Living donor and split-liver transplantation: an overview

"Small-for-flow" syndrome: shifting the "size" paradigm

The "small-for-size" syndrome and "post-hepatectomy liver failure" refers to the development of liver failure (hyperbilirubinemia, coagulopathy, encephalopathy and refractory ascites) resulting from the reduction of liver mass beyond a certain threshold. This complication is associated with a high mortality and is a major concern in liver transplantation involving reduced liver grafts from deceased and living donors as well as in hepatic surgeries involving extended resections of liver mass. The limiting threshold for liver resection or transplantation is currently predicted based on the mass of the remnant liver (or donor graft) in relation to the body weight of the patient, with a ratio above 0.8 being considered safe. This approach, however, has proved inaccurate, because some patients develop the "small-for-size" syndrome despite complying with the "safe" threshold while other patients who surpass the threshold do not develop it. We hypothesize that the development of the "small-for-size" syndrome is not exclusively determined by the ratio of the mass of the liver remnant (or graft) to the body weight, but it is instead strictly determined by the hemodynamic parameters of the hepatic circulation. This hypothesis is based in recent clinical and experimental reports showing that relative portal hyperperfusion is a critical factor in the development of the "small-for-size" syndrome and that maneuvers that manipulate the hepatic vascular inflow are able to prevent the development of the syndrome despite liver-to-body weight ratios well below the "limiting" threshold. Measurements of hepatic blood flow and pressure, however, are not routinely performed in hepatic surgeries. Focusing on the "flow" rather than in the "size" may improve our understanding of the pathophysiology of the "small-for-size" syndrome and "post-hepatectomy liver failure" and it would have important implications for the clinical management of patients at risk. First, hepatic hemodynamic parameters would have to be measured in hepatic surgeries. Second, these parameters (in addition to liver mass) would be the principal basis for deciding the "safe" threshold of viable liver parenchyma. Third, the hepatic hemodynamic parameters are amenable to manipulation and, consequently, the "safe" threshold may also be manipulated. Shifting the paradigm from "small-for-size" to "small-for-flow" syndrome would thus represent a major step for optimizing the use of donor livers, for expanding the indications of hepatic surgery, and for increasing the safety of these procedures.

Laparoscopic parenchymal division of the liver in a porcine model: comparison of the efficacy and safety of three different techniques

BACKGROUND

Bleeding is a known and CO2 embolization a suggested risk factor for increased morbidity after laparoscopic liver resection. Devices for laparoscopic liver parenchymal transection must be evaluated for safety in this context.

METHOD

Twelve piglets underwent laparoscopic surgery during CO2 pneumoperitoneum, each animal receiving three 6 cm long transections into the liver parenchyma made with ultrasonic dissector, ultrasonic shears and vessel sealing system, respectively. Endpoints were bleeding, operation time and gas embolization. The transections and embolization events, evaluated with transesophageal echocardiography, were video recorded. Bleeding and embolization were also assessed on video tapes and operating time measured. Arterial blood gases were recorded on line.

RESULTS

The ultrasonic dissector was least advantageous in terms of bleeding and operation time. Gas embolization was more frequent with the vessel sealing system than with the ultrasonic dissector and ultrasonic shears. During two episodes of gas embolization, pCO2 increased and pO2 and pH decreased.

CONCLUSIONS

Use of all three devices is feasible. Bleeding and operation time are greatest with the ultrasonic dissector. Gas embolization occurs during transection, though in most instances it is completely harmless. Laparoscopic liver surgery with these techniques used may pose a risk of gas embolization with clinical implications. Monitoring for such events is probably to be recommended.

Comparison between staple and vessel sealing device for parynchemal transection in laparoscopic liver surgery in a swine model

BACKGROUND

Advancements in technology have allowed laparoscopic surgery to expand into advanced procedures such as liver resection; however, the transection method is debatable. This study was designed to evaluate the feasibility and outcome of laparoscopic liver resection comparing the vessel sealing device (VSD) versus endomechanical stapling devices for parenchymal transection in a swine model.

MATERIALS AND METHODS

Laparoscopic left hepatectomy was performed in two groups (n=7 in each group) comparing the stapler device with the VSD. The cut surfaces of the liver were evaluated for bleeding and biliary leakage at the time of the operation and 1 week later. The animals were sacrificed 1 week after the operation to determine hemorrhage and bile leakage, and to allow histological evaluation of the liver. Serum liver enzymes were checked before, after, and 1 week postoperatively.

RESULTS

No evidence of biliary leakage or hemorrhage was noted at the time of the operation and 1 week later for both groups. There was a trend toward an increase in blood loss in the stapled group compared with LigaSure (40+/-16.4 cc vs 17+/-3.7 cc, p>0.05). There was also a trend toward shorter transection time in the stapled group compared with the LigaSure group (15+/-4.1 min vs 21.8+/-5.3, p>0.05). The instrument cost was significantly higher in the stapled group (720+/-110 vs 400+/-50; p<0.05). There was no difference in serial liver enzymes and liver histopathology in the two groups.

CONCLUSIONS

The VSD and endomechanical stapler can be safely and effectively used for parenchymal transection during laparoscopic liver resection. However, using endomechanical staplers is associated with an increase in cost.

Surgical experience in splitting donor liver into left lateral and right extended lobes

AIM: To outline the surgical experience with donor liver splitting in split liver transplantation.

METHODS: From March 1 to September 1 in 2004, 10 donor livers were split ex situ into a left lateral lobe (segments II and III) and a right extended lobe (segments I, IV - VIII) in Medical School of Hannover, and thereafter split liver transplantation was performed successfully in 19 cases. The average age, weight and ICU staying period of the donors were 32.7 years (15 - 51 years), 64.5 kg (45 - 75 kg) and 2.4 d (1 - 8 d) respectively.

RESULTS: The average weight of the whole graft and the left lateral lobe was 1 322.6 g (956 - 1 665 g) and 281.8 g (198 - 373 g) respectively, and the average ratio of left lateral lobe to the whole graft was 0.215 (0.178 - 0.274). The average graft to recipient weight ratio (GRWR) of the left lateral lobe and the right extended lobe reached 2.44% (1.22 - 5.41%) and 1.73% (1.31 - 2.30%) respectively. On average it took approximately 105 min (85 - 135 min) to split the donor liver. Five donor organs showed anatomic variation including the left hepatic vein variation in two cases, the left hepatic artery variation in two cases and the bile duct variation in one case.

CONCLUSION: Split liver transplantation has become a mature surgical technique to expand the donor pool with promising results. In the process of graft splitting, close attention needs to be paid to potential anatomic variations, especially to variations of the left hepatic vein, the left hepatic artery, and the bile duct.

First two cases of living related liver transplantation with complicated anatomy of blood vessels in Beijing

AIM: Living related liver transplantation (LRLT) has been developed in response to the paediatric organ donor shortage. Though it has been succeeded in many centers worldwide, the safety of the donor is still a major concern, especially in donors with anatomy variation. We succeeded in performing the first two cases of living related liver transplantation with complicated anatomy of blood vessels as a way to overcome cadaveric organ shortage in Beijing.

METHODS: Two patients, with congenital liver fibrosis and congenital biliary atresia were performed with living donor liver transplantation in our hospital and then followed up from November 12 to December 13, 2001. The two living donors, mother and father, were healthy aged 34 and 35 years. One right lobe (segment V, VI, VII, VIII) and one left lateral lobe (segment II and III) were used. The grafts weighed 394 g and 300 g. The ratio of graft weight to the standard liver volume (SLV) of donors was 68% and 27%. The graft weight to recipient body weight ratio was 3.2% and 4.4%. The graft weight to recipient estimated standard liver mass (ESLM) ratio was 63% and 85%. The two donors had complicated blood vessel variation.

RESULTS: Two patients undergone living donor liver transplantation had good results. Abnormal liver function with high bilirubin level appeared in a few days after operation, but liver function returned to normal one month after operation with bilirubin level almost decreased to near normal. No bleeding, thrombosis, infection and bile leakage occurred. One had an acute rejection and recovered. The two donors recovered in two weeks. One had slight fever because of a little collection in abdomen and recovered after paracentesis and drainage.

CONCLUSION: Living donor liver transplantation has been proved to be a good way that offers a unique opportunity of getting a timely liver graft as a response to shortage of pediatric donors, though it could be a technically difficult operation if there is anatomical variation.