DONOR
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Twenty percent of otherwise suitable organ donors have lungs that meet standard donor lung criteria ( Table 37-1 ).
TABLE 37-1 ▪
Age younger than 55 years
No history of pulmonary disease
Normal serial chest radiographs
Adequate gas exchange (PaO 2 300 mmHg on FiO 2 and PEEP 5 CM [H 2 O])
Normal bronchoscopic examination
Negative serologic screening for hepatitis B and human immunodeficiency virus (HIV)
Recipient matching for ABO blood group
Size matching
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Many brain-dead donors have significant lung parenchymal issues such as contusion, infection, aspiration, or neurogenic pulmonary edema.
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Size matching between donor and recipient lung volumes is important.
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Lung volumes are calculated using standard nomograms based on age, sex, and height.
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In patients with obstructive lung disease, allografts up to 20% larger than the predicted lung volume can be placed due to the increased size of recipient’s pleural space.
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In patients with restrictive lung disease or pulmonary vascular disease, pleural space is reduced in size; therefore allograft should not be oversized.
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In sequential bilateral lung transplant, do not oversize.
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“Marginal” donors refer to organs that are transplanted despite not meeting all of the standard donor selection criteria.
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“Marginal” donors can provide postoperative function that is nearly equivalent to the standard donors.
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Other strategies to increase donor pool include living donor lobar transplantation.
LUNG PRESERVATION
Basic Principles
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Systemic donor heparinization and administration of pulmonary vasodilator prostaglandin E 1 (PGE 1 ) 500 μg into the main pulmonary artery (PA).
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Pulmonary artery flush in a state of moderate inflation/ventilation with an FiO 2 greater than room air.
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Extracellular low potassium dextran solution used (Perfadex at temperature of 4° C). Perfadex (Vitrolife, Sweden), a low-potassium Dextran solution has been shown by several groups to produce better results than Euro-Collins solution. This has not been reproduced in all centers. Despite this, most programs have switched to Perfadex as their flush solutions.
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Ideally, ischemic time should be less than 6 hours.
Donor Extraction
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Chest x-ray study assessed for infiltrates, and fiberoptic bronchoscopy performed at donor hospital by harvesting team.
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Final assessment by gross inspection of lungs after median sternotomy.
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Trachea, vena cavae, and aorta encircled in chest.
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Donor heparinized, then the cardioplegia cannula is placed in the ascending aorta if the heart is being harvested, and a large-bore pulmonary artery flush cannula is placed in main pulmonary artery (MPA) proximal to bifurcation.
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PGE 1 may be given into the MPA, producing immediate drop in systemic blood pressure.
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The superior vena cava is ligated, and inferior vena cava (IVC) is clamped. (Note: IVC drain placed by liver team to drain liver flush.)
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IVC—right atrial junction is incised to allow cardioplegia to vent from coronary sinus to pericardium.
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The aorta is cross-clamped, and cardioplegia and PA flush initiated ( Fig. 37-1 ).
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Left atrial appendage is incised to vent pulmonary artery flush solution.
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The lungs are ventilated as 3 to 4 L of Perfadex solution are delivered at low pressure (<30 mm Hg).
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Topical iced slush is applied.
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Donor heart is removed in situ.
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After the superior vena cava, aorta, and MPA are divided, the heart is retracted to the right, and the left atrium is opened between the coronary sinus and the inferior pulmonary vein.
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The left atrial wall is divided leaving a rim of muscle on the pulmonary vein side ( Fig. 37-2 ).
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Optional retrograde flush of pulmonary veins is performed with balloon tipped catheter.
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The trachea divided with stapler above the carina with the lungs inflated, then the lungs are removed.
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If the individual lungs are going to recipients at different hospitals, the donor left main stem bronchus is divided with a cutting stapler, leaving both lungs inflated ( Fig. 37-3 ). Otherwise both lungs should be transported en bloc to be separated at the recipients hospital.
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The lung allografts are immersed in cold flush solution for transport.
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Before implantation, the pulmonary venous cuffs are trimmed.
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Hint: The donor pericardium can be used to augment the size of the pulmonary venous cuff.
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The pulmonary artery is separated from its pericardial attachments out to its upper lobe branch.
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The main stem bronchus is divided 1 to 2 rings proximal to upper lobe origin.
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Hint: Minimize dissection at site of bronchus transection to preserve bronchial collateral blood flow to donor bronchus after implantation.
Recipient Anesthesia
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Full hemodynamic monitoring is performed with a Foley catheter, PA Swan-Ganz catheter, and radial artery catheter.
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A transesophageal echo probe is useful in patients with pulmonary hypertension to monitor right and left ventricular function.
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Left-sided double-lumen endotracheal tube for separate ventilation of left and right lung.
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A single-lumen tube may be necessary in patients with suppurative lung disease such as cystic fibrosis because thick purulent secretions may need to be suctioned frequently from the tube.
Cardiopulmonary Bypass
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Cardiopulmonary bypass (CPB) is used for patients who do not tolerate single-lung ventilation.
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For patients of small stature when a single-lumen tube is used
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For patients with significant pulmonary hypertension who do not tolerate pulmonary artery occlusion
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For double-lung transplants after implantation of the first lung, to prevent the development of primary graft dysfunction in the first lung due to the entire cardiac output perfusing this lung while implanting the second lung (“first lung syndrome”)
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For patients who do not tolerate left atrial clamping for construction of the pulmonary venous anastomosis
Technique
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Right thoracotomy, ascending aortic cannulation for arterial return and right atrium for venous drainage.
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Left thoracotomy, proximal left pulmonary artery or main pulmonary artery cannulation for venous drainage and descending aorta for arterial return.
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Median sternotomy, or bilateral thoracosternotomy (clamshell), ascending aorta for arterial return and right atrium for venous drainage. MPA vent catheter.
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Femoral artery and vein can be used for peripheral cannulation.
SINGLE-LUNG TRANSPLANTATION
Choice of Side
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Transplant side with least pulmonary function as determined by preoperative quantitative nuclear perfusion scan.
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Right side preferred if CPB needed as in pulmonary fibrosis patients with associated pulmonary hypertension.
Exposure
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Posterolateral thoracotomy through fifth interspace is the preferred incision.
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A median sternotomy can be used for a right-sided single-lung transplant, especially if concomitant coronary bypass surgery or intracardiac repair is performed.
RECIPIENT PNEUMONECTOMY
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Pleural adhesions are divided.
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PA and vein are encircled.
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Care is taken to avoid the phrenic and recurrent laryngeal nerve.
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Need to use CPB assessed by occluding the pulmonary artery and assessing gas exchange and hemodynamic stability.
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Intraoperative transesophageal echocardiogram (TEE) useful to assess left and right ventricular function.
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Upper lobe PA branches are ligated and divided.
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Distal PA is stapled and divided.
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Pulmonary vein branches are divided with silk ligatures or stapler.
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Pericardium around vein stumps is widely opened, and the interatrial groove is dissected.
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The bronchus is divided proximal to upper lobe origin ( Fig. 37-4 ).
IMPLANTATION
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Bronchial anastomosis is performed first. The membranous posterior wall is closed with a continuous #4-0 absorbable monofilament suture (PDS or Maxon). The anterior cartilaginous airway is reapproximated with interrupted simple or figure-of-eight absorbable suture (Vicryl, PDS, or Maxon) ( Fig. 37-5 ).
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No attempt is made to intussuscept the smaller bronchus to avoid future bronchial stenosis.
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The pulmonary artery anastomosis is similarly fashioned with a vascular clamp placed proximally to control the recipient branch pulmonary artery. Excess length is trimmed from the donor and recipient branch PAs before creating an anastomosis with #5-0 polypropylene suture ( Fig. 37-6 ).
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After an atrial clamp is placed controlling the pulmonary vein stumps and part of the recipient left atrial wall, the pulmonary vein stumps are amputated and the bridge of tissue is divided to create a left atrial cuff.
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The pulmonary veins are anastomosed with a #5-0 monofilament suture ( Fig. 37-7 ).