Anastomotic Complications and Their Management

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Complications involving the airway anastomosis in lung transplant patients occur infrequently when appropriate surgical techniques are employed. The majority of pulmonary transplant recipients can be expected to have acceptable healing of the airway anastomosis. However, a consistent subpopulation of patients does develop airway complications in spite of meticulous surgical methods. These complications usually require some form of operative intervention for their resolution.

The etiology of lung transplant airway complications in the majority of cases is related to airway ischemia, almost invariably involving the donor airway. The vascular insult may be manifested acutely, within the first week following transplantation, or in a more subacute fashion in the third or fourth post-transplant week. In many cases, a technical error can be identified.

The most common technical error is using a relatively long segment of donor airway devoid of peribronchial tissues. The resultant ischemia of the proximal donor airway may lead to mucosal ulceration, and subsequent granulation tissue formation, or to transmural necrosis. This type of complication usually manifests within the first week following transplantation. Necrosis of the donor airway typically results in anastomotic dehiscence and perianastomotic sepsis. A wrap of vascularized tissue around the anastomosis can localize the septic focus and prevent mediastinitis. If the tissue used for the wrap has sufficient vascu-larity and if the ischemic region is localized to the proximal portion of the donor airway, then granulation tissue will replace the necrotic region. The final presentation of postischemic granulation tissue is a focal stenosis of the airway at the anastomotic site. In the event of free perforation or fistulization at the site of the anastomosis, reoperation and repair of the site with interposition of a vascularized tissue flap may allow restoration of airway continuity and preservation of graft function.

En bloc double lung transplantation using a supracarinal tracheal anastomosis without bronchial revascularization presents a special circumstance of airway ischemia. The donor airway is essentially an arch comprised of the right main bronchus, the carina, and the left main bronchus. Perfusion to this entire arch is by bronchopulmonary collaterals in the peribronchial tissue. Ischemia is most likely to occur in the middle of this span, corresponding anatomically to the proximal left main bronchus. The resultant necrosis and granulation tissue formation will lead to an anastomotic stenosis at this site, with varying degrees of involvement of the right main bronchus and carina.19

Airway ischemia may also be related to diminished pulmonary flow into the bronchial circulation. Angulation or constriction of the pulmonary arterial or venous anastomoses should be identified at the time of implantation. Compromise of bronchopulmonary collateral flow by this mechanism leads to ischemic sequelae at the anastomosis, resembling those seen with excess donor airway. Surgical revision of a suboptimal vascular anastomosis, as soon as it is identified, will not only prevent airway ischemia but will assure optimal respiratory function of the lung graft.

On rare occasions, diffuse necrosis of the donor airway to the level of the segmental bronchi may occur in the acute postoperative period. The etiology of this event is unknown, although impaired broncho-pulmonary collateral flow due to an unidentified anatomic anomaly is a likely cause, based on the distribution of the ischemic necrosis. The only therapy for this otherwise fatal complication is emergent retransplantation, which is also associated with a high morbidity and mortality.14

Anastomotic airway complications may present in a delayed fashion, after apparently adequate healing initially. In such cases, a localized necrosis of the donor airway leading to anastomotic stenosis is identified more than 3 weeks following transplantation. Late anastomotic stenoses are less common and usually less severe than airway complications occurring in the early postoperative period. The etiology in these instances may be related to recurrent airway ischemia exacerbated by episodes of graft rejection (resulting in a decrease in bronchopulmonary collateral flow) or to a necrotizing infection of a poorly perfused donor airway.

Routine bronchoscopic surveillance should be continued for 6 weeks following transplantation. Such studies allow for inspection of the anastomotic site, for assessment of rejection by transbronchial biopsy, and for monitoring of microbiologic flora in the graft airway. Appropriate preemptive interventions may lessen the incidence of late airway complications from these etiologies.

Anastomotic stenosis is the most common airway complication following lung transplantation.19,23 Most cases are related to donor airway ischemia, and the severity of the stenosis is directly related to the amount of donor airway that was ischemic. Patients are typically symptomatic with progressive exertional dyspnea, stridor, and diminished expired lung volumes. Diagnosis is made by bronchoscopy. Tracheal tomograms or virtual bronchoscopy employing image data acquired from helical chest computed tomography scanners have also been used as diagnostic modalities, but accurate evaluation and therapy will always require primary bronchoscopic evaluation. Management consists of rigid and flexible bronchoscopy with endobronchial dilatation using either graduated esophageal or balloon dilators. In many cases, two or three serial dilatations over the course of several months will suffice to manage the stenosis during maturation of the anastomotic site and stabilization of the stenotic segment.

In other cases, the initial severity of the stenosis or its rapid recurrence following dilatation will require endoscopic stent placement. Careful measurements of the length and caliber of the stenotic region following dilatation are made. An appropriate stent is selected and is positioned through the stenosis under bronchoscopic visualization. A self-anchoring Silastic stent is preferred, although permanent metal stents have been used. The Silastic stents have the advantage of ease of exchange and/or modification. Insertion of the Silastic stent involves its placement over a rigid bronchoscope to which an endoscopic fixation figure 44-5 Endotracheal Y stent. Silastic stents are useful for the management of anastomotic stenoses. A Y stent is commonly required for en bloc double lung transplant patients.

device, such as a 40 F catheter placed over the bronchoscope proximal to the stent, is attached. The bronchoscope is then withdrawn as the stent is held in position by an endoscopic fixation device. The fixation device is then withdrawn and the position of the stent is confirmed by bronchoscopy.

Endobronchial stents are most commonly used for isolated SLTx or for bilateral sequential SLTx. Endotracheal Y stents are useful for stenoses occurring with en bloc double lung transplantation without bronchial revascularization (Figure 44-5). A modified tracheal T tube may be used for stenosis of tracheal anastomoses or for complex carinal stenoses. Unlike other inflammatory airway stenoses, anastomotic strictures in transplant patients may be very malleable. Endobronchial stents may be removed in more than one half of cases within 1 year. Sufficient remodelling of the anastomotic scar will have occurred at this interval to prevent the recurrence of an anastomotic stricture (Figure 44-6). The development of a fibrous stenosis, however, augurs poorly for the possibility of eventual elimination of the stent.24,25 The likelihood of anastomotic stabilization and permanent stent removal is also less for carinal or tracheal stenoses. Although the presence of an indwelling stent does increase the incidence of tracheobronchial infection in transplant patients, the risk of reoperation is sufficiently great to preclude this as an alternative for the management of most such patients.

figure 44-6 A, Tracheal tomogram demonstrating an anastomotic stenosis. The airway stenosis can be seen at the level of the anastomosis in this patient's post-right single lung transplantation for pulmonary fibrosis with secondary pulmonary hypertension. The stenosis was treated by dilatation and stent placement. B, Tracheal tomogram following stent removal. The patient demonstrated in A had an indwelling Silastic stent placed after dilatation of the anastomotic stenosis. The stent was removed after 14 months and subsequently did not recur. A normal anastomotic caliber can be appreciated on this radiograph.

figure 44-6 A, Tracheal tomogram demonstrating an anastomotic stenosis. The airway stenosis can be seen at the level of the anastomosis in this patient's post-right single lung transplantation for pulmonary fibrosis with secondary pulmonary hypertension. The stenosis was treated by dilatation and stent placement. B, Tracheal tomogram following stent removal. The patient demonstrated in A had an indwelling Silastic stent placed after dilatation of the anastomotic stenosis. The stent was removed after 14 months and subsequently did not recur. A normal anastomotic caliber can be appreciated on this radiograph.

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