What is Bronchopleural Fistula?
A bronchopleural fistula (BPF) is a tunnel-like structure that forms between the branches of the windpipe and the space around the lungs. This condition can be a serious complication after operations like lung removal. The condition affects between 25% and 71% of patients undergoing certain procedures and can be challenging to diagnose and treat. Factors that can contribute to a BPF include infection leading to tissue damage, a constant collapsed lung, cancer treatment like chemotherapy or radiation, and tuberculosis.
The treatment options for BPF vary. They can include medication, procedures using a bronchoscope for severely ill patients, and surgery for those with the highest risk factors. However, there is no widely accepted best treatment option due to differences in outcome success. BPFs are classified by how soon after surgery they occur: early (1 to 7 days), intermediate (8 to 30 days), or late (more than 30 days). Most commonly, these fistulas form within three months after surgery, but they can also occur at any time following lung infections.
What Causes Bronchopleural Fistula?
Bronchopleural fistula (BPF), a condition where there’s a channel or passageway between the airways in the lung and the chest cavity, often develops after surgery on the right side of the lungs. It’s typically found near the remaining lung tissue and can be a result of a lack of blood supply to the area or an increase in bacterial growth due to the pooling of secretions. The higher risk of developing a BPF after a removal of the entire lung on the right side (pneumonectomy) is due to the more extensive nature of the surgery.
Several factors can increase the chances of getting a bronchopleural fistula. These include chemotherapy and radiation therapy, diabetic conditions, a history of heavy smoking and chronic lung disease, a lung condition called ‘bullous lung disease’, abnormal build-up of air pockets in the lungs (spontaneous pneumothorax), or other lung tissue abnormalities.
Other risks include having poor nutrition or wounds that heal slowly, a previous surgical procedure on the same side of the chest, having a large bronchial stump (over 25 mm in diameter), extensive removal of lymph nodes in the area, being older than 60 years, an ongoing fever, use of steroids, high white blood cell count, having a tracheostomy (surgical opening in the windpipe), use of bronchoscopy for removal of sputum or mucus, remaining cancerous tissue after surgery, tightness of surgical stitches, extensive surgical exploration around the windpipe and airways, and needing mechanical ventilation for an extended period after surgery.
Several health conditions and medical procedures can also increase the risk of developing a bronchopleural fistula. These include various types of bacterial, fungal and viral infections, inflammation of the esophagus due to acid reflux, a tear in the esophagus, lung, thyroid or esophageal cancers, lymphomas, traumatic injuries to the chest involving the airways, certain procedures for intubation (placing a tube into the airways), necrotizing lung disease associated with radiation or chemotherapy, acute respiratory distress syndrome (especially in patients requiring ventilation with high airway pressures), damage to the lungs caused by a ventilator or forceful manual ventilation, and central line placement.
Risk Factors and Frequency for Bronchopleural Fistula
A bronchopleural fistula (BPF) is a condition that’s usually seen after surgery to remove part or all of a lung. Specifically, it occurs in 4.5% to 20% of cases following the removal of a lung (pneumonectomy) and 0.5% to 1% of cases after the removal of a lobe of the lung (lobectomy).
Signs and Symptoms of Bronchopleural Fistula
Bronchopleural fistula (BPF) is a condition that manifests with various symptoms, which could either be sudden or gradual. Most commonly, these symptoms appear within two weeks after a person has had lung surgery. The early signs of this condition might include shortness of breath, chest pain, unstable heart rate and blood pressure, and pockets of air beneath the skin. These symptoms might not be as sudden if a chest tube is still present from surgery. In such cases, a persistent air leak through the tube might be the primary sign.
If the condition begins to reveal itself more than 14 days after surgery, or if it is a result of other causes like infections or cancer, a patient might start showing signs of a condition called empyema. Symptoms of empyema include:
- Fever
- General feeling of discomfort or illness
- Loss of muscle mass
- Coughing up thick, often yellow or green, mucus
- Reduced breath sounds on the affected side
- A dull sound when the doctor taps on your chest (percussing your chest)
If the empyema is not drained properly and the infection spreads to the chest wall, a hole might develop between the skin and the chest cavity, allowing mucus to drain out; a condition known as empyema necessitans.
Testing for Bronchopleural Fistula
A continuous leak of air after an injury to the lung could mean two things. Either there is a break in one of the bronchi, which are the major air passages of the lungs, or a small air sac in the lungs called an alveolus has burst. To diagnose these, different methods can be used. Examples are feeding a dye called methylene blue into the space around the lungs or using bronchography, which is a type of x-ray that uses a contrast material to highlight the bronchial tubes.
Sometimes, small metal probes are used, which also helps to know how much oxygen and N2O (a kind of gas) a patient with a lung problem is breathing in. A procedure called bronchoscopy allows doctors to check how healthy the bronchial stump is and helps them point out the exact location of the air leak. This procedure also helps rule out tuberculosis or other infectious diseases. Furthermore, it can help doctors introduce substances into the patient’s body that can help to seal the leaking part.
Larger air leaks or fistulas can often be seen during a bronchoscopy, but sometimes doctors need to temporarily block the bronchi with a balloon to find smaller air leaks. The presence of an air leak from a main, lobar, or segmental bronchus to the space around the lungs can help doctors diagnose an air leak or fistula.
Although there are no specific lab tests that can confirm air leaks, some patients who also have an infection around their lungs may show raised levels of white blood cells or an increased erythrocyte sedimentation rate, which is a test that measures how fast red blood cells settle at the bottom of a test tube.
Certain things seen in lung images could suggest the presence of an air leak. Examples are increased space around the lungs, new air-fluid levels, change in existing air-fluid levels, tension pneumothorax (a severe condition where air collects in the space around the lungs), and decreases in air-fluid levels exceeding 2 cm. A CT scan could show these and other features like pneumothorax, pneumomediastinum (air around the lungs), and features related to the original lung problem.
In some patients, CT scans can show evidence of the air leak. If the patient has not had lung surgery, CT scans can even pick up features of the original problem such as cancer with features like a mass that has a hollow region and air-fluid levels.
Specific types of CT scans can show the air leak in about half of the patients. The air leak is usually located towards the outer areas of the lung, and in very rare cases, there is an air leak after lung surgery. Three-dimensional images can clearly show the whole air leak. The presence of continuous bubbles during a procedure called bronchial washing suggests the presence of an air leak.
A bronchoscope with a balloon-like catheter inflated into selected airways can help find the location of the air leak, as the balloon occlusion decreases or stops the air leak. A procedure called capnography measures the level of carbon dioxide at the end of a breath and can identify the part of the bronchus related to the air leak. This method reportedly can correctly identify air leaks in 83% of the cases and doesn’t misdiagnose in 100% of the cases.
Certain techniques use special aerosol inhalation and imaging procedures to locate air leaks. However, these methods need a lot of time and the patient’s cooperation. There may be false positives, meaning the tests could show an air leak when there isn’t one, especially in patients with airway blockages. Moreover, the size of the air leak may not be correctly measured with these methods.
An advanced procedure called computed tomography bronchography (CTB) has been used in diagnosing difficult air leaks. After a bronchoscopy, a contrast medium (a solution that enhances the image) is injected at the suspected air leak site. Afterward, a CT scan is performed immediately with targeted reconstruction of images in different planes, allowing easy visualization of the air leak.
Treatment Options for Bronchopleural Fistula
The first step in treating a Bronchopleural fistula (BPF), a dangerous condition affecting the bronchi and pleural cavity, involves managing any immediate, potentially life-threatening issues like infection, lung inflammation or pressure in the chest (pneumothorax). Most often BPFs aren’t infected and therefore, can be repaired successfully with surgery, typically in the early stages post-operation. For patients not in a condition to undergo surgery, bronchoscopic methods, although variable in success rates, become the appropriate choice.
During treatment, patients are positioned so that their problematic side is lower than the rest of their body. A tube is then inserted in the chest, known as a thoracostomy, to drain air and fluid; this is usually the first step for BPF. Fluid collected from this process is tested to check for infection. However, the chest tube can become a source of infection too. Ventilated patients can benefit from the chest tube as it can regulate chest pressure during their breathing cycle, which helps decrease air leak and reduce flow in the fistula. The chest tube also has the ability to administer sclerosing agents such as talc and bleomycin, which help to seal the pleural space, effectively containing the ailment.
Because the gram stain, cultures, and sensitivities are still pending, all patients are administered a broad-spectrum of antibiotics, which are effective against a wide array of bacteria– gram-positive, gram-negative, and anaerobic. Once specimens have been collected, patients can begin postural drainage provided they are able to cough out, they are producing less than 30 mL of chest and chest tube drainage per day, and pleural irrigation is performed alongside.
In acute cases, where the fistula presents two weeks or less after the surgery, suture reclosure of the bronchial stump with vascularized flap coverage is a definitive treatment. Here, most of the time, a minimally invasive, camera-assisted surgical approach, better known as VATS, will be used. In some cases, however, traditional open chest surgery, or thoracotomy, may become necessary.
For patients whose BPF has developed well after the operation or due to diseases affecting the pleura and lungs, medial treatments, including drainage and reduction of the pleural space, antibiotic therapy, nutritional supplementation, and adequate ventilator management become the courses of action.
Treatment for BPF patients on ventilators can be quite complicated. Regulating the airway pressures to promote healing, while ensuring that there is sufficient gas exchange, is a significant challenge. Common complications for such patients include incomplete lung expansion, ineffective tidal volume, inability to remove carbon dioxide, and extended requirement for ventilation support. They might have large air leaks that can result in accidental triggering of ventilators, thus leading to hyperventilation and unnecessary administration of sedatives or neuromuscular blockers. So, it becomes necessary to reduce the total air pressure on the lung as much as possible.
There have been a few interventions described to decrease air leak. These involve using two ventilators for independent lung ventilation, differential lung ventilation, and high-frequency jet ventilation (HFJV). Some practices involve intubation of the functioning lung, the usage of a double-lumen tube for differential ventilation, or independent lung ventilation along with proper positioning of the patient. HFJV allows you to avoid barotrauma to the healthy lung and decreases air leaks. If HFJV isn’t available, then BPF becomes a strict indication for split lung ventilation.
Localization and size of the fistula often dictate the choice between surgical and endoscopic procedures. However, in cases where patients are extremely weak or have a limited life expectancy, palliative measures, a surgically created pleurocutaneous tract, to vent the pleural space temporarily or permanently, sometimes, might be the only option. Empyema, infection in the pleural cavity, should be investigated and treated for. Bronchial stump revisions aren’t feasible in patients where BPF stemmed from causes other than lung resection, like malignancy and infection, and thus, are treated with bronchoscopic methods hoping that the underlying cause is reversible.
Fistula closure with airway stents, coils, or Amplatzer devices (small self-expanding mesh devices) can be an option for patients with BPFs equal to 8 mm. The largest case series of 31 patients with BPF reported the effectiveness of the Amplatzer device in 96% of cases for up to 18 months. Certain other possibilities for BPF closure existing are silicone stents for the central airway, and angiographic coils.
Several case series exist that describe patients with BPF treated with occlusive materials, although a comparison hasn’t been made between them. Occlusive agents act in a twofold manner, first they act like a plug sealing the leak, and then they induce an inflammatory response leading to a permanent seal of the leak. These include bronchoscopic placement of lead shots sterilized in glutaraldehyde, gel foam and tetracycline, autologous blood patch, fibrin glue, and others.
Patients should be closely monitored after the fistula is sealed for signs of recurrence and with imaging of the chest. Follow up bronchoscopies are not routine and only performed if reoccurrence or a complication is suspected. If the closure had involved valves or stents, a chest CT scan and bronchoscopy are repeated after six weeks to asses for complications. If all else fails, then repeat surgery, alternative bronchoscopic method, or in rare cases, open window thoracostomy such as Eloesser flap thoracostomy or a Claggett window might become necessary.
What else can Bronchopleural Fistula be?
In people who have had surgery to remove a lung, sudden signs of a “tension pneumothorax”, or a build-up of pressure in the chest due to trapped air, usually indicate a problem called a bronchopleural fistula (BPF). This is a hole that forms a link between the bronchial tubes and the pleural space, the area surrounding the lungs.
However, sometimes other issues, like complications due to surgery or bleeding into the pleural space, can also show similar symptoms. But in these cases, the chest area would fill with fluid, not air. A misplaced or blocked chest tube can also cause a pressure build-up. If the chest tube is cleared while images of the chest are taken, it can help tell if the issue is genuinely due to BPF.
Suppose a patient presents with empyema, which is pus accumulating in the pleural space. If there’s air in the pleural fluid and an air leak happens after a chest tube is inserted, BPF is a probable cause. Culturing this fluid can help distinguish if an anaerobic infection (caused by bacteria that can survive without oxygen) or a BPF is present. Also, a procedure called a bronchoscopy, which involves using a thin viewing instrument to check the airways, can help identify a BPF if a defect is observed.
What to expect with Bronchopleural Fistula
A Bronchopleural Fistula (BPF) can lead to serious health problems, extended hospital stays, and can even be fatal. Death rates for patients with BPF differ widely, ranging from 18% to 67%. The most common cause of death for these patients is aspiration pneumonia, which can lead to acute respiratory distress syndrome, or the development of tension pneumothorax.
One study of mechanical ventilation patients at a major trauma center found that out of 1700 patients, 39 had BPFs that lasted for more than 24 hours. Sadly, the death rate among these 39 patients was found to be 67%. Interestingly, the study found that the patients were more likely to die if the BPF developed later as opposed to earlier in the illness, with a 94% mortality rate versus a 45% one.
It was also discovered that patients with large air leaks had a notably higher mortality rate when compared to those with smaller leaks. However, this research concluded that while a BPF during mechanical ventilation is a sign of high mortality, the rate of unmanageable respiratory acidosis that could result from this complication is fortunately rare.
Other studies using omental and thoracic flaps have shown reduced mortality rates. For instance, a study by Sirbu et al. found a mortality rate of just 27.2% among BPF patients.
