Acute rejection: An early immune reaction to transplanted lungs where the immune system detects the new lungs as foreign and tries to mount an inflammatory response against them. Acute rejection occurs in approximately 60 percent of patients in the first year after transplantation and is diagnosed via a transbronchial biopsy obtained during bronchoscopy. Acute rejection is treated with steroids or other medications that suppress the immune system (such as antithymocyte globulin or alemtuzumab). Read about current research studies investigating ways to prevent acute rejection.

Bronchiolitis obliterans syndrome (BOS): A significant limiting factor to long term survival after lung transplantation. BOS is often used interchangeably with chronic lung rejection, and is thought to correlate with a condition of small airway scarring known as bronchiolitis obliterans (BO). BOS is assessed with pulmonary function testing and is diagnosed when the FEV1, a measure of lung function, falls substantially and does not improve. There are no proven treatments for BOS, however, augmented immunosuppression and antibiotics are sometimes used. Nearly 50 percent of lung transplant recipients are living with or have died from BOS five years after transplant.

Bronchoscopy: A procedure where physicians look into the lungs and surrounding airways using a small camera.

Chronic rejection: A condition characterized by scar tissue in the small airways of the lungs. Chronic rejection is the most important factor limiting long-term survival after lung transplant. There are no consistently effective treatments for this condition, which will affect approximately 50 percent of lung transplant patients within five years of transplant. Read about current research studies investigating ways to prevent chronic rejection.

Cytomegalovirus (pneumonitis and viremia): A common viral pathogen that can reactivate or cause disease following transplant. After lung transplantation, cytomegalovirus (CMV) is the most prevalent and serious opportunistic infection despite the use of early post-transplant anti-CMV prophylaxis. CMV can cause pneumonitis, an invasive form of the disease affecting the lungs directly, or a viral syndrome with fever, malaise, and CMV virus detected in the blood. Low CMV counts are often treated to preempt the development of more serious infection.

Gastroesophageal reflux disease: A condition in which the stomach contents (food, liquid, acid, or bile) leak backwards from the stomach into the esophagus. It is evaluated before and after transplant by impedance testing, 24-hour pH testing, esophageal manometry, barium swallow, or stomach emptying studies.

Nissen fundoplication: A surgical procedure used to treat gastroesophageal reflux disease. Laproscopically, the top part of the stomach (the fundus) is sewn 360 degrees around the esophagus to prevent stomach contents from re-entering the esophagus.

Valganciclovir: An antiviral medication used to treat cytomegalovirus infections.