Pulmonary Blebs and Bullae

Pulmonary Blebs and Bullae

A pulmonary bleb is a small collection of air between the lung and the outer surface of the lung (visceral pleura) usually found in the upper lobe of the lung. When a bleb ruptures the air escapes into the chest cavity causing a pneumothorax (air between the lung and chest cavity) which can result in a collapsed lung. If blebs become larger or come together to form a larger cyst, they are called bulla. Unless a pneumothorax occurs, or the bulla becomes very large, there are usually no symptoms. Patients with blebs will typically have emphysema.

Who Is at Risk for Lung Blebs and Bullae?

Men are far more likely than women to develop blebs and bullae by a margin of approximately 70% to 30%.

Likewise, there are certain high-risk occupations that could increase your risk of developing lung blebs, such as those that put you in close contact with dust, chemicals, fibers, germs, or smoke among other things.

Blebs and bullae are thought to be tied to an underlying disease such as bronchitis, emphysema (known as a chronic obstructive pulmonary disease (COPD)), cystic fibrosis, and even cancer.

However, even otherwise healthy young men (18-20+) can fall prey to a primary spontaneous pneumothorax (PSP) event, characterized by abnormal air accumulation in the pleural space.

That accumulated air can lead to a partial or complete lung collapse.

When patients have no other underlying medical conditions or triggering events, doctors call it primary spontaneous pneumothorax (PSP).

What Causes Blebs?

Researchers suspect that tobacco and cannabis smoking, emphysema (also called Chronic obstructive pulmonary disease, or COPD), and other lung conditions can lead to the development of blebs and bullae. That’s because blebs are especially prevalent in damaged lung tissue.

Emphysema is a type of COPD characterized by damage to the lung alveoli (air sacs) attached to the bronchi that complete the gaseous exchanges of air and carbon dioxide.

Emphysematous lung tissue can be particularly weak. Because the lung’s air sac tissue is weakened, it’s easier for air to escape the ruptured alveoli.  

What Is a Pneumothorax?

Pulmonary blebs tend to appear in the upper lobes of the lung. When they rupture, the air held in the bleb escapes into the chest cavity, leading to a collapsed lung, also known as pneumothorax.

Depending on the degree of collapse and a patient’s overall respiratory status, symptoms can include shortness of breath, difficulty breathing, and chest or chest wall pain.

In larger pneumothoraces or complete lung collapse, a patient may become cyanotic or develop other respiratory distress symptoms.

PSP usually isn’t tied to any underlying lung disease. And, clinical experience and research have shown that PSP isn’t caused by the simple rupturing of blebs and bullae.

Instead, it’s associated with diffuse and often bilateral (both lungs) abnormalities, such as pleurisy (pleura inflammation) or “water on the lungs” (pleural effusion), which is a gathering of fluid between the layers of tissue that line your lungs and your chest cavity.

Emphysematous changes in the alveoli, inflammation, and pleural porosity also contribute to PSP.

Diagnosing Pneumothorax

The symptoms of a collapsed lung may be mild or severe and include:

1. Shortness of breath

2. Chest pain, which could be stronger on one side or the other

3. Sharp pain when you inhale

4. Lung pressure that increases with time

5. Lips or skin turning blue

6. Increased heart rate

7. Rapid breathing

In most pneumothorax cases, a chest X-ray is the first-line diagnostic tool. Doctors may also order an ultrasound to identify pneumothorax. For more detailed images, a CT scan may be necessary.

CT scans use multiple X-rays from different angles and computer-processed combinations to produce high-quality images of the pleural space and any blebs or bullae. Those images can determine the size and location of a bleb or bulla.

Technicians may also use computed tomography to help with the placement of a tube thoracostomy.

Pneumothorax Treatment

There are several pneumothorax treatment options, which may be a relief to hear. However, part of the reason for that is some treatments are debated in the medical community.

For instance, while oxygen has been the traditional treatment for small, asymptomatic, or mildly symptomatic pneumothorax, recent medical literature has questioned its effectiveness and recommended further study.

A tube thoracostomy (chest tube placement) is one of the most common lines of treatment. A chest tube or catheter evacuates air from the thoracic cavity, allowing the lung to heal and re-expand. The line is removed after a successful water seal trial, preventing air backflow into the pleural space.

Most surgeons consider video-assisted thoracoscopic surgery (VATS) to be the gold standard in treating pneumothoraces and blebs/bullae. VATS is a low-intrusion technique that can help with diagnosis and treatment.

Clinicians and researchers continue to discuss whether prophylactic VATS is advised. Generally, the criteria for surgical intervention in pneumothorax include:

1. A persistent air leak

2. Recurrence or multiple pneumothoraces

3. Radiologically demonstrated large bulla

4. Only partial lung expansion even with drainage and suction

5. Tension pneumothorax

6. Bilateral pneumothorax

7. Spontaneous pneumothorax for high-risk occupations

During a VATS procedure, the surgeon inserts a thoracoscope (chest tube) and surgical instruments into the chest through small incisions in the chest wall. The thoracoscopetransmits internal images of the chest to a video monitor to guide the surgeon.

It is unknown whether radiological evidence of pulmonary blebs or bullae is a predictor of pneumothorax. Many professionals are also skeptical that blebs or bullae can cause Primary Spontaneous Pneumothorax (PSP). For instance, nearly 89% of PSP patients with PSP in “normal lungs” had visible blebs or bullae when examined by an endoscope.

Typically, the first instance of symptomatic PSP is treated through observation and chest tube placement. Your doctor may recommend bleb or bulla resection combined with mechanical pleurodesis — manual scarring of the pleura to prevent the recurrence of spontaneous pneumothorax or pleural effusion — or a pleurectomy, which removes portions of the parietal pleura.

Resection may be indicated for returning patients who have more than one pneumothoraxevent.

While there’s no real consensus about PSP treatment, clinicians and surgeons tend to treat blebs conservatively because there are still many controversies regarding diagnostic tools and management plans.

After Surgery

For the first day or so, a chest tube is left in to help adhere the once deflated lung to the chest wall (pleural symphysis). The tube will be removed if no leak is apparent, and the patient will be sent home. Patients will undergo physical therapy to promote recovery.

References

Sugarbaker DJ, Bueno R, Krasna MJ, Mentzer SJ, Zellos L (eds). Adult Chest Surgery. New York: The McGraw-Hill Company, 2009.

Ohata M, Suzuki H. Pathogenesis of spontaneous pneumothorax: With special reference to the ultrastructure of emphysematous bullae. Chest. 77:771–6, 1980.

Clagett OT. The management of spontaneous pneumothorax. J ThoracCardiovasc Surg. 55:761–2, 1968.

Mehran RJ, Deslauriers J. Indications for surgery and patient work-up for bullectomy. Chest Surg Clin North Am. 5:717–34, 1995.