Other maneuvers during both CV and HFV can be potentially helpful in patients with BPF. Selective intubation and CV of the unaffected lung in patients with a unilateral BPF may be useful but will predispose to the collapse of the nonintubated lung. The use of differential lung ventilation with CV may be of benefit in some patients. Additionally, positioning the patient such that the BPF is dependent has been shown in one report to decrease fistula flow.
Case reports and animal studies indicate other potential applications of HFV in BPF. Included is the use of independent lung ventilation, with HFV applied to the BPF lung and CV to the normal lung. Additionally, another mode of HFV, ultra-high-frequency jet ventilation, is being explored and has been used with some success particularly in reducing BPF air leak in both patients and animal models. Independent lung ventilation with ultra-high-frequency lung ventilation applied to the BPF lung and CV to the normal lung has led to rapid BPF closure in two of the three patients whose cases have been reported.
Bronchoscopic Applications in BPF
The fiberoptic bronchoscope has had limited use in the setting of BPF. Its use was often limited to assessing the length of the bronchial stump potentially harboring a BPF and to excluding tuberculous endo- bronchitis preoperatively. Today it plays an expanded role as both a diagnostic and a therapeutic modality. The fiberoptic bronchoscope can be used in patients after pneumonectomy and lobectomy to directly visualize the fistula site. More importantly, the fiberoptic bronchoscope can be valuable in the management of BPF. Bronchoscopic therapy of BPF has several potential advantages, including lower cost, shorter hospital stay, and relative noninvasive- ness, particularly valuable in poor operative candidates (Table 4).
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The location of the BPF can be defined by the bronchoscope. Proximal fistulas, such as those associated with lobectomy or pneumonectomy stump breakdown can be directly visualized through the bronchoscope. Distal fistulas cannot be directly visualized and require bronchoscopic passage of an occluding balloon to localize the bronchial segment leading to the fistula. A balloon is systematically passed through the working channel of the bronchoscope and into each bronchial segment in question and then inflated. A reduction in air leak indicates localization of a bronchial segment communicating with the BPF.
Table 4—Bronchoscopic Materials for Bronchopleural Fistulas (BPF)
Once the fistula has been localized, various materials can be passed through a catheter in the working channel of the bronchoscope and into the area of the fistula. Direct application of the sealant through the working channel catheter onto the fistula site is the method generally used for directly visualized proximal fistulas. A recently reported refinement of the technique is useful for distal fistulas and involves the multiple lumen Swan-Ganz catheter both to localize the BPF and pass the occluding material of choice. The distal fistula is located using the Swan- Ganz balloon and, with the balloon inflated, material can be passed through the catheter distal to the balloon. This system has the potential advantages of combining the localizing balloon catheter and application catheter into one system, isolating the bronchoscope from the material passed through the catheter when the balloon is inflated, and allowing better localization of the material to the fistula area when the catheter is inflated.
Multiple agents and devices have been passed through the bronchoscope to occlude BPF in both patients and animals (Table 4). These studies, despite generally reporting success, are limited to only a few patients in each instance. Included in these reports are various balloon devices used not just to locate a fistula but left in place as an occluding device. Balloon devices may be a temporizing measure, although animal studies indicate their possible use as a more definitive treatment of BPF. Other foreign bodies such as lead shot have been used to seal BPF. Agents that appear more practical in their application include silver nitrate, absorbable gelatin sponge (Gelfoam), autologous blood in combination with tetracycline, cyanoacrylate-based agents, and fibrin agents. The cyanoacrylate-based agents and fibrin agents have had the most use with application in seven and eight patients, respectively. These patients had at least a 50 percent reduction of fistula flow with most having closure of the fistula subsequent to sealant application, although multiple applications were necessary in some patients. The cyanoacrylate agents have been recently improved with an additive that slows drying time to permit greater time for modeling of the agent into the fistula site. Fibrin agents are available in commercial preparations or may be prepared by local blood bank facilities.
These agents appear to work in two phases with few associated problems. The agent initially seals the leak by acting as a plug and subsequently induces an inflammatory process with fibrosis and mucosal proliferation permanently sealing the area. The agents are not useful in patients with large proximal tracheal or bronchial ruptures or multiple distal parenchymal defects. Air trapping and infection distal to the plugging agent are potential complications that have not been reported (to our knowledge). These complications were specifically monitored for in balloon occlusion of BPF in dogs and were not found.
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Bronchopleural fistulas are associated with high morbidity and mortality and are particularly challenging in the ventilated patient. Familiarity with both basic and more technical medical management techniques may lessen morbidity and improve survival. Prompt recognition of BPFs and appropriate placement of a chest tube with an adequate suction device are crucial to prevent potential tension pneumothorax and to drain an infected pleural space. The chest tube may be used therapeutically to decrease BPF air leak and to promote fistula repair. Appropriate conventional ventilator manipulations aimed at decreasing fistula air leak and maintaining adequate oxygenation and ventilation may fail and necessitate a trial of HFV Definitive therapy by the bronchoscopic application of a sealing agent to occlude the fistula site can be used, particularly in the poor surgical candidate.