Smita Sihag and Douglas J. Mathisen
INDICATIONS AND CONTRAINDICATIONS
Resection of a mainstem bronchus with pulmonary preservation is indicated when the disease process is limited to the mainstem bronchus only. The first documented bronchial sleeve resection was performed by Price Thomas in 1947 for a carcinoid tumor located in the right mainstem bronchus. A circumferential resection was performed with primary anastomosis, and thus the patient was able to maintain functional use of both lungs postoperatively and survived long term. Frequently, it is low-grade malignant bronchial tumors and very rare benign neoplasms that account for centrally located lesions arising in the mainstem bronchus. Since a minimal bronchial margin is usually required for clearance and cure of these neoplasms, pneumonectomy is very rarely necessary to perform an adequate oncologic resection. Mainstem bronchoplastic procedures, as described in this chapter, allow for removal of the lesion or tumor with conservation of any uninvolved lung parenchyma, thereby yielding the best functional result for the patient (Fig. 39.1).
The most common diseases requiring mainstem bronchial sleeve resection are relatively rare low-grade or benign airway neoplasms, including carcinoids, mucoepidermoid tumors, adenoid cystic carcinomas, fibrous histiocytomas, hemangiopericytoma, and hamartomas. Less common benign lesions include isolated mainstem bronchial stenosis secondary to granulomatous disease, that is, tuberculosis, trauma, or foreign body. Mainstem disruption from blunt or penetrating traumatic injury has also been described. Nonsmall cell bronchogenic carcinomas are quite rare and make up only approximately 2% of mainstem lesions. In two published series from the Massachusetts General Hospital, left mainstem resections appear to be twice as common as right mainstem resections, which may reflect disease predilection, as well as more likely, anatomic considerations such as amenability to resection and length of the mainstem bronchus (Table 39.1).
There are no true absolute contraindications for mainstem bronchoplasty per se. Relative contraindications of mainstem resection apply to all bronchoplastic procedures, and there are three primarily to consider: (1) Active bronchial inflammation, (2) high-dose corticosteroids, and (3) high-dose radiation more than 1 year prior to resection. Active inflammation of the airway, especially in the setting of tuberculosis, at the point of reconstruction has a high likelihood of resulting in postoperative bronchial stenosis. As bronchoplastic procedures tend to be performed under greater tension, in the instance where the patient is undergoing therapy with corticosteroids, it is advisable to buttress the reconstruction with a material more substantial than pleura, that is, pedicled pericardial fat, omentum, or intercostal muscle. Lung transplantation is certainly an example where a bronchial anastomosis is performed routinely in patients on high-dose steroids, but generally not under tension. A history of high-dose radiation to the chest or mediastinum in excess of 5,000 cGy more than 1 year prior to bronchoplasty carries an extraordinarily high risk of dehiscence. The higher the dose and more remote the timing of previous irradiation, the greater the risks associated with bronchoplasty. If undertaken, these reconstructions are most reliably buttressed with an omental flap pedicled on the right gastroepiploic arcade.
Figure 39.1 Lesions of the mainstem bronchus.
Postobstructive pneumonia does not represent a contraindication to sleeve resection, provided that the lung parenchyma is still salvageable. Lung parenchyma that is chronically atelectatic can be re-expanded and regain useful function. Intravenous antibiotic therapy, serial therapeutic aspiration bronchoscopy at the bedside, and possible prebronchoplasty endobronchial core-out to relieve obstruction are all measures that may serve to optimize lung function and clear infection. Aggressive clearance of any pus and secretions in the airway distal to the obstruction is critical.
TABLE 39.1 Pathology of Mainstem Bronchial Lesions
PREOPERATIVE PLANNING
Bronchoscopy, both flexible and rigid, is the single most important component of the preoperative evaluation for sleeve resection to identify and biopsy any endobronchial disease limited to main bronchus, and also to determine the extent of diseased area, and its amenability to resection and reconstruction. It should generally be performed at the time of initial evaluation and diagnosis, as well as immediately prior to any bronchoplastic procedure to assess the quality of the mucosa in terms of active airway inflammation and secretions.
To undergo mainstem bronchoplasty, patients must be cleared from a medical standpoint for open posterolateral thoracotomy. Furthermore, pulmonary function testing and quantitative ventilation–perfusion scanning should be done routinely to evaluate cardiopulmonary reserve. Pneumonectomy is always a possibility during these procedures for either expected or unexpected reasons, ranging from adequacy of oncologic resection to technical complications, and postpneumonectomy pulmonary function needs to be specifically calculated in advance to assess whether it can be tolerated.
In the case of malignant neoplasms, assessment of regional nodal involvement and metastatic disease should be undertaken using computerized tomography with intravenous contrast, if possible, and positron emission tomography, though some of these lesions may demonstrate varying degrees of FDG uptake. Radiologic evaluation via spiral CT or virtual bronchoscopy can also be helpful in revealing tumor size, location, and extent of disease globally. Mediastinoscopy may be indicated to confirm nodal involvement, though not routinely. In addition, mediastinoscopy may be a useful technique to facilitate anterior dissection of the pretracheal planes down to the level of the carina.
SURGICAL TECHNIQUE
Successful airway management during mainstem resection and reconstruction can usually be accomplished with a double-lumen endotracheal tube. An exception to this is when resection of the entire left mainstem bronchus is required to the level of the carina, and in this scenario, a long single-lumen reinforced endotracheal tube may be advanced into the right mainstem bronchus. It has a small balloon cuff to allow for placement in the right mainstem bronchus without occluding the right upper lobe bronchus. Historically, the Wilson tube, described by Newton et al., provided a solution to maintain access and mobility of the carina. The Wilson tube was based on the same principles and referred to a long flexible single-lumen tube with an extender, a square end, and smaller balloon cuff to prevent bronchial injury and occlusion of the right upper lobe bronchus. Ultimately, the most important goal of airway management during bronchoplastic procedures is to extubate the patient at the end of the procedure so as to avoid positive pressure ventilation and a plastic foreign body near a fresh suture line.
Following flexible and rigid bronchoscopy, the surgical approach is typically via a posterolateral thoracotomy in the fourth interspace. Depending on location and extent of resection required, the objective of the initial steps are mobilization and exposure. The inferior pulmonary ligament is freed in nearly all cases. Right-sided mainstem sleeve resection may not require any further mobilization given its short length, but for the left side, additional maneuvers may be necessary such as intrapericardial hilar release, neck flexion, and pretracheal mobilization. Gentle retraction of the aorta, pulmonary artery, and bronchus may also be required as shown below, using Penrose drains or tapes encircling each structure. Furthermore, tapes may be passed with care around the distal trachea and right mainstem bronchus to deliver the carina into the operative field (Fig. 39.2).
Figure 39.2 Left mainstem exposure and anatomy.
It is occasionally possible for a left mainstem lesion to be approached from a right thoracotomy if it is proximal enough to the carina. In this case, airway management becomes more challenging, as right lung deflation is desired for optimal exposure. Thus, a long, flexible, endotracheal tube can be inserted into the left mainstem bronchus to achieve this during the initial dissection. Then once the bronchus is transected, a sterile endotracheal tube is inserted distally into the open mainstem bronchus and a ventilation circuit is passed off the operative field for continued ventilation of the left lung until the bronchus is reconstructed. High-frequency ventilation may be useful during this resection. The right lung can be ventilated with a long single-lumen reinforced endotracheal tube as described above, and may be retracted gently to allow exposure. This approach to the left mainstem bronchus requires careful coordination and communication with the anesthesiologist.
Distal airway mobility can be obtained by using the intrapericardial hilar release technique, which allows for the hilum to ascend by 1 to 2 cm. This amount of length can be critical to facilitating a tension-free anastomosis in proximal, subtotal, and total left mainstem resections. As described by Newton et al., this technique involves a U-shaped incision in the pericardium beneath the inferior pulmonary vein to allow for upward movement of the hilum as illustrated in Fig. 39.3.
During the initial exposure and mobilization of the mainstem bronchus, great care should be taken during the dissection so as not to compromise the bronchial blood supply. The highest risk of devascularization may occur during an aggressive lymphadenectomy, and a balance needs to be struck with consideration of the underlying disease process as well as the patient’s overall prognosis. Preservation of the blood supply is undoubtedly crucial for a durable reconstruction, as is the elimination of tension to as great an extent as possible using the maneuvers described above. Transection of the bronchus should be clean and sharp to avoid jagged or devascularized edges for anastomosis. During a resection undertaken for any kind of neoplastic disease, bronchial margins should be confirmed as negative on frozen section by the pathologist prior to performing the reconstruction. After the specimen is removed, an additional proximal and distal bronchial margin can be taken for evaluation, but again consideration of margins may need to be weighed versus feasibility of reconstruction given the remaining length.
Figure 39.3 Intrapericardial hilar release.
When approaching the anastomosis, absorbable sutures are preferable to avoid suture line granulomas. At our institution, 4-0 Vicryl sutures are used for the anastomosis and 2-0 Vicryl sutures are used for the bronchial traction stitches. These are placed in an interrupted fashion such that knots are on the outside of the lumen. Each stitch is full thickness with minimal handling or injury to the bronchial mucosa. Anterior and lateral stay sutures are placed initially, which divides the anastomosis into three sections. Anastomotic sutures are then placed as shown below, beginning in the posterior midline of the membranous wall, approximately 3 to 4 mm apart extending laterally on the back row until the lateral stay suture is reached. The remaining end of the back row from the midline to the other lateral stay suture is completed next. Each suture is clamped with a hemostat and then secured to the drapes using a second clamp in a fan-like arrangement extending caudad to maintain orientation and exposure. The front row sutures are placed last. Sutures are then tied with the knots on the outside in the reverse order that they were placed. After the traction sutures are tied, the front row and then back row sutures are tied. Sutures should be tied tightly enough to approximate, but not crush the tissue, with no residual slack, and should be cut as they are tied. See Figure 39.4for an illustration of how the anastomosis is performed. Traction sutures are placed primarily for alignment, and when tied together prior to anastomotic sutures, can lead to a reduction in tension. Once the anastomosis is complete, the field should be filled with saline and the lung inflated to 35 to 40 cm H2O to check for air leaks. If the reconstruction is not airtight, additional repair sutures should be placed. Flexible bronchoscopy is then performed to inspect the anastomosis internally. A pedicled flap of pleura or pericardial fat may then be placed to buttress the reconstruction. At the end of the procedure, a guardian chin stitch is placed to maintain neck flexion, or prevent any neck extension, to decrease tension on the reconstruction.
If there is a considerable size discrepancy in the two ends of the bronchus being brought together, this can be overcome by spacing sutures such that they are closer together on the smaller end and farther apart on the larger end. Some telescoping or intussusception may occur, as demonstrated in Figure 39.5, and this should not impede healing and should still allow for an airtight reconstruction. Excessive tailoring of bronchial ends is to be avoided as much as possible, as a complex bronchial suture line will not heal as well due to devascularized edges. If the suture line is at the level of the carina such that the proximal end is flush with the trachea, partial lateral closure of the trachea may be necessary to eliminate the size mismatch. In addition, for these more complex scenarios, an intercostal muscle flap should ideally be used simply to cover any concerning areas and reinforce the reconstruction with mattressed silk stitches to appose it directly on the tissue. It should not be wrapped circumferentially around the anastomosis, however, as it may calcify and constrict the bronchus.
Figure 39.4 Bronchial anastomotic technique. A: “Fan-like” array of sutures. Arrows represent location of traction sutures. B: Sutures are placed 3–4 mm full thickness and 3–4 mm apart. C: Completed anastomosis with traction tied and left in place.
Figure 39.5 Size discrepancy during mainstem reconstruction. A: Size discrepancy dealt with by placing proximal sutures slightly further apart then smaller distal airway. B: Slight intussusception may occur.
POSTOPERATIVE MANAGEMENT
Routine flexible bronchoscopy can serve multiple purposes in the postoperative period following mainstem resection and reconstruction. Sputum clearance if there are copious secretions or lobar consolidation is imperative. In addition, potential anastomotic complications may be identified early. Areas of ischemia, poor healing, and possible fistula may be appreciated and should be followed closely until the situation declares itself. Typically, bronchoscopy is performed at least once prior to discharge to evaluate the anastomosis. If early stenosis is apparent, cautious dilation may be performed with a small balloon dilator so as to minimize trauma. Other less aggressive methods to encourage clearance of secretions and mitigate airway inflammation postoperatively include chest physiotherapy, bronchodilators, low-dose steroids, incentive spirometry, and early ambulation.
Postthoracotomy, a chest tube and Blake drain are typically left in place to monitor for air leak and drainage. If a Blake drain is left in place, it is usually placed at the site of reconstruction. Typically, these are left in place until 2 to 3 days postoperatively and removed sequentially. The guardian chin stitch is left in place for approximately 1 week and is removed once the reconstruction appears to be healing well on bronchoscopy.
COMPLICATIONS
The overall complication rate observed after mainstem resection and reconstruction is approximately 15%. Rates of anastomotic stenosis and stricture, dehiscence with bronchopleural fistula and prolonged air leak, pneumonia, chylothorax, and injury to the left recurrent laryngeal nerve are all reported at less than 5%. Mortality related to mainstem bronchoplasty is exceedingly rare at less than 1%. As mainstem disease and bronchoplastic procedures are relatively uncommon, large case series are not extensively reported in the literature.
Anastomotic dehiscence requires treatment with immediate completion pneumonectomy as attempting to perform a reanastomosis is not advisable given the likely already compromised blood supply and tension. The bronchial stump should be covered with a pedicled omental or intercostal muscle flap to aid in healing and reduce the risk of bronchopleural fistula. Chylothorax may require re-exploration and thoracic duct ligation if it does not cease with parenteral nutrition. If there is concern for recurrent laryngeal nerve injury, laryngoscopy and vocal cord injection may be indicated. A high degree of vigilance with respect to risk of an aspiration event in these patients is critical. Lastly, stenosis or stricturing of the anastomosis can be managed with serial bronchoscopic dilations, though reresection can be considered as a last resort if tension can be maximally reduced and blood supply preserved.
RESULTS
Main bronchial resection with pulmonary conservation using the techniques described above can be carried out with minimal morbidity and mortality based on the experience at Massachusetts General Hospital reported by Newton et al., 1991 and Bueno et al., 1996. These sleeve resections are frequently curative as they are performed for benign pathology or low-grade malignancy and specifically avoid any type of parenchymal resection, that is, pneumonectomy, resulting in long-term survival with normal lung function for the patient.
CONCLUSIONS
If general principles of airway resection and reconstruction are strictly heeded, in terms of preservation of bronchial blood supply, reduction in tension, and use of pedicled tissue flaps to reinforce and protect the reconstruction, mainstem bronchoplastic procedures without concomitant lung resection are safe and effective with excellent results.
Recommended References and Readings
Bueno R, Wain JC, Wright CD, et al. Bronchoplasty in the management of low-grade airway neoplasms and benign bronchial stenoses. Ann Thorac Surg. 1996;62(3):824–828.
Cerfolio RJ, Deschamps C, Allen MS, et al. Mainstem bronchial sleeve resection with pulmonary preservation. Ann Thorac Surg. 1996;61(5):1458–1462.
Frist WH, Mathisen DJ, Hilgenberg AD, et al. Bronchial sleeve resection with and without pulmonary resection. J Thorac Cardiovasc Surg. 1987;93:350–357.
Grillo HC. Surgery of the Trachea and Bronchi. Hamilton, ON: BC Decker Inc; 2004.
Newton JR, Grillo HC, Mathisen DJ. Main bronchial sleeve resection with pulmonary conservation. Ann Thorac Surg. 1991;52:1272–1280.