Lung Transplantation Health Article

Definition

Lung transplantation involves removal of one or both diseased lungs from a patient and the replacement of the lungs with healthy organs from a donor. Lung transplantation may refer to single, double, or even heart-lung transplantation.

Purpose

The purpose of lung transplantation is to replace a lung that no longer functions with a healthy lung. To perform a lung transplantation, there should be potential for rehabilitated breathing function. Other medical treatments should be attempted before transplantion is considered. Many candidates for this procedure have end-stage fibrotic lung disease, are dependent on oxygen therapy, and are likely to die of their disease in 12 to 18 months.

Demographics

In order to qualify for lung transplantation, a patient must suffer from severe lung disease such as:

• emphysema
• cystic fibrosis

• pulmonary fibrosis
• pulmonary hypertension
• bronchiectasis
• sarcoidosis
• silicosis

Patients with emphysema or chronic obstructive pulmonary disease (COPD) should be under 60 years of age, have a life expectancy without transplantation of two years or less, progressive deterioration, and emotional stability in order to be considered for lung transplantation. Young patients with end-stage silicosis may be candidates for lung or heart-lung transplantation. Patients with stage III or stage IV sarcoidosis with cor pulmonale (right-sided heart failure) should be considered as early as possible for lung transplantation.

Description

Once a patient has been selected as a possible organ recipient, the process of waiting for a donor organ match begins. The donor organ must meet specific requirements for tissue match in order to reduce the chance of organ rejection. It is estimated that it takes an average of one to two years to receive a suitable donor lung, and the wait is made less predictable by the necessity for tissue match. Patients on a recipient list must be available and ready to come to the hospital immediately when a donor match is found, since the life of the lungs outside the body is brief.

Single lung transplantation is performed via a standard thoracotomy (incision in the chest wall) with the patient under general anesthesia. Cardiopulmonary bypass (diversion of blood flow from the heart) is not always necessary for a single lung transplant. If bypass is necessary, it involves re-routing of the blood through tubes to a heart-lung bypass machine. Double lung transplantation involves implanting the lungs as two separate lungs, and cardiopulmonary bypass is usually required. The patient's lung or lungs are removed and the donor lungs are stitched into place. Drainage tubes are inserted into the chest area to help drain fluid, blood, and air out of the chest.

Heart-lung transplants always require the use of cardiopulmonary bypass. An incision is made through the middle of the sternum. The heart, lung, and supporting structures are transplanted into the recipient at the same time.

Diagnosis/Preparation

Patients who have diseases or conditions that may make them more susceptible to organ rejection are not selected for lung transplant. This includes patients who are acutely ill and unstable; have uncontrolled or untreatable pulmonary infection; significant dysfunction of other organs, particularly the liver, kidney, or central nervous system; and those with significant coronary disease or left ventricular dysfunction. Patients who actively smoke cigarettes or are dependent on drugs or alcohol may not be selected. There are a variety of protocols that are used to determine if a patient will be placed on a transplant recipient list, and criteria may vary depending on location.

The following diagnostic tests are usually performed to evaluate a patient for lung transplantation:

• Arterial blood gases (ABG) test, which measures the amount of oxygen that the blood is able to carry to body tissues.
• Pulmonary function tests (PFTs), which measure lung volume and the rate of air flow through the lungs; the results measure the progress of the lung disease.
• Radiographic studies (x rays). The most common is the chest x ray (CXR), which takes an internal picture of the chest including the lungs, ribs, heart, and the contours of the major vessels of the chest.
• Computerized tomography (CT) scan. A chest CT scan is taken of horizontal slices of the chest to provide detailed images of the structure of the chest.
• Ventilation perfusion scan (lung scan, V/Q scan) is a test that compares right and left lung function.
• Electrocardiogram (EKG) is performed by placing electrodes on the chest and one electrode on each of the four limbs. A recording of the electrical activity of the heart is obtained to provide information about the rate and rhythm of the heartbeat, and to assess any damage.
• Echocardiogram (ECHO) is an ultrasound of the heart, performed to evaluate the impact of lung disease on the heart. It examines the chambers, valves, aorta, and the wall motion of the heart. ECHO also provides information concerning the blood pressure in the pulmonary arteries. This information is required to plan the transplantation surgery.
• Blood tests. Blood samples are required for both routine and specialized testing.

In addition to tests and criteria for selection as a candidate for transplantation, patients are prepared by discussing at length the procedure, risks, and expected prognosis with the doctor. Patients should continue to follow all therapies and medications for treatment of the underlying disease, unless otherwise instructed by their physician. Since lung transplantation takes place under general anesthesia, patients are advised not to take food or drink from midnight before the surgery.