Liver transplantation: intraoperative changes in coagulation factors in 100 first transplants

An observational study of hemostatic profile during different stages of liver transplant surgery using laboratory-based tests and thromboelastography

Background:

Liver produces most of the blood coagulation factors, so it is not surprising to see a deranged coagulation profile in patients receiving liver transplants. Besides standard laboratory methods to evaluate coagulation profile, point-of-care assays are being used regularly since their results are rapidly available. However, sparse information is available on the comparability of point-of-care coagulation assays with laboratory coagulation assays in this special setting. In this study, our aim is to observe the changing hemostatic profile during different stages of liver transplant surgery using laboratory-based tests and thromboelastography (TEG).

Methods:

Fifty patients undergoing living donor liver transplantation surgery were selected. Coagulation tests (prothrombin time [PT], activated partial thromboplastin time [APTT], platelet count, and fibrinogen) and TEG were performed at various intervals during liver transplant surgeries – before induction of anesthesia, 2 h into dissection phase, 30 min into anhepatic phase, 30 min after reperfusion of homograft, postoperative – at closure of surgery, 12 h postoperative, and 24 h postoperative. Statistical analysis and Pearson correlation were performed between laboratory-based coagulation tests and TEG, and their pattern through various stages of the surgery analyzed.

Results:

Platelet count and fibrinogen have a significant positive correlation with TEG in almost all phases of liver transplant. PT and APTT have a positive correlation with TEG until uptake of new liver and predominantly negative correlation after that. However, this correlation is significant only before induction of anesthesia and anhepatic phase.

Conclusions:

TEG can be used to estimate platelet count and fibrinogen concentrations in all phases but PT and APTT only before induction and anhepatic phase of liver transplant surgery. The decision regarding transfusion of blood products should be based on a combination of the clinical assessment of surgeon and anesthesia personnel combined with results from laboratory and TEG.

Blood Markers of Portal Hypertension Are Associated with Blood Loss and Transfusion Requirements during Orthotopic Liver Transplantation

There is increasing evidence that portal hypertension plays a major role in bleeding risk during orthotopic liver transplantation (OLT). We investigated the association between preoperative blood levels of von Willebrand factor (VWF) and soluble CD163 (sCD163), which are established markers of portal hypertension, and blood loss and transfusion requirements during OLT. We measured levels of VWF and sCD163 in preoperative serum samples of 168 adult patients undergoing a primary OLT between 1998 and 2012. Preoperative levels of VWF and sCD163 correlated with the model of end-stage liver disease (MELD) score (r = 0.414, p < 0.001 and r = 0.382, p < 0.001, respectively). Patients with high VWF or sCD163 levels (VWF and sCD163 levels above the median) had a substantially increased risk of needing red blood cell transfusion compared with patients with low VWF or sCD163 levels (VWF and sCD163 levels below the median) (odds ratio 3.5 [95% confidence interval, CI 1.7-7.0] and 2.3 [95% CI 1.1-4.5], respectively). Blood loss was highest in patients with both high VWF or sCD163 levels and a high preoperative international normalized ratio. Elevated blood levels of markers of portal hypertension are associated with increased blood loss and transfusion requirements during OLT and support the notion that portal hypertension is an important contributor to perioperative blood loss.

Perioperative management of the bleeding patient

Perioperative bleeding remains a major complication during and after surgery, resulting in increased morbidity and mortality. The principal causes of non-vascular sources of haemostatic perioperative bleeding are a preexisting undetected bleeding disorder, the nature of the operation itself, or acquired coagulation abnormalities secondary to haemorrhage, haemodilution, or haemostatic factor consumption. In the bleeding patient, standard therapeutic approaches include allogeneic blood product administration, concomitant pharmacologic agents, and increasing application of purified and recombinant haemostatic factors. Multiple haemostatic changes occur perioperatively after trauma and complex surgical procedures including cardiac surgery and liver transplantation. Novel strategies for both prophylaxis and therapy of perioperative bleeding include tranexamic acid, desmopressin, fibrinogen and prothrombin complex concentrates. Point-of-care patient testing using thromboelastography, rotational thromboelastometry, and platelet function assays has allowed for more detailed assessment of specific targeted therapy for haemostasis. Strategic multimodal management is needed to improve management, reduce allogeneic blood product administration, and minimize associated risks related to transfusion.

Preoperative thrombelastography maximum amplitude predicts massive transfusion in liver transplantation

BACKGROUND

Massive transfusion (MT) is frequently required during liver transplantation. Risk stratification of transplant patients at risk for MT is an appealing concept but remains poorly developed. Thrombelastography (TEG) has recently been shown to reduce mortality when used for trauma resuscitation. We hypothesize that preoperative TEG can be used to risk stratify patients for MT.

MATERIAL AND METHODS

Liver transplant patients had blood drawn before surgical incision and assayed via TEG. Preoperative TEG measurements were collected in addition to standard laboratory coagulation tests. TEG variables including R-time (reaction time), angle, maximum amplitude (MA), and LY30 (clot lysis 30 min after MA) were correlated to red blood cell units, plasma (fresh frozen plasma), cryoprecipitate, and platelets during the first 24 h after surgery and tested for their performance using a receiver-operating characteristic curve.

RESULTS

Twenty-eight patients were included in the analysis with a median Model for End-Stage Liver Disease score of 17; 36% received a MT. The TEG variables associated with MT (defined as ≥10 red blood cell units/24 h) were a low MA (P < 0.001) and low angle (P = 0.014). A high international normalized ratio of prothrombin time (P = 0.003) and low platelet count (P = 0.007) were also associated with MT. MA had the highest area under the curve (0.861) followed by international normalized ratio of prothrombin time (0.803). An MA of less than 47 mm has a sensitivity of 90% and specificity of 72% to predict a MT. MA was the only coagulation variable that correlated strongly to all blood products transfused.

CONCLUSIONS

TEG MA has a high predictability of MT during liver transplantation. The use of TEG preoperatively may help guide more cost effective blood bank preparation for this procedure as only a third of patients required a MT.

Rapid Transfusion Devices for Hemorrhagic Cardiothoracic Trauma

Cardiothoracic trauma patients are frequently hypovolemic and hypothermic and may require massive transfusion, which can itself causesuch complications as acidosis, electrolyte imbalance (hypocalcemia and hyperkalemia), hypothermia, di lutional coagulopathy, and adultrespiratory distress syn drome. At the present time, there are a number of rapid infu sion devices such as Level I® (capable of delivering 37°C at a flow rate of up to 600 ml/min), Fluid Management System® (FMS®) (which can deliver 37.5°C of fluid at a flow rate of up to 500 ml/min), Rapid Infusion System® (RIS®) (which can pro vide up to 1,500 ml of 37°C fluid in one and one half minutes), and Rapid Solution Administration Set® (RSASO) (which can not only deliver a maximum of 2,200 m/min, but can warm the fluid to normothermia at a flow rate of 500 ml/min). However, pressurized devices such as Level IO can cause air embolism, interstitial infiltration and the compartment syndrome, and the flow rate is not operator-controlled. Devices such as FMS®, RIS®, and RSAS® incorporate a cardiotomy reservoir which has the potential for clot formation when any calcium-con taining solution is added. In this article, rapid infusion devices are compared, and complications associated with massive transfusion are described.

Anesthesia Management of Liver Transplantation

Anesthesia for liver transplantation pertains to a continuum of critical care of patients with end-stage liver disease. Hence, anesthesiologists, armed with a comprehensive understanding of pathophysiology and physiologic effects of liver transplantation on recipients, are expected to maintain homeostasis of all organ function. Specifically, patients with fulminant hepatic failure develop significant changes in cerebral function, and cerebral perfusion is maintained by monitoring cerebral blood flow and cerebral metabolic rate of oxygen, and intracranial pressure. Hyperdynamic circulation is challenged by the postreperfusion syndrome, which may lead to cardiovascular collapse. The goal of circulatory support is to maintain tissue perfusion via optimal preload, contractility, and heart rate using the guidance of right-heart catheterization and transesophageal echocardiography. Portopulmonary hypertension and hepatopulmonary syndrome have high morbidity and mortality, and they should be properly evaluated preoperatively. Major bleeding is a common occurrence, and euvolemia is maintained using a rapid infusion device. Pre-existing coagulopathy is compounded by dilution, fibrinolysis, heparin effect, and excessive activation. It is treated using selective component or pharmacologic therapy based on the viscoelastic properties of whole blood. Hypocalcemia and hyperkalemia from massive transfusion, lack of hepatic function, and the postreperfusion syndrome should be aggressively treated. Close communication between all parties involved in liver transplantation is also equally valuable in achieving a successful outcome.

Genome-wide transcriptional response of Silurana (Xenopus) tropicalis to infection with the deadly chytrid fungus

Emerging infectious diseases are of great concern for both wildlife and humans. Several highly virulent fungal pathogens have recently been discovered in natural populations, highlighting the need for a better understanding of fungal-vertebrate host-pathogen interactions. Because most fungal pathogens are not fatal in the absence of other predisposing conditions, host-pathogen dynamics for deadly fungal pathogens are of particular interest. The chytrid fungus Batrachochytrium dendrobatidis (hereafter Bd) infects hundreds of species of frogs in the wild. It is found worldwide and is a significant contributor to the current global amphibian decline. However, the mechanism by which Bd causes death in amphibians, and the response of the host to Bd infection, remain largely unknown. Here we use whole-genome microarrays to monitor the transcriptional responses to Bd infection in the model frog species, Silurana (Xenopus) tropicalis, which is susceptible to chytridiomycosis. To elucidate the immune response to Bd and evaluate the physiological effects of chytridiomycosis, we measured gene expression changes in several tissues (liver, skin, spleen) following exposure to Bd. We detected a strong transcriptional response for genes involved in physiological processes that can help explain some clinical symptoms of chytridiomycosis at the organismal level. However, we detected surprisingly little evidence of an immune response to Bd exposure, suggesting that this susceptible species may not be mounting efficient innate and adaptive immune responses against Bd. The weak immune response may be partially explained by the thermal conditions of the experiment, which were optimal for Bd growth. However, many immune genes exhibited decreased expression in Bd-exposed frogs compared to control frogs, suggesting a more complex effect of Bd on the immune system than simple temperature-mediated immune suppression. This study generates important baseline data for ongoing efforts to understand differences in response to Bd between susceptible and resistant frog species and the effects of chytridiomycosis in natural populations.

Antithrombin effect on coagulation and fibrinolytic profiles after living donor liver transplantation: a pilot study

Early after liver transplantation, patients are in a hypercoagulable state because of an imbalance between coagulation and fibrinolysis because of the slow recovery of depleted anticoagulant proteins. Antithrombin (AT) is used in anticoagulant protocols to prevent thrombosis. The subjects of the present study were 17 men and eight women that underwent living donor liver transplantation. The initial 15 cases were administered AT concentrate (1500 U/day) on postoperative days (POD) 1 through 3 (AT group) and the following 10 consecutive cases were not administered AT (control). AT, thrombin-AT complex, plasmin-alpha2 plasmin inhibitor complex, thrombomodulin, fibrin degradation product D-dimer (FDP-DD) level, prothrombin time international normalized ratio, activated partial thromboplastin time, and platelet counts were measured. In the AT group, AT activity was maintained at levels >80% for 5 days after transplantation. In the control group, AT activity did not return to normal during the first 2 weeks after the operation. FDP-DD levels were significantly higher in the control group than in the AT group (P < 0.05). Six patients in the control group and three patients in the AT group required transfusions with platelet concentrate (P < 0.05). AT supplementation might reduce FDP-DD levels and prevent decreased platelet counts in the early stages after liver transplantation.

Requirements for transfusion and postoperative outcomes in orthotopic liver transplantation: A meta-analysis on aprotinin

AIM: To study the effect of aprotinin used in orthotopic liver transplantation (OLT) on the intraoperative requirement for blood products and on the incidence of laparotomy for bleeding, thrombotic events and mortality.

METHODS: A systematic review of the literature in the electronic database Medline and the Clinic Trials Registry Database was performed. Literature that did not fit our study were excluded. Patients in the reviewed studies were divided into two groups; one group used aprotinin (aprotinin group) while the other did not (control group). The data in the literature that fit our requirements were recorded. Weighted mean differences (WMD) in the requirements for blood products between the aprotinin group and the control group were tested using a fixed effect model. A Z test was performed to examine their reliability; the Fleiss method of fixed effect model was used to analyze data on postoperative events, and odds ratios (ORs) were tested and merged.

RESULTS: Seven citations were examined in our study. Among them, a requirement for blood products was reported in 4 studies including 321 patients, while postoperative events were reported in 5 studies including 477 patients. The requirement for red blood cells and fresh frozen plasma in the aprotinin group was statistically lower than that in the control group (WMD = -1.80 units, 95% CI, -3.38 to -0.22; WMD = -3.99 units, 95% CI, -6.47 to -1.50, respectively). However, no significant difference was indicated in the incidence of laparotomy for bleeding, thrombotic events and mortality between the two groups. Analysis on blood loss, anaphylactic reactions and renal function was not performed in this study due to a lack of sufficient information.

CONCLUSION: Aprotinin can reduce the intraoperative requirement for blood products in OLT, and has no significant effect on the incidence of laparotomy for bleeding, thrombotic events and mortality.

The Balance of Thrombosis and Hemorrhage in Surgery

Postoperative hemorrhage and thrombosis is a significant problem during the perioperative period. Understanding the complex and dynamic interplay of factors, proteins, and enzymes during coagulation is imperative to maintain balance between hemostasis and thrombosis. To improve patient outcome, each patient should be risk stratified for bleeding or thrombosis during the preoperative examination. Additional research focused on improvement in screening tools, monitoring, and therapeutic regimens for surgical patients with a coagulopathy are warranted.

New insights into the coagulopathy of liver disease and liver transplantation

The liver is an essential player in the pathway of coagulation in both primary and secondary haemostasis. Only von Willebrand factor is not synthetised by the liver, thus liver failure is associated with impairment of coagulation. However, recently it has been shown that the delicate balance between pro and antithrombotic factors synthetised by the liver might be reset to a lower level in patients with chronic liver disease. Therefore, these patients might not be really anticoagulated in stable condition and bleeding may be caused only when additional factors, such as infections, supervene. Portal hypertension plays an important role in coagulopathy in liver disease, reducing the number of circulating platelets, but platelet function and secretion of thrombopoietin have been also shown to be impaired in patients with liver disease. Vitamin K deficiency may coexist, so that abnormal clotting factors are produced due to lack of gamma carboxylation. Moreover during liver failure, there is a reduced capacity to clear activated haemostatic proteins and protein inhibitor complexes from the circulation. Usually therapy for coagulation disorders in liver disease is needed only during bleeding or before invasive procedures. When end stage liver disease occurs, liver transplantation is the only treatment available, which can restore normal haemostasis, and correct genetic clotting defects, such as haemophilia or factor V Leiden mutation. During liver transplantation haemorrage may occur due to the pre-existing hypocoagulable state, the collateral circulation caused by portal hypertension and increased fibrinolysis which occurs during this surgery.

Hemostatic defects in end stage liver disease

End stage liver disease results in a complex and variably severe failure of hemostasis that predisposes to abnormal bleeding. The diverse spectrum of hemostatic defects includes impaired synthesis of clotting factors, excessive fibrinolysis, disseminated intravascular coagulation, thrombocytopenia, and platelet dysfunction. Hemostasis screening tests are used to assess disease severity and monitor the response to therapy. Correction of hemostatic defects is required in patients who are actively bleeding or require invasive procedures. Fresh frozen plasma, cryoprecipitate, and platelet transfusion remain the mainstays of therapy until larger trials confirm the safety and efficacy of recombinant factor VIIa in this population.

Recombinant factor VIIa in orthotopic liver transplantation: influence on parameters of coagulation and fibrinolysis

The effect of recombinant factor VIIa (rFVIIa) on blood loss was evaluated in cirrhotic patients undergoing orthotopic liver transplantation. In the present study, we explored the effect of rFVIIa on coagulation and fibrinolysis during orthotopic liver transplantation. Coagulation factors, parameters of thrombin generation and parameters of fibrinolysis were measured in six patients who had received a single dose of 80 micro g/kg rFVIIa and in ten controls, during and after orthotopic liver transplantation. Baseline concentrations and course of coagulation factors were similar in patients and controls. Thrombin generation did not rise after the administration of rFVIIa, but showed a sharp increase after reperfusion in patients, as compared with controls. No difference in fibrinolysis was apparent between patients and controls. No evidence of diffuse intravascular coagulation was seen. We conclude that the use of rFVIIa in orthotopic liver transplantation seems to enhance thrombin generation in a localized and time-limited matter, without causing systemic coagulation.

The management of perioperative bleeding

Excess perioperative bleeding remains a major complication following surgery, resulting in increased morbidity and mortality. The principal causes of non-surgical haemostatic perioperative bleeding are a pre-existing undetected bleeding disorder, related to the nature of the operation itself or from coagulation abnormalities arising from massive blood loss. Very often, it is a combination and coexistence of various pathologies. Identifying patients at risk remains a major component of preventing excessive blood loss. Understanding the haemostatic changes occurring in the perioperative period, especially in complex procedures like cardiopulmonary bypass and orthotopic liver transplantation is crucial in developing new strategies for the management of perioperative bleeding. Pharmacological interventions, especially aprotinin, tranexamic acid, desmopressin and increasingly, recombinant VIIa are being used both in prophylaxis and therapeutically to stop bleeding. The use of near patient testing like thromboelastography and platelet function analyser has allowed for more detailed assessment of the various steps of haemostasis. One of the main goals is to reduce the usage of allogeneic blood transfusion and its attendant risks.

Haemostatic disorders during liver transplantation

Profound and complex coagulation disorders are encountered during liver transplantation. They include preoperative coagulation disorders related to the liver disease and haemostatic changes related to the procedure itself. They commonly lead to increased intraoperative bleeding, especially due to increased fibrinolysis, the contribution of which can be demonstrated by the relative efficacy of antifibrinolytics. Given the multifactorial nature of bleeding in liver transplantation, preoperative coagulation tests cannot predict blood loss even if some statistical relationship is occasionally found. Preoperative correction of coagulation defects has not been shown to be effective in reducing intraoperative bleeding. Throughout the procedure, a rapid and sensitive method for monitoring coagulation is necessary in order to guide the rational use of blood components and pharmacological agents. The usefulness of such a method to assist management of blood loss or blood component requirements is poorly documented and controversial.

Liver transplantation without the use of fresh frozen plasma

In orthotopic liver transplantations (OLT), fresh frozen plasma (FFP) is classically used to normalize coagulation factor concentrations. In this study, 28 OLT were performed without the use of FFP. According to their preoperative factor V (FV) levels, two groups of patients were defined: Group 1 (13 patients, FV > 10% and < 60%) and Group 2 (15 patients, FV > 60%). Spontaneous evolution of coagulation factors, concentration, and bleeding were observed during OLT and up to 48 h after surgery. Total intraoperative bleeding was similar in both groups (3460 +/- 2700 mL and 3470 +/- 2110 mL in Groups 1 and 2, respectively). Levels of clotting factors were not different between groups after the anhepatic stage. The lowest values were noted after reperfusion. Thirty-six hours after surgery, all levels of clotting factors in both groups were more than 50%, with FV level increasing the most rapidly. Hematocrit from the subhepatic drainage liquid was 1.8% and less than 1% at 24 and 48 h, respectively, after surgery. No reintervention for bleeding was necessary. These results suggest that, in OLT, correct hemostasis can be assumed without FFP use when hyperfibrinolysis, platelet count, fibrinogen rate, and hemodynamic status are controlled.

Primary liver transplantation without transfusion of red blood cells

BACKGROUND

This study examines factors associated with the performance of orthotopic liver transplantation (OLT) without red blood cell (RBC) transfusion.

METHODS

Between January 1992 and December 1994, 306 primary OLTs were performed with recipients divided into two groups: group 1 patients (61 recipients, 20% of total) underwent transplantation without packed RBCs, and group 2 patients (245 recipients, 80% of cases) received a transfusion of at least 1 unit of RBCs during operation.

RESULTS

Recipients in group 1 compared with group 2 had less advanced liver disease (20% hospitalized and 48% Child's class C versus 58% hospitalized and 73% Child's class C, p < 0.01) and lower frequency of right upper quadrant surgery (13% versus 25%, p < 0.05). Group 1 recipients also had significantly higher preoperative hematocrits (38% versus 33%, p < 0.01), lower prothrombin times (15.4 versus 16.7 seconds, p < 0.001) and partial thromboplastin times (36.9 versus 42.2 seconds, p < 0.01), a greater proportion of patients transplanted by piggyback technique (87% versus 59%, p < 0.001), and shorter operative times (7.9 hours versus 9.2 hours, p < 0.001). Moreover, a greater percentage of patients underwent OLT without RBC transfusion in each successive year: 9% in 1992, 21% in 1993, and 31% in 1994 (p < 0.001). Logistic regression analysis showed the following factors to be independent predictors of OLT without RBC transfusion. Preoperative Hct, United Network of Organ Sharing status, piggyback technique, operative time, and year of transplantation.

CONCLUSIONS

OLT can be performed without transfusion of RBCs in recipients with less advanced liver disease, and surgical technique, along with increased experience by the transplant team, are important factors.

Continuous small-dose aprotinin controls fibrinolysis during orthotopic liver transplantation

Large doses of aprotinin (1,000,000-2,000,000 kallikrein inhibitor units [KIU] initial dose and a 500,000 KIU/h infusion) have been used during orthotopic liver transplantation (OLT) to reduce the incidence and severity of fibrinolysis. This double-blinded study was designed to investigate whether a small-dose infusion of aprotinin (200,000 KIU/h) would control fibrinolysis. A controlled study was undertaken to compare small-dose aprotinin with a placebo in patients undergoing OLT with veno-venous bypass. Forty-four patients were randomized either to the aprotinin group (n = 21), which received an intravenous infusion of 200,000 KIU/h without an initial dose, or to a control group (n = 23), which received normal saline. Coagulation variables, thrombelastograms, and postoperative blood drainage were measured. Blood levels of fibrin degradation products (FDP) were significantly higher in the control group (95% > 20 micrograms/mL) at the end of surgery compared to the aprotinin group (53% > 20 micrograms/mL, P < 0.01). The transfusion of cryoprecipitate units was more in the control group versus the aprotinin (12.6 +/- 12.8 vs 5.7 +/- 7.5; P < 0.04), as was the number of fresh frozen plasma units (6.6 +/- 3.5 vs 3.6 +/- 6.1; P < 0.05). We conclude that an infusion of a small dose of aprotinin can safely control fibrinolysis during liver transplantation with a concomitant reduction in transfusion of blood products.

Massive ascitic fluid loss and coagulation disturbances after liver transplantation

BACKGROUND & AIMS

A unique syndrome in which massive ascitic fluid loss developing 1-4 weeks after orthotopic liver transplantation (OLT) was associated with a hypercoagulable state and thrombotic complications is described. After OLT, severe coagulation abnormalities (international normalized ratio, 4.6) developed in a patient with ascitic losses of up to 12 L/day. The patient developed hypovolemia and severe systemic antithrombin III deficiency and venoocclusive disease in the graft. The aim of this study was to determine the prevalence of this syndrome after OLT.

METHODS

Coagulation studies were performed in 25 additional patients with large ascitic fluid losses after OLT and in 7 cirrhotic patients not undergoing transplantation.

RESULTS

All transplant recipients developed systemic deficiencies of multiple coagulation factors including antithrombin III. Markers of prothrombin activation were significantly elevated in both ascites and serum in all patients, and thrombotic complications subsequently developed in 5 patients. In the 7 cirrhotic patients, markers of prothrombin activation remained normal or minimally elevated and thrombotic complications were not found.

CONCLUSIONS

Massive ascitic losses after OLT may lead to a hypercoagulable state from unreplaced losses of plasma coagulation factors into ascites and accumulation of thrombin in the systemic circulation. Hypovolemia and major coagulation abnormalities should be corrected with fresh frozen plasma, which may prevent the development of thrombotic complications.

Normotest and abnormal prothrombin in liver transplantation

Postoperative changes in coagulation parameters, including the abnormal plasma prothrombin level, were studied in 95 patients who underwent liver transplantation, and the results were compared with the clinical outcome. The patients were classified into four groups: Group I had a satisfactory postoperative course, (n = 76), Group II suffered graft failure or death at 31 days or more after transplantation (n = 9); Group III suffered graft failure or death from 8 to 30 days after transplantation (n = 4); and Group IV suffered graft failure or death within 7 days of transplantation (n = 6). The Normotest, which closely reflected liver graft function, showed an increase immediately after transplantation in Group I, II, and III, but showed a marked decrease in Group IV. In patients with severe acute cellular rejection, the plasma level of abnormal prothrombin (des-gamma-carboxy prothrombin) was compared with the histology of the liver biopsy specimen. When liver graft function was good after orthotopic transplantation, the Normotest value recovered to the normal range of 70% or more. Subsequently, graft function remained good when the des-gamma-carboxy prothrombin level stayed low, whereas acute cellular rejection was indicated by an elevation of des-gamma-carboxy prothrombin was not produced by graft with early failure, the des-gamma-carboxy prothrombin level also remained low. Thus, the Normotest value and the des-gamma-carboxy prothrombin level were both useful parameters for assessing hepatic function and rejection after transplantation.

Aprotinin reduces the need for blood products during liver transplantation

BACKGROUND

Bleeding complications and blood product consumption have been a major concern during liver transplantation. Prevention of plasminogen activation and fibrinolysis by aprotinin administration has been shown to reduce perioperative bleeding during operations associated with high blood-product consumption.

PATIENTS AND METHODS

Use of blood-products (packed red cells, frozen plasma, platelets, and cryoprecipitate) was analyzed both during the three stages of orthotopic liver transplantation and during total hospitalization of the 26 patients transplanted without aprotinin and the subsequent 40 patients with aprotinin. A similar analysis was performed for 15 patients immediately before and after the introduction of aprotinin to eliminate the "learning curve" effect for liver transplantation. The effect of epsilon-amino-caproic acid was analyzed as 13 patients received neither epsilon-aminocaproic acid nor aprotinin and 13 patients received epsilon-aminocaproic acid but not aprotinin.

RESULTS

There was a significant reduction in total hospital use of cryoprecipitate, frozen plasma, platelets, and red cells in the aprotinin-treated patients. This reduction was seen during the anhepatic and reperfusion stages of liver transplantation. There was no difference in blood product consumption between the groups who were or were not treated with epsilon-aminocaproic acid.

CONCLUSION

Aprotinin significantly reduces the need for red cell, frozen plasma, platelet, and cryoprecipitate transfusion use during orthotopic liver transplantation, and appears to be more efficacious than epsilon-aminocaproic acid.

Blood loss and transfusion requirements in liver transplantation: experience with the first 75 cases

The blood loss data and transfusion requirements including blood bank, salvaged washed red cells, fresh frozen plasma and cryoprecipitate were analysed for the first 75 cases of liver transplantation performed at the Austin Hospital between June 1988 and October 1992. The mean blood loss was 8.8 litres (standard deviation 14.1) with a median value of 4.0 litres. Blood product use expressed as mean number of units (SD) was bank red blood cells 7.1 (12.7), washed red blood cells 3.9 (5.9), fresh frozen plasma 7.1 (9.1), platelets 5.1 (7.4), and cryoprecipitate 1.7 (5.1). These results demonstrate that liver transplantation can be performed without imposing excessive demands on blood transfusion services. Management should include surgical techniques to minimize bleeding and use of autologous transfusion. Use of component therapy (FFP, platelets and cryoprecipitate) should not be empirical. It should be selective on the basis of clinical bleeding assessment and guided by results of the laboratory coagulation profile and changes in thrombelastographic (TEG) parameters.

Prognostic value of the activated partial thromboplastin time after orthotopic liver transplantation. A prospective study

In this prospective study, we evaluated the predictive value of activated partial thromboplastin time on day 8 post transplantation for event-free survival in patients who had had orthotopic liver transplants; both death and retransplantation within 6 months were the events considered. In a 4-year period, 109 patients had orthotopic liver transplants in our hospital, and 104 were eligible for the study since they survived and were not given new transplants within 8 days. The activated partial thromboplastin time was significantly longer in patients who survived event-free for less than 6 months than in those with longer event-free survivals. Kaplan-Meier curves showed that patients with normal activated partial thromboplastin times were nine times more likely to survive more than 6 months without events than patients with prolonged values. The positive predictive value of activated partial thromboplastin time for event-free survival was 88% and the negative predictive value was 54%, indicating that the test is useful for predicting patient outcome. We suggest that activated partial thromboplastin time be performed on day 8 post transplantation to predict the medium-term event-free survival.

Patterns of coagulopathy during liver transplantation: experience with the first 75 cases using thrombelastography

Using both conventional laboratory clotting profile and thrombelastography, coagulation status was monitored intraoperatively during liver transplantation in the first 75 cases performed at the Austin Hospital between June 1988 and October 1992. Superimposed on a baseline coagulopathy due to liver disease is a specific pattern of coagulation disturbance which occurs during a liver transplant. Fibrinolysis occurs in the anhepatic stage, worsens with early reperfusion and then spontaneously resolves. In addition reperfusion is associated with a transient clotting defect. If blood loss is excessive, coagulopathy due to massive transfusion may compound the situation. Thrombelastography is a measurement technique allowing rapid on-site assessment of functional clotting status. It is particularly useful in liver transplant surgery. In combination with clinical bleeding assessment it facilitates selective use of component therapy (fresh frozen plasma, platelets and cryoprecipitate) and specific drug treatment only when it is appropriate. It also acts as a liver function test, being especially useful in assessing the graft after reperfusion.

Coagulation defects in liver disease

A normally functioning hemostasis system is closely related to liver function. The liver parenchymal cells produce most of the factors and inhibitors of the clotting and fibrinolytic systems, and the RES of the liver greatly aids in the clearance of activation products. Hemostasis defects thus depend on the extent of liver damage. A wide spectrum of defects is found in patients with liver cirrhosis. Owing to impaired protein synthesis, most factors and inhibitors of the clotting and the fibrinolytic systems are markedly reduced. Additionally, abnormal vitamin K-dependent factor and fibrinogen molecules have been encountered. Most patients have hyperfibrinolysis that could be DIC in nature. Thrombocytopenia and thrombocytopathy are also found. Acute or chronic hepatocellular disease may display decreased vitamin K-dependent factor levels, especially factor VII and protein C, with other factors still being normal. If patients go into hepatic failure, the abnormalities resemble those found in liver cirrhosis. Vitamin K deficiency is associated with the production of poorly functioning vitamin K-dependent factors. All other hemostasis parameters are normal. Disturbances associated with liver surgeries again depend on the underlying liver problem. Peritoneovenous shunts (LeVeen) may lead to DIC; bleeding from partially resected liver surfaces is usually a mechanical problem. Severe bleeding is encountered with orthotopic liver transplantation. It is greatly influenced by the activation of the fibrinolytic system. This occurs during the anhepatic phase and during the reperfusion phase. The hyperfibrinolysis is mediated by an intense release of t-PA. Antifibrinolytic drugs, if used cautiously, have markedly reduced bleeding and thus reduced need for blood and blood product substitution.

Liver transplantation without the use of blood products

OBJECTIVES

To examine the techniques and the outcome of liver transplantation with maximal conservation of blood products and to analyze the potential benefits or drawbacks of blood conservation and salvage techniques.

DESIGN

Case series survey.

SETTING

Tertiary care, major university teaching hospital.

PATIENTS AND METHODS

Four patients with religious objections to blood transfusions who were selected on the basis of restrictive criteria that would lower their risk for fatal hemorrhage, including coagulopathy, a thrombosed splanchnic venous system requiring extensive reconstruction, active bleeding and associated medical complications. All patients were pretreated with erythropoietin to increase production of red blood cells. All operations were performed at the same institution, with a 36-month follow-up.

INTERVENTIONS

Orthotopic liver transplantation that used blood salvage, plateletpheresis, and autotransfusion and the withholding of the use of human blood products with the exception of albumin.

MAIN OUTCOME MEASURES

Survival and postoperative complications, with the effectiveness of erythropoietin and plateletpheresis as secondary measures.

RESULTS

All patients are alive at 36 months after orthotopic liver transplantation. One patient, a minor (13 years of age), was transfused per a state court ruling. Erythropoietin increased the production of red blood cells as shown by a mean increase in hematocrit levels of 0.08. Platelet-pheresis allowed autologous, platelet-rich plasma to be available for use after allograft reperfusion. Three major complications were resolved or corrected without sequelae. Only one patient developed postoperative hemorrhage, which was corrected surgically. The mean charge for bloodless surgery was $174,000 for the three patients with United Network for Organ Sharing (UNOS) status 3 priority for transplantation. This result was statistically significant when these patients were compared with all the patients with UNOS status 3 priority during the same period who met the same restrictive guidelines (P < .05). Only 19 of 1009 orthotopic liver transplantations performed at our institution were similar according to the UNOS status and the fulfillment of the guidelines. The mean charge for these comparison patients was $327,000, 3.8% of which was related to transfusions.

CONCLUSIONS

Orthotopic liver transplantation without the use of blood products is possible. Blood conservation techniques do not increase morbidity or mortality and can result in fewer transfusion-related, in-hospital charges.

The significance of bile secretion after the transplantation of long-preserved livers in the rat

Although one of the simplest indicators for predicting liver viability is bile secretion, it has never been proven whether it could be a good index for the viability of grafts in liver transplantation after cold ischemia. The present study, conducted on male Wistar rats, was undertaken to determine whether bile secretion reflects the viability of livers which have been preserved long-term. Livers were stored for up to 24 h in Euro-Collins (EC) or University of Wisconsin (UW) solution at 4 degrees C, and transplanted orthotopically. The correlation between 1-week survival, bile flow, and the tissue adenosine triphosphate (ATP) level 4 h after transplantation was then investigated for each subgroup. The survival rates of the animals in the UW subgroups were much higher than those in the EC subgroups. In the rats transplanted with livers preserved for 6 h in EC solution (EC-6), in which 100% survival was observed, both bile flow and ATP recovered sufficiently. Conversely, in the EC-12 group, in which only 10% survival was seen, restoration of bile flow, in ml/h per kg body weight, and ATP resynthesis, in mumol/g wet weight, were severely suppressed, with levels of 1.35 +/- 1.05 and 0.77 +/- 0.34, respectively. Moreover, in the EC-18 group, with 0% survival, neither bile flow nor ATP recovered. In the rats transplanted with livers preserved for 18 h in UW solution (UW-18), bile flow and ATP, being 1.03 +/- 0.56 and 1.12 +/- 0.59, respectively, were much higher than those in the EC-18 group.(ABSTRACT TRUNCATED AT 250 WORDS)

[Monitoring of hemostasis during liver transplantation: contribution of thromboelastography]

Monitoring of coagulation is mandatory during liver transplantation (LT). Standard coagulation tests may be routinely used. However, they give static information and may be inadequate in case of severe coagulation defect. Interest has been recently focused on thromboelastography (TEG) which could give more suitable and rapid information in these cases. Few studies have evaluated the clinical interest of TEG compared to conventional tests. This comparison was the aim of the present study, performed in 89 patients scheduled for LT. The anaesthetic management as well as procedure of transfusion were similar in all patients. Before unclamping, 5000 KIU.kg-1 of aprotinin were injected. Routine tests and TEG were performed at the beginning and end of both pre-anhepatic and anhepatic phases, and 5, 30, 60, and 120 min after the revascularisation of the new liver. A phase of hypocoagulability was observed after unclamping. Biological signs included an increase in activated thromboplastin time, a reduction of alpha angle and maximum amplitude on TEG with a lengthening of its r + k component. A strong correlation existed between maximum amplitude and platelets, maximum amplitude and fibrinogen, alpha and fibrinogen at each time of the surgical procedure. Euglobulin lysis time decreased significantly after clamping, whereas fibrin degradation products increased at the same time. However, typical fibrinolysis with a clot lysis index (CLI) below 55% was only observed in 15 patients. Twelve of them had a CLI value reaching 0%, associated with severe generalized oozing. Aprotinin (200,000 to 600,000 KIU) corrected these abnormalities. These results show that TEG may not be very helpful to determine whether platelets or fibrinogen are involved in the phase of hypocoagulability detected after unclamping.(ABSTRACT TRUNCATED AT 250 WORDS)

Antithrombin III supplementation during orthotopic liver transplantation in cirrhotic patients: a randomized trial

Severe intraoperative bleeding is one of the main problems during liver transplantation. Acquired hemostatic defects, namely primary or secondary hyperfibrinolysis, are considered significant pathogenetic events. Antithrombin III (ATIII), the main physiological serine protease inhibitor, has a critical role in the regulation of hemostasis. 29 patients with post necrotic cirrhosis undergoing liver transplantation were randomized to receive or not ATIII replacement therapy before the induction of anaesthesia and thereafter throughout surgery. Activation of both coagulation and fibrinolysis (increase of thrombin-antithrombin complexes, fibrin and fibrinogen degradation products) were demonstrated in both groups. Blood loss and transfusion requirements were not affected by ATIII administration.

Increased tissue-type plasminogen activator activity in orthotopic but not heterotopic liver transplantation: the role of the anhepatic period

The major cause of the increased tissue-type plasminogen activator activity during orthotopic liver transplantation is still unclear. Both the lack of hepatic clearance of tissue-type plasminogen activator in the anhepatic period and increased endothelial release from the graft on reperfusion have been proposed as the major causes. Heterotopic liver transplantation avoids the resection of the host liver and is a useful model to help differentiate between these two possibilities. In this study the fibrinolytic system was evaluated in 10 orthotopic liver transplantations, 18 heterotopic liver transplantations and a control group of 10 partial hepatic resections. A marked increment in tissue-type plasminogen activator activity, from 0.2 to 5.2 IU/ml (p less than 0.02), was observed during the anhepatic period of orthotopic liver transplantation, which rapidly normalized after reperfusion. In contrast, tissue-type plasminogen activator activity levels remained normal in heterotopic liver transplantation and partial hepatic resections. In orthotopic liver transplantation and in heterotopic liver transplantation no increase occurred in tissue-type plasminogen activator activity after reperfusion. The first venous hepatic outflow after reperfusion did not contain elevated tissue-type plasminogen activator activity levels. Plasma degradation products of fibrin and fibrinogen increased during the anhepatic period of orthotopic liver transplantation (from 2.60 to 8.80 micrograms/ml [p less than 0.008] and from 0.40 to 1.60 micrograms/ml [p less than 0.04], respectively) and remained elevated thereafter. In heterotopic liver transplantation and partial hepatic resections these levels remained low. In conclusion, the lack of hepatic clearance during the anhepatic period is probably the most important factor in the evolution of increased tissue-type plasminogen activator activity during orthotopic liver transplantation.