A giant bulla is a complication of emphysema. In areas of the lung completely damaged by the disease, air pockets can develop. These areas threaten the patient’s health not only because of the underlying emphysema. As an air pocket—a bulla—grows, it takes up space in the chest cavity and can encroach on the lungs. Severe disruption of normal lung function due to the crowding and pressure is a common result.
Bullous emphysema is also known as vanishing lung syndrome. It is most often treated by surgical removal of the bulla, which can grow to 20 centimeters—more than a foot—in diameter. A bulla that takes up a third or more of the space in and around the affected lung is called a giant bulla. Because of its close association with emphysema, giant bullae are most often found in older patients who smoke or used to smoke. A giant bulla is classified as a chronic obstructive pulmonary disease (COPD), along with chronic bronchitis and asthma.
The Mechanics of Giant Bullae
Emphysema causes a loss of elasticity in the walls of the small air sacs in the lung. Eventually, the walls of the sacs stretch and break, which creates larger, less efficient sacs that can’t properly handle the normal exchange of oxygen and carbon dioxide that occurs during breathing. Difficulty in fully exhaling usually leads to the capture of air in the lungs, known as hyperinflation. A giant bulla is a large cavity of captured air.
But giant bullae begin to take on an identity of their own. On chest x-rays they appear as entities somewhat independent of the remaining normal structure of the affected lung, separated by a thin, fibrous, irregular membrane. As they fill with air and grow, giant bullae can also fill with fluid to create an infectious mix. Not only can a giant bulla obstruct the function of the host lung; it can put pressure on the other lung and interfere with its proper function. So even tissue not affected by the disease becomes less effective.
Most giant bullae reach their size and status slowly over time. But there are instances of bullae experiencing “growth spurts” and changing the situation in the patient’s chest cavity rather quickly. Bullae also can disappear or “deflate” either spontaneously or following an infection or hemorrhage.
Because of its size, a giant bulla makes its presence known and produces symptoms. On its way to becoming a giant bulla, however, the air pocket in the lung doesn’t show symptoms beyond what the patient is experiencing from the underlying emphysema.
Symptoms from a giant bulla can include:
- Pressure in the chest
- Difficulty drawing breath
- A bloated feeling
- General fatigue (due to lack of oxygen)
Smoking cigarettes is by far the most common cause of emphysema. And emphysema is by far the most common cause of giant bullae in the lungs. There are limited cases of bullae appearing in the lungs as a result of bronchial illnesses from high air pollution levels, or occupational exposure to chemical fumes.
Despite the fact that vanishing lung syndrome is a condition most often found in older people, giant bullae have also been found in young men.
A diagnosis seeks to determine whether the patient’s lung functions are being impeded by the pressure caused by a giant bulla or the general effects of the underlying emphysema. Like most other lung cancers, doctors rely on non-invasive chest x-rays and the more detailed CT (computed tomography) scans to initially locate and identify giant bullae. For more precise information, a doctor might retrieve and analyze a sample of the bulla’s cells or fluid within the bulla. Retrieval is performed by inserting a long surgical needle into the affected area, or by a localized surgical biopsy.
In virtually every case, the treatment for a giant bulla is a bullectomy—surgical removal of the growth. Patients with a giant bulla are divided into four groups:
- Group I—single giant bulla with underlying normal lung
- Group II—multiple giant bullae with underlying normal lung
- Group III—multiple bullae with underlying lung broadly affected by emphysema
- Group IV—multiple bullae with underlying lung affected by other diseases
Patients in the first two groups are “ideal candidates” and stand the best chance of success. Success is defined as both a lessening of the pressure and other symptoms, and the recovery or restoration of lung function. There are possible complications, such as an air leak or an infection in the incision.
Group III and IV patients cannot expect similar success rates. In cases where the lung is widely destroyed, they might be advised to undergo a lung transplant.