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.