The evolution of liver transplantation practices:

Training, work, and lifestyle of transplant physicians and surgeons in Germany

BACKGROUND

International data on training, work, and lifestyle of transplant physicians and surgeons are scarce. Such data might help in development of uniform education paths and provide insights for young clinicians interested in this field. This study aimed at the evaluation of these data in all transplant-associated medical disciplines.

METHODS

A survey on professional and academic training, workload, and lifestyle was generated. The questionnaire was distributed to all members of the German Transplant Association (DTG), utilizing the tool SurveyMonkey(®) .

RESULTS

A total of 127 members of the DTG responded (male/female 66.1%/33.9%, 45.8±10.3 years). The majority had been working in transplant medicine for more than 10 years (61.9%). Fifteen respondents (11.8%) obtained an official European certification (European Union of Medical Specialists). A total of 57 (48.3%) respondents worked full time on research during training. The research focus was clinical for most respondents (n=72, 61.5%). An average working time of 62±1.5 h/wk was reported. Fifty-eight percent of all respondents complained of inadequate remuneration and 50% reported inadequate acknowledgment of their professional performance.

CONCLUSION

This is the first study reporting characteristics of training, work, and lifestyle in an interdisciplinary cohort of German transplant physicians and surgeons. Enormous efforts in clinical and research work were reported, associated with high rates of professional and financial dissatisfaction.

The Effects of Direct Oxygen Supply During Static Cold Preservation of Rat Livers: An Experimental Study

OBJECTIVES

We aimed to determine the biochemical and histopathologic effects of direct oxygen supply to the preservation fluid of static cold storage system with a simple method on rat livers.

MATERIALS AND METHODS

Sixteen rats were randomly divided into 2 groups: the control group, which contained Ringer's lactate as preservation fluid; and the oxygen group, which contained oxygen and Ringer's lactate for preservation. Each liver was placed in a bag containing 50 mL Ringer's lactate and placed in ice-filled storage containers. One hundred percent oxygen supplies were given via a simple, inexpensive system created in our laboratory, to the livers in oxygen group. We obtained samples for histopathologic evaluation in the 12th hour. In addition, 3 mL of preservation fluid was subjected to biochemical analysis at 0, sixth, and twelfth hours. Aspartate aminotransferase, alanine aminotransferase, lactate dehydrogenase, and pH levels were measured from the preservation fluid.

RESULTS

In oxygen-supplemented group, the acceleration speed of increase in alanine aminotransferase and lactate dehydrogenase levels at sixth hour and lactate dehydrogenase, alanine aminotransferase, and lactate dehydrogenase levels at 12th hour were statistically significantly reduced. In histopathologic examination, all parameters except ballooning were statistically significantly better in the oxygen-supplemented group.

CONCLUSIONS

This simple system for oxygenation of liver tissues during static cold storage was shown to be effective with good results in biochemical and histopathologic assessments. Because this is a simple, inexpensive, and easily available method, larger studies are warranted to evaluate its effects (especially in humans).

A German survey of the abdominal transplantation surgical work force

This manuscript reports the results of a nationwide survey of transplant surgeons in Germany, including the demographics, training, position, individual case loads, center volumes, program structure, professional practice, grade of specialization, workload, work hours, salary, and career expectations. We contacted all 32 German transplant centers that perform liver, kidney, and pancreas transplantation. Surgeons engaged in transplantation were asked to reply to the survey. Eighty-five surgeons responded, with a mean age of 44 ± 8 years, 13% of whom were female. The median transplant frequency per active transplant surgeon was relatively low, with 16 liver transplants, 15 kidney transplants, and three pancreas transplants. The median reported center volumes were 45 liver transplants, 90 kidney transplants, and five pancreas transplants per year. Most of the surgeons reported a primary focus on hepato-pancreato-biliary surgery, and only 10% of effective work time was actually dedicated to perform transplant surgeries. The majority of respondents estimated their weekly work hours to be between 55 and 66 h. When asked about their career satisfaction and expectations, most respondents characterized their salaries as inappropriately low and their career prospects as inadequate. This survey provides a first impression of the transplant surgery work force in Germany.

A population pharmacokinetic study of tacrolimus in healthy Chinese volunteers and liver transplant patients

AIM

To develop a population pharmacokinetic (PopPK) model of tacrolimus in healthy Chinese volunteers and liver transplant recipients for investigating the difference between the populations, and for potential individualized medication.

METHODS

A set of 1100 sparse trough concentration data points from 112 orthotopic liver transplant recipients, as well as 851 dense data points from 40 healthy volunteers receiving a single dose of tacrolimus (2 mg, p.o.) were collected. PopPK model of tacrolimus was constructed using the program NONMEM. Related covariates such as age, hepatic and renal functions that were potentially associated with tacrolimus disposition were evaluated. The final model was validated using bootstrapping and a visual predictive check.

RESULTS

A two-compartment model of tacrolimus could best describe the data from the two populations. The final model including two covariates, population (liver transplant recipients or volunteers) and serum ALT (alanine aminotransferase) level, was verified and adequately described the pharmacokinetic characteristics of tacrolimus. The estimates of V2/F, Q/F and V3/F were 22.7 L, 76.3 L/h and 916 L, respectively. The estimated CL/F in the volunteers and liver transplant recipients was 32.8 and 18.4 L/h, respectively. Serum ALT level was inversely related to CL/F, whereas age did not influence CL/F. Thus, the elderly (≥65 years) and adult (<65 years) groups in the liver transplant recipients showed no significant difference in the clearance of tacrolimus.

CONCLUSION

Compared with using the sparse data only, the integrating modeling technique combining sparse data from the patients and dense data from the healthy volunteers improved the PopPK analysis of tacrolimus.

Review of anesthesia in liver transplantation

Liver transplantation (LT) is a well-accepted treatment modality of many end-stage liver diseases. The main issue in LT is the shortage of deceased donors to accommodate the needs of patients waiting for such transplants. Live donors have tremendously increased the pool of available liver grafts, especially in countries where deceased donors are not common. The main ethical concern of this procedure is the safety of healthy donors, who undergo a major abdominal surgery not for their own health, but to help cure others. The first part of the review concentrates on live donor selection, preanesthetic evaluation, and intraoperative anesthetic care for living liver donors. The second part reviews patient evaluation, intraoperative anesthesia monitoring, and fluid management of the recipient. This review provides up-to-date information to help improve the quality of anesthesia, and contribute to the success of LT and increase the long-term survival of the recipients.

Risk Factors Associated with Reoperation for Bleeding following Liver Transplantation

Introduction. This study's objective was to identify risk factors associated with reoperation for bleeding following liver transplantation (LTx). Methods. A retrospective study was performed at a single institution between 2001 and 2012. Operative reports were used to identify patients who underwent reoperation for bleeding within 2 weeks following LTx (operations for nonbleeding etiologies were excluded). Results. Reoperation for bleeding was observed in 101/928 (10.8%) of LTx patients. The following characteristics were associated with reoperation on multivariable analysis: recipient MELD score (OR 1.06/MELD unit, 95% CI 1.03, 1.09), number of platelets transfused (OR 0.73/platelet unit, 95% CI 0.58, 0.91), and aminocaproic acid utilization (OR 0.46, 95% CI 0.27, 0.80). LTx patients who underwent reoperation for bleeding had a longer ICU stay (5 days ± 7 versus 2 days ± 3, P < 0.001) and hospitalization (18 days ± 9 versus 10 days ± 18, P < 0.001). The risk of death increased in patients who underwent reoperation for bleeding (HR 1.89, 95% CI 1.26, 2.85). Conclusion. Reoperation for bleeding following LTx was associated with increased resource utilization and recipient mortality. A lower threshold for intraoperative platelet transfusion and antifibrinolytics, especially in patients with high lab-MELD score, may decrease the incidence of reoperation for bleeding following LTx.

Hematopoietic chimerism in liver transplantation patients and hematopoietic stem/progenitor cells in adult human liver

Liver transplantation (LT) is a cure for many liver diseases. Blood chimerism of donor origin can develop after LT, which raises the possibility of the existence of hematopoietic stem/progenitor cells (HSPCs) in the liver. We characterized the blood chimerism in a large cohort of 249 LT patients and analyzed putative HSPCs in adult human livers. The overall incidence of chimerism was 6.43%, of which 11.11% was among short-term (1 day to 6 months) and 3.77% was among long-term (6 months to 8 years) LT patients. Hematopoietic Lin(-) CD34(+) CD38(-) CD90(+) populations have been demonstrated to generate long-term lymphomyeloid grafts in transplantations. In human adult livers, we detected Lin(-) CD34(+) CD38(-) CD90(+) populations accounting for 0.03% ± 0.017% of the total single liver cells and for 0.05% ± 0.012% of CD45(+) liver cells. Both Lin(-) CD34(+) and Lin(-) CD45(+) liver cells, from extensively perfused human liver grafts, were capable of forming hematopoietic myeloid-lineage and erythroid-lineage methylcellulose colonies. More importantly, Lin(-) CD45(+) or CD45(+) liver cells could be engrafted into hematopoietic cells in an immunodeficient mouse model. These results are the first evidence of the presence of putative HSPC populations in the adult human liver, where the liver is a good ectopic niche. The discovery of the existence of HSPCs in the adult liver have implications for the understanding of extramarrow hematopoiesis, liver regeneration, mechanisms of tolerance in organ transplantation, and de novo cancer recurrence in LT patients.

CONCLUSION

The human adult liver contains a small population of HSPCs. In LT patients, there are two types of chimerisms: transient chimerism, resulting from mature leucocytes, and long-term chimerism, derived from putative HSPCs in the liver graft.

Anesthesia for liver transplantation in US academic centers: institutional structure and perioperative care

Investigators at a single institution have shown that the organization of the anesthesia team influences patient outcomes after liver transplant surgery. Little is known about how liver transplant anesthesiologists are organized to deliver care throughout the United States. Therefore, we collected quantitative survey data from adult liver transplant programs in good standing with national governing agencies so that we could describe team structure and duties. Information was collected from 2 surveys in a series of quantitative surveys conducted by the Liver Transplant Anesthesia Consortium. All data related to duties, criteria for team membership, interactions/communication with the multidisciplinary team, and service availability were collected and summarized. Thirty-four of 119 registered transplant centers were excluded (21 pediatric centers and 13 centers not certified by national governing agencies). Private practice sites (26) were later excluded because of a poor response rate. There were minimal changes in the compositions of the programs between the 2 surveys. All academic programs had distinct liver transplant anesthesia teams. Most had set criteria for membership and protocols outlining the preoperative evaluation, attended selection committees, and were always available for transplant surgery. Fewer were involved in postoperative care or were available for patients needing subsequent surgery. Most trends were associated with the center volume. In conclusion, some of the variance in team structure and responsibilities is probably related to resources available at the site of practice. However, similarities in specific duties across all teams suggest some degree of self-initiated specialization.

Usefulness of the Pinch-Burn-Cut (PBC) technique for recipient hepatectomy in liver transplantation

BACKGROUNDS/AIMS

Surgical bleeding during recipient hepatectomy is a major concern in liver transplantation (LT). Effective intraoperative control of bleeding is necessary. In the Pinch-Burn-Cut (PBC) technique, a small amount of tissue around the dissection plane is pinched with forceps, electocauterized and gently cut. The present study sought to estimate the usefulness of the PBC technique in LT.

METHODS

Between June 2007 and December 2010, 123 adult cases underwent LT in our center. Of these, 72 involved a recipient hepatectomy using the PBC technique (PBC group). and 51 involved the conventional technique (non-PBC group). Clinical parameters were compared between two groups.

RESULTS

The amount of blood loss and related transfusions were significantly reduced, and the operating time was shorter in the PBC group than in the non-PBC group (p=0.006, p<0.05 and p=0.002, respectively). There was also shorter duration of mechanical ventilation after LT in the PBC group (p=0.017). The incidence of postoperative hemorrhage was lower in the PBC group than in the non-PBC group, but had no statistical significance between two group (19.6% vs. 8.3%, p=0.101).

CONCLUSIONS

Our data suggest that the PBC technique is effective for bleeding control during recipient hepatectomy in LT.

Hyperbaric oxygen therapy reduces the severity of ischaemia, preservation and reperfusion injury in a rat model of liver transplantation

BACKGROUND

  Approaches to increase organ availability for orthotopic liver transplantation (OLT) often result in the procurement of marginal livers that are more susceptible to ischaemia, preservation and reperfusion injury (IPRI).

METHODS

  The effects of post-OLT hyperbaric oxygen (HBO) therapy on IPRI in a syngeneic rat OLT model were examined at various time-points. The effects of IPRI and HBO on hepatocyte necrosis, apoptosis, proliferation, and sinusoidal morphology and ultrastructure were assessed.

RESULTS

  Post-OLT HBO therapy significantly reduced the severity of IPRI; both apoptosis [at 12 h: 6.4 ± 0.4% in controls vs. 1.6 ± 0.7% in the HBO treatment group (p < 0.001); at 48 h: 2.4 ± 0.2% in controls vs. 0.4 ± 0.1% in the HBO treatment group (p < 0.001)] and necrosis [at 12 h: 18.7 ± 1.8% in controls vs. 2.4 ± 0.4% in the HBO treatment group (p < 0.001); at 48 h: 8.5 ± 1.3% in controls vs. 3.4 ± 0.9% in the HBO treatment group (P= 0.019)] were decreased. Serum alanine transaminase was reduced [at 12 h: 1068 ± 920 IU/l in controls vs. 370 ± 63 IU/l in the HBO treatment group (P= 0.030); at 48 h: 573 ± 261 IU/l in controls vs. 160 ± 10 IU/l in the HBO treatment group (P= 0.029)]. Treatment with HBO also promoted liver regeneration [proliferation at 12 h: 4.5 ± 0.1% in controls vs. 1.0 ± 0.3% in the HBO treatment group (p < 0.001); at 48 h: 8.6 ± 0.7% in controls vs. 2.9 ± 0.2% in the HBO treatment group (p < 0.01)] and improved sinusoidal diameter and microvascular density index.

CONCLUSIONS

  Hyperbaric oxygen therapy has persistent positive effects post-OLT that may potentially transfer into clinical practice.

Optimizing cost-effectiveness in perioperative care for liver transplantation: a model for low- to medium-income countries

Although liver transplantation (LT) is a highly effective treatment, it has been considered too costly for publicly funded health systems in many countries with low to medium average incomes. However, with economic growth and improving results, some governments are reconsidering this position. Cost-effectiveness data for LT are limited, especially in perioperative care, and the techniques and costs vary widely between centers without overt differences in outcomes. Anesthesiologists working in new programs find it difficult to determine which modalities are essential, which are needed only in exceptional circumstances, and which may be omitted without effects on outcomes. We investigated key elements of preoperative evaluations, intraoperative management, and early postoperative care that might significantly affect costs in order to develop a best-value approach for new programs in resource-limited health systems. We identified all modalities of care commonly used in anesthesia and perioperative care for adult LT along with their costs. Those considered to be universally accepted as minimum requirements for safe care were excluded from the analysis, and so were those considered to be safe and low-cost, even when evidence of efficacy was lacking. The remaining items were, therefore, those with uncertain or context-restricted value and significant costs. A systematic review of the published evidence, practice surveys, and institutional guidelines was performed, and the evidence was graded and summarized. With respect to costs and benefits, each modality was then cited as strongly recommended, recommended or optional, or no recommendation was made because of insufficient evidence. Sixteen modalities, which included preoperative cardiovascular imaging, venovenous bypass, pulmonary artery catheterization, high-flow fluid warming devices, drug therapies for hemostasis, albumin, cell salvage, anesthetic drugs, personnel (staffing) requirements, and early extubation, were assessed. Only high-flow fluid warming was strongly recommended. The recommended modalities included preoperative echocardiography, cell salvage, tranexamic acid and early extubation. Six others were rated optional, and there was insufficient evidence for 5 modalities. We conclude that some costly techniques and treatments can be omitted without adverse effects on outcomes.

Anesthesia care for liver transplantation

Intraoperative transfusion practices for liver transplantation have evolved dramatically since the first transplants of the 1960s. It is important for today's clinicians to be current in their understanding of how transplant patients should be managed with regard to their coagulation profile, volume status, and general hemodynamic state. The anesthesia team is presented with the unique task of manipulating this tenuous balance in a rapid and precise manner when managing patients undergoing liver transplantation. Although significant progress has been made in reducing blood product administration, it is still common to encounter large volume blood loss in these cases. Increasingly, clinicians are challenged to justify transfusion practices with a stronger evidentiary base. The current state of the literature for transfusion guidelines and blood product management in this particular patient subset will be discussed, as well as a variety of means (both pharmacologic and otherwise) used to reduce the need for transfusion. The aim was to review the latest evidence on these topics, as well as to highlight areas that need further clarification regarding their role in the optimal care of these patients.

Improved survival after liver transplantation in patients with hepatopulmonary syndrome

Hepatopulmonary syndrome (HPS) is present in 10-32% of chronic liver disease patients, carries a poor prognosis and is treatable by liver transplantation (LT). Previous reports have shown high LT mortality in HPS and severe HPS (arterial oxygen (PaO(2)) < or =50 mmHg). We reviewed outcomes in HPS patients who received LT between 2002 and 2008 at two transplant centers supported by a dedicated HPS clinic. We assessed mortality, complications and gas exchange in 21 HPS patients (mean age 51 years, MELD score 14), including 11/21 (52%) with severe HPS and 5/21 (24%) with living donor LT (median follow-up 20.2 months after LT). Overall mortality was 1/21 (5%); mortality in severe HPS was 1/11 (9%). Peritransplant hypoxemic respiratory failure occurred in 5/21 (24%), biliary complications in 8/21 (38%) and bleeding or vascular complications in 6/21 (29%). Oxygenation improved in all 19 patients in whom PaO(2) or SaO(2) were recorded. PaO(2) increased from 52.2 +/- 13.2 to 90.3 +/- 11.5 mmHg (room air) (p < 0.0001) (12 patients); a higher baseline macroaggregated albumin shunt fraction predicted a lower rate of postoperative improvement (p = 0.045) (7 patients). Liver transplant survival in HPS and severe HPS was higher than previously demonstrated. Severity of HPS should not be the basis for transplant refusal.

Survival benefit of liver transplantation and the effect of underlying liver disease

BACKGROUND

The benefit of liver transplantation relative to initial degree of underlying liver disease and time on the waiting list remains poorly defined. We sought to examine the survival benefit attributable to liver transplantation across a wide range of Model for End-Stage Liver Disease (MELD) scores.

METHODS

The study population included patients with end-stage liver disease enlisted in Rio Grande do Sul, Brazil, between 2001 and 2005. Survival and hazard function for enlisted and transplanted patients were estimated using parametric and nonparametric methods. MELD score was utilized to account for underlying liver disease.

RESULTS

Of 1,130 eligible patients, 520 (46.0%) were transplanted, 266 (23.5%) died on the waiting list, 141 (12.5%) were excluded from the waiting list, and 203 (18.0%) remained enlisted and were awaiting transplantation at the time of last observation. At 1 year after transplantation, a MELD score of 15 represented a transition point in terms of overall survival benefit (MELD 10, 90% vs 83%; MELD 15, 81% vs 80%; MELD 20, 63% vs 78%; MELD 25, 42% vs 74%; MELD 30, 21% vs71%; enlisted vs transplant patients, respectively). MELD scores at which transplantation seemed to be beneficial relative to the amount of follow-up time was MELD 23, 17, 15, and 12 at 6 months, and 1, 2, and 5 years, respectively, from time of transplantation/enlistment.

CONCLUSION

Although patients with greater MELD scores enjoy a pronounced and early benefit from transplantation, patients with lesser MELD scores do gain from transplantation, although a greater period of time is needed to realize the survival benefit.