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(August 9, 2005). doi:10.1510/mmcts.2004.000984 Copyright © 2005 European Association for Cardio-thoracic Surgery Procedure Split lung transplantation with intraoperative extracorporeal membrane oxygenation (ECMO) supportMedical University of Vienna, Department of Cardio-Thoracic Surgery, Waehringer Guertel 18–20, 1090 Vienna, Austria * Corresponding author: * Tel.: +43-1-40400 5644; fax: +43-1-40400 5642. E-mail: walter.klepetko{at}meduniwien.ac.at
Pulmonary bipartitioning or split lung transplantation, which was first described in 1997, presently represents the most efficient use of donor lungs. With this technique, a left donor lung can be separated into an upper and lower lobe and used for bilateral transplantation in a smaller recipient. The right donor lung remains for use as a single lung graft in another patient. In 2001, a similar technique for splitting a right lung was described. The technique of harvesting and procurement of the donor organ for split lung transplantation is identical to the standard lung transplantation technique. The final separation of the donor lung is performed at the level of the interlobar fissure immediately prior to implantation. The lower lobe is implanted in the left recipient hemithorax, whereas the upper lobe, after closing of the central end of the left main pulmonary artery, and a 180° rotation along the vertical axis, is grafted into the right hilus. The use of extracorporeal membrane oxygenation (ECMO) provides intraoperative hemodynamic stability and protects the first implanted lobe from overflow and resulting reperfusion injury. This report discusses the technique developed at the department of cardiothoracic surgery of the Medical University of Vienna.
Key Words: ECMO • Lobar transplantation • Lung transplantation • Pulmonary bipartitioning • Size-reduced transplantation • Split lung
One major limitation of lung transplantation is the donor organ supply, and especially small donor organs which are sometimes rare in several areas. To overcome these problems, different techniques, including the use of lobes from cadaveric and living donors, have been emphasized. Without any doubt, the most efficient technique for the use of donor lungs represents the technique of pulmonary bipartitioning or the so-called split lung technique [1,2], which basically consists of a separation of the upper and lower lobes of a left donor lung, which are then used as a bilateral graft in a smaller recipient (Photo 1a and b). The right lung remains for use as a single lung graft in another patient [3]. Recently, a similar technique for splitting a right lung was described by Couetil et al. [4].
The general recipient inclusion criteria for such a procedure are similar to those of a standard lung transplantation and suitable recipients are either pediatric or smaller adult patients suffering from cystic fibrosis (CF), idiopathic pulmonary fibrosis (IPF) or primary pulmonary hypertension (PPH).
Organ harvesting and size matching Selection of donor organs for this procedure has to be done very carefully and only optimal organs should be used. Harvesting of the donor lung is identical as for standard lung transplantation and consists in an "en bloc" removal and back-table separation of the donor lungs into a left and a right lung. Low potassium dextran solution (Perfadex® – MMCTSLink 57) is almost uniformly used for donor lung preservation. Adequate size matching of the donor lung is crucial and is based on morphometric data and actual and predicted TLC of donor and recipient. TLC is calculated using the regression equations of the European Respiratory Society (ERS) [5].
For males:
Anaesthesiological management
Mechanical cardiopulmonary support during the transplantation is absolutely mandatory in order to avoid reperfusion injury of the first implanted lobe. This can be achieved either by conventional cardiopulmonary bypass or alternatively by extracorporeal membrane oxygenation (ECMO), which is described in this presentation [6]. The prolonged use of the latter, in particular, allows ventilating the transplanted lung with low tidal volumes and low pressures and reduces pulmonary artery pressure (PAP) during the reperfusion period [7].
Patient positioning and operative approach
The standard approach for split lung transplantation is a bilateral transverse thoracosternotomy (clamshell incision), which provides an excellent overview and good access to both hili (Photo 2).
ECMO management The ECMO system used by our group is the Carmeda System, which consists of an Affinity Hollow-Fiber Oxygenator (MMCTSLink 58), a Bio-Medicus BP-80 centrifugal pump (MMCTSLink 59), a flow probe and 3/8-inch internal diameter heparin-bound tubing (Video 3).
The use of a heparin-coated tubing set prevents high dose systemic heparin administration and thus limits anticoagulation to an intravenous bolus of 50 IU/kg heparin before cannulation. A mixture of 500 ml 5% human albumin and 500 ml physiological saline infusion supplemented with 1000 IU of heparin is used as a priming solution. Arterial oxygen saturation is continuously monitored at the level of the right upper limb. Cannulation can be performed either centrally through the ascending aorta and the right atrium, similar to standard cardiopulmonary bypass, or peripherally through a femoro-femoral veno-arterial access (Photo 3). For the latter, demonstrated in this presentation, the size of the cannulas is chosen after exploration of the femoral vessels in order not to compromise the distal femoral arterial flow. In the case of a small femoral artery, and complete occlusion due to the cannula, a separate cannula has to be inserted for perfusion of the distal leg (Photo 4).
ECMO flow during the operation is maintained at a level that guarantees adequate systemic pressure and oxygenation, while still allowing a cardiac ejection. Modalities of running ECMO become more important after implantation of the first lung. To guarantee adequate perfusion of the graft, ECMO should be run at a level that provides a pulsatile PA flow with an upper limit of 30 mmHg for systolic PAP. To ensure perfusion of the lung, end tidal pCO2 must be monitored and kept at a level of 10–15 mmHg. Ventilation of the lung during the reperfusion period is performed in a gentle way, with FiO2 of 0.5 and low tidal volumes limited by a peak pressure of 21 mmHg.
Left recipient pneumonectomy
Thereafter, the bronchus is divided. In patients with cystic fibrosis, stapling (Tyco TA3048S – MMCTSLink 61) followed by endobronchial rinsing and cleaning of secretions is recommended. The bronchus should be cut to a short length in order to avoid later kinking and to guarantee optimal blood supply. At the end of the hilar preparation the venous cuff is circumcised and freed from the pericardium (Video 5).
Preparation of the donor lung The left donor lung is prepared at the back-table. The stapled bronchus is cut to allow the lung to deflate, bacterial swabs are taken and the endobronchial system is cleaned and rinsed with cold saline solution (Video 6). The central stump of the left main pulmonary artery is closed with a vascular stapler (Video 7). Parenchymal bridges between the upper and lower lobe are separated with staplers (TCT75 – MMCTSLink 62 or TSB45 – MMCTSLink 63), electrocautery or scissors (Video 8). Afterwards, the venous cuff is separated at the bridge between the origin of the upper and lower lobe vein (Video 9) and the pulmonary artery is divided in an oblique way at the level of the fissure. This is one of the most crucial parts of the operation because it is extremely important to carefully preserve the orifices of all segmental arteries and concomitantly have a sufficient margin for the vascular suture (Video 10).
Finally, the upper and lower lobe bronchus is divided at the carina. The usually very dense bronchial tissue of the carina must be completely resected to allow the lobar bronchus to expand (Video 11).
The now separated lobes are inspected and the lower lobe is ready for implantation on the left side, whereas the upper lobe is stored on ice until implantation on the right side (Photo 5).
Implantation on the left side During implantation, the lobe is placed in a sterile bag together with slushed ice in order to provide topical cooling. The bronchial anastomosis is performed end-to-end with one single running 5/0 PDS suture [8], and no additional coverage is added (Video 12).
Implantation continues with the venous cuff, which is clamped and only one single venous orifice is created. Anastomosis is performed with a 4/0 running Prolene suture which is left untied to allow later de-airing (anterograde flushing). The arterial anastomosis is created in a similar way with 5/0 Prolene. After cross-clamping, the central artery is cut in a parallel way to the arterial cutting line of the donor lobar artery. During cutting, any injuries to the segmental arterial orifices should be avoided (Videos 13 and 14).
Finally, 500 to 1000 mg methylprednisolone are administered and de-airing of the lung with retrograde, and thereafter antegrade flushing, is performed under gentle ventilation of the implanted lung (Video 15). After tying of the sutures, the chest cavity is cleaned, the lung is mechanically ventilated and ECMO is run according to the criteria described above.
Implantation on the right side The pneumonectomy on the right side, with the exception of bronchial stump management, is identical to the left side. In order to achieve a longer bronchial stump, the right upper lobe bronchus is stapled at its origin (Video 16) and the bronchial anastomosis is sutured between the recipient bronchus intermedius and the upper lobe bronchus of the donor. For implantation, the left upper donor lobe is rotated by 180° around its vertical axis and positioned in the right chest. The donor cartilaginous portion of the bronchus is adapted to the recipient membranous portion and vice versa (Video 17).
The venous anastomosis can either be performed with the whole venous cuff of the recipient or with one of the pulmonary veins, depending on the size differences. Short pedicles are needed to avoid kinking (Video 18).
Positioning the donor lobe in this position, allows the recipient main pulmonary artery stump to have a close contact to the fissural aspect of the left upper lobe and consecutively to the donor upper lobe pulmonary artery and thus permitting a good arterial anastomosis between the two vessels (Video 19).
All other handling is identical to that of the other side (Video 20).
Final management At the end of the implantation, a careful inspection of both lungs and hili for any bleeding or air leaks is mandatory. Coagulation with electrocautery together with sealing of the hilus and, eventually, of the parenchymal preparation site is recommended. This can either be done by use of fibrin glue (Tissucol Duo Quick® – MMCTSLink 64) or of fleece-bound sealants (Tachosil® – MMCTSLink 65). Thus, postoperative bleeding and prolonged air leak can be avoided (Video 21).
Four 24-inch Charriere chest drains are inserted and the chest is closed. Special attention is paid to adaptation and closing of the sternum using Vicryl cords (Video 22).
Thereafter, according to the hemodynamic parameters, the surgeon can decide either, to gradually reduce and terminate the ECMO support, or to prolong it for another few hours in order to provide an extended smooth reperfusion period, as demonstrated in this report (Video 23).
The intubated patient can now be transferred to the ICU with or without an ECMO support and under moderate ventilation. Several hours later ECMO support is terminated and the device is explanted on the ICU (Photo 6).
The Vienna group experience [9,10] includes 8 patients (4 males and 4 females) with a mean age of 33±23 years (7–69 years) who received split lung transplantation in the period 2001–2005. In-hospital mortality was 1/8 (12.5%) with one patient dying after 34 days due to an infectious complication.
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Summary
Introduction
