Does the standard vs piggyback surgical technique affect the development of early acute renal failure after orthotopic liver transplantation?

Venovenous bypass in adult liver transplant recipients: A single-center observational case series

BACKGROUND

Very little information is currently available on the use and outcomes of venovenous bypass (VVB) in liver transplantation (LT) in adults in Australia. In this study, we explored the indications, intraoperative course, and postoperative outcomes of patients who underwent VVB in a high-volume LT unit.

METHODS

The study was a single-center, retrospective observational case series of adult patients who underwent VVB during LT at Austin Health in Melbourne, Australia between March 2008 and March 2022. Information on baseline preoperative status and intraoperative variables, including specific VVB characteristics as well as postoperative and VVB-related complications was collected. The lengths of intensive care unit and hospital stays as well as intraoperative and in-hospital mortality were recorded.

RESULTS

Of the 900 LTs performed at this center during the aforementioned 14-year period, 27 (3%) included a VVB procedure. VVB was performed electively in 16 of these 27 patients (59.3%) and as a rescue technique to control massive bleeding in the other 11 (40.1%). The median (interquartile range [IQR]) age of those who underwent VVB procedures was 48 (39-55) years; the median age was 56 (47-62) years in the non-VVB group (p<0.0001). The median model for end-stage liver disease (MELD) scores were similar between the two patient groups. Complete blood data was available for 622 non-VVB patients. Twenty-six VVB (96.3%) and 603 non-VVB (96.9%) patients required intraoperative blood transfusions. The median (IQR) number of units of packed red blood cells transfused was 7 (4.8-12.5) units in the VVB group compared to 3.0 units (1.0-6.0) in the non-VVB group (p<0.0001). Inpatient mortality was 18.5% and 1.1% for the VVB and non-VVB groups, respectively (p<0.0001). There were no significant differences in length of hospital stay or incidence of acute kidney injury, primary graft dysfunction, or long-term graft failure between the two groups. Patients in the VVB group experienced a higher rate of postoperative non-anastomotic biliary stricture compared to patients in the non-VVB group (33% and 7.9%, respectively; p = 0.0003).

CONCLUSIONS

VVB continues to play a vital role in LT. This case series highlights the heightened risk of major complications linked to VVB. However, the global transition to selective use of VVB underscores the urgent need for collaborative multi-center studies designed to address outstanding questions and parameters related to the safe implementation of this procedure.

Comparison of the modified piggyback with standard piggyback and conventional orthotopic liver transplantation techniques: a network meta-analysis

BACKGROUND

In conventional orthotopic liver transplantation (OLT), the recipient's retrohepatic inferior vena cava (IVC) is completely clamped and replaced with the donor IVC. The piggyback technique has been used to preserve venous return, either via an end-to-side or standard piggyback (SPB), or via a side-to-side or modified piggyback (MPB) anastomosis, using a venous cuff from the recipient hepatic veins with partially clamping and preserves the recipient's inferior vena cava. However, whether these piggyback techniques improve the efficacy of OLT is unclear. To address the low quality of the available evidence, we performed a meta-analysis to compare the efficacy of conventional, MPB, and SPB techniques.

METHODS

Literature was searched in Medline and Web of Science databases for relevant articles published until 2021 without any time restriction. A Bayesian network meta-analysis was performed to compare the intra- and postoperative outcomes of conventional OLT, MPB, and SPB techniques.

RESULTS

Forty studies were included, comprising 10,238 patients. MPB and SPB had significantly shorter operation times and fewer transfusions of red blood cell and fresh frozen plasma than conventional techniques. However, there were no differences between MPB and SPB in operation time and blood product transfusion. There were also no differences in primary non-function, retransplantation, portal vein thrombosis, acute kidney injury, renal dysfunction, venous outflow complications, length of hospital and intensive care unit stay, 90-day mortality rate, and graft survival between the three techniques.

CONCLUSION

MBP and SBP techniques reduce the operation time and need for blood transfusion compared with conventional OLT, but postoperative outcomes are similar. This indicates that all techniques can be implemented based on the experience and policy of the transplant center.

Incidence of Invasive Fungal Infections in Liver Transplant Recipients under Targeted Echinocandin Prophylaxis

Invasive fungal infections (IFIs) are one of the most important infectious complications after liver transplantation, determining morbidity and mortality. Antimycotic prophylaxis may impede IFI, but a consensus on indication, agent, or duration is still missing. Therefore, this study aimed to investigate the incidence of IFIs under targeted echinocandin antimycotic prophylaxis in adult high-risk liver transplant recipients. We retrospectively reviewed all patients undergoing a deceased donor liver transplantation at the Medical University of Innsbruck in the period from 2017 to 2020. Of 299 patients, 224 met the inclusion criteria. We defined patients as being at high risk for IFI if they had two or more prespecified risk factors and these patients received prophylaxis. In total, 85% (190/224) of the patients were correctly classified according to the developed algorithm, being able to predict an IFI with a sensitivity of 89%. Although 83% (90/109) so defined high-risk recipients received echinocandin prophylaxis, 21% (23/109) still developed an IFI. The multivariate analysis identified the age of the recipient (hazard ratio-HR = 0.97, p = 0.027), split liver transplantation (HR = 5.18, p = 0.014), massive intraoperative blood transfusion (HR = 24.08, p = 0.004), donor-derived infection (HR = 9.70, p < 0.001), and relaparotomy (HR = 4.62, p = 0.003) as variables with increased hazard ratios for an IFI within 90 days. The fungal colonization at baseline, high-urgency transplantation, posttransplant dialysis, bile leak, and early transplantation showed significance only in a univariate model. Notably, 57% (12/21) of the invasive Candida infections were caused by a non-albicans species, entailing a markedly reduced one-year survival. The attributable 90-day mortality rate of an IFI after a liver transplant was 53% (9/17). None of the patients with invasive aspergillosis survived. Despite targeted echinocandin prophylaxis, there is still a notable risk for IFI. Consequently, the prophylactic use of echinocandins must be critically questioned regarding the high rate of breakthrough infections, the increased occurrence of fluconazole-resistant pathogens, and the higher mortality rate in non-albicans Candida species. Adherence to the internal prophylaxis algorithms is of immense importance, bearing in mind the high IFI rates in case algorithms are not followed.

Vagus nerve stimulation attenuates acute kidney injury induced by hepatic ischemia/reperfusion injury in rats

Hepatic ischemia/reperfusion (I/R) injury, caused by limited blood supply and subsequent blood supply, is a causative factor resulting in morbidity and mortality during liver transplantation and liver resection. Hepatic I/R injury frequently contributes to remote organ injury, such as kidney, lung, and heart. It has been demonstrated that vagus nerve stimulation (VNS) is effective in remote organ injury after I/R injury. Here, our aim is to investigate the potential action of VNS on hepatic I/R injury-induced acute kidney injury (AKI) and explore its underlying mechanisms. To test this hypothesis, male Sprague-Dawley rats were randomly assigned into three experimental groups: Sham group (sham operation, n = 6); I/R group (hepatic I/R with sham VNS, n = 6); and VNS group (hepatic I/R with VNS, n = 6). VNS was performed during the entire hepatic I/R process. Our results showed that throughout the hepatic I/R process, VNS significantly regulated the expression levels of various iconic factors and greatly enhanced the protein expression levels of nuclear factor erythroid 2-related factor 2 (Nrf2) and hemeoxygenase-1 (HO-1) in the kidneys. These findings suggested that VNS may ameliorate hepatic I/R injury-induced AKI by suppressing inflammation, oxidative stress, and apoptosis probably through activating the Nrf2/HO-1 signaling pathway.

Comparison of Three Inferior Vena Cava Reconstruction Techniques in Adult Orthotopic Liver Transplantation: Result From King Chulalongkorn Memorial Hospital, Thailand

BACKGROUND

In orthotopic liver transplantation (OLT), 3 caval reconstruction techniques are being performed worldwide. These are conventional, piggyback technique, and side-to-side cavocaval anastomosis (CCA). Each has its own advantages and drawbacks. Herein we report the result from our hospital comparing the 3 techniques.

METHODS

We retrospectively reviewed the detail of OLT performed from January 2008 to March 2020. Data being collected included type of caval reconstruction, blood loss, operative time, ischemic time, length of stay in the intensive care unit (ICU) and total hospital stay, and several postoperative complications.

RESULTS

In the given period, 11 conventional, 90 piggyback, and 113 CCA caval reconstruction were done. There were no statistically significant differences in blood loss, operative time, cold ischemic time, and length of ICU and hospital stay. The CCA group had the lowest warm ischemic time (40 minutes) followed by the piggyback technique (43 minutes) and the conventional technique (47 minutes; P < .001). Regarding postoperative complications, there were no statistically significant differences in rate of primary nonfunction, early allograft dysfunction, hepatic artery/portal vein/biliary complication, or rate of acute kidney injury. The hepatic venous outflow complication rate was indifferent between 3 groups.

CONCLUSIONS

The present study showed no difference in outflow obstruction rate among the 3 techniques. The choice for reconstruction should rely on the preference of each institute and the suitability of each patient. The CCA technique may provide the lowest warm ischemic time.

Vagus Nerve Stimulation Attenuates Acute Kidney Injury Induced by Hepatic Ischemia/Reperfusion Injury by Suppressing Inflammation, Oxidative Stress, and Apoptosis in Rats.. [DOI: 10.21203/rs.3.rs-1937916/v1] [Citation(s) in RCA: 0] [Impact Index Per Article: 0]

Hepatic ischemia reperfusion (I/R) injury, caused by limited blood supply and subsequent blood supply, is a causative factor resulting in morbidity and mortality during liver transplantation (LT) and liver resection. Hepatic I/R injury frequently contributes to remote organ injury, such as kidney, lung, and heart. It has been demonstrated that vagus nerve stimulation (VNS) is effective in remote organ injury after ischemia reperfusion injury. Here, our aim is to investigate the potential action of VNS on hepatic I/R injury-induced acute kidney injury (AKI) and explore its underlying mechanisms. To test this hypothesis, male Sprague-Dawley rats were randomly assigned into three experimental groups: Sham group (sham operation, n=6); I/R group (hepatic I/R with sham VNS, n=6); and VNS group (hepatic I/R with VNS, n=6). VNS was performed during the entire hepatic I/R process. Our results showed that throughout the hepatic I/R process, VNS significantly reduced inflammation, oxidative stress, and apoptosis, and greatly enhanced the protein expression levels of nuclear factor erythroid 2-related factor 2 (Nrf2) and hemeoxygenase-1 (HO-1) in the kidneys. These findings suggest that VNS may ameliorate hepatic I/R injury-induced AKI by suppressing inflammation, oxidative stress, and apoptosis probably through activating the Nrf2/HO-1 signaling pathway.

Continuous Renal Replacement Therapy after Liver Transplantation: Peri-Operative Associated Factors and Impact on Survival

Continuous renal replacement therapy (CRRT) following orthotopic liver transplantation (OLT) is usually started for multifactorial reasons, with variable incidence among series. This paper presents a single-center retrospective observational study on the early use (within one week) of CRRT after consecutive cadaveric OLT from January 2008 to December 2016. Preoperative patient characteristics and intraoperative data were collected, and patients were divided into two groups (CRRT and no CRRT) to explore the factors associated with the use of CRRT. Repeated measurements of postoperative creatinine were analyzed with generalized estimating equation (GEE) models. Among 528 OLT patients, 75 (14.2%) were treated with CRRT at least once in the first week. Patients treated with CRRT showed lower survival in a Kaplan−Meier curve (log-rank p value < 0.01). Patients treated with CRRT had a more severe preoperative profile, with a significantly higher age, MELD, BUN, creatinine, and total bilirubin, as well as a longer surgery time and a higher number of transfusions of red blood cells, plasma, and platelets (all p values < 0.05). In a stepwise multiple analysis, the following characteristics remained independently associated with the use of CRRT: the MELD score OR 1.12 (95% CL: 1.07−1.16), p value < 0.001, and the preoperative value for blood urea nitrogen OR 1.016 (95% CL: 1.010−1.023), p value < 0.001. The early use of CRRT after OLT occurred at a low rate in this large cohort; however, it was associated with worse outcomes. Apart from the preoperative severity, repeated intraoperative hypotension episodes, which were likely modifiable or preventable, were associated with the increased use of CRRT and higher postoperative creatinine.

Peritransplant Renal Dysfunction in Liver Transplant Candidates

Renal function is intricately tied to Model for End-Stage Liver Disease score and overall prognosis among patients with cirrhosis. The estimation of glomerular filtration rate (GFR) and etiology of renal impairment are even more magnified among cirrhotic patients in the period surrounding liver transplantation. Novel biomarkers including cystatin C and urinary neutrophil gelatinase-associated lipocalin have been demonstrated to more accurately assess renal dysfunction and aid in the diagnosis of competing etiologies. Accurately identifying the severity and chronicity of renal dysfunction among transplant candidates is an imperative component with respect to stratifying patients toward simultaneous liver-kidney transplantation versus liver transplantation alone.

A meta-analysis on the prevalence of chronic kidney disease in liver transplant candidates and its associated risk factors and outcomes

Pre-liver transplant (LT) chronic kidney disease (CKD) has emerged as a leading cause of post-operative morbidity. We aimed to report the prevalence, associated risk factors, and clinical outcomes in patients with pre-LT CKD. Meta-analysis and systematic review were conducted for included cohort and cross-sectional studies. Studies comparing healthy and patients with s pre-LT CKD were included. Outcomes were assessed with pooled hazard ratios. 15 studies were included, consisting of 82,432 LT patients and 26,754 with pre-LT CKD. Pooled prevalence of pre-LT CKD was 22.35% (CI: 15.30%-32.71%). Diabetes mellitus, hypertension, viral hepatitis, and non-alcoholic fatty liver disease, and older age were associated with increased risk of pre-LT CKD: (OR 1.72 CI: 1.15-2.56, P = 0.01), (OR 2.23 CI: 1.76-2.83, P < 0.01), (OR 1.09; CI: 1.05-1.13, P < 0.01), (OR 1.73; CI: 1.10-2.71 P = 0.03), and (MD: 2.92 years; CI: 1.29-4.55years; P < 0.01) respectively. Pre-LT CKD was significantly associated with increased mortality (HR 1.38; CI: 1.2-1.59; P < 0.01), post-LT end-stage renal disease and post-LT CKD. Almost a quarter of pre-LT patients have CKD and it is significantly associated with post-operative morbidity and mortality. However, long-term outcomes remain unclear due to a lack of studies reporting such outcomes.

Post-Liver Transplant Acute Kidney Injury

Acute kidney injury (AKI) is a common condition following liver transplantation (LT). It negatively impacts patient outcomes by increasing the chances of developing chronic kidney disease and reducing graft and patient survival rates. Multiple definitions of AKI have been proposed and used throughout the years, with the International Club of Ascites definition being the most widely now used for patients with cirrhosis. Multiple factors are associated with the development of post-LT AKI and can be categorized into pre-LT comorbidities, donor and recipient characteristics, operative factors, and post-LT factors. Many of these factors can be optimized in an attempt to minimize the risk of AKI occurring and to improve renal function if AKI is already present. A special consideration during the post-LT phase is needed for immunosuppression as certain immunosuppressive medications can be nephrotoxic. The calcineurin inhibitor tacrolimus (TAC) is the mainstay of immunosuppression but can result in AKI. Several strategies including use of the monoclonoal antibody basilixamab to allow for delayed initiation of tacrolimus therapy and minimization through combination and minimization or elimination of TAC through combination with mycophenolate mofetil or mammalian target of rapamycin inhibitors have been implemented to reverse and avoid AKI in the post-LT setting. Renal replacement therapy may ultimately be required to support patients until recovery of AKI after LT. Overall, by improving renal function in post-LT patients with AKI, outcomes can be improved.

Not All Piggybacks Are Equal: A Retrospective Cohort Analysis of Variation in Anhepatic Transcaval Pressure Gradient and Acute Kidney Injury During Liver Transplant

OBJECTIVES

Complete inferior vena cava clamping in cavalreplacement during livertransplantis associated with substantial physiological derangement and postoperative morbidity. Partial clamping in the piggyback technique may be relatively protective, but evidence is lacking. Having observed substantial variation in transhepatic inferior vena cava pressure gradient with piggyback, we hypothesized that the causative mechanism is the extent of caval clamping rather than the surgical approach.

MATERIALS AND METHODS

We used internal jugular and femoral catheters to estimate suprahepatic and infrahepatic inferior vena cava pressures during clamping. Pressure gradients were calculated, and distributions were compared by surgical technique. We estimated adjusted odds ratios for pressure gradient on acute kidney injury at 72 hours.

RESULTS

In 115 case records, we observed substantial variation in maximum pressure gradient; median values were 18.0 mm Hg(interquartile range, 8.0-25.0 mm Hg) with the piggyback technique and 24.0 mm Hg (interquartile range, 19.5-27.0 mm Hg) with caval replacement. Incidence of acute kidney injury was 25% (29 patients). Pressure gradient was linearly associated with probability of acute kidney injury (odds ratio, 1.06; 95% CI, 1.01-1.13).

CONCLUSIONS

We report 2 novel findings. (1) Anhepatic inferior vena cavapressuregradient variedsubstantially in individuals undergoing piggyback, and (2) gradient was positively associatedwith early acute kidney injury. We hypothesize that this (unmeasured) variation explains the conflictingfindings ofprevious studies that compared surgical techniques. Also, we propose that caval pressure gradient could be routinely assessed to optimize real-time piggyback clamp position during livertransplant surgery.

An Alternative Surgical Technique of Native Hepatectomy in Liver Transplantation

Background

Orthotopic liver transplantation has become the procedure of choice for end-stage liver disease. There are 3 commonly used methods of vena cava anastomosis. Here, we report a new technique for native hepatectomy.

Material/Methods

The data of 12 patients who underwent orthotopic liver transplantation using a new surgical technique were retrospectively collected for analysis. The new separation and reconstruction surgical technique mainly involved the second portal isolation and hepatectomy that followed. We performed recipient liver resection without the occlusion of the inferior vena cava, which was then followed by classic, piggyback, modified piggyback, or side-to-side orthotopic liver transplantation. The graft function index and complications were collected after transplantation.

Results

The length of the anhepatic phase was 30.92±9.1 min. Alanine transaminase (ALT) levels were 138 to 2027 U/L, with a median of 361.5 U/L. The ALT levels of all patients gradually decreased to normal levels 7 to 10 days after surgery. Only 2 recipients had elevated levels of ALT higher than 1000 U/L. Four of 12 patients did not require red blood cell transfusion during surgery. Four patients appeared to have early allograft dysfunction, while others recovered smoothly.

Conclusions

This new surgical technique may shorten the anhepatic phase and decrease blood loss volume, aiding the success of liver transplant surgery. It can be used for most patients and does not increase the risk of complications or impair prognosis.

Complex Liver Transplantation Using Venovenous Bypass With an Atypical Placement of the Portal Vein Cannula

In liver transplantation (LT) medical literature, venovenous bypass (VVB) with the interposition of a venous graft attached to the inferior mesenteric vein (IMV) or to the splenic vein (SV) has not been reported previously. Here, we report the decompression of the portomesenteric compartment in 2 patients with complex cases of orthotopic LT. A femoroaxillary percutaneous VVB was installed prior to abdominal opening to decompress massive collateral veins in the abdominal wall. In the first patient, the IMV was connected to a donor vein graft with a lateroterminal anastomosis, and the distal part of the vein graft was cannulated and connected to the VVB. In the second patient, because of the excessive size of the spleen, it was necessary to perform a splenectomy to gain sufficient space in the abdomen to implant the new liver. The SV was connected to a donor vein graft with a terminoterminal anastomosis, and the distal part of the vein graft was cannulated and connected to the VVB. In both patients, the decompression of the portomesenteric compartment was crucial to reduce portal hypertension and to access the hepatic hilum, where the dissection was very complex due to previous major surgeries. In conclusion, VVB with the interposition of a venous graft attached to the IMV or to the SV during LT is a safe and simple technique, and it may be useful for patients needing VVB with no standard access to the portal compartment, particularly in the case of severe portal hypertension and re-LTs.

Peri-transplant renal dysfunction in patients with non-alcoholic steatohepatitis undergoing liver transplantation

Non-alcoholic fatty liver disease (NAFLD) is currently the most common etiology of chronic liver disease (CLD) caused by an accumulation of fat in the liver and globally is the leading indication of liver transplantation. Emerging data has recognized an increased association of NAFLD with risk of other metabolic liver diseases like type 2 diabetes mellitus, chronic kidney disease (CKD) and cardiovascular diseases. Pathophysiologically, NAFLD patients have a state of low-grade systemic inflammation, insulin resistance and atherogenic dyslipidemia which causes renal dysfunction. Patients with NAFLD cirrhosis awaiting liver transplant (LT) face unique challenges and have a significantly higher requirement of simultaneous-liver-kidney transplant as compared to other etiologies. Further, NAFLD not only recurs but also occurs as a de novo manifestation post-LT. There is also a significantly higher risk of waiting list stagnation and dropouts due to burdensome cardiometabolic disorders in NAFLD patients. The current review aims to understand the prevalence and pathogenetic basis of renal dysfunction in NAFLD. Additionally, the review describes the choice of immunosuppression protocols and use of intraoperative renal replacement therapy in context of intra and post-operative renal dysfunction in NAFLD patients. Prospective controlled trials focusing on NAFLD and development of CKD are needed to assess the existence of a causal and/or a bidirectional relationship between NAFLD and CKD.

Piggyback or Cava Replacement: Which Implantation Technique Protects Liver Recipients From Acute Kidney Injury and Complications?

The cava-preserving piggyback (PB) technique requires only partial cava clamping during the anhepatic phase in liver transplantation (LT) and, therefore, maintains venous return and may hemodynamically stabilize the recipient. Hence, it is an ongoing debate whether PB implantation is more protective from acute kidney injury (AKI) after LT when compared with a classic cava replacement (CR) technique. The aim of this study was to assess the rate of AKI and other complications after LT comparing both transplant techniques without the use of venovenous bypass. We retrospectively analyzed the adult donation after brain death LT cohort between 2008 and 2016 at our center. Liver and kidney function and general outcomes including complications were assessed. Overall 378 transplantations were analyzed, of which 177 (46.8%) were performed as PB and 201 (53.2%) as CR technique. AKI occurred equally often in both groups. Transient renal replacement therapy was required in 22.6% and 22.4% comparing the PB and CR techniques (P = 0.81). Further outcome parameters including the complication rate were similar in both cohorts. Five-year graft and patient survival were comparable between the groups with 81% and 85%, respectively (P = 0.48; P = 0.58). In conclusion, both liver implantation techniques are equal in terms of kidney function and overall complications following LT.

Weaning of Veno-venous Bypass in Liver Transplantation: A Single Center Experience

BACKGROUND

Veno-venous bypass (VVB) has been used in liver transplantation (LT) to minimize hemodynamic instability during caval anastomosis of anhepatic phase. With the introduction of the piggyback (PB) technique, which is a caval-sparing technique, the use of VVB progressively decreased over the world. The aim of this study was to introduce our experience using VVB with the focus on its weaning process.

METHODS

A total of 300 consecutive LT cases from May 1996 to November 2003 were examined. Except for pediatric LT, 242 LT cases were investigated to evaluate the trends in VVB use, surgical technique, the amount of transfusion requirements, and durations of operation and anhepatic phase.

RESULTS

For the early 100 LT cases, VVB was used in 97.5% of recipients, especially in all the recipients of deceased donor LT (DDLT). Then, the frequency of VVB use was decreased, and VVB was not used after the 268th recipient. In DDLT, the PB technique was first introduced in the 58th recipient and became a routine procedure of the DDLT since the 191th recipient. Living donor LT was increased, and the amount of transfusion requirement, duration of operation, and duration of anhepatic phase was reduced over time.

CONCLUSIONS

The increasing experience and sophisticated surgical and anesthetic techniques were important factors responsible for the weaning of VVB. The advancement of the PB technique used in living donor LT might be a main factor of its weaning.

Comparison of three caval reconstruction techniques in orthotopic liver transplantation: A retrospective review

BACKGROUND

Classic caval reconstruction during liver transplantation involves complete cross-clamping and resection of the recipient inferior vena cava (IVC) followed by donor IVC interposition. Other techniques preserve the IVC, with piggyback (PB) to the hepatic veins or side-to-side (SS) caval anastomosis. Avoidance of cross-clamping may be beneficial for minimizing hemodynamic instability and transfusion requirements.

METHODS

Retrospective review of a provincial transplant database (2007-2011). MELD score was used to measure disease severity. Intraoperative blood loss and volume resuscitation were compared between three caval reconstruction techniques using ANOVA.

RESULTS

200 deceased-donor transplants (Classic:58, PB:72, SS:70) were included. Baseline disease severity was equal. Mean case duration was shorter in the PB technique (Classic:366, PB:306, SS:385 min, p < 0.001). Despite similar blood loss, there was significantly less cell saver return, FFP, platelets, and overall resuscitation volume (Classic:12.8, PB:9.5, SS:13.2 L, p = 0.001) utilized in the piggyback technique.

CONCLUSIONS

The PB technique was faster and used less cell saver return, FFP and platelets, despite similar blood loss. Availability of different caval reconstruction techniques allows for a breadth of options in difficult cases.

Risk factors of acute renal failure after orthotopic liver transplantation: single-center experience

BACKGROUND

Acute renal failure (ARF) is one of the most significant complications of orthotopic liver transplantation (OLT), associated with increased mortality rate and the development of chronic renal dysfunction. The aim of the study was to determine the perioperative risk factors for ARF in patients without previous history of renal disease who are undergoing OLT.

MATERIALS AND METHODS

Forty-six patients who developed ARF after OLT performed in 1 transplant center were included in the study, and 52 consecutive patients without that complication served as a control group. Renal dysfunction was defined as a glomerular filtration rate <60 mL/min/1.73 m(2). The data concerning preoperative diseases, perioperative renal function, first-line immunosuppressive therapy, and blood transfusion requirement were retrospectively analyzed and compared among groups. Logistic regression modeling was used to determine risk factors for ARF.

RESULTS

Patients who developed ARF were significantly older (mean age 53.3 vs 46.3 years, P = .057), had higher level of preoperative (0.79 vs 0.71 mg/dL, P = .0062) and intraoperative (0.85 vs 0.74 mg/dL, P = .0045) creatinine. The risk factors for ARF were intraoperative and 24-hour post-transplant creatinine level >0.9 mg/dL and high-dose tacrolimus-based immunosuppression. Transfusion of ≤6 units of red blood cells diminished the risk of ARF. Sex and preoperative diseases were not predictive to ARF in our regression models.

CONCLUSION

Careful operative technique with low blood loss and immunosuppressive therapy of low nephrotoxic potential should be recommended in older patients to diminish the risk of renal dysfunction after orthotopic liver transplantation. Patients with higher levels of perioperative creatinine should be considered to have first-line immunosuppression without calcineurin inhibitors or with low-dose immunosuppressants of known nephrotoxic potential.

Prospective Randomized Trial Comparing Hepatic Venous Outflow and Renal Function after Conventional versus Piggyback Liver Transplantation

Background

This randomized prospective clinical trial compared the hepatic venous outflow drainage and renal function after conventional with venovenous bypass (n = 15) or piggyback (n = 17) liver transplantation.

Methods

Free hepatic vein pressure (FHVP) and central venous pressure (CVP) measurements were performed after graft reperfusion. Postoperative serum creatinine (Cr) was measured daily on the first week and on the 14^th, 21^st and 28^th postoperative days (PO). The prevalence of acute renal failure (ARF) up to the 28th PO was analyzed by RIFLE-AKIN criteria. A Generalized Estimating Equation (GEE) approach was used for comparison of longitudinal measurements of renal function.

Results

FHVP-CVP gradient > 3 mm Hg was observed in 26.7% (4/15) of the patients in the conventional group and in 17.6% (3/17) in the piggyback group (p = 0.68). Median FHVP-CVP gradient was 2 mm Hg (0–8 mmHg) vs. 3 mm Hg (0–7 mm Hg) in conventional and piggyback groups, respectively (p = 0.73). There is no statistically significant difference between the conventional (1/15) and the piggyback (2/17) groups regarding massive ascites development (p = 1.00). GEE estimated marginal mean for Cr was significantly higher in conventional than in piggyback group (2.14 ± 0.26 vs. 1.47 ± 0.15 mg/dL; p = 0.02). The conventional method presented a higher prevalence of severe ARF during the first 28 PO days (OR = 3.207; 95% CI, 1.010 to 10.179; p = 0.048).

Conclusion

Patients submitted to liver transplantation using conventional or piggyback methods present similar results regarding venous outflow drainage of the graft. Conventional with venovenous bypass technique significantly increases the harm of postoperative renal dysfunction.

Trial Registration

ClinicalTrials.gov https://clinicaltrials.gov/ct2/show/NCT01707810

Caval reconstruction techniques in orthotopic liver transplantation

There are several caval reconstruction techniques currently in use for orthotopic liver transplantation. These include caval replacement or the conventional technique, performed with or without venovenous bypass, piggyback technique with anastomosis with two or three hepatic veins with or without cavotomy and modifications of the piggyback technique including end-to-side and side-to-side cavocaval anastomosis. There are few randomized controlled trials comparing the use of these techniques and our knowledge of their comparability is based on a few multi- and many single-center retrospective and prospective reviews. Although there are advantages and disadvantages for each technique, it is advisable that the surgeon perform the technique with which they have the most the experience and at which they are the most skilled as excellent outcomes can be obtained with any of the caval reconstruction options discussed.

Bypass during Liver Transplantation: Anachronism or Revival? Liver Transplantation Using a Combined Venovenous/Portal Venous Bypass-Experiences with 163 Liver Transplants in a Newly Established Liver Transplantation Program

Introduction. The venovenous/portal venous (VVP) bypass technique has generally become obsolete in liver transplantation (LT) today. We evaluated our experience with 163 consecutive LTs that used a VVP bypass. Patients and Methods. The liver transplant program was started in our center in 2010. LTs were performed using an extracorporal bypass device. Results. Mean operative time was 269 minutes and warm ischemic time 43 minutes. The median number of transfusion of packed cells and plasma was 7 and 14. There was no intraoperative death, and the 30-day mortality was 3%. Severe bypass-induced complications did not occur. Discussion. The introduction of a new LT program requires maximum safety measures for all of the parties involved. Both surgical and anaesthesiological management (reperfusion) can be controlled very reliably using a VVP bypass device. Particularly when using marginal grafts, this approach helps to minimise both surgical and anaesthesiological complications in terms of less volume overload, less use of vasopressive drugs, less myocardial injury, and better peripheral blood circulation. Conclusion. Based on our experiences while establishing a new liver transplantation program, we advocate the reappraisal of the extracorporeal VVP bypass.

Different cava reconstruction techniques in liver transplantation: piggyback versus cava resection

BACKGROUND

Originally, cava reconstruction (CR) in liver transplantation meant complete resection and reinsertion of the donor cava. Alternatively, preservation of the recipients inferior vena cava (IVC) with side-to-side anastomosis (known as "piggyback") can be performed. Here, partial clamping maintains blood flow of the IVC, which may improve cardiovascular stability, reduce blood loss and stabilize kidney function. The aim of this study was to compare both techniques with particular focus on kidney function.

METHODS

A series of 414 patients who had had adult liver transplantations (2006-2009) were included. Among them, 176 (42.5%) patients had piggyback and 238 had classical CR operation, 112 (27.1%) of the patients underwent CR accompanied with veno-venous bypass (CR-B) and 126 (30.4%) without a bypass. The choice of either technique was based on the surgeons' individual preference. Kidney function [serum creatinine, calculated glomerular filtration rate (GFR), RIFLE stages] was assessed over 14 days.

RESULTS

Lab-MELD scores were significantly higher in CR-B (22.5+/-11.0) than in CR (17.3+/-9.0) and piggyback (18.8+/-10.0) (P=0.008). Unexpectedly, the incidences of arterial stenoses (P=0.045) and biliary leaks (P=0.042) were significantly increased in piggyback. Preoperative serum creatinine levels were the highest in CR-B [1.45+/-1.17 vs 1.25+/-0.85 (piggyback) and 1.13+/-0.60 mg/dL (CR); P=0.033]. Although a worsening of postoperative kidney function was observed among all groups, this was most pronounced in CR-B [creatinine day 14: 1.67+/-1.40 vs 1.35+/-0.96 (piggyback) and 1.45+/-1.03 mg/dL (CR); P=0.102]. Accordingly, the proportion of patients displaying RIFLE stages ≥2 was the highest in CR/CR-B (26%/19%) when compared to piggyback (18%).

CONCLUSIONS

Piggyback revealed a shorter warm ischemic time, a reduced blood loss, and a decreased risk of acute kidney failure. Thus, piggyback is a useful technique, which should be applied in standard procedures. When piggyback is unfeasible, cava replacement, which displayed a lower incidence of vascular and biliary complications in our study, remains as a safe alternative.

Conventional versus piggyback techniques: do they have different outcomes?

BACKGROUND

Conventional orthotopic liver transplant includes resection of the recipient's native liver, together with the retrohepatic inferior vena cava, whereas with the piggyback technique, the recipient's vena cava is preserved and the donor's vena cava is anastomosed with the recipient's hepatic veins. So the caval flow is maintained during explantation, but on the other hand, the cava must be dissected completely from the liver, prolonging hepatic excision.

OBJECTIVE

To compare outcomes of conventional versus piggyback techniques. Primary outcomes were serious adverse events or complications, and secondary outcomes were graft survival for 3 and 12 months, quality of life, days in the intensive care unit and in the hospital, and days spent receiving mechanical ventilation.

MATERIALS AND METHODS

From January 3, 2007, to December 31, 2008, 120 liver transplant patients were divided into 2 groups: conventional (n = 93) and piggyback (n = 27).

RESULTS

Intraoperative and postoperative complications, graft survival for 3 and 12 months, quality of life, and hospital stay did not differ significantly between the 2 groups. However, the stay in the intensive care unit (median, 2 vs 3 days; range, 1-101 vs 1-60 days) and the number of days on ventilatory support (median, 1 vs 2 days; range, 0-41 vs 1-60 days) were notably lower in the conventional group.

CONCLUSION

The conventional liver transplant technique had significantly better results than the piggyback technique in terms of length of stay in the intensive care unit and duration of mechanical ventilation.

A comparative study of the classic and piggyback techniques for orthotopic liver transplantation

Background:

The classic technique of hepatectomy with venovenous bypass may cause a longer anhepatic phase and increase the rate of some complications, such as post-operative renal failure and thromboembolic events. But, in some cases, such as tumors and anatomic difficulties, the surgeon is obligated to use the classic technique even though there is some controversy about the safety of this technique without venovenous bypass in liver transplantation. The aim of this study was to compare the results of using the classic technique without venovenous bypass and the piggyback technique for liver transplantation.

Methods:

A retrospective case-series study was conducted on 227 consecutive successful liver transplants, including 55 cases in which the classic technique was used and 172 cases in which the piggyback technique was used. The transplants were performed from March 2010 through June 2011 in the Visceral Transplantation Ward at Namazi Hospital in Shiraz, Iran. The piggyback method was the preferred approach for hepatectomy, but the classic technique without venovenous bypass was performed in cirrhotic cases with anatomic difficulties, when there was a tumor, or when the surgeon preferred it.

Results:

There were no significant differences in post-operative rise in creatinine, decreases in intraoperative blood pressure, transfused packed red blood cells (RBC), or survival rates between the groups. Warm ischemic time (duration that donor liver is out of ice until it’s blood reperfusion in the recipient) was approximately seven minutes longer in the classic group (P = 0), but it was less than 52 minutes, which is an acceptable time for this phase. Hospital stays were shorter in the classic group than in the piggyback group (P = 0.024).

Conclusion:

Although the piggyback technique is the preferred technique for hepatectomy in liver transplantation, the classic technique without venovenous bypass can be used safely in cirrhotic livers when necessary or if the physician prefers it.

Prediction of newly developed acute renal failure using serum phosphorus concentrations after living-donor liver transplantation

OBJECTIVE

This retrospective study investigated the predictive role of serum phosphorus concentration for acute renal failure (ARF), defined by the Risk Injury Failure Loss End-stage kidney disease (RIFLE) criteria, after living-donor liver transplantation (LDLT).

METHODS

Perioperative factors, including serum phosphorus concentrations, in LDLT recipients without pre-existing renal dysfunction were retrospectively analysed and compared between patients with or without post-LDLT ARF.

RESULTS

A total of 45 patients out of 350 (12.9%) met the RIFLE ARF criteria and experienced significantly higher postoperative mortality, longer intensive care unit stay and more frequent graft dysfunction than those patients without post-LDLT ARF. Multivariate logistic regression analyses showed that a serum phosphorus concentration ≥ 4.5 mg/dl on postoperative day 1 (relative risk [RR] 5.31; 95% confidence interval [CI] 2.56, 11.03), a preoperative model for end-stage liver disease score 20 points (RR 4.17, 95% CI 2.04, 8.52), and packed red blood cell transfusion 10 units (RR 2.55, 95% CI 1.13, 5.88) were independent risk factors for post-LDLT ARF.

CONCLUSIONS

Hyperphosphataemia on postoperative day 1 could be an early and simple indicator of ARF occurrence after LDLT.

Postoperative kidney injury does not decrease survival after liver transplantation

PURPOSE

To explore the effect of acute kidney injury (AKI) on long-term survival after conventional orthotopic liver transplantation (OLT) without venovenous bypass (VVB).

METHODS

A retrospective cohort study was carried out on 153 patients with end-stage liver diseases transplanted by the Department of General Surgery and Liver Transplantation of the University of Pernambuco, from August, 1999 to December, 2009. The Kaplan-Meier survival estimates and log-rank test were applied to explore the association between AKI and long-term patient survival, and multivariate analyses were applied to control the effect of other variables.

RESULTS

Over the 12.8-year follow-up, 58.8% patients were alive with a median follow-up of 4.5-year. Patient 1-, 2-, 3- and 5-year survival were 74.5%, 70.6%, 67.9% and 60.1%; respectively. Early postoperative mortality was poorer amongst patients who developed AKI (5.4% vs. 20%, p=0.010), but long-term 5-year survival did not significantly differed between groups (51.4% vs. 65.3%; p=0.077). After multivariate analyses, AKI was not significantly related to long-term survival and only the intraoperative transfusion of red blood cells was significantly related to this outcome (non-adjusted Exp[b]=1.072; p=0.045).

CONCLUSION

The occurrence of postoperative acute kidney injury did not independently decrease patient survival after orthotopic liver transplantation without venovenous bypass in this data from northeast Brazil.

Orthotopic liver transplantation without venovenous bypass: 125 cases from a single center

AIM

This study analyzed a 10-year single-center experience in orthotopic liver transplantation (OLT) without venovenous bypass (VVB).

METHODS

We retrospectively analysed a nonrandomized series (1999-2008) of 125 adult OLT patients without VVB.

RESULTS

The main causes of liver failure were viral hepatitis (n = 39), alcoholic liver disease (n = 22), and liver cancer (n = 17). One-year survival was 76.4%. The most common postoperative complications were bile duct stenosis (n = 12), postoperative bleeding (n = 8), hepatic artery thrombosis (n = 7), and primary liver failure (n = 6). Twelve patients required hemodialysis and four underwent retransplantations of the liver. Fourteen patients died before postoperative day 30(th). Univariate analysis showed significant differences between patients who did and did not survive 30 days among donor death diagnoses (P = .05), red blood cell units transfused (P = .03), aspartate aminotranferase on the first postoperative day (P = .002), ABO type (P = .04), time of orotracheal intubation (P = .001), hemodialysis (P = .001), and period of postoperative vasoactive drug use (P = .006). The total length of orotracheal tube intubation showed a significant independent association with mortality before 30 days (P < .001).

CONCLUSION

OLT without VVB can be safely performed even in severe cases of chronic liver failure.

The relationship between preoperative creatinine clearance and outcomes for patients undergoing liver transplantation: a retrospective observational study

Background

Renal failure with following continuous renal replacement therapy is a major clinical problem in liver transplant recipients, with reported incidences of 3% to 20%. Little is known about the significance of postoperative acute renal failure or acute-on-chronic renal failure to postoperative outcome in liver transplant recipients.

Methods

In this post hoc analysis we compared the mortality rates of 135 consecutive liver transplant recipients over 6 years in our center subject to their renal baseline conditions and postoperative RRT. We classified the patients into 4 groups, according to their preoperative calculated Cockcroft formula and the incidence of postoperative renal replacement therapy. Data then were analyzed in regard to mortality rates and in addition to pre- and peritransplant risk factors.

Results

There was a significant difference in ICU mortality (p=.008), hospital mortality (p=.002) and cumulative survival (p<.0001) between the groups. The highest mortality rate occurred in the group with RRT and normal baseline kidney function (20% ICU mortality, 26.6% hospital mortality and 50% cumulative 1-year mortality, respectively). The hazard ratio in this group was 9.6 (CI 3.2-28.6, p=.0001).

Conclusion

This study shows that in liver transplant recipient’s acute renal failure with postoperative RRT is associated with mortality and the mortality rate is higher than in patients with acute-on-chronic renal failure and postoperative renal replacement therapy.

Ex-situ liver surgery without veno-venous bypass

AIM: To evaluate the results of hepatic resection with ex-situ hypothermic perfusion and without veno-venous bypass.

METHODS: In 3 patients with liver tumor, the degree of the inferior vena cava and/or main hepatic vein involvement was verified when the liver was dissociated in the operation. It was impossible to resect the tumors by the routine hepatectomy, so the patients underwent ex-situ liver surgery, vein cava replacement and hepatic autotransplantation without veno-venous bypass. All surgical procedures were carried out or supervised by a senior surgeon. A retrospective analysis was performed for the prospectively collected data from patients with liver tumor undergoing ex-situ liver surgery, vein cava replacement and hepatic autotransplantation without veno-venous bypass. We also compared our data with the 9 cases of Pichlmayr’s group.

RESULTS: Three patients with liver tumor were analysed. The first case was a 60-year-old female with a huge haemangioma located in S1, S4, S5, S6, S7 and S8 of liver; the second was a 64-year-old man with cholangiocarcinoma in S1, S2, S3 and S4 and the third one was a 55-year-old man with a huge cholangiocarcinoma in S1, S5, S7 and S8. The operation time for the three patients were 6.6, 6.4 and 7.3 h, respectively. The anhepatic phases were 3.8, 2.8 and 4.0 h. The volume of blood loss during operation were 1200, 3100, 2000 mL in the three patients, respectively. The survival periods without recurrence were 22 and 17 mo in the first two cases. As for the third case complicated with postoperative hepatic vein outflow obstruction, emergency hepatic vein outflow extending operation and assistant living donor liver transplantation were performed the next day, and finally died of liver and renal failure on the third day. Operation time (6.7 ± 0.47 h vs 13.7 ± 2.6 h) and anhepatic phase (3.5 ± 0.64 h vs 5.7 ± 1.7 h) were compared between Pichlmayr’s group and our series (P = 0.78).

CONCLUSION: Ex-situ liver resection and liver autotransplantation has shown a potential for treatment of complicated hepatic neoplasms that are unresectable by traditional procedures.

Liver transplantation with preservation of the inferior vena cava: lessons learned through 2,000 cases

BACKGROUND

We aim to demonstrate the utility and efficacy of the "piggyback technique" (PBT); liver transplant (LT) with caval preservation.

STUDY DESIGN

Adult LTs were performed with intent to use the PBT except in cases of juxtacaval malignancy or technical difficulty. Hepatic venous outflow was established between the donor suprahepatic cava and the joined ostia of all recipient suprahepatic veins. Technical variants with the donor cava and recipient retrohepatic cava were used as needed. The experience was divided into 2 eras: E1 (1994-2002), E2 (2002-2010).

RESULTS

We completed 945 of 1080 LTs in E1 (87.5%) and 851 of 920 LTs in E2 (92.5%) using the PBT. Thirty day mortality was 4.6% in E1, 3% in E2 (p = 0.02) with 2 intra-operative deaths in E1. One, 3, 5 year patient survival was 83.7, 75.6, 69.3% in E1 vs. 86, 78.4, 73.8% in E2 (p = 0.057). Graft survival was 77.7, 69, 62.3% in E1 vs. 84, 76.2, 71.2% in E2 (p < 0.0001). Median operative time and hospital length of stay improved in E2 (p < 0.0001, 0.0001). Outflow variants were used more frequently in E2 (11.3% vs. 6.1%). Nine patients (0.5%) developed outflow obstruction, 6 in E1, and 3 in E2. Twice, it was recognized and corrected intraoperatively. Seven patients presented with refractory ascites. Six were successfully treated (4 balloon dilatation, 2 surgical revision), one patient died after attempted dilatation.

CONCLUSIONS

The PBT can be used as the preferred technique in adult LT. With experience, the technique was used more frequently, with more variants, with improved outcomes. Outflow obstruction was a rare complication.

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.

Management of renal dysfunction in patients receiving a liver transplant

Renal dysfunction is a frequent complication in patients with endstage liver disease awaiting orthotopic liver transplantation. Although the stereotypical form of renal dysfunction is the hepatorenal syndrome, common causes of acute kidney injury include prerenal azotemia and acute tubular necrosis in this population. Management involves hemodynamic support, renal replacement therapy, and mitigation of risk factors. Renal dysfunction in a cirrhotic patient usually implies a poor prognosis in the absence of liver transplantation. An important issue is the frequent need for kidney, in addition to liver, transplantation if renal insufficiency has been persistent in a decompensated cirrhotic.

Preditores de injúria renal aguda em pacientes submetidos ao transplante ortotópico de fígado convencional sem desvio venovenoso

RADICAL: Injúria renal aguda é uma das complicações mais comuns do transplante ortotópico de fígado. A ausência de critério universal para sua definição nestas condições dificulta as comparações entre os estudos. A técnica convencional para o transplante consiste na excisão total da veia cava inferior retro-hepática durante a hepatectomia nativa. Controvérsias sobre o efeito da técnica convencional sem desvio venovenoso na função renal continuam. OBJETIVO: Estimar a incidência e os fatores de risco de injúria renal aguda entre os receptores de transplante ortotópico de fígado convencional sem desvio venovenoso. MÉTODOS: Foram avaliados 375 pacientes submetidos a transplante ortotópico de fígado. Foram analisadas as variáveis pré, intra e pós-operatórias em 153 pacientes submetidos a transplante ortotópico de fígado convencional sem desvio venovenoso. O critério para a injúria renal aguda foi valor da creatinina sérica > 1,5 mg/dl ou débito urinário < 500 ml/24h dentro dos primeiros três dias pós-transplante. Foi realizada análise univariada e multivariada por regressão logística. RESULTADOS: Todos os transplantes foram realizados com enxerto de doador falecido. Sessenta pacientes (39,2%) apresentaram injúria renal aguda. Idade, índice de massa corpórea, escore de Child-Turcotte-Pugh, ureia, hipertensão arterial sistêmica e creatinina sérica pré-operatória apresentaram maiores valores no grupo injúria renal aguda. Durante o período intraoperatório, o grupo injúria renal aguda apresentou mais síndrome de reperfusão, transfusão de concentrado de hemácias, plasma fresco e plaquetas. No pós-operatório, o tempo de permanência em ventilação mecânica e creatinina pós-operatória também foram variáveis, com diferenças significativas para o grupo injúria renal aguda. Após regressão logística, a síndrome de reperfusão, a classe C do Child-Turcotte-Pugh e a creatinina sérica pós-operatória apresentaram diferenças. CONCLUSÃO: Injúria renal aguda após transplante ortotópico de fígado convencional sem desvio venovenoso é uma desordem comum, mas apresenta bom prognóstico. Síndrome de reperfusão, creatinina sérica no pós-operatório e Child C são fatores associados a injúria renal aguda pós-transplante ortotópico de fígado convencional sem desvio venovenoso.

Critical care issues in patients after liver transplantation

The majority of patients who undergo liver transplantation (LT) spend some time in the intensive care unit during the postoperative period. For some, this is an expected part of the immediate posttransplant recovery period, whereas for others, the stay is more prolonged because of preexisting conditions, intraoperative events, or postoperative complications. In this review, 4 topics that are particularly relevant to the postoperative intensive care of LT recipients are discussed, with an emphasis on current knowledge specific to this patient group. Infectious complications are the most common causes of early posttransplant morbidity and mortality. The common patterns of infection seen in patients after LT and their management are discussed. Acute kidney injury and renal failure are common in post-LT patients. Kidney injury identification, etiologies, and risk factors and approaches to management are reviewed. The majority of patients will require weaning from mechanical ventilation in the immediate postoperative period; the approach to this is discussed along with the approach for those patients who require a prolonged period of mechanical ventilation. A poorly functioning graft requires prompt identification and appropriate management if the outcomes are to be optimized. The causes of poor graft function are systematically reviewed, and the management of these grafts is discussed.

Urinary neutrophil gelatinase-associated lipocalin as a marker of acute kidney injury after orthotopic liver transplantation

BACKGROUND

Urinary neutrophil gelatinase-associated lipocalin (NGAL) is a novel, sensitive and specific biomarker that is rapidly released after kidney injury. It predicts acute kidney injury (AKI) in multiple clinical scenarios. We hypothesized that urinary NGAL can predict AKI after liver transplantation.

METHODS

Urine was collected in 92 patients undergoing liver transplantation (18 living-related and 74 deceased) before surgery, after reperfusion of the liver graft and then 3, 18 and 24 h later. NGAL was analyzed with enzyme-linked immunosorbent assay and corrected for dilution/concentration by calculating urinary NGAL/urine creatinine ratios. AKI was defined by Risk-Injury-Failure-Loss-Endstage stage kidney disease (RIFLE)-risk criteria (increase of serum creatinine by >50%).

RESULTS

Urinary NGAL/urine creatinine ratio was low prior to surgery and increased immediately after reperfusion, peaked 3 h later and remained elevated at 18 and 24 h. Urinary NGAL/urine creatinine ratios were higher in patients with post-operative (post-OP) AKI defined by RIFLE--risk criteria 3 and 18 h after reperfusion. The area under the curve of the receiver operator characteristics curve of urinary NGAL/urine creatinine ratio to predict AKI was 0.800 (95% CI: 0.732-0.869, P < 0.0001) 3 h and 0.636 (95% CI: 0.551-0.720, P < 0.005) 18 h after reperfusion.

CONCLUSIONS

We conclude that urinary NGAL/urine creatinine ratio is able to predict post-OP AKI 3 and 18 h after transplantation with good discrimination.

Causes of intra-abdominal hemorrhage in rhesus monkeys after liver transplantation

AIM: To analyze the causes of abdominal hemorrhage in rhesus monkeys after liver transplantation.

METHODS: Healthy male rhesus monkeys weighing 7.2-11.5 kg were used as recipients, while healthy females or males weighing 5.3-8.1 kg were use as donors. Donor operation was performed quickly by making a big crucial incision in the abdomen. The improved dual-cuff of the portal vein and inferior vena cava was completed except for keeping biliary support tube within the donor liver. Classical orthotopic liver transplantation was performed in recipients.

RESULTS: Classical orthotopic liver transplantation was successful in all 25 rhesus monkeys. Eleven rhesus monkeys suffered from abdominal hemorrhage in the early postoperative stage, and 5 of them died. The distribution of abdominal hemorrhage site was as follows: anastomotic hemorrhage of the inferior vena cava in 5 cases, anastomotic hemorrhage of the portal vein in 5 cases, anastomotic hemorrhage of the superior vena cava in 4 cases, anastomotic hemorrhage of the liver bed in 4 cases, hemorrhage from mechanical injury in 3 cases, subcapsular hemorrhage of the liver in 3 cases, and hemorrhage of the right suprarenal vein and lumbar vein in 2 cases.

CONCLUSION: The most common cause of abdominal hemorrhage in rhesus monkeys after classical orthotopic liver transplantation is anastomotic hemorrhage of the inferior vena cava and portal vein.

Management of renal dysfunction in the liver transplant recipient

PURPOSE OF REVIEW

Acute and chronic kidney injury following orthotopic liver transplantation (OLT) is associated with increased morbidity and mortality. With the increasing longevity of liver transplant recipients, chronic kidney disease (CKD) has become an increasingly prevalent complication among long-term survivors. This article provides an overview of the literature on suggested risk factors for acute and CKD following OLT and a discussion of an approach to their medical management.

RECENT FINDINGS

In OLT candidates with pretransplant renal dysfunction, the use of interleukin-2 receptor blockers or antithymocyte globulin induction therapy in conjunction with delayed introduction of calcineurin inhibitors may preserve early renal function. In long-term stable OLT recipients with established calcineurin inhibitor nephrotoxicity, calcineurin inhibitor minimization or withdrawal protocols may halt or ameliorate renal dysfunction without compromising patient and graft survival. However, large-scale, multicenter, randomized controlled trials are still needed.

SUMMARY

The occurrence of acute kidney injury is common immediately after OLT, whereas the incidence of CKD and end-stage renal disease increases with time. Identifying patients at risk for acute kidney injury and CKD following OLT and early implementation of measures to preserve, halt, or ameliorate the progression of renal dysfunction should be an integral part in the management of OLT recipients.

The need for venovenous bypass in liver transplantation

Since introduction of the conventional liver transplantation (CLTx) by Starzl, which was based on the resection of recipient inferior vena cava (IVC) along the liver, the procedure has undergone several refinements. Successful use of venovenous bypass (VVB) was first introduced by Shaw et al., although in recent decades there has been controversy regarding the routine use of VVB during CLTx. With development of piggyback liver transplantation (PLTx), the use of caval clamping and VVB is avoided, leading to fewer complications related to VVB. However, some authors still advocate VVB in PLTx. The great diversity among centers in their use of VVB during CLTx, or even along the PLTx technique, has led to confusion regarding the indication setting for VVB. For this reason, we present an overview of the use of VVB in CLTx, the target of patients for whom VVB could be beneficial, and the needs assessment of VVB for patients undergoing PLTx. Recent studies have shown that with the advancement of surgical skills, refinement of surgical techniques, and improvements in anesthesiology, there are only limited indications for doing CLTx with VVB routinely. PLTx with preservation of IVC can be performed in almost all primary transplants and in the majority of re-transplantations without the need for VVB. Nevertheless, in a few selective cases with severe intra-operative hemodynamic instability, or with a failed test of transient IVC occlusion, the application of VVB is still justifiable. These indications should be judged intra-operatively and the decision is based on each center's preference.

Predictors of blood product use in orthotopic liver transplantation using the piggyback hepatectomy technique

Orthotopic liver transplantation (OLT) has historically been associated with massive blood loss and hemodynamic instability related to the coexistence of varices, coagulopathy, thrombocytopenia, and portal hypertension. Piggyback hepatectomy (PGB) is a technique increasingly utilized in OLT to avoid veno-venous bypass and vena cava clamping. This study evaluated the factors associated with blood loss and blood product requirement in PGB.

METHODS

This study is a retrospective review of the anesthesia preoperative and operative notes and computerized lab values for all adult cadaveric liver transplants over a 42-month period. These data were combined with the liver transplant database for analysis. Approximately 98% of the transplants were performed using a standard piggyback approach with no use of veno-venous bypass.

RESULTS

Data were included for all 526 transplants performed during this time period. Estimated blood loss (EBL) was 1000 cc. Median transfusion requirement was 3 units packed red blood cells, 7 units fresh frozen plasma, and 6 units platelets. Multivariate linear regression demonstrated that predictors of EBL were age, MELD score, preoperative hemoglobin, initial fibrinogen, initial central venous pressure, and total anesthesia time. Predictors of PRBC useage were age, MELD score, preoperative hemoglobin, initial fibrinogen, and anesthesia time. Postoperatively increased transfusion requirement was associated with increased length of hospital stay and lower 90-day and 1-year graft and patient survivals.

CONCLUSION

These results demonstrate that PGB can be safely accomplished in nearly all liver transplant patients without venovenous bypass or vena cava clamping and with less warm ischemia, which may ultimately be associated with less perioperative morbidity and improved outcomes.

The Effect of Clamping of Inferior Vena Cava and Portal Vein on Urine Output During Liver Transplantation

BACKGROUND

Intraoperative hypotension, massive transfusion, liver disease, coexistent renal dysfunction, and decreased glomerular filtration rate during the anhepatic phase are major hazards for kidney function. We undertook this study to determine the change in urine output during clamping.

METHOD

Twenty-four patients without preexistent renal disease, who were undergoing liver transplantation using the piggyback method, were enrolled in this study. Patients with a serum creatinine level >1.2 mg/dL were excluded. Urine output was monitored over 30 minutes before inferior vena cava and portal vein clamping, during clamping, and for 30 minutes after declamping. None of the patients had a clamping time >70 minutes. Our goal was to maintain mean arterial blood pressure and heart rate just by fluid administration diuretics were avoided.

RESULTS

Participants had a mean age of 39.12 +/- 13.52 years (range, 15-67 years) with a male to female ratio of 1:4. Urine output 30 minutes before clamping was 3.64 +/- 3.58 (range, 1.25-15.18) mL/kg/h, decreased to 1.28 +/- 2.58 (range, 0-11.39) mL/kg/h during clamping (P=.00), and increased to 3.56 +/- 3.64 (range, 0.51-15.18) mL/kg/h 30 minutes after declamping (P=.00).

CONCLUSION

Urine output was significantly reduced in all patients after clamping of the IVC and portal veins. This observation may be explained by increased venous pressure leading to decreased renal perfusion pressure. It has been stated that one of the advantages of veno-veno bypass (VVB) is increased renal perfusion pressure. However, if the clamping time in the piggyback method is <70 minutes and patients have normal preoperative renal function, the decreased renal perfusion pressure will not cause postoperative kidney dysfunction.

Conventional versus piggyback technique of caval implantation; without extra-corporeal veno-venous bypass. A comparative study

Conventional orthotopic liver transplantation (CON-LT) involves resection of recipient cava, usually with extra-corporeal circulation (veno-venous bypass, VVB), while in the piggyback technique (PC-LT) the cava is preserved. Along with a temporary portacaval shunt (TPCS), better haemodynamic maintenance is purported with PC-LT. A prospective, consecutive series of 384 primary transplants (2000-2003) were analysed, 138 CON-LT (with VVB) and 246 PC-LT (54 without TPCS). Patient/donor characteristics were similar in the two groups. PC-LT required less usage of fresh-frozen plasma and platelets, intensive care stay, number of patients requiring ventilation after day 1 and total days spent on ventilator. The results were not different when comparing, total operating and warm ischaemia time (WIT), red cell usage, requirement for renal support, day 3 serum creatinine and total hospital stay. TPCS had no impact on outcome other than WIT (P = 0.02). Three patients in PC-LT group (three of 246;1.2%) developed caval outflow obstruction (P = 0.02). There was no difference in short- or long-term graft or patient survival. PC-LT has an advantage over CON-LT unsing VVB with respect to intraoperative blood product usage, postoperative ventilation requirement and ITU stay. VVB is no longer required and TPCS may be used selectively in adult transplantation.

Analysis of renal function in the immediate postoperative period after partial liver transplantation

Although renal dysfunction is common after liver transplantation, postoperative renal function after split liver transplantation (SLT) has not been well studied. Renal function immediately after surgery was analyzed retrospectively in 16 patients that received a SLT (SLT group). The results were compared with corresponding data from 31 matched patients that received a full-size liver transplant (FSLT group) during the same period. Serum creatinine (SCr) was measured before surgery, and, after transplantation, daily during the first week and at days 14, 21, and 28. Renal dysfunction (RD) was defined as the requirement for renal replacement therapy (RRT) or a 100% increase in SCr if the basal value had been <1.0 mg/dL or a 50% increase in SCr if the basal value had been >1.0 mg/dL. SCr had to be at least 1.5 mg/dL for a diagnosis of RD to be considered. The classification of RD was: mild, SCr 1.5-2.4 mg/dL; moderate, SCr 2.5-4.0 mg/dL; or severe, SCr >4.0 mg/dL (the requirement for RRT). Both donor and recipient age and cold ischemia time were lower in the SLT group than in the FSLT group (P < 0.05). Length of surgery was longer in the SLT group (P < 0.05). There were no significant differences between groups with respect to Model for End-Stage Liver Disease scores, the need for transfusions, the length of admission to the intensive care unit (ICU), survival rate, individual severity index, or sepsis-related organ failure assessment scores at the time of diagnosing RD. Immunosuppression regimens were similar in both groups. RD developed in 82% of SLT patients, but in only 58% of FSLT patients (P = not significant [NS]). Among SLT patients, RD (23.0% mild, 15.5% moderate, and 61.5% severe) was more severe (P = 0.007) than in FSLT patients (63.1% mild, 15.8% moderate, and 24.1% severe). The requirement for RRT in the SLT group (43.7%) was significantly greater (P < 0.05) than that in the FSLT group (12.9%). This finding may be due to the different incidence of sepsis in the 2 groups (SLT 37.5% vs. FSLT 9.7%; P < 0.05). In conclusion, although the number of patients studied was small, our data suggest a higher incidence of RD and a greater requirement for RRT in patients that receive a split liver graft than in those that receive a full size liver graft.

Analysis of differences in outcome of two European liver transplant centers

Authors analyzed the differences in the outcome of two European liver transplant centers differing in case volume and experience. The first was the Transplantation and Surgical Clinic, Semmelweis University, Budapest, Hungary (SEB) and the second the University Medical Center Groningen, Groningen, The Netherlands (UMCG). We investigated if such differences could be explained. The 1-, 3- and 5-year patient survival in the UMCG was 86%, 80%, and 77% compared with 65%, 56%, and 55% in SEB. Graft survival at the same time points was 79%, 71%, and 66% in the UMCG and 62%, 55%, and 53% in SEB. Significant differences were present regarding the donor and recipient age, diagnosis mix, disease severity and operation variables, per-operative transfusion rate, vascular complications, postoperative infection rate, and need for renal replacement. To determine factors correlating with survival, a separate uni- and multivariate analysis was performed in each center individually, between study parameters and patient survival. In both centers, peri-operative red blood cell (RBC) transfusion rate was a significant predictor for patient survival. The difference in blood loss can be explained by different operation techniques and shorter operation time in SEB, with consequently less time spent on hemostasis. It was jointly concluded that measures to reduce blood loss by adapting the operation technique might lead to improved survival and reduced morbidity.

Risk factors of acute renal failure after liver transplantation

The objective of this study was to determine the risk factors of postoperative acute renal failure (ARF) in orthotopic liver transplantation (OLT). We reviewed 184 consecutive OLT. Postoperative ARF was defined as a persistent rise of 50% increase or more of the S-creatinine (S-Cr). The patients were classified as early postoperative ARF (E-ARF) (first week) and late postoperative ARF (L-ARF) (second to fourth week). Preoperative variables were age, sex, comorbidity, indication for OLT, Child-Pugh stage, united network for organ sharing status, analysis of the blood and urine, and donor's data. Intraoperative variables were systolic arterial pressure, mean arterial pressure, pulmonary capillary wedge pressure, cardiac index, and systemic vascular resistance index. Surgical technique, number of blood products transfused, need for adrenergic agonist drugs, and intraoperative complications were also important. Postoperative variables were duration of stay in the intensive care unit, time on mechanic ventilation, liver graft dysfunction, need for adrenergic agonist drugs, units of blood products infused, episodes of acute rejection, re-operations, and bacterial infections. Firstly we carried out a univariate statistical analysis, and secondly a logistic regression analysis. The risk factors for E-ARF were: pretransplant ARF (odds ratio (OR)=10.2, P=0.025), S-albumin (OR=0.3, P=0.001), duration of treatment with dopamine (OR=1.6, P=0.001), and grade II-IV dysfunction of the liver graft (OR=5.6, P=0.002). The risk factors for L-ARF were: re-operation (OR=3.1, P=0.013) and bacterial infection (OR=2.9, P=0.017). The development of E-ARF is influenced by preoperative factors such as ARF and hypoalbuminemia, as well as postoperative factors such as liver dysfunction and prolonged treatment with dopamine. The predicting factors of L-ARF differ from E-ARF and correspond to postoperative causes such as bacterial infection and surgical re-operation.