Bronchiolitis obliterans is prevented from lowering the failure of lung transplants. Therefore, an important point regarding bronchiolitis obliterans is to prevent lung function from decreasing. Important points to remember regarding the prevention of bronchiolitis obliterans are:

• The infections are treated previously from the main stem. The infections can be bacterial, viral, or fungal.

• Treatment of any rejection episodes with short treatment with medications of corticosteroids.

• If any GERD (gastroesophageal reflux disorder) occurs, then the doctor should recommend the patient anti-reflux medications to prevent it.

• Sometimes, long-term treatment with Azithromycin can reduce the effects of inflammation. It also controls the lung function test by reversing it.

• Adding immunosuppressive therapy in the transplantation treatment.

• Including one immunosuppressive medicine in treatment can be a better opinion.

If bronchiolitis obliterans continues or is very severe to be uncured by the treatment. Then the patient should go for a second lung transplantation.

Conclusion

Bronchiolitis obliterans is a condition in which the lung gets infected and inflamed. Such infections can occur after lung transplantation if the donor's lung is retrieved during the patient's episode of injury. The bronchioles present in it get blocked, and fewer air passages occur. And they eventually lead to symptoms like shortness of breath, fever, chills, cough, and fatigue. Therefore, diagnosis of bronchiolitis obliterans is important and is performed by lung function test and bronchoscopy. However, bronchiolitis obliterans must be prevented as they can lead to lung transplantation failure. Although they lead to certain complications, with prompt diagnosis and treatment, the living condition of the patient can be improved.