Intraoperative hepatic artery blood flow predicts early hepatic artery thrombosis after liver transplantation. Transplant Proc. 2012;44:2078-2081. [PMID: 22974916 DOI: 10.1016/j.transproceed.2012.07.077]

Graft-to-recipient weight ratio and risk of systemic inflammatory response syndrome early after liver transplantation in children

BACKGROUND

Systemic inflammatory responses soon after liver transplantation in children can lead to complications and poor outcomes, so here we examined potential risk factors of such responses.

METHODS

Data were retrospectively analyzed for 69 children who underwent liver transplantation at a single center between July 2017 and November 2019 through follow-up lasting up to one years. Numerous clinicodemographic factors were compared between those who suffered early systemic inflammatory response syndrome (SIRS) or not.

RESULTS

Of the 69 patients in our analysis, early SIRS occurred in 35 [50.7%, 95% confidence interval (CI), 38.6-62.8%]. Those patients showed significantly higher graft-to-recipient weight ratio (3.69 ± 1.26 vs. 3.12 ± 0.99%, P = 0.042) and lower survival rate at one year (85.7% vs. 100%, P = 0.023). Multivariate analysis found graft-to-recipient weight ratio > 4% to be an independent risk factor for early SIRS [odds ratio (OR) 3.8, 95% CI 1.08-13.371, P = 0.037], and a cut-off value of 4.04% predicted the syndrome in our patients, and area under the receiver operating characteristic curve of 0.656 (95% CI 0.525-0.788, P = 0.026).

CONCLUSIONS

Graft-to-recipient weight ratio > 4% may predict higher risk of SIRS soon after liver transplantation in children.

Vascular complications after liver transplantation: contemporary approaches to detection and treatment. A literature review

Vascular complications (VCs) after liver transplantation (LT) are rare but are one of the most dreaded conditions that can potentially lead to graft loss and recipient death. This paper has analyzed the international experience in the early diagnosis of various VCs that can develop following LT, as well as the optimal timing and methods of treatment of these complications.

Importance of Anatomical Variation of the Hepatic Artery for Complicated Liver and Pancreatic Surgeries: A Review Emphasizing Origin and Branching

Knowledge of anatomical variations of the hepatic artery from its origin to intrahepatic segmentation is of utmost importance for planning upper abdominal surgeries including liver transplantation, pancreatoduodenectomy, and biliary reconstruction. The origin and branching pattern of the hepatic artery was thoroughly described by the classification of Michels and Hiatt. Some rare variations of the hepatic artery were classified by Kobayashi and Koops. By the use of the multidetector computed tomography (MDCT) technique, the branching pattern of the hepatic artery can be visualized quite accurately. Unawareness of these arterial variations may lead to intraoperative injuries such as necrosis, abscess, and failure of the liver and pancreas. The origin and course of the aberrant hepatic arteries are crucial in the surgical planning of carcinoma of the head of the pancreas and hepatobiliary surgeries. In liver transplant surgeries, to minimize intraoperative bleeding complications and postoperative thrombosis, exact anatomy of the branching of the hepatic artery, its variations and intrahepatic course is of utmost importance. This review discusses variations in the anatomy of the hepatic artery from its origin to branching by the use of advanced imaging techniques and its effect on the liver, pancreatic, biliary and gastric surgeries.

Viscoelastic Management of Coagulopathy during the Perioperative Period of Liver Transplantation

Viscoelastic testing (VET) in liver transplantation (LT) has been used since its origin, in combination with standard laboratory testing (SLT). There are only a few, small, randomized controlled trials that demonstrated a reduction in transfusion rates using VET to guide coagulation management. Retrospective analyses contrasting VET to SLT have demonstrated mixed results, with a recent concern for overtreatment and the increase in postoperative thrombotic events. An oversight of many studies evaluating VET in LT is a single protocol that does not address the different phases of surgery, in addition to pre- and postoperative management. Furthermore, the coagulation spectrum of patients entering and exiting the operating room is diverse, as these patients can have varying anatomic and physiologic risk factors for thrombosis. A single transfusion strategy for all is short sighted. VET in combination with SLT creates the opportunity for personalized resuscitation in surgery which can address the many challenges in LT where patients are at a paradoxical risk for both life-threatening bleeding and clotting. With emerging data on the role of rebalanced coagulation in cirrhosis and hypercoagulability following LT, there are numerous potential roles in VET management of LT that have been unaddressed.

Updates in the Management of Perioperative Vasoplegic Syndrome

Vasoplegic syndrome occurs relatively frequently in cardiac surgery, liver transplant, major noncardiac surgery, in post-return of spontaneous circulation situations, and in pateints with sepsis. It is paramount for the anesthesiologist to understand both the pathophysiology of vasoplegia and the different treatment strategies available for rescuing a patient from life-threatening hypotension.

Use of Intravenous Hydroxocobalamin for Vasoplegic Syndrome in Simultaneous Liver-Kidney Transplant: A Case Report

Vasoplegic syndrome can occur after reperfusion in liver transplantation. Generally, vasopressor infusions along with volume resuscitation are used to combat this process. There are case reports of the use of hydroxocobalamin to improve vasoplegia in liver transplant and cardiac surgery. In this case report, we describe a patient who received hydroxocobalamin for a simultaneous liver-kidney transplant. Use of this medication facilitated a prompt decrease of very high-dose vasopressor infusions and allowed completion of the kidney transplantation portion of this case. To our knowledge, use in combined liver-kidney transplant has not been described. In light of the dearth of medications to improve vasoplegia outside of vasopressor infusions, the use of hydroxocobalamin as a therapeutic intervention may gain importance.

Perioperative management of antithrombotic treatment

End-stage liver disease is characterized by multiple and complex alterations of hemostasis that are associated with an increased risk of both bleeding and thrombosis. Liver transplantation further challenges the feeble hemostatic balance of patients with decompensated cirrhosis, and the management of antithrombotic treatment during and after transplant surgery, which is particularly difficult. Bleeding was traditionally considered the major concern during and early after surgery, but it is increasingly recognized that transplant recipients may also develop thrombotic complications. Pathophysiology of hemostatic complications during and after transplantation is multifactorial and includes pre-, intra-, and postoperative risk factors. Risk stratification is important, as it helps the identification of high-risk recipients in whom antithrombotic prophylaxis should be considered. In recipients who develop thrombosis during or after surgery, prompt treatment is indicated to prevent graft failure, retransplantation, and death.

Liver Transplantation

The field of liver transplantation has changed since the MELD scoring system became the most widely used donor allocation tool. Due to the MELD-based allocation system, sicker patients with higher MELD scores are being transplanted. Persistent organ donor shortages remain a challenging issue, and as a result, the wait-list mortality is a persistent problem for most of the regions. This chapter focuses on deceased donor and live donor liver transplantation in patients with complications of portal hypertension. Special attention will also be placed on donor-recipient matching, perioperative management of transplant patients, and the impact of hepatic hemodynamics on transplantation.

Hepatic flow is an intraoperative predictor of early allograft dysfunction in whole-graft deceased donor liver transplantation: An observational cohort study

BACKGROUND

Early allograft dysfunction (EAD) after liver transplantation (LT) is an important cause of morbidity and mortality. To ensure adequate graft function, a critical hepatocellular mass is required in addition to an appropriate blood supply. We hypothesized that intraoperative measurement of portal venous and hepatic arterial flow may serve as a predictor in the diagnosis of EAD.

AIM

To study whether hepatic flow is an independent predictor of EAD following LT.

METHODS

This is an observational cohort study in a single institution. Hepatic arterial blood flow and portal venous blood flow were measured intraoperatively by transit flow. EAD was defined using the Olthoff criteria. Univariate and multivariate analyses were used to determine the intraoperative predictors of EAD. Survival analysis and prognostic factor analysis were performed using the Kaplan-Meier and Cox regression models.

RESULTS

A total of 195 liver transplant procedures were performed between January 2008 and December 2014 in 188 patients. A total of 54 (27.7%) patients developed EAD. The median follow-up was 39 mo. Portal venous flow, hepatic arterial flow (HAF) and total hepatic arterial flow were associated with EAD in both the univariate and multivariate analyses. HAF is an independent prognostic factor for 30-d patient mortality.

CONCLUSION

Intraoperative measurement of blood flow after reperfusion appears to be a predictor of EAD; Moreover, HAF should be considered a predictor of 30-d patient mortality.

Predictive Value of Hepatic Venous Pressure Gradient for Graft Hemodynamics in Living Donor Liver Transplantation

The hepatic venous pressure gradient (HVPG) measurement is known to correlate with the severity of portal hypertension in patients with liver cirrhosis. This retrospective study investigated the clinical value of preoperative measurement of HVPG in patients who underwent adult-to-adult living donor liver transplantation (LDLT) and its predictive value for hepatic hemodynamics after graft reperfusion. For this study, 75 patients who underwent adult-to-adult LDLT were divided into 2 groups (HVPG <16 mm Hg or HVPG ≥16 mm Hg) to investigate the correlation between preoperative HVPG and characteristics and surgical outcomes of the patients, including portal vein flow (PVF) and hepatic artery flow (HAF) after graft reperfusion. In total, 35 (46.7%) patients had an HVPG ≥16 mm Hg. These patients had significantly higher international normalized ratio values, serum creatinine levels, and Model for End-Stage Liver Disease scores compared with the 40 patients with HVPG <16 mm Hg. They also had higher rates of variceal bleeding, encephalopathy, and intractable ascites as well as lower serum albumin levels and platelet counts compared with those patients with HVPG <16 mm Hg. Portal inflow modulation (PIM) was frequently performed in the patients with HVPG ≥16 mm Hg compared with those with HVPG <16 mm Hg. No significant differences in surgical outcomes after LDLT were found between these 2 groups except for postoperative ascites. Preoperative HVPG showed a positive correlation with PVF and a negative correlation with HAF after graft reperfusion (false discovery rate [FDR] P = 0.08 and FDR P = 0.08, respectively). In linear regression analyses, preoperative HVPG was independently associated with PVF after graft reperfusion. In conclusion, our findings indicate that preoperative HVPG is associated with hepatic hemodynamics after graft implantation in LDLT. HVPG as a routine preoperative evaluation may be helpful for surgical planning of PIM.

Donor Risk Index Has an Impact in Intraoperative Measure of Hepatic Artery Flow and in Clearance of Indocyanine Green: An Observational Cohort Study

BACKGROUND

The increase in indications for liver transplantation has led to acceptance of donors with expanded criteria. The donor risk index (DRI) was validated with the aim of being a predictive model of graft survival based on donor characteristics. Intraoperative arterial hepatic flow and indocyanine green clearance (plasma clearance rate of indocyanine green [ICG-PDR]) are easily measurable variables in the intraoperative period that may be influenced by graft quality. Our aim was to analyze the influence of DRI on intraoperative liver hemodynamic alterations and on intraoperative dynamic liver function testing (ICG-PDR).

METHODS

This investigation was an observational study of a single-center cohort (n = 228) with prospective data collection and retrospective data analysis. Measurement of intraoperative flow was made with a VeriQ flowmeter based on measurement of transit time (MFTT). The ICG-PDR was obtained from all patients with a LiMON monitor (Pulsion Medical Systems AG, Munich, Germany). DRI was calculated using a previously validated formula. Normally distributed variables were compared using Student's t test. Otherwise, the Mann-Whitney U test or Kruskal-Wallis test was applied, depending on whether there were 2 or more comparable groups. The qualitative variables and risk measurements were analyzed using the chi-square test. P < .05 was considered statistically significant.

RESULTS

DRI score (mean ± SD) was 1.58 ± 0.31. The group with DRI >1.7 (poor quality) had an intraoperative arterial flow of 234.2 ± 121.35 mL/min compared with the group having DRI < 1.7 (high quality), with an intraoperative arterial flow of 287.24 ± 156.84 mL/min (P = .02). The group with DRI >1.70 had an ICG-PDR of 14.75 ± 6.52%/min at 60 minutes after reperfusion compared to the group with DRI <1.70, with an ICG-PDR of 16.68 ± 6.47%/min at 60 minutes after reperfusion (P = .09).

CONCLUSION

Poor quality grafts have greater susceptibility to ischemia-reperfusion damage. Decreased intraoperative hepatic arterial flow may represent an increase in intrahepatic resistance early in the intraoperative period.

Intraoperative Portal Vein Flow > 123 mL/min Per 100 g Predicts a Better Survival of Patients After Liver Transplantation

OBJECTIVE

To assess the importance of intraoperative portal vein flow measurement during liver transplantation in relation to postoperative complications and graft and patient survival.

MATERIALS AND METHODS

Retrospective review including 291 patients who had all the information and covering a period of 10 years (2007-2017). Using a receiver operating characteristic curve, a cut-off point that would have the greatest impact on the probability of being alive at 5 years was established. In relation to this value, 2 groups were formed (low and high flow) and demographic variables, intraoperative variables, postoperative complications, and graft and patient survival were compared.

RESULTS

A portal flow of 123 mL/min per100 g of liver tissue was established (area under the curve = 0.58), obtaining a low-flow (n = 129) and a high-flow group (n = 162). The 2 groups were similar in their preoperative characteristics, except for a higher proportion of preoperative ascites, a higher Model for End-Stage Liver Disease score and a lower weight of donors in the high-flow group. The arterial and portal flows were significantly higher in the high-flow group. In the postoperative period, the high-flow group presented a higher rate of ascites. The 5-year survival rate of patients was significantly higher in the high-flow group (76% vs 84%, P = .03).

CONCLUSIONS

Patients undergoing liver transplantation with an intraoperative portal vein flow measurement >123 mL/min per 100 g present a greater 5-year survival rate.

Case report of high-dose hydroxocobalamin in the treatment of vasoplegic syndrome during liver transplantation

A 66-year-old man with cryptogenic cirrhosis secondary to nonalcoholic steatohepatitis presented for orthotopic liver transplantation. Following organ reperfusion, the patient developed vasoplegic syndrome, with arterial blood pressures of approximately 60-70/30-40 mm Hg (mean arterial pressure [MAP] <45 mm Hg) for >90 minutes. He required high-dose norepinephrine and vasopressin infusions, as well as i.v. bolus doses of norepinephrine and vasopressin to reach a goal MAP> 60 mm Hg. There was minimal response to a 2 mg/kg i.v. bolus of methylene blue. Following the administration of 5 g of i.v.hydroxocobalamin, the patient had a profound improvement in arterial blood pressure, with subsequent discontinuation of the vasopressin infusion and rapid reduction of norepinephrine infusion from 20 to 2 μg/min. While there have been several reports of the efficacy of hydroxocobalamin for vasoplegia after cardiopulmonary bypass, there have been only limited cases of hydroxocobalamin used in liver transplantation, and none with high-dose administration. We present a case of vasoplegic syndrome during liver transplantation that was refractory to high-dose vasopressors and methylene blue but responsive to high-dose i.v. hydroxocobalamin.

Coagulopathy Before and After Liver Transplantation: From the Hepatic to the Systemic Circulatory Systems

The hemostatic environment in patients with cirrhosis is a delicate balance between prohemostatic and antihemostatic factors. There is a lack of effective laboratory measures of the hemostatic system in patients with cirrhosis. Many are predisposed to pulmonary embolus, deep vein thrombosis, and portal vein thrombosis in the pretransplantation setting. This pretransplantation hypercoagulable milieu seems to extend for at least several months post-transplantation. Patients with nonalcoholic fatty liver disease, inherited thrombophilia, portal hypertension in the absence of cirrhosis, and hepatocellular carcinoma often require individualized approach to anticoagulation. Early reports suggest a potential role for low-molecular-weight heparins and direct-acting anticoagulants.

Vascular complications following liver transplantation: A literature review of advances in 2015

Although vascular complications (VCs) following orthotopic liver transplantation (OLT) seldom occur, they are the most feared complications with a high incidence of both graft loss and mortality, as they compromise the blood flow of the transplant (either inflow or outflow). Diagnosis and therapeutic management of VCs constitute a major challenge in terms of increasing the success rate of liver transplantation. While surgical treatment used to be considered the first choice for management, advances in endovascular intervention have increased to make this a viable therapeutic option. Considering VC as a rare but a major and dreadful issue in OLT history, and in view of the continuing and rapid progress in recent years, an update on these uncommon conditions seemed necessary. In this sense, this review comprehensively discusses the important features (epidemiological, clinical, paraclinical, prognostic and therapeutic) of VCs following OLT.

Perioperative thrombotic complications in liver transplantation

Although the perioperative bleeding complications and the major side effects of blood transfusion have always been the primary concern in liver transplantation (OLT), the possible cohesion of an underestimated intrinsic hypercoagulative state during and after the transplant procedure may pose a major threat to both patient and graft survival. Thromboembolism during OLT is characterized not only by a complex aetiology, but also by unpredictable onset and evolution of the disease. The initiation of a procoagulant process may be triggered by various factors, such as inflammation, venous stasis, ischemia-reperfusion injury, vascular clamping, anatomical and technical abnormalities, genetic factors, deficiency of profibrinolytic activity, and platelet activation. The involvement of the arterial system, intracardiac thrombosis, pulmonary emboli, portal vein thrombosis, and deep vein thrombosis, are among the most serious thrombotic events in the perioperative period. The rapid detection of occlusive vascular events is of paramount importance as it heavily influences the prognosis, particularly when these events occur intraoperatively or early after OLT. Regardless of the lack of studies and guidelines on anticoagulant prophylaxis in this setting, many institutions recommend such an approach especially in the subset of patients at high risk. However, the decision of when, how and in what doses to use the various chemical anticoagulants is still a difficult task, since there is no common consensus, even for high-risk cases. The risk of postoperative thromboembolism causing severe hemodynamic events, or even loss of graft function, must be weighed and compared with the risk of an important bleeding. In this article we briefly review the risk factors and the possible predictors of major thrombotic complications occurring in the perioperative period, as well as their incidence and clinical features. Moreover, the indications to pharmacological prophylaxis and the current treatment strategies are also summarized.

Hepatic artery thrombosis in live liver donor transplantation: how to solve--a case report

The decrease in the number of cadaveric donors has proved a limiting factor in the number of liver transplants, leading to the death of many patients on the waiting list. The living donor liver transplantation is an option that allows, in selected cases, increase the number of donors. One of the most serious complications in liver transplantation is hepatic artery thrombosis, in the past considered potentially fatal without urgent re-transplantation. A white male patient, 48 years old, diagnosed with hepatocellular carcinoma in chronic liver failure caused by hepatitis B virus, underwent living donor liver transplantation (right lobe). Doppler echocardiography performed in the immediate postoperative period did not identify arterial flow in the right branch, having been confirmed thrombosis of the right hepatic artery in CT angiography. Urgent re-laparotomy was performed, which consisted of thrombectomy and re-anastomosis of the hepatic artery with segmental splenic artery allograft interposition. The patient started anticoagulation and antiplatelet therapy with acetylsalicylic acid. Serial evaluation with Doppler echocardiography showed hepatic artery patency. At present, the patient is asymptomatic. One of the most devastating complications in liver transplantation, and particularly in living liver donor, is thrombosis of the hepatic artery; thus, early diagnosis and treatment is vital. The rapid intervention for revascularization of the graft avoids irreversible ischemia of the bile ducts and hepatic parenchyma, thus avoiding the need for re-transplantation.

Detection of hepatic hemodynamics in normal rhesus monkeys using high-frequency ultrasound

The rhesus monkey liver disease model provides useful information for hepatic research, as studies of hepatic hemodynamics in humans are rare. A 3-9 MHz high-frequency linear transducer (iU22, Philips Medical Systems, Royal Philips Electronics, The Netherlands) was used to obtain ultrasonograms of the livers of 28 normal rhesus monkeys (16 males, 12 females). Diameters of the portal vein and proper hepatic artery; maximum velocity of the portal vein; and peak-systolic and end-diastolic velocity and resistive index of the proper hepatic artery were also assessed. The portal vein and proper hepatic artery were 0.584 ± 0.123 and 0.151 ± 0.052 cm in diameter, respectively. The maximum velocity of the portal vein was 40.2 ± 13.7 cm/s. Peak systolic velocity and resistive index of the proper hepatic artery were 72.2 ± 25.4 cm/s and 0.67 ± 0.10, respectively. We found that high-frequency Doppler ultrasonography can be used to obtain clear portal vein and proper hepatic artery ultrasonograms and to measure the hemodynamic parameters of the portal vein and proper hepatic artery in rhesus monkeys. It is thus an effective method for studying changes in hepatic hemodynamics and has interesting technical and therapeutic implications. Our results provide useful information and establish normal reference values for future studies of adult healthy rhesus monkeys.