Hemostatic evaluation of patients undergoing liver transplantation

Hypocoagulability in severe yellow fever infection is associated with bleeding: results from a cohort study

Background

Severe yellow fever infection (YFI) may be complicated by a hemorrhagic diathesis. However, the hemostasis profile of YFI has rarely been reported.

Objectives

The aim of this study was to characterize the hemostatic features of YFI by using a rotational thromboelastometry (ROTEM).

Methods

We evaluated clinical, laboratory, and ROTEM parameters in adults with severe YFI and their correlation with hemostatic variables according to bleeding and death.

Results

A total of 35 patients were included (median age, 49 years). ROTEM was performed in 22 patients, of whom 21 (96%) presented bleeding and 4 (18%) died. All patients who died had major bleeding. Patients who died presented prolonged clotting time (CT; median, 2326 seconds; IQR, 1898-2986 seconds) and reduced alpha angle (median, 12°; IQR, 12°-15°) in comparison with patients who had minor (median CT, 644 seconds; IQR, 552-845 seconds and alpha angle, 47°; IQR, 28°-65°) and major (median CT, 719 seconds; IQR, 368-1114 seconds and alpha angle, 43°; IQR, 32°-64°) bleeding who survived. In patients who had bleeding, CT showed a strong negative correlation with factor (F)V (r = -.68), FIX (r = -.84), and FX (r = -.63) as well as alpha angle showed a strong negative correlation with FIX (r = -.92). In patients who died, the correlations were even stronger. A total of 19/21 (90%) patients presented hypocoagulability assessed by ROTEM.

Conclusion

Hypocoagulabitity is the hallmark of the bleeding diathesis of severe YFI. Abnormal CT and alpha angle associated with death and could be used as potential predictors of adverse outcome in severe YFI.

Thromboelastography-Guided Blood Component Use in Patients With Cirrhosis With Nonvariceal Bleeding: A Randomized Controlled Trial

Thromboelastography (TEG) provides a more comprehensive global coagulation assessment than routine tests (international normalized ratio [INR] and platelet [PLT] count), and its use may avoid unnecessary blood component transfusion in patients with advanced cirrhosis and significant coagulopathy who have nonvariceal upper gastrointestinal (GI) bleeding. A total of 96 patients with significant coagulopathy (defined in this study as INR >1.8 and/or PLT count < 50 × 10⁹ /L) and nonvariceal upper GI bleed (diagnosed after doing upper gastrointestinal endoscopy, which showed ongoing bleed from a nonvariceal source) were randomly allocated to TEG-guided transfusion strategy (TEG group; n = 49) or standard-of-care (SOC) group (n = 47). In the TEG group, only 26.5% patients were transfused with all three blood components (fresh frozen plasma [FFP], PLTs, and cryoprecipitate) versus 87.2% in the SOC group (P < 0.001). Although 7 (14.3%) patients in the TEG group received no blood component transfusion, there were no such patients in the SOC group (P = 0.012). Also, there was a significantly lower use of blood components (FFP, PLTs, and cryoprecipitate) in the TEG group compared with the SOC group. Failure to control bleed, failure to prevent rebleeds, and mortality between the two groups were similar. Conclusion: In patients with advanced cirrhosis with coagulopathy and nonvariceal upper GI bleeding, TEG-guided transfusion strategy leads to a significantly lower use of blood components compared with SOC (transfusion guided by INR and PLT count), without an increase in failure to control bleed, failure to prevent rebleed, and mortality.

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.

The utility of thromboelastography in inherited and acquired bleeding disorders

Thromboelastography (TEG) was first described by Hartert in 1948, and was designed to monitor viscoelastic clot strength in whole blood in real time. The current TEG method and Rotational Thromboelastometry (ROTEM) were subsequently developed from the original principles. Both of the modern methods provide data by measuring changes in the viscoelastic strength of a small sample of clotting blood in response to a constant rotational force. The important advantage of these techniques is to visually observe and quantify blood coagulation including the propagation, stabilization and dissolution phases of clot formation under low shear conditions. Analysis of the results provides detailed kinetic data on fibrin generation, clot strength and fibrinolysis. These TEG/ROTEM analyses therefore enable evaluation of global clotting function and the monitoring of haemostatic treatment in various clinical situations, not only in patients with genetic bleeding disorders, such as haemophilia, but also in patients undergoing cardiac surgery, liver transplantation or suffering from traumatic injury. Some evidence suggests that haemostatic management using TEG/ROTEM leads to a reduction in total transfusions of whole blood or clotting factors. Wider clinical application of this technology seems likely.

TEG-guided resuscitation is superior to standardized MTP resuscitation in massively transfused penetrating trauma patients

BACKGROUND

For nearly a decade, our center performed thromboelastograms (TEGs) to analyze coagulation profiles, allowing rapid data-driven blood component therapy. After consensus recommendations for massive transfusion protocols (MTPs), we implemented an MTP in October 2009 with 1:1:1 ratio of blood (red blood cells [RBC]), plasma (fresh-frozen plasma [FFP]), and platelets. We hypothesized that TEG-directed resuscitation is equivalent to MTP resuscitation.

METHODS

All patients receiving 6 units (U) or more of RBC in the first 24 hours for 21 months before and after MTP initiation in an urban Level I trauma center were examined. Demographics, mechanism of injury (MOI), Injury Severity Score (ISS), 24-hour volume of RBC, FFP, platelets, crystalloid, and 30-day mortality were compared, excluding patients with traumatic brain injuries. Variables were analyzed using Student's t-test and χ2 or Fisher's exact test.

RESULTS

For the preMTP group, there were 165 patients. In the MTP group, there were 124 patients. There were no significant differences in ISS, age, or sex. PreMTP patients with 6U or more RBC had significantly more penetrating MOI (p = 0.017), whereas preMTP patients with 10U or more RBC had similar MOIs. All patients received less crystalloid after MTP adoption (p < 0.001). There was no difference in volume of blood products or mortality in patients receiving 6U or more RBC. Blunt trauma MTP patients who received 10U or more RBC received more FFP (p = 0.02), with no change in mortality. Penetrating trauma patients who received 10U or more RBC received a similar volume of FFP; however, mortality increased from 54.1% for MTP versus 33.3% preMTP (p = 0.04).

CONCLUSION

TEG-directed resuscitation is equivalent to standardized MTP for patients receiving 6U or more RBC and for blunt MOI patients receiving 10U or more RBC. MTP therapy worsened mortality in penetrating MOI patients receiving 10U or more RBC, indicating a continued need for TEG-directed therapy. A 1:1:1 strategy may not be adequate in all patients.

LEVEL OF EVIDENCE

Therapeutic study, level IV.

Thrombocytopenia after pig-to-baboon liver xenotransplantation: where do platelets go?

BACKGROUND

In baboons with orthotopic pig liver xenografts, profound thrombocytopenia was observed within 1 h after reperfusion. Assessment of the fate of platelets may shed light on the underlying mechanisms leading to thrombocytopenia and may allow preventive therapies to be introduced.

METHODS

Platelet-white blood cell (WBC) aggregation was studied in two baboons that received orthotopic liver xenografts from α1,3-galactosyltransferase gene-knockout pigs transgenic for human CD46 (GTKO/CD46). Percentages of CD42a-positive platelet aggregates with WBC-subtypes were determined by flow cytometry, and absolute numbers (per mm(3) ) were calculated. Platelet aggregates in the liver xenografts were identified by immunofluorescence and electron microscopy. Mean platelet volume (MPV) was determined before and after transplantation.

RESULTS

After pig liver reperfusion, profound thrombocytopenia was associated with aggregation of platelets with WBC-subtypes. Increasing aggregation of platelets with WBC-subtypes was detected throughout the post-transplant period until the recipient was euthanized. Significant negative correlation was found between platelet counts in the blood and aggregation of platelets with monocytes (P < 0.01) and neutrophils (P < 0.01), but not with lymphocytes. MPV remained within the normal range. Two hours after reperfusion, platelet and fibrin deposition were already detected in the liver xenografts by immunofluorescence and by electron microscopy.

CONCLUSIONS

Following liver xenotransplantation, the early disappearance of platelets from the circulation was at least in part due to their aggregation with circulating WBC, which may augment their deposition in the liver xenograft and native lungs. Prevention of platelet aggregation with monocytes and neutrophils is likely beneficial in reducing their subsequent sequestration in the liver xenograft and native organs.

Risk factors and outcomes of massive red blood cell transfusion following living donor liver transplantation

OBJECTIVES

To identify the factors influencing blood loss and secondary blood transfusion and to investigate the outcomes of patients who underwent a massive blood transfusion (MBT) following living donor liver transplantation (LDLT).

METHODS

Patients who underwent primary adult-to-adult right hepatic lobe LDLT were included in the study, and were divided into the MBT group [≥6 red blood cell (RBC) units in 24 h] and the non-massive blood transfusion (NMBT) group (<6 RBC units in 24 h). All potential risk factors, length of intensive care unit (ICU) stay and long-term survival rate of the patients in the two groups were analyzed.

RESULTS

The data of 181 eligible patients were retrospectively analyzed. A decreased long-term survival rate, a higher incidence of postoperative infection and prolonged ICU stay were observed in the MBT group. No significant difference was observed in survival rate between patients having platelet transfusion>2 units and ≤2 units. Hemoglobin<100 g/L, platelet counts<70×10(9)/L, fibrinogen level<1.5 g/L and history of upper abdominal surgery were found to be independent risk factors.

CONCLUSIONS

Blood transfusion during LDLT can be predicted using preoperative variables. Massive RBC transfusion may lead to poor long-term survival, higher postoperative infection rate and prolonged ICU stay. Platelet transfusion may not be a risk factor for long-term survival.

Minimal effects of acute liver injury/acute liver failure on hemostasis as assessed by thromboelastography

BACKGROUND & AIMS

Patients with acute liver injury/failure (ALI/ALF) are assumed to have a bleeding diathesis on the basis of elevated INR; however, clinically significant bleeding is rare. We hypothesized that patients with ALI/ALF have normal hemostasis despite elevated INR.

METHODS

Fifty-one patients with ALI/ALF were studied prospectively using thromboelastography (TEG), which measures the dynamics and physical properties of clot formation in whole blood. ALI was defined as an INR ≥1.5 in a patient with no previous liver disease, and ALF as ALI with hepatic encephalopathy.

RESULTS

Thirty-seven of 51 patients (73%) had ALF and 22 patients (43%) underwent liver transplantation or died. Despite a mean INR of 3.4±1.7 (range 1.5-9.6), mean TEG parameters were normal, and 5 individual TEG parameters were normal in 32 (63%). Low maximum amplitude, the measure of ultimate clot strength, was confined to patients with platelet counts <126×10(9)/L. Maximum amplitude was higher in patients with ALF than ALI and correlated directly with venous ammonia concentrations and with increasing severity of liver injury assessed by elements of the systemic inflammatory response syndrome. All patients had markedly decreased procoagulant factor V and VII levels, which were proportional to decreases in anticoagulant proteins and inversely proportional to elevated factor VIII levels.

CONCLUSIONS

Despite elevated INR, most patients with ALI/ALF maintain normal hemostasis by TEG, the mechanisms of which include an increase in clot strength with increasing severity of liver injury, increased factor VIII levels, and a commensurate decline in pro- and anticoagulant proteins.

Minimal effects of acute liver injury/acute liver failure on hemostasis as assessed by thromboelastography

BACKGROUND & AIMS

Patients with acute liver injury/failure (ALI/ALF) are assumed to have a bleeding diathesis on the basis of elevated INR; however, clinically significant bleeding is rare. We hypothesized that patients with ALI/ALF have normal hemostasis despite elevated INR.

METHODS

Fifty-one patients with ALI/ALF were studied prospectively using thromboelastography (TEG), which measures the dynamics and physical properties of clot formation in whole blood. ALI was defined as an INR ≥1.5 in a patient with no previous liver disease, and ALF as ALI with hepatic encephalopathy.

RESULTS

Thirty-seven of 51 patients (73%) had ALF and 22 patients (43%) underwent liver transplantation or died. Despite a mean INR of 3.4±1.7 (range 1.5-9.6), mean TEG parameters were normal, and 5 individual TEG parameters were normal in 32 (63%). Low maximum amplitude, the measure of ultimate clot strength, was confined to patients with platelet counts <126×10(9)/L. Maximum amplitude was higher in patients with ALF than ALI and correlated directly with venous ammonia concentrations and with increasing severity of liver injury assessed by elements of the systemic inflammatory response syndrome. All patients had markedly decreased procoagulant factor V and VII levels, which were proportional to decreases in anticoagulant proteins and inversely proportional to elevated factor VIII levels.

CONCLUSIONS

Despite elevated INR, most patients with ALI/ALF maintain normal hemostasis by TEG, the mechanisms of which include an increase in clot strength with increasing severity of liver injury, increased factor VIII levels, and a commensurate decline in pro- and anticoagulant proteins.

ADP-dependent platelet function prior to and in the early course of pediatric liver transplantation and persisting thrombocytopenia are positively correlated with ischemia/reperfusion injury

Little is known about the role of platelets in relation to ischemia/reperfusion injury (IRI) of the liver graft especially in children. Thrombocyte function was prospectively analysed in 21 consecutive pediatric liver transplantation (pLT) patients by platelet aggregometry secondary to adenosine diphosphate (ADP), collagen, and the von Willebrand factor activator ristocetin (VWF:rco). Post-OP serum levels of ALT were used to divide patients into groups with high (highHD, n = 8) and low (lowHD, n = 13) hepatocellular damage. Clinically, highHD-patients showed impaired plasmatic coagulation and elevated serum bilirubin levels early after pLT when compared with lowHD-patients. Further, platelet counts markedly decreased between pre-OP and postreperfusion (postrep.) in the highHD group (P = 0.003) and did not recuperate by POD6. In lowHD individuals thrombocytopenia improved from both pre-OP (P < 0.05) and postrep. (P < 0.001) respectively towards POD6. Experimental thrombocyte testing revealed that before graft reperfusion only ADP-dependent platelet aggregation correlated with reperfusion injury, thrombocytopenia and early graft function. During the first 48 h after graft reperfusion, all inducers tested demonstrated elevated platelet aggregation levels in the highHD group. Our data suggest a possible role of platelets and their aggregative status in liver IRI subsequent to clinical pLT. Reperfusion-independent ADP-triggered platelet function may be a determinant for IRI in the pediatric hepatic graft recipient.

No evidence for systemic platelet activation during or after orthotopic liver transplantation

Platelet function is thought to deteriorate during liver transplantation as a result of platelet activation and proteolysis of platelet receptors by plasmin following reperfusion. However, this hypothesis has never been formally tested. Twenty patients undergoing a first or second liver transplant were included in the study. Blood samples were taken at standardized time points during transplantation and up to 10 days after transplantation. Platelet activation was assessed by detection of the activation markers P-selectin and activated integrin alphaIIbbeta3 with flow cytometry. Proteolytic cleavage of platelet receptors was assessed by flow cytometry measurement of the constitutively expressed platelet receptors glycoprotein Ibalpha and integrin alphaIIbbeta3. In addition, using enzyme-linked immunosorbent assay techniques, we measured plasma levels of platelet activation products beta-thromboglobulin and platelet factor 4 and plasma levels of cleaved fragments of glycoproteins Ibalpha and V. Flow cytometry analyses provided no evidence of substantial platelet activation during transplantation. In fact, the expression of activated integrin alphaIIbbeta3 decreased postoperatively; this indicated that platelets were in a slightly activated state prior to surgery. Plasma levels of beta-thromboglobulin and platelet factor 4 also substantially decreased after transplantation. In addition, no changes were observed in the constitutively expressed platelet receptors or in the plasma levels of platelet receptor fragments, and this indicated a lack of substantial receptor proteolysis. In conclusion, no evidence was found for significant activation of circulating blood platelets or the proteolysis of key platelet receptors during liver transplantation. These findings suggest that the platelet functional capacity does not decrease during liver transplantation. Liver Transpl 15:956-962, 2009. (c) 2009 AASLD.

Platelets in liver transplantation: friend or foe?

Apart from the well-known role of blood platelets in hemostasis, there is emerging evidence that platelets have various nonhemostatic properties that play a critical role in inflammation, angiogenesis, tissue repair and regeneration, and ischemia/reperfusion (I/R) injury. All these processes may be involved in the (patho)physiological alterations occurring in patients undergoing liver transplantation. Experimental and clinical research points toward a dualistic role of platelets in patients undergoing liver transplantation, resulting in both beneficial and detrimental effects. Although a low platelet count is generally considered a risk factor for perioperative bleeding, recent studies have indicated that platelet function in patients with cirrhosis may not be as abnormal as previously assumed. Platelet transfusions are frequently considered in liver transplant recipients to correct low platelet counts and to prevent bleeding; however, evidence-based transfusion thresholds are lacking, and the other detrimental and nonhemostatic properties of platelets are generally not weighed in this respect. First, platelets have been shown to contribute to I/R injury of the liver graft via induction of sinusoidal endothelial cell apoptosis. Second, platelet transfusion has been identified as an independent risk factor for reduced survival via mechanisms that are not completely understood yet. On the other hand, recent studies indicate that platelets are critically involved in restoration after liver injury and in liver regeneration via serotonin-mediated mechanisms. These findings make platelets both friend and foe in liver transplantation. The scientific challenge will be to further dissect the mechanisms and clinical relevance of these contrasting roles of platelets in liver transplantation.

Transfusion triggers in orthotopic liver transplantation: a comparison of the thromboelastometry analyzer, the thromboelastogram, and conventional coagulation tests

OBJECTIVES

The Thromboelastogram (TEG; Haemoscope Corporation, Niles, IL) and the ROTEM thromboelastometry analyzer (Pentapharm GmbH, Munich, Germany) are coagulation monitors that measure the viscoelastic changes accompanying whole-blood coagulation generation and lysis. It is not clear whether TEG and ROTEM transfusion algorithms suggest similar blood component intervention. This study aims to report the extent to which administration of platelets, fresh frozen plasma, and cryoprecipitate would be indicated using protocol-dictated interventions by the Rotem, TEG, and conventional coagulation screens during orthotopic liver transplantation (OLT).

DESIGN

Prospective observational study.

SETTING

University hospital.

PARTICIPANTS

Twenty patients undergoing orthotopic liver transplantation.

INTERVENTIONS

Coagulation was managed with native TEG protocols. Additional samples for kaolin TEG, kaolin heparinase TEG, Rotem in-TEM, Rotem hep-TEM, Rotem fib-TEM, full blood count, prothrombin time, and Clauss fibrinogen assays were taken at 5 fixed operative stages.

MEASUREMENTS AND MAIN RESULTS

Results were reviewed and protocol-indicated interventions recorded. There was moderate agreement between Clauss fibrinogen and Rotem fib-TEM assays about fulfilling fibrinogen transfusion criteria (kappa = 0.42, p < or = 0.05). Agreement between TEG and Rotem to transfuse platelets was fair (Rotem in-TEM/native heparinase TEG, kappa = 0.33, Rotem in-TEM/kaolin heparinase TEG, kappa = 0.28). There was moderate agreement between Rotem in-TEM and prothrombin time (kappa = 0.42), and poor agreement between other tests about the point to administer fresh frozen plasma.

CONCLUSIONS

Transfusion practice is likely to differ according to the method of coagulation monitoring used. A prospective case-matched study using the viscoelastic tests used in this study would be beneficial in determining the optimal therapy. Rotem fib-TEM monitoring may improve hemostasis management.

Peroxynitrite Decreases Hemostasis in Human Plasma In Vitro

Coagulopathy has been associated with clinical scenarios that involve reactive nitrogen species such as peroxynitrite (OONO-). Further, OONO- decreases tissue factor and fibrinogen function in vitro. Thus, we hypothesized that exposure of plasma to the OONO- generated with 3-morpholinosydnonimine (SIN-1), a molecule that produces both nitric oxide and superoxide, would result in a decrease in hemostatic function via diminished coagulation protein activity. Hemostatic function of plasma exposed to SIN-1 (0, 1, 5, and 10 mM for 60 min at 37 degrees C) was assessed with thrombelastography, activated partial thromboplastin time, and prothrombin time in the presence or absence of superoxide dismutase (SOD) or an OONO- scavenger. SIN-1 exposure resulted in a significant (P < 0.05), dose-dependent decrease in plasma hemostatic function and concurrent significant (P < 0.05) decreases in activities of factor VII, factor VIII complex, and factor X. Fibrinogen concentration was not affected by SIN-1. Antithrombin and protein C activity also decreased significantly (P < 0.05). Coincubation with SOD or an OONO- scavenger significantly (P < 0.05) attenuated SIN-1 mediated changes in hemostasis and procoagulant/ anticoagulant activity. We conclude that OONO- may decrease hemostatic function in human plasma by nitration of key procoagulants and that OONO- may play a significant role in hemorrhagic states.

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.

[Reproducibility and interchangeability of the Thromboelastograph, Sonoclot and Hemochron activated coagulation time in cardiac surgery]

PURPOSE

Despite their common use in cardiac surgery, few studies have evaluated the reproducibility of the Thromboelastograph (TEG), of the Sonoclot (SCT), and of the activated coagulation time with celite (ACT-C) or kaolin (ACT-K) measured with the Hemochron, in clinical conditions of on-site monitoring of hemostasis. This study determined the reproducibility of those measurements, and evaluated the ability of various devices to substitute for the ACT-C.

METHODS

Blood samples collected from 20 volunteers and 21 patients undergoing myocardial revascularization were analyzed in the two channels of the TEG, in two SCT and four Hemochron analyzers. The overall of TEG and SCT coagulation profiles were analyzed by a computerized TEG and an experienced observer respectively. The variation rate (V%) was calculated for each variable. The ability of ACT-K and SCT to substitute for ACT-C under different clinical conditions was evaluated.

RESULTS

ACT-C and ACT-K V% ranged between 5.6% and 10.8% and between 6.7% and 12.4% respectively. TEG and SCT V% ranged between 3.1% and 9.5% and between 5.8% and 33.6% respectively, according to different conditions and parameters. In volunteers and non-heparinized patients, the ACT-C and ACT-K were interchangeable. No other test can substitute for the ACT-C when patients are heparinized during cardiopulmonary bypass (CPB).

CONCLUSIONS

In the clinical conditions of use, on-site hemostasis monitoring devices providing the most reproducible measurements are, in decreasing order, the TEG, the Hemochron and the SCT. In heparinized patients and during CPB, results from different tests are not interchangeable, stressing the importance of establishing appropriate instrument-specific values for monitoring anticoagulation during cardiac surgery.

Thrombopoietin induces rapid resolution of thrombocytopenia after orthotopic liver transplantation through increased platelet production

Thrombopoietin (TPO) deficiency has been proposed as an important etiologic factor for thrombocytopenia in advanced-stage liver disease. To clarify the contributions of platelet production, platelet consumption, coagulation activation, and splenic sequestration to thrombocytopenia in liver disease, we studied TPO serum levels and markers of platelet production, platelet activation, and coagulation activation before and 14 days after orthotopic liver transplantation (OLT) in 18 patients with advanced liver cirrhosis. Thrombocytopenia before transplantation occurred with low-normal serum levels of TPO, normal levels of platelet and coagulation activation markers, and no increase in bone marrow production of platelets. TPO serum levels increased significantly on the first day after OLT, preceding the increase of reticulated platelets by 3 days and peripheral platelets by 5 days. Normalization of the peripheral platelet count occurred in most patients within 14 days of OLT, irrespective of the change in spleen size assessed by computed tomography volumetry. Normalization of platelet counts was not hampered by a certain degree of platelet activation observed during the steepest increase in the peripheral platelet count. Bone marrow production of platelets increased significantly within 2 weeks of transplantation. Low TPO serum levels with low platelet counts and without platelet consumption suggests low TPO production in end-stage liver disease. The rapid increase in TPO serum levels after transplantation induces an increase in the bone marrow production of platelets. Decreased TPO production in the cirrhotic liver is an important etiologic factor for thrombocytopenia in liver disease that is rapidly reversed by transplantation.

Conjugated estrogen reduces transfusion and coagulation factor requirements in orthotopic liver transplantation

We conducted a prospective, randomized study to determine the efficacy of conjugated estrogen in reducing blood product transfusion during orthotopic liver transplantation (OLT). Patients undergoing OLT were included in the study. Only those having a reaction time of more than 30 mm or 15 min (19 -28 mm) on computed thromboelastography (CTEG) at the beginning of surgery were enrolled in the study. Patients were randomized to receive either conjugated estrogen (CE) or placebo. Every patient received a first dose of CE (100 mg i.v.) (20 mL) or placebo (20 mL of isotonic sodium chloride solution) at the beginning of the procedure and a second dose of CE (100 mg i.v.) or 20 mL of placebo (20 mL of isotonic sodium chloride solution) just after reperfusion of the new graft. The two groups were similar in age, weight, requirement for veno-veno bypass, time on veno-veno bypass, CTEG measurement, and preoperative hemoglobin and platelet values. Blood products were given in relation to hematocrit and coagulation (CTEG) variables, which were measured every hour during the surgery. The amount of transfused blood products did not differ in terms of units of cryoprecipitate, but the intraoperative requirements for red blood cells (6 +/- 3 vs 9 +/- 6 U; P = 0.05), platelets (12 +/- 8 U vs 18 +/- 10 U; P = 0.05) and fresh-frozen plasma (3 +/- 3 U vs 6 +/- 4 U; P = 0.001) was significantly less in the estrogen group than in the control group. We conclude that CE is associated with a significant decrease in use of fresh-frozen plasma, platelets, and red blood cells during OLT.

IMPLICATIONS

In this study, we prospectively investigated whether i.v. conjugated estrogen could decrease blood product transfusion during orthotopic liver transplantation. Conjugated estrogen-treated patients received less fresh-frozen plasma, red blood cells, and platelets. In this population of patients, conjugated estrogen can be a useful addition in coagulation management during orthotopic liver transplantation.

Conjugated estrogen reduces transfusion and coagulation factor requirements in orthotopic liver transplantation

We conducted a prospective, randomized study to determine the efficacy of conjugated estrogen in reducing blood product transfusion during orthotopic liver transplantation (OLT). Patients undergoing OLT were included in the study. Only those having a reaction time of more than 30 mm or 15 min (19 -28 mm) on computed thromboelastography (CTEG) at the beginning of surgery were enrolled in the study. Patients were randomized to receive either conjugated estrogen (CE) or placebo. Every patient received a first dose of CE (100 mg i.v.) (20 mL) or placebo (20 mL of isotonic sodium chloride solution) at the beginning of the procedure and a second dose of CE (100 mg i.v.) or 20 mL of placebo (20 mL of isotonic sodium chloride solution) just after reperfusion of the new graft. The two groups were similar in age, weight, requirement for veno-veno bypass, time on veno-veno bypass, CTEG measurement, and preoperative hemoglobin and platelet values. Blood products were given in relation to hematocrit and coagulation (CTEG) variables, which were measured every hour during the surgery. The amount of transfused blood products did not differ in terms of units of cryoprecipitate, but the intraoperative requirements for red blood cells (6 +/- 3 vs 9 +/- 6 U; P = 0.05), platelets (12 +/- 8 U vs 18 +/- 10 U; P = 0.05) and fresh-frozen plasma (3 +/- 3 U vs 6 +/- 4 U; P = 0.001) was significantly less in the estrogen group than in the control group. We conclude that CE is associated with a significant decrease in use of fresh-frozen plasma, platelets, and red blood cells during OLT.

IMPLICATIONS

In this study, we prospectively investigated whether i.v. conjugated estrogen could decrease blood product transfusion during orthotopic liver transplantation. Conjugated estrogen-treated patients received less fresh-frozen plasma, red blood cells, and platelets. In this population of patients, conjugated estrogen can be a useful addition in coagulation management during orthotopic liver transplantation.

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.

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.

Quantification of thrombelastographic changes after blood component transfusion in patients with liver disease in the intensive care unit

Thrombelastography (TEG) can be used to monitor hemostasis and guide transfusion therapy during orthotopic liver transplantation. However, data are limited regarding the type and quantity of blood components necessary for TEG-guided blood component transfusion in coagulopathic critically ill patients with liver disease. We evaluated changes in four thrombelastogram variables (reaction time, thrombin constant time, alpha angle, and maximum amplitude) in whole blood samples after 74 separate blood component transfusions in 60 critically ill patients with a coagulopathy and liver disease. Only platelets significantly improved TEG variables in patients who received a single type of blood component. Each unit of platelets decreased the reaction and thrombin constant time by 0.43 (P < 0.05) and 0.82 (P < 0.005) min, respectively, increased the alpha angle by 1.5 degrees (P < 0.005), and the maximum amplitude by 1.4 mm (P < 0.005). In patients who received multiple blood components, cryoprecipitate decreased the thrombin constant time by 0.56 min/U (P < 0.05), and each unit of platelets decreased the thrombin constant time by 0.39 min (P < 0.005), and increased the alpha angle and maximum amplitude by 0.63 degrees (P < 0.05) and 0.99 mm (P < 0.005), respectively. We conclude that platelet transfusions, alone or in combination with other blood components, are most effective for improving abnormal TEG variables in coagulopathic critically ill patients with liver disease.

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.

Predictive factors of early postoperative graft function in human liver transplantation

To identify factors predictive of early postoperative graft function, we analyzed 54 variables--including easily available clinical and laboratory data prospectively obtained from organ donors, transplant recipients and surgical procedures in 168 consecutive liver transplantations. Early postoperative graft function was classified into three groups according to a scoring system ranging from 3 to 9 based on peak serum ALT values, mean bile output and lowest prothrombin activity measured during the 72 hr after transplant: group 1 (score 3 to 4, good graft function; n = 73), group 2 (score 5 to 6, moderate dysfunction; n = 50) and group 3 (score, 7 to 9, severe dysfunction; n = 45). In univariate analyses, 8 of the 54 variables analyzed were statistically significant (p < 0.05) predictors of severe graft dysfunction: high serum sodium concentration and brain death caused by cranial trauma in organ donors, advanced age and low prothrombin activity in transplant recipients, prolonged total ischemia time and large transfusions of red blood cells, fresh frozen plasma and platelets during surgery. After introduction of these eight variables in a multivariate analysis, only four were found to independently predict early postoperative graft function: donor serum sodium concentration, total ischemia time, platelet transfusion during surgery and recipient prothrombin activity. In 52 liver transplantations, in which the predictive value of liver tissue adenine nucleotide concentration and several biochemical sensitive markers of donor nutritional status was also analyzed, only the ATP level in liver tissue obtained at the time of organ reperfusion was identified as an independent predictor of initial graft function.(ABSTRACT TRUNCATED AT 250 WORDS)

Medical assessment of bleeding in the surgical patient

The key to avoidance of hemostatic failure during surgery is to be able to identify the high-risk patient and make a diagnosis and treat the defect before surgery. A thorough history and physical examination are mandatory in this regard. A screening coagulation profile is not a substitute for the history and physical examination. Selected presurgical tests are useful in major surgical cases and in certain high-risk cases. Otolaryngologists have advised presurgical testing for patients undergoing tonsillectomy, but the subject of presurgical testing is still a matter for investigation in view of the necessity for cost containment. Knowledge of the hemostatic system combined with a knowledge of the tests available to diagnose coagulation defects permits a rational approach to therapy of the bleeding surgical patient.

Platelet function defects associated with hemorrhage or thrombosis

Platelet dysfunction, especially acquired forms, is a common cause of hemorrhage, especially when associated with trauma or surgery. Although the hereditary platelet function defects are generally quite rare, hereditary storage pool disease is common enough to be suspected in an individual, usually a child, with characteristic historical and clinical findings. The acquired platelet function defects, especially those resulting from drugs, are common and should promptly be suspected in patients developing easy and spontaneous bruising, mild-to-moderate mucosal membrane hemorrhage, or unexplained bleeding associated with trauma or surgery. The template bleeding time is generally useful as a screening test of platelet function, but a normal template bleeding time, in the face of a suggestive history, suggestive clinical findings, or in a patient frankly bleeding, is not reliable, and platelet aggregation or lumiaggregation should be done in appropriate clinical situations. Also, prolongation of the template bleeding time is an unreliable predictor of clinical bleeding propensity. The mainstay of therapy for almost all these defects, if bleeding is significant, is the liberal infusion of appropriate numbers of platelet concentrates. The acquired platelet function defects should also be managed by attempts to treat or control the underlying disease, if possible, and offending drugs or potentially offending drugs should immediately be stopped.

New whole blood analyzers and their impact on cardiac and critical care

Miniaturized whole blood biosensors, patient-focused hospitals, and rising expectations of patients and physicians are shifting laboratory diagnostics to the point of care. Expanding transplantation and intensive care are increasing the need for rapid test results. Whole blood analysis improves accuracy, eliminates centrifugation, reduces response time, and conserves blood volume. Several hand-held, and over 20 portable or transportable whole blood instruments are now available. Criteria for instrument evaluation include test menus, point-of-care features, analysis time, on-site performance, and information integration. Whole blood analyzers measure several vital indicators (pO2, pCO2, pH, hematocrit, K+, Ca2+, Na+, Cl-, glucose, and lactate) simultaneously in less than 2 min with less than 200 microliters of whole blood. Other in vitro tests are available (Mg2+, osmolality, CO2 content, urea nitrogen, beta-hydroxybutyrate, hemoglobin, coagulation) or under development (HCO3- phosphorus). Some can be monitored in vivo (O2 saturation, pO2, pCO2, pH, glucose) or ex vivo. The clinical impact is demonstrated by ionized calcium, now established in importance for cardiac and neurologic problems, and ionized magnesium, a promising new measurement. The hybrid laboratory (a composite of conventional clinical laboratory and patient-focused testing), performance maps, and quality paths facilitate implementation of new whole blood analyzers for optimal support of cardiac and critical care, and improved patient outcomes (prospects).

Hemostatic studies of ex situ hepatic surgery

Ex situ hepatic surgery, in which a diseased liver is resected from outside the body, was first reported in 1988. This study investigates the hemostatic changes occurring during such surgery in two cases. During the anhepatic period of more than 5 hours, veno-venous bypass without heparin was performed. The tests included platelet count, prothrombin activity (PT), partial thromboplastin time (PTT), fibrinogen (Fbg), factor II (F.II), factor V (F.V), and thromboelastography (TEG). Three to 4 hours after entering the anhepatic phase, marked fibrinolysis and a fall in the values of PT, Fbg and F.V. were observed. Every parameter temporarily deteriorated immediately after revascularization of the graft, however, all returned to almost normal values within 1-2 hours after hepatic reperfusion except for F.V and platelets. In conclusion, the coagulopathy during ex situ hepatic surgery is caused by the marked fibrinolysis and depletion of hemostatic factors which develop 3-4 hours after the onset of the anhepatic phase.

A comparative study on changes in hemostasis in orthotopic and auxiliary liver transplantation in pigs

We compared blood loss and hemostasis in pigs which had undergone either orthotopic liver transplantation (OLT) (group A, n = 12) or auxiliary heterotopic partial liver transplantation (APLT) (group B, n = 11). Blood samples were taken at regular intervals during and after the operations. In both groups, nine animals survived longer than 24 h and data from these animals were used for analysis. Median (range) intraoperative blood loss was 825 ml (250-1500 ml) in OLT and 425 ml (300-750) in APLT (P less than 0.01). Routine clotting times, as the activated partial thromboplastin time, prothrombin time and thrombin time, showed no major intraoperative changes in either group. Fibrinogen levels decreased in both groups, but no significant difference was found between the two groups. The only significant difference between group A and B was a more sustained increase in fibrinolytic activity after graft recirculation in group A. Postoperatively, restoration of fibrinogen, antithrombin-III and alpha 2-antiplasmin levels was slightly faster in group B, resulting in significantly higher levels during the first day. We conclude that, in this animal model, APLT is associated with significantly lower blood loss and less severe fibrinolytic activity, than OLT. This difference might result from the lack of an anhepatic period and the reduced surgical trauma in auxiliary heterotopic liver transplantation.

Role of the nurse in the multidisciplinary team approach to care of liver transplant patients

Nursing plays an important contributory role in the multidisciplinary team approach to patient care. The nurse who is responsible for the care of liver transplant patients requires special preparation to meet the patient's needs during the critical phases of the liver transplant process. In the hospital setting, a primary nursing-care delivery system enhances the nurse's role in supporting the goal of patient recovery. Primary nursing places the accountability and responsibility for planning, administering, and evaluating the care of the liver transplant patient with the primary nurse. The transplant nurse acts as a key link in the communication network within the multidisciplinary team, and effective communication is essential in the care of the liver transplant patient. For achievement of a life-style of independence after transplantation, the patient is assisted by the nurse, who provides instruction in such areas as diet, medications, monitoring of vital signs, and record keeping. Although the nurse is only one member contributing to the care of liver transplant patients, the nurse's role in the success of treatment is vital.

Intensive-care unit experience in the Mayo liver transplantation program: the first 100 cases

The first 100 liver transplantations at the Mayo Clinic were performed in 83 patients, who required a total of 917 patient days in the intensive-care unit (ICU). The mean duration of stay in the ICU was 5.91 days after liver transplantation and 6.15 days for patients who subsequently required readmission to the ICU. During the immediate postoperative period, hypothermia and hyperglycemia invariably occurred. Later during the initial admission or on readmission to the ICU, there arose the possibility of infections and renal insufficiency. Prompt diagnosis and treatment are necessary for hypertension, hypokalemia, severe metabolic alkalosis, fever, altered mental status, oliguria, and signs of graft failure in liver transplant patients. In our patient series, selective bowel decontamination minimized the occurrence of gram-negative and fungal sepsis, and use of antihypertensive agents and correction of coagulopathies may have decreased the risk of intracranial bleeding in patients with hypertension and clotting defects. Anticipation of potential conditions postoperatively and early implementation of treatment are key factors in the successful ICU management of patients who have undergone liver transplantation.

Anesthesia approach to hepatic transplantation

Anesthesia support for patients undergoing orthotopic liver transplantation can be complicated because of multiple medical problems in such patients and rapid hemodynamic, metabolic, and coagulation changes intraoperatively. Preoperative assessment should include careful review of the cardiovascular, respiratory, and hematologic systems. Use of isoflurane as the main anesthetic agent will minimize toxicity to the liver. During liver transplantation, hemodynamic monitoring and immediate laboratory studies should be available. In our experience during the first 100 liver transplantations performed at our institution, use of a rapid infusion pump and venovenous bypass has helped normalize hemodynamic and renal function.

Hemodynamic and metabolic changes in hepatic transplantation

In this study, we retrospectively analyzed the intraoperative hemodynamic, laboratory, and coagulation data on the first 83 patients who underwent an initial liver transplantation procedure at our institution. The major hemodynamic changes at the time of reperfusion of the donor liver were significant decreases in arterial blood pressure, systemic vascular resistance, and pulmonary artery temperature and significant increases in cardiac output and pulmonary capillary wedge pressure. The alterations in laboratory values reflected intraoperative therapeutic manipulations. Citrate toxicity is a concern, and the amount of calcium chloride administered reflected the volume of blood transfused. On reperfusion, the fibrinogen concentration decreased and both the prothrombin time and the activated partial thromboplastin time increased. This coagulopathy was also evident in the thromboelastographic values. Aggressive monitoring and prompt intervention are necessary to maintain hemodynamic and metabolic homeostasis in these patients.