109: Lung Transplantation Technique

Since its inception in 1963, over 32,000 lung transplants have been performed globally. For several decades, chronic obstructive pulmonary disease (COPD) was the most common indication for lung transplantation. However, in the United States, the donor lung allocation system has changed the scenario and idiopathic pulmonary fibrosis (IPF) is emerging as a more common indication. IPF accounts for about 25% of lung transplant at our center and 33% nationally.¹ Cystic fibrosis (CF) is the third most common indication.

To be eligible for bilateral lung transplantation, potential transplant recipients should be without significant comorbid disease. Patients with emphysema generally are older than other patient groups (e.g., CF) and thus perhaps are more at risk for cardiovascular or cerebrovascular events. In contrast, CF patients often have occult renal insufficiency secondary to years of antibiotic therapy, particularly with aminoglycosides. Unique infectious concerns are also seen in the CF population because these patients frequently are infected with one or more strains of Pseudomonas aeruginosa and often are colonized with mycobacterial or fungal pathogens. Furthermore, CF patients often have a degree of liver disease, pancreatic insufficiency, or both owing to the multiorgan system effects of the CF genetic defect. Patients with primary pulmonary hypertension (PPH) commonly have residual right-sided heart dysfunction immediately after transplantation and need greater attention to cardiac hemodynamics, often requiring an increase of right-sided filling pressures for hemodynamic stability. Finally, the widespread use of IV prostacyclin (Flolan) has permitted many patients with PPH to delay transplantation. Thus, by the time these patients present for transplant, the degree of right-sided heart failure is often quite severe.

The decision to perform a single-, double-, or heart–lung transplant depends on numerous factors, including recipient characteristics (e.g., disease, age, and comorbidities), institutional bias, organ availability, and the urgency of the transplant. Single-lung transplantation is a good option for patients with IPF.² Selected patients with emphysema, specifically those of shorter stature and older age, also can expect good results with single-lung transplantation. Unilateral transplantation is also acceptable for patients with PPH.³ However, because these cases are challenging and management can be difficult during the first few postoperative days,⁴ some programs prefer the double-lung or even combined heart–lung transplantation for patients with PPH. Double-lung transplant is mandatory for patients with CF and bronchiectasis because in both cases the septic native lungs must be excised. When the native disease is accompanied by a pre-existing mycetoma⁵ or other chronic fungal or mycobacterial infection, double-lung transplantation is also a better option because it minimizes the post-transplant risk of recurrent infection. The heart–lung transplant is reserved for the rare patient with combined end-stage cardiac and pulmonary disease. Most patients requiring heart–lung transplant have Eisenmenger syndrome with PPH and significant left ventricular dysfunction, perhaps owing to an uncorrected congenital defect. The annual rate of heart–lung transplantation has declined significantly not only because single- or double-lung transplant alone is appropriate in the majority of patients but also because no clear survival advantage has been demonstrated in this patient group.⁶ The different types of lung transplantation that are performed currently are shown in Figure 109-1.

We prefer the double-lung transplant at our institution irrespective of disease category. Double-lung transplantation has been documented to produce a superior result in patients with obstructive lung disease,⁷ and we find that survival is superior and that early postoperative management is far less complicated with the bilateral approach.

Donor Lung Procurement

If the initial evaluation (i.e., donor history, chest radiograph, bronchoscopy) reveals no contraindications, we proceed with donor lung procurement. Our technique has been described previously.^8,9 A T-shaped incision centered on the sternal angle is performed over the sternum. After median sternotomy and opening of the pleural spaces, the pericardium is opened, and stay sutures are placed, permitting exposure of the great vessels. The superior vena cava (SVC) is encircled caudal to the azygos vein with silk ties. Alternatively, if heart is also being procured, the azygos vein can be carefully ligated. Usually it is not necessary to encircle the inferior vena cava. The periadventitial tissue overlying the right pulmonary artery (PA) is dissected. The plane between the artery and the SVC is dissected. In similar fashion, the right PA is separated from the posterior aspect of the ascending aorta.

The aorta-pulmonary artery window is dissected in preparation for the aortic cross-clamp. The SVC and aorta are gently retracted laterally, and the posterior pericardium is incised above the right PA, permitting access to the trachea. The plane of the trachea is developed manually and two-thirds of the trachea dissected. We do not encircle the trachea completely at this point to avoid bleeding and inadvertent injury to membranous trachea. Instead of amputating the left atrial appendage, we routinely vent the left heart through the interatrial groove, especially when both heart and lungs are being harvested. This avoids the need of suturing the left atrial appendage after cardiac implantation. In order to do this, the interatrial groove is dissected. After the thoracic dissection is complete, the donor is heparinized with 30,000 units of heparin. The ascending aorta is cannulated with a routine cardioplegia cannula for cardiac preservation. At the bifurcation of the main PA, a Sarns (Ann Arbor, MI) 6.5-mm curved metal cannula is placed and secured with a purse-string suture. If the cannula is placed close to the PA bifurcation, as is in case of heart procurement, the tip of the cannula should face the pulmonic valve to prevent preferential perfusion of any one main PA (Fig. 109-2). After the cannulas have been placed, a bolus dose of prostaglandin E₁ (500 μg) is given directly into the PA using a 16-gauge needle.

Immediately after the prostaglandin E₁ infusion, the SVC is ligated, the interatrial groove is incised and the inferior vena cava is divided, permitting the right and left side of the heart to decompress. The aorta is cross-clamped, and cardioplegia is initiated. The pulmonary flush consisting of several liters (50–75 mL/kg) of cold (4°C) Perfadex® is initiated. The chest cavity is cooled with ice-slush normal saline. Gentle ventilation is continued throughout to prevent hyperinflation or atelectasis and to enhance distribution of the flush solution.

After the cardioplegia and antegrade pulmonary flushes are completed, the cannulas are removed. The heart then is extracted. The inferior vena cava is freed posteriorly and dissected up to the level of the right atrium. Division of the left atrium proceeds from the venting incision in the interatrial groove with the cooperation of the heart and lung teams. The orifices of the superior and inferior pulmonary veins are visualized to leave adequate cuff for lung implantation. The surgeon on the left side of the table can visualize the right vein orifices best and should divide the left atrial cuff over the right pulmonary veins. An appropriate residual atrial cuff should have a rim of left atrial muscle around each of the pulmonary vein orifices. An adequate cuff can be ensured if the interatrial groove is developed on the right (Fig. 109-3). The SVC is transected between ties, followed by both division of the aorta proximal to the cross-clamp and the PA at its bifurcation. The heart then is passed off the field. The appearance of the surgical anatomy after passing off the heart is shown in Figure 109-4.

After extracting the heart, we use a Foley catheter to deliver a retrograde flush via the pulmonary vein orifices (approximately 250 mL of cold Perfadex® in each orifice). During retrograde flushing, residual blood and small clots are often flushed out of the opened PA bifurcation. Alternatively, this retrograde flush can be done on the back table before departing from the donor site. We incorporated this retrograde flushing procedure into our donor procurements after experimental¹⁰ and clinical research¹¹ found it to be superior to the antegrade flush, with less pulmonary edema, lower airway resistance, and better oxygenation during the first several hours after transplantation.

We then proceed with en bloc removal of the contents of the thoracic cavity. Removal of the lungs by this technique prevents injury to the membranous trachea, pulmonary arteries, and pulmonary veins. The tracheal dissection is completed at least two to three rings above the carina. The endotracheal tube is opened to atmosphere, and the lungs are permitted to deflate to approximate end-tidal volume while the endotracheal tube is backed into the proximal trachea. The trachea is sealed with a linear stapler and divided at least two rings above the carina (Fig. 109-4). Immediately posteriorly, the esophagus is encircled, stapled, and divided using a linear stapler. While retracting both lungs, heavy scissors are used to divide all the mediastinal tissue down to the spine. Staying directly on the spine, the posterior mediastinal tissue is divided. At this point, the pericardium near the diaphragm is transected. The inferior pulmonary ligaments are sharply divided. The lower esophagus is encircled and divided with the linear stapler. Posterior mediastinal tissue is sharply divided to connect with the superior aspect of the dissection. The lungs then are removed en bloc along with the thoracic esophagus and aorta.

If the lungs are returning to the same institution, they are tripled-bagged together with cold preservation solution and transported on ice. Alternatively, if the lungs are to be used at separate institutions, they are divided on the back table. While the lung bloc is kept in an ice-slush bath, the donor esophagus and aorta are removed, and the pericardium is excised. The lungs are separated by dividing the posterior pericardium, the left atrium between the pulmonary veins, the main PA at the bifurcation, and the left bronchus above the takeoff of the upper lobe bronchus. The left bronchus is divided between staples to maintain the inflation of each lung.

Donor Heart–lung Procurement

The donor harvest procedure for a heart–lung bloc is similar to the separate harvests for heart and lungs, with the exception that the heart and lungs are removed en bloc. After the pulmonary flush and cardioplegia are completed, the SVC is transected between ties, followed by division of the aorta proximal to the cross-clamp. The trachea is completely encircled, doubly stapled, and transected, again permitting the lungs to deflate to approximate end-tidal volume. En bloc removal of the contents of the thoracic cavity proceeds as in the lung procurement technique.

It is estimated that only about 15% to 20% of all multiorgan donors are used for clinical lung transplantation.¹² Most lung offers are considered unsuitable due to marginal donor lung function. Injuries from multiple sources such as brain death, ventilator-associated barotrauma, sepsis, and pulmonary edema lead to deterioration of donor lung function. However, such injuries might be reversible and if given time to recover, a proportion of these lungs will ultimately turn out to be acceptable for clinical transplantation. Ex vivo lung perfusion (EVLP) is a novel strategy of differentiating between suitable and suboptimal lung grafts in this donor population with marginal lung function.

There are various protocols being developed for clinical EVLP. Here we discuss briefly the one published recently by the Toronto Lung Transplant Group.¹³ The donor lungs are harvested in standard fashion and undergo a period of hypothermic preservation. Subsequently, they are brought to the center for EVLP where they are removed from the hypothermic preservative. The lungs are transferred to the perfusion chamber and the left atrium and PA on the donor lungs cannulated. The lungs are perfused with special acellular perfusate. Retrograde flow is initially performed to de-air the lungs through the PA cannula. The PA cannula is then connected to the circuit and antegrade flow is started with the perfusate at room temperature. As the lungs get warmed to about 32 degrees, ventilation is started and the perfusate flow rate gradually increased. The target maximum maintenance perfusate rate is about 40% of the estimated cardiac output. The flow of gas used to deoxygenate and provide carbon dioxide to the inflow perfusate via a gas exchange membrane is started at 1 L/min. A protective mode of mechanical ventilation is applied using a tidal volume of 7 mL/kg of ideal donor body weight, positive end-expiratory pressure (PEEP) of 5 cm H₂O, and an inspired oxygen fraction (Fio₂) of 21% (Fig. 109-5). The lungs are recruited with a peak airway pressure of 20 cm H₂O every hour.

EVLP is done for 4 hours. Following completion, the lungs are cooled down in the circuit to 10°C over 10 minutes. Subsequently, perfusion and ventilation are stopped and the trachea is clamped to maintain the lungs in an inflated state. The lungs are then preserved at 4°C in Perfadex® until transplantation.

Before anesthesia is induced, most of our patients have epidural catheters placed. If cardiopulmonary bypass (CPB) is planned, we do not place an epidural because of the requirement for heparinization during CPB. Double-lumen endotracheal intubation is routine. When the indication for transplantation is septic lung disease (e.g., CF or bronchiectasis), the patients are intubated initially with a large single-lumen endotracheal tube to permit vigorous suctioning of purulent secretions through an adult fiberoptic bronchoscope. This step maximizes the effective ventilation during independent lung ventilation and decreases the likelihood that CPB will be required.

Routine monitoring devices include a Swan–Ganz catheter, radial and femoral arterial lines, Foley catheter, and a transesophageal echocardiography probe. For bilateral sequential lung transplants, the patient is positioned supine with all extremities padded and arms tucked in at the sides. A pillow is placed behind the knees to prevent hyperextension and peroneal nerve palsy, which can result from prolonged hyperextension of the knees. A heating blanket is placed up to the mid-abdomen. If a posterolateral thoracotomy is used for a single-lung transplant recipient, the patient is positioned in the appropriate lateral decubitus position.

CPB is used routinely for children, for lobar transplants, for patients in whom a double-lumen tube cannot be placed (small adults), whenever intracardiac procedures are indicated, and for most patients with pulmonary hypertension. For most of our patients, however, we do not use CPB (but we prepare to do so should it be emergently required). We also do not routinely use the cell saver because the majority of our transplants are performed with less than 500 mL of blood loss.

Incisions

Bilateral Anterolateral Thoracotomy

Our standard exposure is the bilateral anterolateral thoracotomy, which prevents the complication of sternal healing associated with the clamshell incision.¹⁴ The skin incision is performed along the inframammary crease at the level of the fourth intercostal space. The skin over the sternum is not divided. The breast tissue and the lower edge of the pectoral muscle are elevated off the chest wall. The chest cavity is entered by dividing the intercostal muscle directly overlying the fifth rib. The internal mammary arteries are identified, isolated, ligated, and divided bilaterally. Alternatively, the internal mammary arteries can be preserved if a 1-cm segment of costal cartilage of the fourth rib is resected at the sternal border, permitting upward mobility of the fourth rib when retracted. More mobility is obtained by dividing the intercostal muscle from within the pleural space to the paraspinal muscles. The serratus anterior muscle and the long thoracic nerve are not divided; rather, they are pulled away from the chest wall to permit access to the posterolateral intercostal space. Optimal exposure then is obtained by appropriate placement of chest retractors at 90-degree angles from one another (Fig. 109-6). The table is tilted right or left as necessary to maximize exposure during hilar dissection, lung removal, and implantation.

Transsternal Bilateral Thoracotomy (Thoracosternotomy) Incision

This incision provides excellent exposure to the hilar structures as well as the mediastinum and both pleural spaces (Fig. 109-7). Bilateral retractors are used to elevate the chest wall upward. We resort to the full clamshell incision under the following circumstances: (1) a concomitant heart operation is planned, (2) the patient has pulmonary hypertension with secondary cardiomegaly, or (3) the patient has restrictive lung disease and small chest cavities that preclude adequate exposure via bilateral thoracotomies. On occasion, this anterolateral approach does not provide adequate exposure to the left hilum. Usually, this limitation is owing to a small pleural space with shift of the heart to the left. In this circumstance, we have frequently opened the pericardium and used the suction heart-stabilizing device to elevate the heart upward and to the right. This maneuver exposes the left hilum very well and often avoids the need for CPB.

When an otherwise straightforward transplant requires CPB, we do not usually proceed with the clamshell incision because the ascending aorta and right atrium can be cannulated easily through the medial aspect of the right anterolateral thoracotomy.

If a transverse sternotomy has been performed, our preference is to reapproximate the sternum with two figure-of-eight no. 7 sternal wires. Other techniques to reapproximate the sternum have been developed.¹⁵

Posterolateral Thoracotomy and Anterolateral Thoracotomy

Patients with restrictive lung diseases and small chest cavities and patients with secondary pulmonary hypertension and cardiomegaly may present with their heart filling much of the left anterior hemithorax, making access to the left hilum via the anterior approach quite difficult. In these circumstances, CPB can be avoided by performing the left lung transplant first through a left posterolateral thoracotomy. The patient then is turned supine, and the right lung transplant is performed via a right anterolateral approach.

The lungs are removed from the bags and placed on ice and covered with icy laps. First, the tracheal staple line is excised and lungs opened to air. The aorta and esophagus are removed posteriorly. The PA orifice is then examined to the first branch of right and left main PA visualized. The PA is divided by staying right on the raphe at the bifurcation. The atrial cuff is then inspected and divided equally so there is ample sewing ring on both sides. The tissue between the divided PA and atrial cuff is divided to expose the left main bronchus. The left main bronchus is divided distal to the tracheal carina and the lung separated, covered in ice, and labeled. The final preparation of the PA, atrial cuff, and bronchus is done on the operative field in order to make precise assessment of the required length of each structure. Usually, the bronchi are divided such that no more than one ring remains before the secondary carina. A longer donor bronchus predisposes to anastomotic ischemia and stricture.¹⁶ Care is taken to minimize dissection of the donor bronchus to preserve collateral flow through the peribronchial nodal tissue. The PA is also divided fairly close to the first branch as a long and redundant donor PA predisposes to kinking. The PA and left atrial cuffs are freed from any pericardial attachments because these may cause kinking after the anastomosis is completed. The right and left PAs are cleaned back to their first branches and inspected for any injuries or embolic material.

To reduce the likelihood of requiring CPB, the least functional lung, as determined by preoperative quantitative ventilation/perfusion imaging, is resected and replaced first. An attempt is made to detach all pleural adhesions and fully mobilize the hila of both lungs before the first lung is explanted. Great care is taken to avoid injuring the phrenic nerve as it passes just anterior to the hilum and the vagus nerve that lies posterior to the hilum. This preliminary dissection shortens the time that the first implanted lung is exposed to the entire cardiac output and thus lessens the likelihood of reperfusion edema in that lung. In this respect, both donor lungs should be prepared for implantation before removing the recipient's lungs, if possible.

The pulmonary arteries and pulmonary veins are dissected beyond their primary bifurcations to preserve the length of the main trunks. The pulmonary veins are divided between ties or staple lines at second branch points saving maximal length for the future recipient atrial cuff. The right PA is usually transected between firings of a vascular stapling device 1 cm beyond the ligated first branch to the right upper lobe. Before PA stapling and division, it is important to be sure the PA catheter is not too far peripheral and at risk of division. The left PA is transected between staple lines beyond the second branch to the left upper lobe. The bronchus is transected between cartilaginous rings well into the mediastinum at a site suitable for anastomosis. The posterior bundle of lymphatics and bronchial arteries is exposed and divided with electrocautery or ligated and divided.

The lung is removed from the chest, and the operative field is prepared for implantation of the graft. The PA stump is grasped with atraumatic Duval triangular clamp and mobilized centrally. After sufficient mobilization both anteriorly and posteriorly, the Duval clamp is placed on anterior traction by wrapping a heavy silk tie around it and snapping to the drapes toward the head. The pulmonary vein stumps then are grasped with smaller Duval clamps and retracted laterally to permit circumferential opening of the pericardium. With the pericardium freed, the vein stumps then are retracted and temporarily fixed anteriorly, providing an excellent view of the bronchus. The left-sided, double-lumen endobronchial tube may impair the ability to trim the left bronchus to an appropriately short length, in which case the tube should be backed out a few millimeters. Meticulous hemostasis in the posterior mediastinum is achieved at this point with the knowledge that reaching this portion of the operative field after implantation of the graft lung will be extremely difficult. Finally, a small suction catheter is placed down the appropriate limb of the endotracheal tube to assist in keeping the airway clear by aspiration of blood and iced saline during implantation.

The donor lung is placed within the recipient's chest cavity covered by a cold lap pad. If space permits, a layer of slush is placed in the empty chest cavity first. We find it simplest to perform the anastomoses from posterior to anterior in the following sequence: bronchus, artery, and atrium. A silk traction suture is placed at the midpoint of the anterior bronchus of the recipient and is used to retract the bronchus out of the mediastinum to help with visibility during the anastomosis. Two corner stitches are placed at the cartilagino-membranous junction of the donor and recipient airway using double armed 4-0 PDS suture and tied down. From one end, the membranous part of the bronchial anastomosis is performed in a running fashion sewing the donor airway to recipient (Fig. 109-8). When the opposite end is reached, the stitch is brought outside either the donor or recipient airway and tied down to the other previously placed corner stitch. From that point, one end of the suture material is used to sew the cartilaginous portion of the bronchi in a running fashion, again, sewing donor to the recipient. Halfway through the cartilaginous anastomosis, the previously placed traction silk stitch in the anterior wall is removed. The other stitch is brought toward the middle from the opposite end and both are tied down to complete the cartilaginous anastomosis. Alternatively, the front cartilaginous wall can be anastomosed in an interrupted fashion using 4-0 PDS or 3-0 Vicryl suture (Fig. 109-9). The bronchial anastomosis is completed by sewing the peribronchial tissue anteriorly over the cartilaginous portion of the airway. If the bronchi are of small caliber, or if there is a size mismatch, which is seen most commonly on the left side, we opt for reapproximating the anterior wall with simple interrupted 3-0 Vicryl sutures to prevent stricturing of the airway. We have stopped reapproximating the posterior peribronchial tissue and we feel that the main purpose of peribronchial tissue is to separate the bronchial and vascular anastomosis and both the PA and vein anastomoses lie anterior to the bronchial anastomosis. Hence, closing the peribronchial tissue anteriorly suffices.

Next, the PAs of the donor and recipient are aligned in proper orientation. The recipient's PA then is clamped centrally with a small Satinsky clamp, with care taken to avoid including the Swan–Ganz catheter in the jaws of the clamp. The vascular staple line is resected at a location that matches the size of the donor and recipient arteries. Both donor and recipient PAs are trimmed to prevent excessive length and possible kinking postoperatively. An end-to-end arterial anastomosis is performed with a running continuous 5-0 polypropylene suture (Fig. 109-10). This anastomosis must be made with precise, small suture bites to avoid anastomotic stenosis.

Both vein stumps then are retracted laterally, and a Satinsky clamp is placed centrally on the recipient's left atrium. Once the clamp is placed, an umbilical tape is used to tie the clamp in closed position to minimize the likelihood of dislodgement during subsequent lateral retraction of the clamp. The vein stumps then are amputated, and the bridge of atrium between vein stumps is divided to create the atrial cuff (Fig. 109-11). Gentle lateral traction on the Satinsky clamp can bring this anastomosis to a more accessible location. Alternatively, a retraction suture placed in the pericardium 2 to 3 cm above the inferior pulmonary vein, with care taken to avoid injury to the phrenic nerve, can be used to partially suspend the heart, providing better exposure to the left atrial anastomosis. The anastomosis is performed with continuous 4-0 polypropylene suture. Sutures are placed using a mattress technique, which achieves good intima-to-intima apposition and excludes all atrial muscle. This limits the thrombogenicity of this suture line. The suture line is left open on its anterior aspect. The lung is partially inflated, and the PA clamp is loosened momentarily. The lung is flushed with the atrial clamp still in place so as to flush out residual pulmonary perfusate solution. The left atrial clamp then is opened momentarily to completely de-air the atrium. The atrial suture line is secured, and the clamps are removed completely. All suture lines, as well as the cut edges of pericardium, then are checked for hemostasis as ventilation and perfusion are restored.

The contralateral transplant is conducted in the same fashion. Traditionally, we have drained the pleural space with two large-caliber chest tubes, one angled and one straight. More recently, if hemostasis during the procedure is excellent, we use two no. 24 Blake drains (Ethicon, Somerville, NJ) in each pleural space, one placed apically and one placed along the diaphragm. The ribs are reapproximated with interrupted figure-of-eight monofilament nonabsorbable suture. The pectoralis muscle and fascia are reapproximated with standard suture material, as is the subcutaneous layer. If a major submammary dissection has been necessary, we drain the submammary space. Staples or a running subcuticular suture is used for the skin, and then sterile dry dressings are applied. Before leaving the OR, bronchoscopy is performed to inspect the bronchial anastomosis and clear away any secretions. The patient is taken while still intubated to the thoracic ICU for postoperative monitoring.

Choice of Side

The choice of side of transplant is based on several factors. Usually, the side with the poorest function determined by preoperative ventilation/perfusion scanning is transplanted. If need for CPB is anticipated, the right side is preferred because cannulation of the ascending aorta and right atrial appendage can be performed easily through the anterior aspect of the thoracotomy. Cannulation of the descending aorta and main PA can be accomplished through the left chest but is somewhat more tedious. We avoid groin cannulation whenever possible. For patients with Eisenmenger syndrome, we prefer the right side to facilitate closure of the coexisting atrial or ventricular septal defects. A patent ductus arteriosus can be repaired in association with a transplant on either side.

Exposure

The standard incision is a generous posterolateral thoracotomy through the fifth interspace. Some groups have recommended the anterior axillary muscle-sparing thoracotomy for emphysema patients.¹⁷ Alternatively, an anterolateral fourth interspace thoracotomy provides excellent exposure, particularly on the right side. This is especially useful if a need for CPB is anticipated.

Pneumonectomy and Implantation

The techniques of pneumonectomy and implantation are identical to those just described for double-lung transplantation.

Use of Cardiopulmonary Bypass in Lung Transplantation

When CPB is planned we prefer to do the majority of the dissection before administration of heparin and cannulation. A two-stage venous cannula is placed in the atrium, and an aortic perfusion cannula is placed in the ascending aorta. We also place a PA vent. After cannulation, the bypass pump is instituted at full flow, and both lungs are excised. After the first lung is implanted, the left atrium is de-aired and the left atrial clamp removed. The PA clamp is left in place. If the left atrial clamp is also left in place, there is often not enough atrium available for clamp placement on the opposite side. The lung is packed in iced saline and slush while the second lung is implanted.

Postoperative Care After Lung Transplantation

Immediately after the surgery, patients are transported intubated to the ICU for constant monitoring. Once stabilized, a standard ventilator pressure-support weaning protocol is initiated. We favor pressure-control ventilation to limit peak airway pressures and prevent barotrauma to the bronchial anastomosis. Plateau pressures should be limited to no more than 35 mm Hg. Fifty percent of lung transplant recipients at our institution are weaned from mechanical ventilation and extubated within 24 hours of transplantation. Patients typically leave the OR on high Fio₂. However, if the initial postoperative arterial blood gas demonstrates a Pao₂ of more than 70 mm Hg and/or saturations greater than 90%, then the Fio₂ is weaned, and repeat measurements of arterial oxygenation are made after each change to minimize the risk of oxygen toxicity. In most patients without significant reperfusion edema, the Fio₂ can be weaned successfully to 40% or less within the first 24 hours of transplantation. Postoperatively, a quantitative lung perfusion scan can be performed to assess patency of vascular anastomosis and graft flow. If a lobar or greater perfusion defect is appreciated, the cause should be further interrogated by angiography or operative exploration.

In single-lung transplant patients with COPD, zero or minimal PEEP is used, along with an adequate expiratory phase of ventilation, to prevent air trapping in the native lung. An expiratory hold maneuver may be useful to detect air trapping in these patients. Careful fluid management is necessary to avoid substantial transplant lung edema, and usually negative fluid balance is attempted within the first 48 hours. Adequate urine output is carefully maintained with combinations of blood, colloid, and diuretics. Recent evidence suggests that lung injury caused by transplantation significantly reduces the ability of the lungs to clear edema fluid.¹⁸ Although often employed in renal doses to facilitate diuresis, the role of low-dose dopamine at 2 to 3 μg/kg/min remains controversial. Overly aggressive diuresis can result in renal insufficiency, which may be exacerbated by high postoperative calcineurin inhibitor levels. Therefore, careful monitoring of immunosuppressive medication levels and renal function is essential in the immediate postoperative period.

Before extubation, patients undergo bronchoscopy to ensure adequate clearance of secretions and viability of the donor bronchi. After extubation, the apical chest tubes are removed in the absence of an air leak, commonly within 48 hours postoperatively. Because of the frequent occurrence and recurrence of pleural effusions postoperatively, especially in bilateral lung transplant recipients, the basal chest tubes remain for several days and usually are removed on postoperative days 5 to 7 (chest tube drainage <150 mL/24 hours).

Vigorous chest physiotherapy, postural drainage, inhaled bronchodilators, and frequent clearance of pulmonary secretions is required in the postoperative care of these patients. Early and constant involvement of the physical therapy team ensures that transplant recipients are out of bed to chair, ambulatory with assistance, and using the treadmill or exercise bikes as soon as possible, even if they remain intubated. In patients with early allograft dysfunction requiring prolonged intubation, early tracheostomy permits easier mobility and better patient comfort, oral hygiene, and clearance of pulmonary secretions.

Adequate pain control is a necessity to prevent atelectasis owing to poor chest movement and inadequate coughing effort secondary to post-thoracotomy incisional pain. An epidural catheter provides an excellent means of achieving pain control with minimal systemic effects. In one study after lung transplantation, use of an epidural catheter was associated with faster extubation and decreased ICU days compared with IV morphine.¹⁹ Patients often require at least some oral narcotics in the first few weeks after transplantation for pain management. Use of oral narcotics or acetaminophen is preferred to nonsteroidal anti-inflammatory drugs that can exacerbate renal insufficiency in these patients already on cyclosporine or other potentially nephrotoxic drugs. Procedure-specific and postoperative complications are reviewed in a different chapter.

Preparation of Recipient

The recipient undergoes general anesthesia and double-lumen tube is preferred in order to have the option of single-lung ventilation. Routine monitoring devices are the same as those detailed for lung transplantation.

Technique

The type of incision performed is based on surgeon preference with either a median sternotomy or an antero-transsternal (clamshell) thoracotomy, each of which provides excellent exposure. For CPB, arterial cannula is placed in ascending aorta and bicaval cannulation is used for venous drainage. Both pleural spaces are opened, and adhesions are divided. After full bypass, the recipient is cooled to between 28 and 32°C, and mechanical ventilation ceased to permit better exposure. The pericardium around the level of the hilum is excised, and the PA and veins mobilized in the intrapericardial space. The right atrium is excised adjacent to the atrioventricular groove anteriorly, and the excision is extended circumferentially along the atrial septum. The aorta is divided above the aortic valve and retracted superiorly. The remaining PAs, left atrium, and ventricular structures are dissected free from the surrounding mediastinal tissue, and the patient's heart is removed (Fig. 109-12).

The bronchi on each side are mobilized, stapled proximally, and divided. The bronchi are divided beyond the staple line, and both lungs are removed separately. It is important to identify and preserve both phrenic nerves (Fig. 109-13).

The bronchial stumps and tracheal carina are mobilized, and the recipient trachea is divided immediately above the carina (Fig. 109-14). Care must be taken to ensure that bronchial vessels in the subcarinal space are controlled and that hemostasis is ensured before the graft is placed and anastomoses are completed. Exposure to the posterior mediastinum to establish hemostasis after heart–lung implantation is difficult and hazardous. Before the graft is placed, the pericardial openings are extended inferiorly and superiorly to create bilateral openings through which each donor lung can be introduced into its respective pleural space.

The donor heart–lung bloc is brought into the operative field, and each lung is passed through the opening in the pericardium into the pleural cavities posterior to the phrenic nerve–pericardial pedicles. Lick et al.²⁰ have reported a modified technique in which the lungs are placed anterior to the phrenic nerves into each hemithorax. Placing the hila in front of the phrenic nerves minimizes dissection around and traction on the phrenic nerves and additionally permits the heart–lung bloc to be rotated anteriorly and medially to inspect for hemostasis in the posterior mediastinum after implantation.²⁰

The tracheal anastomosis is performed first. We use a running 4-0 monofilament absorbable suture (Fig. 109-15). After the tracheal anastomosis, the right atrial anastomosis is performed either by the bicaval technique or by the right cuff technique described by Shumway and Lower.

The aortic anastomosis is performed last while the patient is being rewarmed. Attention to de-airing the heart and aorta is imperative. Transesophageal echocardiography is extremely useful for assessing residual air and for assessing cardiac function. After achieving stable hemodynamics and gas exchange, the patient is weaned from CPB, and the cannulas are removed. Temporary pacing wires are placed on the donor right atrium and ventricle (Fig. 109-16). Appropriate chest tubes are placed in both pleura and mediastinum and the chest closed.

Postoperative Care

While much of the postoperative care for heart–lung graft recipients is similar to that detailed earlier for lung transplant recipients, there are some important points to keep in mind. Between 10% and 20% of heart–lung recipients experience a short period (usually less than 1 week) of transient sinus node dysfunction that perioperatively often presents as sinus bradycardia. Recipients routinely have atrial and ventricular pacing wires placed at the time of the operation, and maintenance of a paced heart rate between 90 and 110 beats/min may be necessary for adequate cardiac output, given the dependency of the denervated heart on rate. Alternatively, isoproterenol (0.005–0.01 μg/kg/min) may be used for the first few days postoperatively to maintain heart rate. Persistence of sinus node dysfunction, although rare, may require a permanent pacemaker. Other dysrhythmias are seen commonly as well and need to be treated appropriately.

Right-sided heart dysfunction can occur in the immediate postoperative period and has several potential causes, for example, air embolism in right coronary, ischemia, and inadequate preservation. It can be exacerbated by ischemia-reperfusion injury in the transplanted lungs with the increased pulmonary vascular resistance. Early identification and treatment are necessary. In addition to pulmonary vasodilators, right-sided heart failure usually is treated successfully with inotropic support. Global depressed myocardial performance also can occur and usually is treated successfully with inotropic support. Contributing causes such as hypovolemia, sepsis, cardiac tamponade, and bradycardia should be considered and treated when found. Inotropic support is weaned gradually over the first several postoperative days.

A major barrier in the early years of lung transplantation was anastomotic failure secondary to poor healing. In retrospect, many of the early donor airways were too long. Since the antegrade bronchial circulation was divided when the organ was procured, anastomotic healing was dependent upon retrograde pulmonary blood flow to the donor bronchus. A major development in lung transplantation was the recognition that a short donor bronchus was more likely to be adequately perfused by retrograde blood flow and much less likely to dehisce. This principle of retrograde perfusion of the divided bronchus also applies to the healing of sleeve reconstructions.