Draining the Pleural Space
Acute management focuses on controlling life-threatening conditions, including postural drainage with the affected lung positioned down in cases of airway flooding, early thorough pleural drainage to prevent sepsis and aspiration pneumonia, and appropriate antibiotic therapy. Adequate nutrition is also paramount to a favorable outcome.
Drainage can be performed at the bedside with a tube thoracostomy under local anesthesia placed to either balanced drainage system or water seal but not suction. Immediate drainage is especially important for patients who present with large fistulas in which a significant volume of pleural contents is draining into the airways, potentially flooding the contralateral lung. Care must be taken to place the tube above the level of the previous thoracotomy incision because the diaphragm will be elevated as part of the normal thoracic remodeling that occurs after pneumonectomy. In addition, the patient should be in the supine position when the thoracostomy tube is placed. Lateral positioning places the remaining lung in a dependent position and encourages further aspiration. Once the tube is in place, further positional maneuvers to prevent aspiration include maintaining the patient in as close to an upright position as possible and rotating the patient such that the pneumonectomy side is down.
Once the urgent situation is controlled and the patient is started on appropriate parenteral antibiotics, the remaining pleural debris and necrotic tissue are removed. Debridement can be accomplished by means of an open thoracic window or thoracotomy. The selection of technique depends on the patient's overall condition. At this stage, debilitated or critically ill patients may tolerate a major thoracic procedure poorly, especially a prolonged procedure involving muscle flaps or other approaches used to definitively address the fistula. These patients often benefit from a period of treatment with a simple open window thoracostomy to permit control of sepsis and nutritional support followed by delayed definitive closure.
Technique for Open Window Thoracostomy
Open window thoracostomy allows open drainage of an infected intrathoracic space by using a U-shaped incision over the most dependent portion of the space (Fig. 82-2). Segments of one or two ribs are removed to limit the tendency of the opening to contract and close. The skin flap then is sutured directly to the parietal pleura with interrupted absorbable sutures to create an epithelialized tract, which both maintains the patency of the window and encourages healing. The window should not be placed too far posteriorly such that it is difficult for the patient to manage. Similar care is taken to avoid placing the window too far inferiorly, where it might interfere with the diaphragm. Other techniques, including placement of large-bore drainage tubes through the window as stents, also will help to maintain patency. Dressing changes with moistened gauze then are performed until the cavity is sterilized. Very small fistulas may close spontaneously once the local sepsis is eradicated. Most, however, require definitive closure. Patients in generally good condition at the time of presentation can proceed directly to simultaneous debridement of the pleural space and definitive closure.
Open-window thoracostomy drainage was first proposed by Eloesser. Note the U-shaped incision over the infected space and technique (inset) for securing the skin flap directly to the parietal pleura.
Closing the Bronchopleural Fistula
Most patients can tolerate early exploration and closure of the fistula, and this procedure should be undertaken as soon as the patient is medically stable. Exploration is preferentially performed by means of a posterolateral thoracotomy on the ipsilateral side, with lung isolation via selective intubation of the contralateral mainstem bronchus to prevent further soilage of the remaining lung. If not readily visible, the fistula can be identified with the aid of positive-pressure ventilation while covering the area of the bronchial stump with irrigation. The pleural space is thoroughly irrigated and debrided to remove all necrotic tissue. The bronchial stump is carefully dissected to minimize trauma to its blood supply. All attempts are made to leave a final stump that is less than 1 cm in length measured from the carina (Fig. 82-3). If sufficient length remains on initial exploration, stapling device can be used to reclose the stump. In most cases, there is too much inflammation to permit stapling, however, and the mobilized bronchial stump is reclosed with interrupted monofilament sutures. A balance must be obtained between exposing enough bronchus to avoid tension on the closure and avoiding too much exposure, which could damage the blood supply.
Ideally, the length of the bronchial stump should be less than 1 cm. A. If there is sufficient length on the stump after initial exploration, a stapling device can be used to reclose the stump. B. Often there is too much inflammation to permit stapling, and the mobilized bronchial stump is reclosed with interrupted monofilament sutures.
Reinforcing the suture line with vascularized tissue is perhaps the most important aspect of closure. Pedicled flaps of the muscle or omentum are mobilized into the chest and sutured over the bronchial stump.3,11 Flap choice depends on the quality of the tissue, damage to potential flap muscles from the previous thoracotomy, and the amount of space to be filled. The serratus anterior is used commonly after pneumonectomy. This muscle is often preserved during the initial operation even when an open procedure was done, because of its utility in dealing with potential complications. The flap is based on the vascular pedicle that runs on the lateral undersurface of the scapula. The muscle is mobilized and inserted between the ribs in either the second or third interspace, where it will generally reach the hilum with no tension. If the interspaces are tight and can possibly compromise the vascular supply of the flap, a segment of the third rib can be removed to allow the flap to comfortably enter the pleural space. The flap generally is secured with interrupted absorbable sutures to the peribronchial or mediastinal areolar tissue. This tissue aids in healing and infection control because its blood supply emanates from regions beyond the inflamed field. In cases where the stump is frankly necrotic or densely scarred into the mediastinum, the fistula may not be able to be closed directly. In this event, a muscle or omental flap is sutured to the freshened edges of the open fistula or surrounding mediastinum to occlude the communication and permit healing. An advantage of using a relatively large muscle such as the serratus anterior to close the fistula is that it also contributes bulk to fill some of the dead space in the postpneumonectomy chest.
In severely ill patients with difficult bronchial stumps, simultaneously placing a temporary tracheostomy with a long cuffed tube in the contralateral mainstem bronchus may be useful. The tracheostomy is left in place for several weeks to permit the flap to become fixed over the opening of the fistula without the stress of positive-pressure ventilation, which can slow healing.
Case reports and small case series have also reported successful BPF treatment using endoscopic techniques. The use of bronchoscopic placement of stents, glues, sealants, coils, submucosal tissue expander injection, and devices designed for transcatheter closure of cardiac defects have all been reported to successfully lead to closure of BPFs after pneumonectomy.3 However, these techniques should likely be considered only when primary repair fails or is not possible because of patient condition. Generally, these only work with smaller BPFs.
Once the fistula is closed, the pleural space must be sterilized. In early-onset BPF, when there has been minimal contamination, thorough operative debridement and irrigation may be sufficient. In more advanced cases with greater contamination, sterilization can be accomplished by creating an open window with dressing changes as described earlier or by closure over irrigation catheters after the fistula has been repaired. Chest tubes or other irrigation catheters can be placed and irrigated either continuously or several times daily with antibiotic solution. When there is no remaining evidence of infection within the space, on the basis of either Gram stain of granulation tissue or culture of irrigation fluid, definitive closure is performed.
More recently, several retrospective studies have reported successful management of empyema cavities using vacuum-assisted closure (VAC) devices, even in the setting of a BPF. Although limited, these studies suggest that VAC, as an adjunct to the standard treatment, can potentially alleviate the morbidity and reduce inpatient length of treatment in patients with empyema after lung resection.12 Management typically involves filling the intrathoracic cavity with foam to the superficial wound edges. Negative pressure, gradually increased from –25 to –125 mm Hg over time, is applied to clean the wound and support healing. The VAC is generally changed every 2 to 3 days.
Occasionally, it is impossible to access the bronchial stump for effective repair, especially on the left side when the stump is retracted underneath the aorta (Fig. 82-4). In such cases, fistula closure can be approached via median sternotomy.13 This approach permits exposure of the carina in a previously nonoperated field between the superior vena cava and the aorta, and the mainstem bronchus can be redivided and closed in a field free of infection. After median sternotomy, the pericardium is opened, and dissection between the superior vena cava and aorta exposes the carina. If possible, a segment of the mainstem bronchus should be resected to provide a fresh edge for stapling or suture closure and to avoid contamination from the distal bronchial remnant. Another approach to the carina is through the right chest for a left-sided fistula. A right posterolateral thoracotomy is performed in this approach, and the lung is mobilized and retracted anteriorly so the mediastinal pleura can be incised at the level of the subcarinal area. The left bronchial stump can be mobilized, restapled flush with the carina, and covered with a flap of intercostal muscle, pericardial fat, or mediastinal tissue.14 Central extracorporeal membrane oxygenation (ECMO) can be utilized if necessary if the patient has instability during the attempted repair.
A median sternotomy approach can be used when the left mainstem bronchus is retracted underneath the aorta, limiting access to the bronchial stump. This approach exposes the carina between the superior vena cava and the aorta and permits operation in a sterile field.
Obliterating the Remaining Pleural Cavity
The final step in the treatment of BPF is obliteration of the remaining pleural space. The patient's overall condition and suitability for complete closure must be carefully reevaluated before taking this final step. Most closure failures are related to persistent or recurrent BPF. Patients with a chronic fistula, carcinomatosis within the space, persistent infection within the space, or poor nutritional status should not undergo obliteration maneuvers unless or until these issues have been addressed. A period of treatment with open thoracic window and adequate nutritional support can improve the patient's likelihood of a positive long-term outcome.
Obliteration of the pleural space can be accomplished by one or a combination of three techniques. The first option is to fill the sterilized cavity with antibiotic solution (Clagett maneuver). If the chest was closed initially over irrigation catheters, obliteration is a simple procedure. Antibiotic solution is infused into the cavity until it is completely filled, the irrigation catheters are removed, and the site is suture closed. If the patient was treated initially with an open thoracic window, the skin edges are excised and flaps are mobilized to permit closure without tension. The chest is filled with antibiotic solution in a similar fashion, and the window then is closed in multiple layers to prevent leakage of fluid. Antibiotic selection is tailored to culture and sensitivity tests rather than to a set of standard antibiotics. Excessive doses of intrapleural antibiotics can result in renal failure or other systemic complications and should be avoided. This technique was described originally by Clagett and Geraci15 in 1963 as a two-stage procedure in which open-window drainage was followed by obliteration of the space with antibiotic fluid without direct fistula closure. The technique is used rarely in its original form today, however, because of recurrences related to persistence of the fistula. The more common approach is the modified version with an intermediate step of fistula closure with muscle flap as described earlier.
The second technique involves transposition of muscle flaps that fill the pleural space with vascularized tissue (Fig. 82-5). Muscle flaps are an excellent choice because of their rich blood supply and ability to extend to almost any region of the pleural space. The choice of flaps depends on the availability and suitability of local muscles. Latissimus dorsi is often the largest muscle available in this location but frequently has been transected at the time of the original thoracotomy. Previously transected latissimus dorsi is unlikely to survive as a transposed flap. Many groups intentionally preserve the serratus anterior at initial operation for later use as a flap (Fig. 82-6). The serratus anterior is mobilized with maintenance of its attachments to the upper scapula and passed into the chest between the ribs or through a window created by resecting a segment of the second or third rib. Other useful local muscles include pectoralis major for the anterior portion, trapezius for the apical portion, and rectus abdominis for the caudal portion of the space. The number of muscles required relates to both the size of the remaining cavity and the quality and bulk of the muscles. Many patients with BPF have diminished muscle bulk from chronic debilitation and may not have sufficient muscle tissue to fill the space. In such cases, the highly vascularized omentum is an excellent replacement for or addition to local muscle flaps and can be mobilized from the abdomen through a substernal tunnel (Fig. 82-7).
Muscle flaps available for transposition into the pleural space. The serratus anterior is ideal for filling small defects, such as BPF. It takes its blood supply from the lateral thoracic artery, and entrance into the chest is made from the primary incision. The pectoralis major receives blood from two sources, the thoracoacromial artery and the internal mammary artery. Entry into the chest is made through a 5-cm rib resection. It is used most commonly for sternal infections and for BPFs that originate from an upper lobe bronchus. The trapezius is used to fill the apical pleural space, and the rectus abdominis provides tissue for the caudal pleural space.
The serratus anterior is often preserved at initial operation by maintaining its attachment to the upper scapula and used later as a muscle pedicle. The free end is passed into the chest between the ribs or through a window created by resecting a segment of the rib.
Patients with BPF may be severely debilitated from long-term illness that leaves a paucity of muscle bulk. In these patients, the omentum is an excellent substitute for a pedicled muscle flap and has a rich vascular supply. It is mobilized from the abdomen through a substernal tunnel.
The third technique is thoracoplasty, in which multiple ribs are resected to allow chest wall soft tissue to collapse inward and fill the pneumonectomy space. Thoracoplasty was described originally by Alexander16 in 1937 for the therapy of tuberculosis and involved resection of 10 or 11 ribs. This procedure was highly morbid and disfiguring, and had a profoundly negative impact on the physiologic function of the remaining lung. Most postpneumonectomy spaces can be completely filled by removing ribs two to eight; however, this is still significantly disfiguring, may limit arm and shoulder function, causes chest wall paresthesias, and requires prolonged convalescence. In the current era, thoracoplasty has a limited role in combination with muscle flap transposition (Fig. 82-8). Available muscle flaps are transposed to fill as much space as possible. Then, simultaneously or in a separate procedure, a limited thoracoplasty (often involving only two to three ribs) is performed to obliterate any remaining space.
Limited thoracoplasty involving as few as two or three ribs has a limited role in combination with muscle flap transposition.