The Association Between Vena Cava Implantation Technique and Acute Kidney Injury After Liver Transplantation

Serum from patients with cirrhosis undergoing liver transplantation induces permeability in human pulmonary microvascular endothelial cells ex vivo

Introduction

Patients with cirrhosis undergoing liver transplantation frequently exhibit systemic inflammation, coagulation derangements, and edema, indicating endothelial dysfunction. This syndrome may worsen after ischemia-reperfusion injury of the liver graft, coincident with organ dysfunction that worsens patient outcomes. Little is known about changes in endothelial permeability during liver transplantation. We hypothesized that sera from these patients would increase permeability in cultured human endothelial cells ex vivo.

Methods

Adults with cirrhosis presenting for liver transplantation provided consent for blood collection during surgery. Sera were prepared at five time points spanning the entire operation. The barrier function of human pulmonary microvascular endothelial cells in culture was assessed by transendothelial resistance measured using the ECIS ZΘ system. Confluent cells from two different endothelial cell donors were stimulated with human serum from liver transplant patients. Pooled serum from healthy men and purified inflammatory agonists served as controls. The permeability response to serum was quantified as the area under the normalized resistance curve. Responses were compared between time points and analyzed for associations with clinical characteristics of liver transplant patients and their grafts.

Results

Liver transplant sera from all time points during surgery-induced permeability in both endothelial cell lines. The magnitude of permeability change was heterogeneous between patients, and there were differences in the effects of sera on the two endothelial cell lines. In one of the cell lines, the severity of liver disease was associated with greater permeability at the start of surgery. In the same cell line, serum collected 15 min after liver reperfusion induced significantly more permeability as compared to that collected at the start of surgery. Early postreperfusion sera from patients undergoing living donor transplants induced more permeability than sera from deceased donor transplants. Sera from two exemplary cases of patients on preoperative dialysis, and one patient with an unexpectedly long warm ischemia time of the liver graft, induced exaggerated and prolonged endothelial permeability.

Discussion

Serum from patients with cirrhosis undergoing liver transplantation induces permeability of cultured human pulmonary microvascular endothelial cells. Increased endothelial permeability during liver transplantation may contribute to organ injury and present a target for future therapeutics.

Angiotensin II in liver transplantation (AngLT-1): protocol of a randomised, double-blind, placebo-controlled trial

INTRODUCTION

Catecholamine vasopressors such as norepinephrine are the standard drugs used to maintain mean arterial pressure during liver transplantation. At high doses, catecholamines may impair organ perfusion. Angiotensin II is a peptide vasoconstrictor that may improve renal perfusion pressure and glomerular filtration rate, a haemodynamic profile that could reduce acute kidney injury. Angiotensin II is approved for vasodilatory shock but has not been rigorously evaluated for treatment of hypotension during liver transplantation. The objective is to assess the efficacy of angiotensin II as a second-line vasopressor infusion during liver transplantation. This trial will establish the efficacy of angiotensin II in decreasing the dose of norepinephrine to maintain adequate blood pressure. Completion of this study will allow design of a follow-up, multicentre trial powered to detect a reduction of organ injury in liver transplantation.

METHODS AND ANALYSIS

This is a double-blind, randomised clinical trial. Eligible subjects are adults with a Model for End-Stage Liver Disease Sodium Score ≥25 undergoing deceased donor liver transplantation. Subjects are randomised 1:1 to receive angiotensin II or saline placebo as the second-line vasopressor infusion. The study drug infusion is initiated on reaching a norepinephrine dose of 0.05 µg kg-1 min-1 and titrated per protocol. The primary outcome is the dose of norepinephrine required to maintain a mean arterial pressure ≥65 mm Hg. Secondary outcomes include vasopressin or epinephrine requirement and duration of hypotension. Safety outcomes include incidence of thromboembolism within 48 hours of the end of surgery and severe hypertension. An intention-to-treat analysis will be performed for all randomised subjects receiving the study drug. The total dose of norepinephrine will be compared between the two arms by a one-tailed Mann-Whitney U test.

ETHICS AND DISSEMINATION

The trial protocol was approved by the local Institutional Review Board (#20-30948). Results will be posted on ClinicalTrials.gov and published in a peer-reviewed journal.

TRIAL REGISTRATION NUMBER

ClinicalTrials.govNCT04901169.

Real-world implementation of normothermic machine perfusion: A detailed analysis of intraoperative and early postoperative impact

BACKGROUND

Outcome data for the great majority of liver normothermic machine perfusion (NMP) cases derive from the strict confines of clinical trials. Detailed specifics regarding the intraoperative and early postoperative impact of NMP on reperfusion injury and its sequelae during real-world use of this emerging technology remain largely unavailable.

METHODS

We analyzed transplants performed in a 3-month pilot period during which surgeons invoked commercial NMP at their discretion. Living donor, multi-organ, and hypothermic machine perfusion transplants were excluded.

RESULTS

Intraoperatively, NMP (n = 24) compared to static cold storage (n = 25) recipients required less peri-reperfusion bolus epinephrine (0 vs. 60 μg; p < .001) and post-reperfusion fresh frozen plasma (2.5 vs. 7.0 units; p = .0069), platelets (.0 vs. 2.0 units; p = .042), and hemostatic agents (0% vs. 24%; p = .010). Time from incision to venous reperfusion did not differ (3.6 vs. 3.1; p = .095) but time from venous reperfusion to surgery end was shorter for NMP recipients (2.3 vs. 2.8 h; p = .0045). Postoperatively, NMP recipients required fewer red blood cell (1.0 vs. 4.0 units; p = .0083) and fresh frozen plasma (4.0 vs. 7.0 units; p = .046) transfusions, had shorter intensive care unit stays (33.5 vs. 58.4 h; p = .012), and experienced less early allograft dysfunction according to both the Model for Early Allograft Function Score (3.4 vs. 5.0; p = .0047) and peak AST within 10 days of transplant (619 vs. 1,181 U/L; p = .036). Liver acceptance for the corresponding recipient was conditional on NMP use for 63% (15/24) of cases.

CONCLUSION

Real-world NMP use was associated with significantly lower intensity of reperfusion injury and intraoperative and postoperative care that may translate into patient benefit.

Stapled Anastomosis for Side-to-Side Cavo-Cavostomy in Orthotopic Liver Transplantation

In liver transplantation, a side-to-side anastomosis is one of the commonly performed techniques of the inferior vena cava reconstruction. The authors report a case of an application of an endoscopic vascular linear stapler for a side-to-side caval anastomosis during deceased-donor liver transplantation. The back table procedure was performed in a standard fashion for a side-to-side anastomosis. The linear vascular stapler was introduced during the temporary clamping of the recipient's inferior vena cava and the anastomosis was created without problems. Suturing of the resulting defect completed the anastomosis. The use of the stapler resulted in a shortening of the anastomosis time. The staple line after the reperfusion of the graft was completely sealed. The patient's postoperative course was uncomplicated and post-operative ultrasound and computed tomography confirmed the patency of the anastomosis. This case demonstrates a novel approach to a side-to-side caval reconstruction during liver transplantation that enables a shortening of the implantation time and may improve the quality of anastomoses.

Perioperative clinical practice in liver transplantation: a cross-sectional survey

PURPOSE

The objective of this study was to describe some components of the perioperative practice in liver transplantation as reported by clinicians.

METHODS

We conducted a cross-sectional clinical practice survey using an online instrument containing questions on selected themes related to the perioperative care of liver transplant recipients. We sent email invitations to Canadian anesthesiologists, Canadian surgeons, and French anesthesiologists specialized in liver transplantation. We used five-point Likert-type scales (from "never" to "always") and numerical or categorical answers. Results are presented as medians or proportions.

RESULTS

We obtained answers from 130 participants (estimated response rate of 71% in Canada and 26% in France). Respondents reported rarely using transesophageal echocardiography routinely but often using it for hemodynamic instability, often using an intraoperative goal-directed hemodynamic management strategy, and never using a phlebotomy (medians from ordinal scales). Fifty-nine percent of respondents reported using a restrictive fluid management strategy to manage hemodynamic instability during the dissection phase. Forty-two percent and 15% of respondents reported using viscoelastic tests to guide intraoperative and postoperative transfusions, respectively. Fifty-four percent of respondents reported not pre-emptively treating preoperative coagulations disturbances, and 91% reported treating them intraoperatively only when bleeding was significant. Most respondents (48-64%) did not have an opinion on the maximal graft ischemic times. Forty-seven percent of respondents reported that a piggyback technique was the preferred vena cava anastomosis approach.

CONCLUSION

Different interventions were reported to be used regarding most components of perioperative care in liver transplantation. Our results suggest that significant equipoise exists on the optimal perioperative management of this population.

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.

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.

Development and validation of a nomogram for predicting acute kidney injury after orthotopic liver transplantation

BACKGROUND

We aim to develop and validate a nomogram model for predicting severe acute kidney injury (AKI) after orthotopic liver transplantation (OLT).

METHODS

A total of 576 patients who received OLT in our center were enrolled. They were assigned to the development and validation cohort according to the time of inclusion. Univariable and multivariable logistic regression using the forward variable selection routine were applied to find risk factors for post-OLT severe AKI. Based on the results of multivariable analysis, a nomogram was developed and validated. Patients were followed up to assess the long-term mortality and development of chronic kidney disease (CKD).

RESULTS

Overall, 35.9% of patients were diagnosed with severe AKI. Multivariable logistic regression analysis revealed that recipients' BMI (OR 1.10, 95% CI 1.04-1.17, p = 0.012), hypertension (OR 2.32, 95% CI 1.22-4.45, p = 0.010), preoperative serum creatine (sCr) (OR 0.96, 95% CI 0.95-0.97, p < 0.001), and intraoperative fresh frozen plasm (FFP) transfusion (OR for each 1000 ml increase 1.34, 95% CI 1.03-1.75, p = 0.031) were independent risk factors for post-OLT severe AKI. They were all incorporated into the nomogram. The area under the ROC curve (AUC) was 0.73 (p < 0.05) and 0.81 (p < 0.05) in the development and validation cohort. The calibration curve demonstrated the predicted probabilities of severe AKI agreed with the observed probabilities (p > 0.05). Kaplan-Meier survival analysis showed that patients in the high-risk group stratified by the nomogram suffered significantly poorer long-term survival than the low-risk group (HR 1.92, p < 0.01). The cumulative risk of CKD was higher in the severe AKI group than no severe AKI group after competitive risk analysis (HR 1.48, p < 0.05).

CONCLUSIONS

With excellent predictive abilities, the nomogram may be a simple and reliable tool to identify patients at high risk for severe AKI and poor long-term prognosis after OLT.

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.