The process of organ procurement: Liver - the warm dissectionWritten by Ivo Mitsiev at in "Transplant Surgery".
This is the second part of the posting series "The process of organ procurement".
Please start with the first part if you have not done so.
The preparation in the OR includes placing of two electrocautery ("Bovie") pads and two suction lines.
I usually fixate both arms next to the body unless the anesthesia colleagues have a good reason for extending one or both of them. Shaving and decontamination of the skin I perform only in a line about 5-10 cm on both sides of the midline as I never make lateral incisions.
The midline laparotomy extends from the Xyphoid to the Pubis. The (obliterated umbilical cord in the) round ligament is divided between two Kelly clamps and ligated with a 2-0 silk tie. The liver should be grossly assessed and if there is no contraindication for a transplant, proceeding with the thoracotomy is allowed. A special consideration here is the situation of a prior thoracic and especially heart surgery. In this case, the complete warm dissection should be made prior to the thoracotomy.
My own experience includes opening of the chest after a heart surgery was performed some years ago. I did not have this kind of case and did not think that almost the complete right heart might be adherent to the sternum. The thoracotomy went (retrospectively surprisingly) well, there was no bleeding. After placing and opening of the Finochietto retractor, the right ventricle literally opened. An attempt to close the defect with a suture failed, so that over the course of the following (very quick) warm dissection, the resident was asked to keep the wholes closed with the fingers.
The presternal skin is opened with the Bovie. I open the skin just below the jugular notch and perform a blunt dissection behind the sternum. The left innominate vein runs sometimes very superficial but more often a vein from the lower thyroid plexus might be injured during a sharp dissection with the Bovie causing annoying bleedings at this early point of the procedure.
This blunt dissection should be extended until the finger tip can be placed retrosternal around the jugular notch. The dissection of the sternum from distal is easily done only blunt so that usually almost the whole finger can be placed retrosternal. The sternotomy should be performed from cranial with the sternum saw because coming from distally could injure the left innominate vein.
Before doing it I usually place a lap pad on top of the left lateral lobe of the liver to avoid a possible injury with the saw.
The sternotomy could be performed also from distally of course. Should you be forced (for whatever reason) to do so, you should just pay attention to use the usual appropriate ventral force on the sternum saw and slow down as you approach the jugular notch in order to avoid touching the left innominate vein.
Usually I do not pay additional attention to the bleedings that occur from crossing intercostal vessels as well as from the sternal trabecula. Some surgeons prefer "closing" the bone spongiosa with wax as well as electrocautering the vessels. In my experience, placing blue towels around the sternal edges and retracting with the Finochietto retractor, provides a sufficient hemostasis here.
Retracting the abdominal wall with the modified Balfour retractor (with the long extensions) together with the already retracted sternum makes the best surgical exposure ever possible. Sometimes, in donors with very high BMI, incisions (on one or both sides) of the diaphragm at the level of the sternal edges might give additional exposure. However, I rarely had to do this.
The dissection of the left triangular ligament of the liver is the next step. Some surgeons place their right index finger behind the ligament and dissect it with the Bovie on top of the finger while retracting the left lateral liver lobe with the right thumb to the opposite side. Others use a lap pad placed between the ligament and the diaphragm and dissect also with the Bovie on top of the pad.
I personally use a combination of both techniques wrapping my right index finger with a lap pad, placing it behind the ligament and opening it with the Bovie on top of the wrapped finger. Maybe I do something wrong but using the Bovie on top of my finger was always too hot for me giving me sometimes unnecessary burns. This is the reason for me "wrapping" the finger with a pad as in this step.
Dividing the falciform ligament up to the suprahepatic Inferior Vena Cava (IVC) gives more mobility of the liver and is easily performed with the Bovie while retracting the liver away from the diaphragm. Attention should be paid though not to open the IVC at this point. In fact, dividing the falciform ligament only is what provides the liver mobility at this point and not exposing the Cava.
As I started with my transplant surgery training I was told a story by one of the senior fellows about an organ procurement in the past with an injury of the IVC, while opening the falciform ligament, which fixed the finger of one of the participating surgeons on the vein defect for the rest of the procedure.
According to my experience more than half of the donors have adhesions on the inferior and lateral surfaces of the liver. These should be thoroughly dissected sharp as a tension in a later point might cause a significant tear of the liver capsule.
I remember a case when I procured a very friable liver (although the fat content was < 10% on the biopsy). Obviously not having paid enough attention to these lateral adhesions, I produced a tear of the liver capsule of about 3 cm over the segments 6 and 7 during the cold dissection and mobilization of the liver. This tear turned out to be atypically deep into the parenchyma of the liver as it extended during the further movements of the organ and the back-table preparation into a real crack over the right lobe. Liver stitches and hemostatic agents became necessary during the transplant to stop the bleeding from this parenchyma defect. The postoperative course was unremarkable with a perfect liver function and a quick recovering patient but the stress of the liver injury which appeared initially small, made me more meticulous in dissecting the lateral liver adhesions.
Before starting the dissection of the hepatoduodenal ligament I usually palpate the ventral border of the foramen of Winslow in order to identify a possible accessory or replaced right hepatic artery.
The next step I do is the dissection of the Common Bile Duct (CBD). The hepatoduodenal ligament could be better exposed by retracting the liver laterally with the sweetheart retractor. I perform the dissection of the CBD on the level of the edge of the second duodenal portion after opening of the peritoneum and visualization of the duct. Sometimes the CBD is embedded deeper in the hepatoduodenal ligament (correlating with a high BMI). If at this point the dissection of the CBD becomes difficult, following the cystic duct out of the gall bladder might provide some help identifying the CBD. This should be generally avoided though as should any higher dissection in the hilum of the donor liver. Besides the risk for injury of structures closer to the hilum, the dissection of the CBD towards the liver could compromise its circulation.
Coming around the CBD should be performed with the right angle clamp towards the lateral border of the hepatoduodenal ligament in order to avoid an injury of the Portal Vein. A 2-0 silk tie is then placed around the CBD. The opinions on how to proceed here divide. Some surgeons tie and open the CBD, open the gall bladder and flush the extrahepatic ducts with normosaline. Others perform this as a part of the cold dissection.
Here is the reason for this pluralistic approach: Even though the CBD has usually a specific color and should be therefore easily identified, sometimes this structure happens to be an artery and in the worst scenario, the Common Hepatic Artery (CHA). Cutting the CHA at this stage of the procurement would clearly damage the biliary tree.
In fact, I was told about a procurement, done by a senior fellow, when exactly this happened. The liver damage has been major and has seriously affected the postoperative course of the recipient.
Therefore waiting for the cold dissection to cut the CBD has its reasons.
On the other hand, the idea to perform the flush at this stage is to avoid an ischemic damage of the bile ducts after the cross-clamp due to the digestion of the duct mucosa by the bile in a setting of no perfusion, preventing the mucosa from producing protective mucus.
And here is the way I use to come out of this dilemma: A 18-24 Gauge needle is used to aspirate in the lumen of the just dissected structure and help this way to identify it.
It happened once that I aspirated blood and could later identify the structure to be the GDA. Even though the identification of the CBD is not a hard task, the verification I use gives me some more confidence. I have to admit that the idea with the aspiration came from a perfusionist who saw it performed by a procurement team from another transplant center.
I then cut the CBD with the Metzenbaum scissors coming from medially. The gall bladder is then opened with the Bovie and flushed with the bulb syringe until the fluid coming out of the just opened CBD becomes clear.
Identifying a replaced or accessory left hepatic artery is done by exploration of the hepatogastric ligament and opening of the bursa by dividing the lesser omentum. This ligament is usually very thin and transparent so that vessels running through it should be visible. Sometimes a vein only can be identified but seeing a vein should make one always suspicious for existing artery and at least a palpation should be done before proceeding with the further dissection. Vagal branches could have the look of an artery and provide some confusion too. The lesser omentum could be opened over the entire length unless a left artery is being identified.
Performing the Cattell-Braasch maneuver starts with the packing of the small bowel in a blue towel and retracting it to the left side.
This way the white line of Toldt is exposed laterally to the right colon. This line is being beautifully described by Dr. Sidney Schwab as the "dotted line on which a surgeon cuts to unveil the colon".
Mobilizing the right colon should be performed on top of the Gerota's fascia and should be extended into a Kocher's maneuver in order to mobilize the duodenum to the left for uncovering the infrahepatic IVC and the abdominal aorta. The bifurcation of the aorta can be identified by palpation. On top of the big vessels is lymphatic tissue as well as splanchnic nerve plexus which is divided to dissect a 3-4 cm long segment of the aorta just above the bifurcation. Special attention should be paid to possible lumbar arteries which can be identified by dissecting on both sides of the aorta with the right angle clamp while retracting the vessel with the DeBakey forceps to the opposite site. The lumbar arteries could be either tied or clipped and then cut in order to provide mobility of the aorta and allow the cannulation. Sometimes the offspring of the Inferior Mesenteric Artery (IMA) is very distal so that it could be divided if needed.
Two umbilical tapes are placed around the dissected segment of the distal abdominal aorta and secured by clamps. Some surgeons place routinely a tie around the IVC just above the confluence of the iliac veins. The IVC can be then ligated after the cross-clamp to prevent the warm blood from the legs to interfere with the cold environment in the abdomen. The Inferior Mesenteric Vein (IMV) is most commonly used for access into the portal system. This vein provides outflow for the blood of the left colon and is therefore not packed in the blue towel containing the small bowel and the transverse colon. While retracting the "blue-towel pack" towards the diaphragm, the IMV runs next to the ligament of Treitz and can be localized in the right edge of the mesentery, just going into our pack. A 2-3 cm segment could be easily dissected with the DeBakey forceps and the Bovie. A 2-0 silk tie is used for ligating the distal part of the dissected IMV-segment and could be left uncut to retract the vein with a Mosquito clamp which could be then hooked on the Balfour retractor. Another 2-0 tie is placed around the cranial portion of the dissected vein and can be used for occlusion of the vein by retracting it while a cranio-posterior incision of the vein in 45 deg. is performed with the Metzenbaum scissors between the two ties. The portal cannula is inserted into the IMV while the tension of the occluding tie decreases and allows advancing before tying it around vein and inserted cannula. Additional air knot fixation is optional.
Should the assistant (who is supposed to make the tie after insertion of the portal catheter) be inexperienced, a Tonsil clamp can be used for fixating the cannula in the vein and the tie can be performed just above the clamp.
In the rare cases when the IMV can not be dissected, is too tiny, or has been damaged, the splenic vein provides an alternative access to the portal system. This approach might be also usable in the case when the procurement should be done more quickly than usual, e.g. DCD situation or hard to control bleeding (like heart damage during the thoracotomy). For this purpose the spleen is mobilized so that its hilum is exposed and the vein can be dissected. This technique could be performed also immediately after the cross-clamp to prevent excessive bleeding during the spleen mobilization and hilum dissection while still on perfusion. About 10-12 ml. of heparinized saline is used to flush the portal access. The catheter is then controlled with a Tonsil clamp. The cross-clamp is performed on the supraceliac aorta which can be dissected intraabdominal or intrathoracic.
The intraabdominal approach starts with the isolation of the abdominal portion of the esophagus. The donors have been usually ICU patients and have an Naso-Gastric Tube (NGT) which allows easy identification of the esophagus. After dividing the ventral peritoneum of the esophagus with the Bovie, the isolation could be easily done manually with the two index fingers. Umbilical tape is then placed around the esophagus which could be then retracted to expose the supraceliac aorta located between the esophagus and the spine. On both sides of the aorta are the two diaphragmatic crura. I divide usually only the right one but some surgeons dissect both in order to achieve better exposure. Palpating the crus and clamping it with a Tonsil clamp allows a retraction of the muscle ventrally and a dissection with the Bovie on top of the clamp. This technique can be repeated until the whole crus is dissected. The aortic clamp is then placed around the aorta ready for the cross-clamp.
I usually place the right branch of the clamp on the right side of the aorta on top of the spine and leave the left branch on the left side of the aorta. By scratching with the right branch on the left surface of the spine and pushing the clamp towards the back I could always achieve a good position of the clamp even in patients with high BMI and lack of good exposure. Probably this technique prevents me in the most cases from dissecting the left diaphragmatic crus.
Some surgeons perform routinely intrathoracic dissection of the supraceliac aorta. This is made by opening the left parietal pleura and dissecting the aorta between the esophagus and the spine. Identification of the esophagus is more difficult in the DCD situation when there is no pulsation of the aorta. The NGT can help here again.
At this point the 30 000 IU Heparin should be given to prevent the blood from clotting after the cross-clamp. The cross-clamp should be done at least 3 minutes after the injection of the Heparin. In this time I perform the cannulation of the aorta. The "blue-towel pack" is retracted towards the diaphragm so that the distal aorta can be exposed again. The distal umbilical tape is tied just above the aortic bifurcation. The cranial umbilical tape should be hold by the assistant ready for tying. The surgeon occludes the aorta between the two umbilical tapes with the thumb and index finger of the left hand and performs the incision of the aorta with Mayo or Metzenbaum scissors. The aortic cannula is introduced in the vessel and the cranial umbilical tape is tied around the aorta.
If the assistant is inexperienced, the tie might not be sufficient for occluding the aorta around the cannula. In this case a Tonsil clamp can be placed tangential on the dorsal portion of the cannula to narrow the vessel and occlude the leak.
Another way to do this is looping the cranial umbilical tape so that just by retraction it would provide a closure of the aortic wall around the cannula.
In the case the aorta is very atherosclerotic, placing the cannula through the plaques would increase the risk for dissection. In these cases I use one of the common iliac arteries. The other one should be ligated.
The cannula should be then retracted back until the retention ring "hits" the tied umbilical tape. This is to ensure that the tip of the cannula is placed below the renal arteries and the kidneys are well perfused.
We have now access to the portal (IMV) and the arterial (aorta) system, the CBD is been already identified, and the supraceliac aorta is dissected for clamping. The right parietal pleura is opened and a big access to the right pleural cavity is created for the exsanguinated blood to be collected there initially.
At this point I want to make sure that several things are prepared:
- the heparin was given more than 3 minutes ago,
- the flush lines are air-free and properly connected to the aortic and portal cannulas respectively,
- the ice bucket is placed close,
- pool-tips are connected to both suction lines.
The warm dissection ends with the cross-clamp: the aorta is clamped with the already placed clamp. The exsanguination is performed by opening of the supradiaphragmatic IVC or even higher (right atrium) and collecting the blood in the right pleural cavity where it should be evacuated by pool-tip suctions.
At this time I thank very much the anesthesiologists as their job is done with the exsanguination unless a thoracic team is procuring the lungs.
The flush lines and the control clamps on the aortic and portal cannulas are opened now. The flush starts. Ice is placed all over the abdominal organs as well as on top of the right diaphragmatic dome as the liver might be damaged by the warm blood which collects there at this point. Special attention should be paid for placing ice around the left kidney as it is often insufficiently cooled.
I always ask the perfusionist about the quality of flow.
At this (or earlier) point some surgeons place a big clamp around the mesentery to exclude the bowel from being perfused with the preservation solution allowing more volume to flush the liver and kidneys. On the other hand the coloration of the bowel is a good indicator for the quality of the aortic flush: it should become quickly quite pale as the blood is being replaced by the colorless UW (or any other preservation) solution.
Also, it is now the time to tie the IVC above its iliac confluence, should you have placed a tie around it at earlier point or would like to do it now.
The warm dissection is done. The cold dissection can be started when the perfusion with the preservation solution is completed.