A lung transplant is a major surgical procedure intended to replace a patient’s diseased lungs with healthy lungs from a deceased donor. This intervention is reserved for individuals with chronic, irreversible, end-stage lung disease when all other medical treatments have failed. The primary purpose is to restore pulmonary function, significantly improving the recipient’s quality of life and prolonging survival. It is pursued only when a patient’s lung condition has become life-threatening.
Primary Lung Conditions Requiring Intervention
The need for a lung transplant typically arises from a small number of progressive, debilitating lung diseases that cause permanent damage to the pulmonary architecture. These conditions fall into distinct categories based on how they impair the lungs’ ability to exchange oxygen and carbon dioxide. Obstructive lung diseases, such as severe Chronic Obstructive Pulmonary Disease (COPD) and emphysema, are a common cause for transplant referral.
In obstructive diseases, the airways narrow and the air sacs (alveoli) are destroyed, trapping air and making it difficult to exhale fully. This destruction, often caused by smoking or Alpha-1 antitrypsin deficiency, leads to hyperinflation and inefficient gas exchange. Idiopathic Pulmonary Fibrosis (IPF) and other interstitial lung diseases (ILDs) represent the restrictive category, causing scarring (fibrosis) that makes the lungs stiff and unable to fully expand.
Another major group includes suppurative diseases, like advanced Cystic Fibrosis (CF) and severe bronchiectasis, where chronic infection and inflammation lead to thick, sticky mucus and permanent widening of the airways. This process results in continuous bacterial colonization and recurrent, destructive infections. Finally, certain vascular diseases, notably Primary Pulmonary Hypertension (PH), can also necessitate a transplant. PH involves dangerously high blood pressure in the arteries of the lungs, which strains the right side of the heart and ultimately causes heart failure.
Defining End-Stage Lung Failure
A disease’s name alone is not enough to warrant a transplant; the functional severity must reach a point defined as end-stage lung failure, indicating a severely limited life expectancy. This determination relies on specific functional metrics, such as rapidly declining results on Pulmonary Function Tests (PFTs). For example, for obstructive diseases like COPD, a forced expiratory volume in one second (FEV1) that is less than 15% to 20% of the predicted value is a strong indicator of severe failure.
For restrictive diseases, a significant decline in the forced vital capacity (FVC) or the diffusing capacity of the lung for carbon monoxide (DLCO) over a short period suggests a poor prognosis. Patients are often considered candidates when their life expectancy is predicted to be only one to two years without the procedure. A high risk of imminent death is frequently demonstrated by the need for continuous supplemental oxygen, especially during rest or mild activity, or by severe limitation on a six-minute walk test.
The decision to list a patient occurs when their quality of life is severely compromised despite receiving maximal medical therapy. This advanced stage is often associated with frequent hospitalizations due to respiratory decline and an inability to perform routine daily activities. The timing is crucial, aiming to transplant the patient when they are sick enough to need it but well enough to survive the intensive surgery.
Essential Physical and Social Requirements for Candidacy
Even with confirmed end-stage lung failure, a patient must meet strict non-pulmonary requirements to be eligible for transplantation, focusing on maximizing the chances of a successful long-term outcome. The function of other major organ systems must be stable, as the stress of surgery and the necessary post-transplant medications can heavily impact them. Significant dysfunction of the kidneys or liver, for example, would likely preclude isolated lung transplantation.
A patient’s nutritional status is also carefully evaluated, with a Body Mass Index (BMI) needing to be less than 35 to avoid poor outcomes associated with severe obesity or cachexia. Beyond physical health, a robust psychological profile and social support system are mandatory for candidacy. Patients must demonstrate a strong commitment to medical adherence, as the post-transplant regimen involves complex medication schedules and lifelong immunosuppression.
The transplant team assesses the patient’s capacity to manage the rigorous follow-up care, which includes frequent clinic visits, rehabilitation, and financial stability to cover prescription costs. A reliable network of family and friends is necessary to provide emotional and logistical support throughout the recovery. Patients must be ambulatory and possess the physical and mental stamina to participate fully in post-operative rehabilitation.
Conditions That Prevent Eligibility
Certain pre-existing conditions are considered absolute contraindications, even in the face of severe lung disease. Active or recent malignancy is a major disqualifier, with most programs requiring a cancer-free period of at least five years, due to the risk that immunosuppressive drugs could cause cancer recurrence or rapid spread.
Active smoking or substance abuse is also an absolute exclusion criterion, and patients must demonstrate sustained abstinence from nicotine for a minimum of six months before being considered for listing. These exclusion criteria ensure that the limited supply of donor organs is directed toward candidates who have the highest probability of long-term survival and quality of life. Other major contraindications include:
- Significant, irreversible dysfunction of other major organ systems outside of the lungs, such as severe coronary artery disease or advanced kidney failure, which would make the patient too high-risk.
- A chronic, untreatable infection outside of the lungs.
- A severe neurologic deficit.