Another lecture without a lecture outline, so guess I'll have to wing it. There were also a lot of details in this lecture that I didn't quite get, such as variations on some of the surgical techniques, but I think I'll just cross my fingers and hope that that doesn't come up on the exam 0_o
Types of donors
Just like for bone graft donations, organ donors can be living or deceased. Obviously, not all organs can be taken from a living donor. (Well, I suppose you could take all of their organs, but then they wouldn't be living any more. Also that shit would never pass an ethics board.)
Donations from the deceased can be classified into two categories: DBD (Donation after Brain Death) and DCD (Donation after Cardiac Death). In DBD, the heart is still beating, so the organs maintain their perfusion. In DCD, the organs lose their perfusion, so they are not as high quality as organs donated from DBD. Usually only kidneys and lungs are taken from a DCD donor.
An important consideration is the ischaemia time, or the time that the organs have to go without blood perfusion after being removed. There are two types of ischaemia time: WIT (warm ischaemia time) and CIT (cold ischaemia time). Organs can be kept for longer if they are cold: for example, warm kidneys can only be kept for around 60-90min after removal, but if they are cooled down, they can be kept for longer than 24 hours. A cold heart can be kept for 6-8 hours and a cold liver can be kept for 12-16 hours. Part of the reason why DBD organs are of higher quality is because the WIT is basically zero: their heart is still beating when the donor passes away, and the functional circulation is directly replaced with a cool fluid, so their organs essentially go straight from perfusion to CIT.
Organ retrieval
Now for the real shitshow! (Not the surgery, that is- my writing. A lot of the details from here on in went over my head. Maybe it would have made more sense if I was a surgeon, but I'm not, and probably never will be. I value my sleep too much.)
When organs are retrieved, UW (University of Wisconsin) solution is inserted into the aorta and drained out through the inferior vena cava. UW solution helps to minimise cell metabolism and keep the cell membranes stable, which is good for preservation purposes. The gallbladder and bile duct are washed, and a liver biopsy might be done in order to assess viability (particularly if the donor appears to have fatty liver disease or something similar). During the removal process, several factors must be taken into consideration. One of these factors is variability in the hepatic artery (see here for the normal anatomy of arteries supplying the gastrointestinal tract). Some people may also have an accessory right hepatic artery from the superior mesenteric artery, and others may have an accessory left hepatic artery from the left gastric artery (which in turn comes from the coeliac artery).
After an organ is removed, it is packed in three bags. The first bag is filled with UW fluid, which helps to preserve the organ. The next bag is filled with ice water, but if the organ is going to be sent to its destination by air, just normal water is used (to prevent over-freezing). The third and final bag simply provides an extra layer of protection.
Transplantation
Now for the transplantation bit! This part of this post is going to be extremely lacking because he went into detail on surgical techniques, and I got kind of lost.
Obviously, blood loss is a concern in most types of surgery. Argon gas can be used to stop small areas from oozing. Machines can collect blood that are lost during the transplantation so that it can be re-infused. (This is normally only done after the new organ has been implanted, especially if the old organ was cancerous- you wouldn't want any risk of any of those cancerous cells re-infecting the patient.) Finally, traditional blood transfusions can be done. Only around 1/3 of liver transplant patients require these transfusions.
There are several ways in which all of the vessels can be joined up. In this post, I'm just going to talk about the vena cava and the bile duct, for no other reason than that those were the only two procedures that I kind of understood.
For the vena cava there are three main options: caval replacement, piggyback and side-to-side cavaplasty. In caval replacement, the inferior vena cava from the patient is replaced with the vena cava of the transplant. In a piggyback anastomosis, one end of the donor inferior vena cava is joined up with the patient's inferior vena cava, which remains intact. In side-to-side cavaplasty, the donor and recipient inferior vena cavas are opened on one side and joined together.
For the bile duct there are two main options: end-to-end and roux-en-Y (not sure whether or not this is the same roux-en-Y used for bariatric surgery). In roux-en-Y, the bile is drained directly into the small intestine. There's a nice picture here if you want a better idea.
Other types of liver transplant
Aside from transplanting a whole liver, there are other things you can do. In a split liver transplant, a single liver is used for two patients (usually one adult and one child). A reduced size liver transplant uses only part of a liver. Finally, a live donor liver transplant takes part of a live donor's liver (obviously not so much that they die- enough needs to be left to allow the donor's liver to regenerate).
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