Explantation

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Under explantation [Latin for (manufacturer) planting ] is understood in the transplantation medicine , the operation in which one or more organs are taken to another individual, they implant or to transfer into a nutrient solution (tissue culture). The term is also used for the surgical removal of organs or medical devices (screws, plates, artificial joints or active devices such as pacemakers, defibrillators , Brindleys ) that have already been implanted .

Explants are performed under the same conditions as other operations .

Explantation for organ donation

Explantation as part of an organ donation in Germany is different, depending on whether it is a living donation or an organ removal from a brain-dead person .

In the case of organ donation in the case of brain dead, the surgical team consists of employees of the German Organ Transplantation Foundation (removal surgeon, coordinator and perfusion service employee ) as well as the anesthesia team and surgical nurses from the removal hospital. Multiple teams can be involved in multiple organ removals. The DSO collection team provides the equipment required for optimal collection, preservation and further transport: special instruments, perfusion solutions, sterile ice, sterile packaging material and organ transport boxes.

Explantation with living donation

The kidneys and liver are suitable organs for living donation, but only partial donation is possible for the latter so as not to endanger the life of the donor. The generally healthy donor usually comes from the immediate family. The advantage of organ donation from relatives is that the donor and recipient tissue match antigenic , which means that the risk of transplant rejection is lower. The explantation as well as the subsequent transplantation can be planned, which means that the organ to be transferred (in comparison to the donor organ of a brain-dead person) is not supplied with blood for a short time and its functionality is therefore less impaired.

If a kidney is donated, the left kidney is preferably removed. The nephrectomy can also be performed laparoscopically . The donation of liver tissue usually consists of a hemihepatectomy on the right, which, if necessary, is expanded to include a vessel interponate from the great saphenous vein in order to be able to connect the liver segment to the arterial blood supply of the recipient. During the explantation, the living donor is u. a. monitored by means of CVP and invasive blood pressure measurement. A central venous pressure that is too high can occur in hypervolemia , which increases the risk of interstitial edema and the risk of thrombosis in the hepatic vessels.

The greatest risk for the living donor is the loss of large amounts of blood. However, since the procedure can be well prepared, the donor has the option of donating his or her own blood in advance (autologous blood donation), which is transfused instead of foreign blood if necessary .

Explantation for organ donation after diagnosed brain death

The prerequisite for the removal of vital organs is the correct diagnosis of brain death from the donor. If brain death has been determined, which is considered death in Germany, the donor is monitored and cared for until explantation as part of the organ-protective intensive therapy . The main aim is to maintain the optimal function of the organs that can be transplanted. Without intensive medical interventions, a brain-dead person would come to a cardiovascular arrest within a few minutes, with the consequent death of all organs.

preparation

Before and during the explantation, the donor body is monitored as with any other operation and treated if necessary. As a rule, no anesthesia is performed , only muscle relaxation , since it is assumed that there is no sensation of pain in the event of brain death. The main priority for anesthesia is to switch off the vegetative nervous system in the spinal cord. Depending on what has been agreed with the collection team, heparin , vasodilators , corticoids and other drugs are administered during the explantation .

To remove all organs suitable for transplantation, the donor is placed on his back with arms spread apart. The skin incision leads from the jugular fossa ( thrush fossa between the clavicles) to the pubis (pubic bone); the sternum (breastbone) and abdomen (abdomen) are opened. During this process, spinal reflexes are activated, which causes the release of endogenous catecholamines . Within about 15 minutes after the sternotomy , the catecholamine plasma level rises to almost 50 times its initial value, thereby increasing blood pressure and heart rate. In the further course it drops again somewhat, but no longer reaches the initial values.

Organ dissection and perfusion

The organs to be removed are exposed so that an initial assessment of their suitability for transplantation can take place. At the same time, a cardiac surgeon opens the pericardium and freely dissects the large vessels. This can lead to a situation requiring defibrillation due to a drop in blood pressure or cardiac arrhythmias . The abdominal aorta , ascending aorta and the pulmonary artery are cannulated then be inferior vena cava and - superior and the auricle atrii (atrial appendage) opened the left. The abdominal aorta is clamped above the celiac trunk (abdominal cavity trunk ). From now on the ischemia begins . A pressure perfusion (flushing) of the organs with cold preservation solution takes place via the abdominal aorta , a solution that paralyzes the heart muscle is administered via the aortic root. These processes lead to a cardiac arrest of the donor, which is desirable in this phase of the operation. A quick lowering of the body temperature is also achieved by pouring ice-cold saline or crushed ice (both sterile ) over the opened body . This shortens the warm ischemia time. The anesthesiological measures are discontinued; only if the lungs are planned to be removed will they continue to be ventilated in order to avoid the formation of atelectasis through regular unfolding and to achieve an even distribution of preservatives.

Organ removal

First, organs of the thorax (chest) are removed, the lungs in a distended state and with a hermetically sealed trachea (windpipe). The lungs (like the heart) only tolerate a short period of ischemia, which is why the appropriate removal team leaves the operating room before the abdominal explantations are completed in order to ensure that the upcoming transplantation is carried out as quickly as possible. Next, the abdominal organs are removed. It was previously determined whether the organ dissection should be carried out in situ (within the body) or an en bloc removal with subsequent ex situ dissection (for example, the ex situ method is usually chosen for liver splitting, if done by an experienced liver surgeon).

The organs are packed in the special transport containers provided for this purpose and are quickly brought to the appropriate transplant centers by authorized transport services.

graduation

At the end of the organ removal, the tube and other access points are removed from the donor body. The thorax and abdomen are closed and bandaged, the urinary catheter is pulled, the body is washed. The corpse should leave the operating theater in a dignified condition and be prepared for any desired laying out. Relatives now have the opportunity to say goodbye.

Medical device explantation

Implanted medical devices (such as pacemakers , defibrillators , screws, plates, port catheters ) can or must be removed again in certain situations, for example if they are damaged, infected or if they are no longer needed. Depending on where the implant is located or for what reason it is being explanted, the corresponding intervention is more or less complex. Many interventions take place on an outpatient basis; this may require a short anesthetic or even just a local anesthetic. However, the removal of a breast implant requires an operation under general anesthesia.

Before a cremation, certain devices must be removed by the medical officer or the undertaker (after the examination), otherwise damage to the environment or to an incinerator could result. This measure is only omitted in the case of infectious deceased persons for reasons of infection protection.

literature

  • B. Sinner, BM Graf: Anesthesia for organ removal. Der Anaesthesist 51 (2002), pp. 493-513.
  • Margret Liehn: Organ exploration - multi-organ removal , in: Margret Liehn, Brigitte Lengersdorf, Lutz Steinmüller, Rüdiger Döhler : OP manual. Basics, instruments, operating procedures , 6th, updated and expanded edition. Springer, Berlin Heidelberg New York 2016, ISBN 978-3-662-49280-2 , pp. 749-753.

Web links

Individual evidence

  1. ↑ Scientific Advisory Board of the German Medical Association (2001): Announcement on the sensation of pain in brain death .
  2. ↑ Information material on biological hazards, 2nd edition, 2005 at: www.bevoelkerungsschutz.de , accessed on August 30, 2012.