Surgery on the thorax, especially pulmonary resection, is the most common etiology of a bronchopleural fistula (BPF). The incidence is highly dependent on surgical technique, complexity of surgery, and experience of the surgeon. Postoperative bronchopleural fistula has been reported to occur in 1.5–28% of all pulmonary resections. Multiple surgical and nonsurgical risk factors have been associated with the development of postoperative BPF (Table 42.2). Surgical complexity and extensive dissection are important risk factors. Although postoperative BPF may be seen in up to 20% of pneumonectomies, this complication is seen in only about 0.5% of lobectomies. Right-sided surgery is an important risk factor for BPF formation. A 10-year review of surgical data demonstrated almost threefold higher risk of BPF after right pneumonectomy compared to left (13.2% vs. 5.0%, p  =  0.047). A subsequent meta-analysis demonstrated BPF to be an independent risk factor for death after right pneumonectomy with a relative risk (RR) of 3.39 for death after right pneumonectomy. Right-sided operations are technically more complicated and more likely to involve extended dissection, hand-sewn closures, closed buttress, or intrapericardial dissection. Postoperatively, right-sided stumps also tend to pool secretions more which can impair complete healing. In patients undergoing pulmonary resection for malignancy, a longer bronchial stump was an independent risk factor for BPF. Patient factors including diabetes mellitus, concurrent steroid use, hypoalbuminemia, cirrhosis, Haemophilus influenzae in sputum, residual tumor at stump, and postoperative mechanical vent for >24-h postsurgery have all been implicated in the development of a postoperative BPF.

Most patients with symptoms compatible with a BPF will initially be evaluated with a chest radiograph. Findings on radiographs may be nonspecific and include pneumothorax, subcutaneous emphysema, and/or pneumomediastinum. In a postoperative patient, a fluid collection adjacent to the stump may be identified. Although a computer tomography (CT) of the chest is much more sensitive at identifying abnormalities related to a BPF, it likely will not identify the location of the fistula itself. In a small study by Westcott and Volpe in 1995, in patients with clinical suspicion for BPF, the fistula site could be isolated on a CT scans in only 50% of the patients. Figure 42.2 demonstrates the radiographic appearance of a BPF.

Bronchoscopy should be performed in all patients suspected of having a BPF. In large or central lesions, it may be possible to directly visualize the fistula opening. In the case of a suspected postoperative BPF, the stump should be closely examined. If stump dehiscence is not seen, saline should be instilled onto the stump. The presence of continuous bubbling of saline from the stump indicates a fistula is present (Fig. 42.3). In the immediate postoperative patient, installation of methylene blue onto stump can be performed. Its presence in the chest tube output indicates a BPF is present.

If a fistula cannot be seen within the central airways, a bronchoscopy can still be helpful in determining the approximate location of a peripheral bronchopleural fistula. In patients with a chest tube, a balloon can be inserted via the working channel of the bronchoscope and inserted into the segment or subsegment of the airway with suspected fistula (Fig. 42.4). Once inflated, the balloon will occlude airflow through the fistula, and therefore, the airleak will decrease or disappear in the waterseal chamber of a pleural collection device. If the segment does not contain a fistula, inflation of the balloon will have no impact on the airleak. If even the general location of the fistula is unknown, a larger balloon can be inflated in the larger airways before proceeding to the segmental bronchi to provide the bronchoscopist with the general location of the fistula. In some cases, more than one airway may be contributing to a fistula so multiple balloon inflations may be necessary to identify the culprit airways.

A peripheral BPF can also be identified by a change in the pressure of the airway leading to the fistula. The Chartis System (Pulmonx, Redwood City, CA) is able to measure airflow and pressure in the airway distal to the bronchoscope (Fig. 42.5). It was originally designed to quantify collateral ventilation for endoscopic lung volume reduction. Once the bronchoscope is navigated to the target airway, a balloon catheter is inflated and the airway is occluded. The tip of the catheter has a pressure sensor which provides measurement of airflow and pressure in the occluded airway (Please see Fig. 42.5 for details). As long as the airway is intact and there is adequate seal with the balloon, a small or no drop in pressure will occur with balloon inflation. If the pressure remains negative during both inspiration and expiration, a BPF is present. Capnography (measurement of exhaled carbon dioxide) can also be helpful in identifying the location of a fistula. A polyurethane catheter attached to a capnometer can be placed through the bronchoscope and inserted into sequential airways. During exhalation, carbon dioxide should be detected within the airway. The absence of an end tidal CO₂ tracing in a particular segment identifies the segment with the fistula as the carbon dioxide leaks out into the pleural space. Both airway pressure measurement and capnography are useful in identifying BPFs in patients without chest tubes or in situations where subtle changes in bubbling through the waterseal chamber occur when a balloon is occluding airflow.

Advanced imaging techniques may be helpful in the diagnosis of a bronchopleural fistula. Bronchography can be done if any of the above-mentioned bronchoscopic techniques are inconclusive. In bronchography, 20–30 mL of a water-based nonionic low osmolar iodinated contrast medium (i.e., Omnipaque, GE Healthcare) is injected through a catheter placed through the working channel of a bronchoscope (Fig. 42.6). Fluoroscopy or CT can then be performed with visualization of contrast media extravasation from a site of a bronchopleural fistula. Scintigraphy with 99mTc-albumin (Technetium-albumin) colloid fog inhalation has been described as a simple and accurate test for the detection of BPF. This is accomplished by aerosolization of a radiotracer and inhalation into the lungs with accumulation of the radiotracer at location of a BPF. This technique requires substantial time and cooperation on the part of a non-intubated patient and can be inconclusive in the setting of small fistulas or underlying lung disease such as COPD. Alternatively, ventilation scintigraphy with other radioactive tracers such as 81mKr (Krypton), 133Xe (Xenon), 99mTc-DTPA (technetium-labeled diethylenetriamine penta-acetate), and 99mTc-sulfur colloid has also been described. All of the advanced radiographic techniques mentioned above are now infrequently used with the advent and safety of balloon occlusion of the airway. Historically, bronchography was used for many years with excellent diagnostic accuracy.