Coagulation tests during cardiopulmonary bypass correlate with blood loss in children undergoing cardiac surgery.

OBJECTIVES: To examine whether coagulation tests, sampled before and during cardiopulmonary bypass (CPB), are related to blood loss and blood product transfusion requirements, and to determine what test value(s) provide the best sensitivity and specificity for prediction of excessive hemorrhage. DESIGN: Prospective. SETTING: University-affiliated, pediatric medical center. PARTICIPANTS: Four hundred ninety-four children. INTERVENTIONS: Coagulation tests. MEASUREMENTS AND MAIN RESULTS: Demographic, coagulation test, blood loss, and transfusion data were noted in consecutive children undergoing cardiac surgery. Laboratory tests included hematocrit (Hct), prothrombin time, partial thromboplastin time (PTT), platelet count, fibrinogen concentration, and thromboelastography. Stepwise linear regression analysis indicated that platelet count during CPB was the variable most significantly associated with intraoperative blood loss (in milliliters per kilogram) and 12-hour chest tube output (in milliliters per kilogram). Other independent variables associated with blood loss were thromboelastography maximum amplitude (MA) during CPB, preoperative PTT, preoperative Hct, and preoperative thromboelastography angle and shear modulus values. Thromboelastography MA during CPB was the only variable associated with total products transfused (in milliliters per kilogram). Of all tests studied, platelet count during CPB (< or = 108,000/microL) provided the maximum sensitivity (83%) and specificity (58%) for prediction of excessive blood loss (receiver operating characteristic analysis). Blood loss was inversely related to patient age; neonates received the most donor units (median, 8 units; range, 6 to 10 units). CONCLUSIONS: During cardiac surgery, coagulation tests (including thromboelastography) drawn pre-CPB and during CPB are useful to identify children at risk for excessive bleeding. Platelet count during CPB was the variable most significantly associated with blood loss.     

Comparison of viscoelastic measures of coagulation after cardiopulmonary bypass

Postoperative hemorrhage remains a major cause of morbidity after cardiopulmonary bypass (CPB). Treatment remains empiric because of the need for immediate correction and the lack of availability of rapid intraoperative coagulation monitoring (except for ACT) at most institutions. Thrombelastography (TEG) and Sonoclot analysis (SCT) are measures of viscoelastic properties of blood which allow rapid intraoperative evaluation of coagulation factor and platelet activity as well as overall clot integrity from a single blood sample. Routine coagulation tests (RCT) including activated clotting time (ACT), prothrombin time (PT), partial thromboplastin time (PTT), fibrinogen level (FIB), and platelet count (PLT) were determined and compared to TEG and SCT to assess which best predicted clinical hemostasis after CPB. Forty-two patients prospectively felt to be at high risk for excessive post-CPB bleeding had blood obtained for RCT, TEG, and SCT analysis before systemic heparinization and 30 min after protamine administration. Nine of 42 patients had excessive chest tube drainage, but no reoperations were required. After CPB, mean values for RCT were normal, but there were abnormalities in TEG and SCT parameters that reflect platelet-fibrin interaction. Both TEG and SCT were 100% accurate in predicting bleeding in these nine patients and, overall, both tests were significantly better predictors of postoperative hemorrhage than RCT. We conclude that viscoelastic determinants of clot strength may be abnormal after CPB and that SCT and TEG are, therefore, more useful than RCT for the detection and management of coagulation defects associated with CPB.     

Prediction of excessive bleeding after coronary artery bypass graft surgery: the influence of timing and heparinase on thromboelastography

OBJECTIVE: To compare the ability of thromboelastography, when done at either 10 or 60 minutes after protamine reversal of heparin, to predict excessive bleeding after coronary artery bypass graft (CABG) surgery and to investigate, with the use of heparinase, whether heparin contamination was responsible for the difference, if any. DESIGN: Prospective study. SETTING: University hospital, single institution. PARTICIPANTS: Patients undergoing elective CABG surgery (n = 40). INTERVENTIONS: Blood samples for thromboelastography and routine coagulation tests were collected before induction of anesthesia and at 10 and 60 minutes after protamine reversal of heparin. Blood loss and blood product use were recorded postoperatively. MEASUREMENTS AND MAIN RESULTS: Of 40 patients undergoing elective CABG surgery, 10 fulfilled the criteria for excessive postoperative bleeding. The sensitivity of thromboelastography to identify patients who bled was better at 60 minutes than at 10 minutes after protamine reversal of heparin (100% v 70%). There was greater specificity (83% v 40% at 10 minutes; 73% v 20% at 60 minutes) and positive predictive value (58% v 28% at 10 minutes; 55% v 29% at 60 minutes) when heparinase was added. At both times, thromboelastography showed only moderate correlation with total blood loss and the use of fresh frozen plasma or platelets or both. Conventional coagulation tests did not predict excessive postoperative bleeding. CONCLUSION: This study suggests that timing and the use of heparinase influence the predictive ability of thromboelastography, but its usefulness as a sole predictor of post-CABG surgery bleeding is limited.     

The predictive value of modified computerized thromboelastography and platelet function analysis for postoperative blood loss in routine cardiac surgery

Hemorrhage after cardiopulmonary bypass (CPB) remains a clinical problem. Point-of-care tests to identify hemostatic disturbances at the bedside are desirable. In the present study, we evaluated the predictive value of two point-of-care tests on postoperative bleeding after routine cardiac surgery. Prospectively, 255 consecutive patients were studied to compare the ability of modified thromboelastography (ROTEG) as well as a platelet function analyzer (PFA-100) to predict postoperative blood loss. Measurements were performed at three time points: preoperatively, during CPB, and after protamine administration with three modified thromboelastography and PFA tests. The best predictors of increased bleeding tendency were the tests performed after CPB. The angle alpha is the best predictor (area under the receiver operating characteristic curve 0.69) and, in combination with the adenosine diphosphate-PFA test, the predictive accuracy is enhanced (area under the receiver operating characteristic curve 0.73). The negative predictive value for the angle alpha is 82%, although the positive predictive value is small (41%). Thromboelastography is a better predictor than PFA. In routine cardiac surgery, impaired hemostasis as identified by point-of-care tests does not inevitably lead to hemorrhage postoperatively. However, patients with normal test results are unlikely to bleed for hemostatic reasons. Bleeding in these patients is probably caused surgically. The high negative predictive value supports early identification and targeted treatment of surgical bleeding by distinguishing it from a significant coagulopathy. IMPLICATIONS: Thrombelastography and platelet function analysis in routine cardiac surgery demonstrate high negative predictive values for postoperative bleeding, which supports early identification and targeted treatment of surgical bleeding by distinguishing it from a significant coagulopathy. The positive predictive values are small. The best predictors are thrombelastography values obtained after cardiopulmonary bypass.     

The accuracy of coagulation tests during spinal fusion and instrumentation.

Patients undergoing major spine surgery may acquire a perioperative coagulopathy from dilution of coagulation factors and/or platelets or fibrinolysis. The mechanisms of the coagulopathy and role of coagulation testing during these procedures are poorly defined. Theoretically, coagulation tests could be used perioperatively to determine which patients are at risk for significant bleeding and guide transfusion therapy. We retrospectively evaluated the sensitivity, specificity, and accuracy of coagulation tests in predicting excessive surgical bleeding in 244 consecutive patients undergoing thoracic, lumbar, or sacral spinal fusion with or without instrumentation. Excessive bleeding was reported by the surgeon in 39 of the patients and was defined as recurrent microvascular bleeding despite adequate use of electrocautery and suture or decreased clot formation of blood pooled within the surgical field. Patients with excessive clinical bleeding sustained larger estimated blood losses than those with normal hemostasis. The total number of allogeneic red blood cells, platelets, and fresh frozen plasma units were also larger in patients with excessive bleeding noted during surgery. The intraoperative coagulation tests with the most sensitivity and specificity were the international normalized ratio (INR), prothrombin time (PT), and activated partial thromboplastin time (aPTT). The INR had a sensitivity of 94%, a specificity of 88%, and an accuracy of 0.9 at a value of 1.4 (normal, 0.8-1.2). The PT had a sensitivity of 90%, a specificity of 64%, and an accuracy of 0.73 at a value of 13.5 s (normal, 8.4-12.0 s). The aPTT had a sensitivity of 85%, a specificity of 64%, and an accuracy of 0.71 at a value of 30.9 s (normal, 23-37 s). The thromboelastogram values were of marginal use. We conclude that the INR, PT, and aPTT may be helpful in guiding transfusion therapy in patients undergoing major spine surgery. Implications: Patients undergoing major surgery to the spine often acquire a perioperative coagulopathy. The prothrombin time and activated partial thromboplastin time had the greatest sensitivity and specificity for predicting bleeding in major surgery of the spine. The test values that differentiated normal from excessively bleeding patients could be used to guide transfusion therapy during surgery.     

Markers of coagulation activation after hepatic resection for cancer: evidence of sustained upregulation of coagulation

We investigated the possibility that despite postoperative derangements of routine laboratory coagulation tests, markers of coagulation activation and thrombin generation would be normal or increased in patients undergoing hepatic resection for cancer In addition to the conventional coagulation tests prothrombin time and activated partial thromboplastin time, we measured select markers of coagulation activation prothrombin fragments 1 and 2 (PF1 + 2), thrombin-antithrombin complexes and plasma von Willebrand Factor antigen in 21 patients undergoing hepatic resection. The impact of hepatic resection on coagulation and fibrinolysis was studied with thromboelastography. Preoperatively, routine laboratory coagulation and liver function tests were normal in all patients. On the first postoperative day, prothrombin time was prolonged (range 16 to 22 seconds) in eight patients (38%). For these patients, thromboelastography was normal in six (75%), PF1 + 2 was elevated in four (50%), and thrombin-antithrombin complexes and von Willebrand Factor antigen were elevated in all, which was evidence of acute phase reaction, sustained coagulation factor turnover and activation. By the fifth postoperative day, despite normalisation of prothrombin time, markers of increased coagulation activity remained greater than 85% of baseline values. The findings indicate that in patients undergoing liver resection for cancer, there is significant and prolonged postoperative activation of the haemostatic system despite routine coagulation tests being normal or even prolonged. Before considering therapeutic interventions an integrated approach to interpreting haematological data with clinical correlation is essential.     

Using reagent-supported thromboelastometry (ROTEM((R))) to monitor haemostatic changes in congenital heart surgery employing deep hypothermic circulatory arrest

Objective: Cardiac surgery employing cardiopulmonary bypass (CPB) and deep hypothermic circulatory arrest (DHCA) can induce coagulation disturbances and bleeding complications that may be especially severe in infants. A better understanding of the coagulopathy and a quick method for its evaluation would be helpful in the management of patients exposed to CPB and DHCA. This study aimed to monitor coagulation defects in congenital heart surgery using rotational thromboelastometry (ROTEM((R))), standard coagulation tests and platelet flow cytometry. Methods: The study comprised 10 infants undergoing surgery for congenital heart disease on CPB and DHCA. Blood was sampled at skin incision, after heparinisation during CPB (directly pre- and directly post-DHCA) and after protamine administration post-CPB. ROTEM((R)) using different reagents including a heparinase-containing assay to evaluate coagulation during heparinisation, APTT and INR, and flow cytometry to evaluate platelet activation were performed. Results: During CPB, the ROTEM((R)) indicated CPB-induced clotting factor depletion and platelet dysfunction that persisted after CPB and heparin neutralisation. ROTEM((R)) results were available within 15min and therefore much faster than standard tests. ROTEM((R))-guided specific blood product treatment resulted in satisfactory coagulatory function. The highest degree of platelet activation was found directly after DHCA. Conclusions: A major benefit of ROTEM((R)) is the quick detection of a developing coagulopathy already during CPB. ROTEM((R)) guides quick and specific blood product treatment after CPB, which may decrease bleeding complications in cardiac surgery. The finding of maximal platelet activation directly after DHCA suggests that not only CPB but also hypothermia activates platelets in vivo, thereby contributing to platelet dysfunction.     

Comparative Assessment of Coagulation Changes Induced by Two Different Types of Heart–Lung Machine

The cardiopulmonary bypass (CPB) used in heart surgery has a deleterious effect on hemostasis. The aim of our study was to assess by means of standard laboratory and point-of-care methods changes induced by CPB in coagulation parameters, particularly in platelet function, and to determine whether these changes differ depending on the type of heart–lung machine (HLM) used: minimal extracorporeal circulation system (MECC) and standard HLM. The study enrolled 88 patients scheduled for coronary artery bypass surgery performed on pump. Forty-four interventions were performed with MECC and 44 with standard HLM. Blood was sampled preoperatively, after 30 min on CPB, after weaning from CPB, and 24 h postoperatively. Coagulation and platelet function were assessed using multiple electrode aggregometry (MEA), rotation thromboelastometry, as well as standard laboratory tests. Rotation thromboelastometry and standard laboratory reflected significantly impaired hemostasis after weaning from CPB but no significant differences between the two groups at different time points. Aggregation decreased significantly in both groups as early as 30 min after the institution of CPB ( P  < 0.05, Mann–Whitney U -test) and recovered within the first 24 h postoperatively, without reaching the preoperative level. Intraoperatively, aggregometry values reflected a significantly more severe reduction of platelet function in standard HLM group than in the MECC group ( P  < 0.01, ProcMixed test). Our findings suggest that MEA and thromboelastometry reflect impairment of coagulation in cardiac surgery performed on different types of HLM and that platelet function is less affected by MECC than by standard HLM.     

Intraoperative coagulation was more interfered by HES 200/0.5 than normal saline in off-pump coronary artery bypass surgery

AIM: Rapid fluid administration is often necessary for anesthesiologists to maintain intravascular volume in off-pump coronary artery bypass (OPCAB) with acceptable hematocrits. Postoperative hypocoagulation involving postoperative bleeding and hypercoagulation involving graft patency were focused in previous studies but bleeding and blood transfusion are often peaked during vascular anastomoses during OPCAB. This study is designed to investigate the sequential effects of intraoperative coagulation with normal saline and hydroxyethyl starch (HES) solution by thromboelastography (TEG) and standard coagulation tests (SCT). METHODS: Twenty adult patients scheduled for OPCAB were enrolled in this study. After anesthetic induction, one group received HES 200/0.5 infusion up to 20 mL/kg and the other received 0.9% normal saline (NS) to maintain central venous pressure (CVP) and pulmonary artery occlusion pressures (PAOP). SCT and TEG were measured at T0 (baseline), T1 (after heparin 150 IU/kg, before vascular anastomoses), T2 (after protamine reversal), and T3 (24 hrs after the surgery) to compare the coagulation status. RESULTS: Baseline data were comparable in both groups. The number of patient who need blood components is higher in HES group. Dilutional hypocoagulation was shown by a significant prolongation of R time at T1 and T2 but also returned comparable at T3 in both groups. K, a-angle, CI and G remained unchanged in NS group but significantly affected in HES group. A statistically significant interaction between groups and treatments on maximal amplitude (MA) (P<0.01) with more blood loss in HES group 24 hours postoperatively (P=0.05). International Normalized Ratio (INR) increased significantly at T2 and T3 in both groups. CONCLUSION: A rapid infusion of either normal saline or HES solution to maintain intraoperative intravascular volume induce a significant diluted hypocoagulation during OPCAB. The use of HES solution has a prolonged dilutional hypocoagulation and a significant decrease of MA by specific platelet inhibition effects and more transfusion of blood components. All the above changes were not shown in standard coagulation tests.     

Laboratory Evaluation of Hemostasis Before Cardiac Operations

Background. Several opinions prevail on the necessity and on the choice of laboratory coagulation tests to perform before cardiac operations. This review aims at providing simple and clinically relevant recommendations.

Methods. The literature on preoperative coagulation testing was reexamined, taking into account the low prevalence of unknown and unsuspected hemorrhagic disease, and the risk of false positive results.

Results. Carefully controlled, randomized trials are lacking but it seems appropriate to perform a few inexpensive tests (platelet count, activated partial thromboplastin time, and prothrombin time), mainly to obtain baseline values for patients who are about to undergo a major hemostatic challenge. A more complete coagulation profile (eg, bleeding time, fibrinogen concentration, thrombin time) should be considered in patients who present with a history of bleeding.

Conclusions. A careful medical history is the key element to detect a bleeding disorder. Only a very limited coagulation profile should be obtained in asymptomatic patients before cardiac operations.     

Assessment of Changes in Coagulation in Parturients with Preeclampsia Using Thromboelastography

Background: Preeclampsia is associated with a risk of abnormal hemostasis that occurs most commonly secondary to thrombocytopenia. Thromboelastography measures whole blood coagulation and has been used to manage coagulation defects in obstetric patients. The authors conducted this investigation in a large number of preeclamptic women to assess changes in coagulation using thromboelastography.

Methods: Thromboelastography and platelet counts were performed in 52 healthy pregnant women, 140 mild preeclamptic women, and 114 severe preeclamptic women in active labor using disposable plastic cups and pins and native whole blood. In preeclamptic patients with a platelet count <100,000/mm3, conventional coagulation tests were also performed. Epidural analgesia was provided in some women when they requested pain relief.

Results: Fifteen percent of all preeclamptic women (38 of 254) and 2% (1 of 52) of healthy pregnant women had a platelet count <100,000/mm3. The incidence of thrombocytopenia <100,000/mm3 was 3% (4 of 140) and 30% (34 of 114) in mild preeclamptic patients and severe preeclamptic patients, respectively. Severe preeclamptic patients with a platelet count <100,000/mm (3) were significantly hypocoagulable when compared to the other study groups. Ten severe preeclamptic women with a platelet count <100,000/mm3 had a maximum amplitude <54 mm (the lower limit of maximum amplitude in healthy pregnant women enrolled in this investigation). None of the mild preeclamptic women had a maximum amplitude <54 mm. Five severe preeclamptic women with a platelet count <100,000/mm3 had an abnormal coagulation profile, whereas all four mild preeclamptic women with a platelet count <100,000/mm3 had a normal coagulation profile.     

Coagulation Profile of Neonates Undergoing Arterial Switch Surgery With Crystalloid Priming of the Cardiopulmonary Bypass Circuit

ObjectivesThe aim was to evaluate changes in the coagulation profile of cyanotic neonates, to analyze the effects of cardiopulmonary bypass (CPB) with crystalloid priming on their coagulation status, and to determine factors predicting a requirement for hemostasis-derived transfusion.DesignRetrospective cohort.SettingSingle-center, tertiary academic hospital.ParticipantsIn total, 100 consecutive neonates who underwent arterial switch surgery between December 2014 and June 2020.InterventionsRotational thromboelastometry (ROTEM) and coagulation parameters before surgery and before termination of CPB were evaluated. Transfusion of platelets, fresh frozen plasma, and fibrinogen, defined as hemostasis-derived transfusion (HD transfusion), were determined. Patients with and without HD transfusion were compared to identify predictors.Measurements and Main ResultsAfter CPB, fibrinogen was reduced by 24.5% (interquartile range [IQR] 8.9-32.1) to 201 mg/dL (IQR 172-249), resulting in a reduction of FIBTEM A10 by 20% (1.8-33.3) to 8 mm (6-11). The platelet count decreased by a median of 47.2% (25.6-61.3) to 162 × 10³/µL (119-215). However, the median fibrinogen concentration and platelet count remained within normal range. Neonates with abnormal ROTEM results were more likely to receive HD transfusions. The HD transfusions were more likely with lower preoperative FIBTEM maximum clot firmness values (p = 0.031), lower hemoglobin concentrations at termination of CPB (p = 0.02), and longer CPB duration (p = 0.017). Perioperative hemostasis without any HD transfusion was achieved in 64 neonates.ConclusionsGuidance from ROTEM analyses facilitates hemostasis management after neonatal CPB. Circuit miniaturization with transfusion-free CPB is associated with acceptable changes in ROTEM in most patients, and allows sufficient hemostasis without any HD transfusions in most patients.     

Clinical utility of the Quantra® point-of-care haemostasis analyser during urgent cardiac surgery

Coagulopathic bleeding during and after cardiac surgery is associated with increased morbidity and mortality. Viscoelastic testing is increasingly used instead of laboratory testing. Our aim was to compare a new viscoelastic point-of-care device, the Quantra ^® System, with thromboelastography and standard laboratory testing. After ethical approval and with written informed consent, we prospectively recruited adult patients undergoing urgent cardiac surgery at increased risk of bleeding. Clot time and clot stiffness values were compared before, during and after cardiopulmonary bypass. We prospectively recruited 52 patients, of whom 34 (65%) were transfused with red blood cells. Our usual transfusion thresholds for fibrinogen (1.5 g.l⁻¹), platelets (100,000.μl⁻¹), prothrombin time (20 s), activated partial thromboplastin time (48 s) and maximum amplitude on thromboelastography (50 mm) corresponded to Quantra values of fibrinogen clot stiffness 2.0 hPa, platelet clot stiffness 13.5 hPa, clot time 159 s, clot time 183 s and clot stiffness 17.0 hPa, respectively. These Quantra thresholds showed high negative predictive value for low platelets (platelet clot stiffness, 97.4%), prolonged activated partial thromboplastin time (clot time, 92.6%) and reduced maximum amplitude on thromboelastography (clot stiffness, 93.6%). The Quantra predicted clinical need for transfusion of platelets (area under the curve 0.71, p = 0.001) but all tests performed poorly at predicting the need for fresh frozen plasma transfusion. We have shown that point-of-care testing using the novel Quantra system provides useful data for guiding transfusion management.     

Impact of Sonoclot hemostasis analysis after cardiopulmonary bypass on postoperative hemorrhage in cardiac surgery

Purpose The Sonoclot Analyzer provides a functional test of whole blood coagulation by measuring the viscous property of the blood sample. In this study, we used a modified Sonoclot assay, using cuvettes with a glass bead activator containing heparinase, and compared the Sonoclot data before and after cardiopulmonary bypass (CPB) to assess the usefulness in predicting postoperative hemorrhage. Methods In 41 cardiac surgery patients, Sonoclot data were obtained immediately after heparin administration (pre-bypass) and just before protamine administration (post-bypass). Excessive bleeding was defined as chest tube drainage greater than 2 ml·kg⁻¹·h⁻¹ in 1 h during the first 4 h after surgery. Results There were no significant differences in Sonoclot values before and after CPB in patients with acceptable bleeding (n = 29). In patients with excessive bleeding (n = 12), Sonoclot variables reflecting fibrin formation (activated clotting time [ACT], rate of fibrin formation [clot rate], and peak clot signal) were preserved after CPB; however, the variables reflecting platelet-fibrin interaction (time to peak, peak angle, and clot retraction rate) were significantly different from their respective pre-bypass values. Sonoclot analysis showed impairment of clot maturation after CPB in patients with excessive postoperative bleeding. Conclusion Our results suggest that abnormal postoperative hemorrhage can be predicted by Sonoclot analysis with a new glass bead-activated heparinase test performed after CPB.     

经血栓弹力图检测的梗阻性黄疸患者血凝动力学紊乱

目的 通过血栓弹力图检测探究早期梗阻性黄疸对患者凝血功能的影响.方法 前瞻性连续分析31例梗阻性黄疸患者与15 例非黄疸患者的常规凝血指标、血常规、肝功能及血栓弹力图.结果 两组患者的肿瘤类别、年龄等基本资料无统计学差异,黄疸时间为(22±24)d.常规凝血检测结果两组间未见明显差异;尽管梗阻性黄疸组患者血小板数量与无...     

Efficacy of a simple intraoperative transfusion algorithm for nonerythrocyte component utilization after cardiopulmonary bypass

BACKGROUND: Abnormal bleeding after cardiopulmonary bypass (CPB) is a common complication of cardiac surgery, with important health and economic consequences. Coagulation test-based algorithms may reduce transfusion of non-erythrocyte allogeneic blood in patients with abnormal bleeding. METHODS: The authors performed a randomized prospective trial comparing allogeneic transfusion practices in 92 adult patients with abnormal bleeding after CPB. Patients with abnormal bleeding were randomized to one of two groups: a control group following individual anesthesiologist's transfusion practices and a protocol group using a transfusion algorithm guided by coagulation tests. RESULTS: Among 836 eligible patients having all types of elective cardiac surgery requiring CPB, 92 patients developed abnormal bleeding after CPB (incidence, 11%). The transfusion algorithm group received less allogeneic fresh frozen plasma in the operating room after CPB (median, 0 units; range, 0-7 units) than the control group (median, 3 units; range, 0-10 units) (P = 0.0002). The median number of platelet units transfused in the operating room after CPB was 4 (range, 0-12) in the algorithm group compared with 6 (range, 0-18) in the control group (P = 0.0001). Intensive care unit (ICU) mediastinal blood loss was significantly less in the algorithm group. Multivariate analysis demonstrated that transfusion algorithm use resulted in reduced ICU blood loss. The control group also had a significantly greater incidence of surgical reoperation of the mediastinum for bleeding (11.8% vs. 0%; P = 0.032). CONCLUSIONS: Use of a coagulation test-based transfusion algorithm in cardiac surgery patients with abnormal bleeding after CPB reduced non-erythrocyte allogeneic transfusions in the operating room and ICU blood loss.     

The preoperative bleeding time as a predictor of postoperative hemorrhage after cardiopulmonary bypass

To determine whether the preoperative bleeding time, the most reliable indicator of in vivo platelet dysfunction, can prognosticate excessive postoperative hemorrhage and, hence, the need for infusion of platelet concentrations, we studied blood loss versus bleeding time in 43 patients undergoing coronary bypass grafting. There was no correlation between bleeding time and either fall in hemoglobin level (r = 0.04) or chest tube drainage (r = 0.004). In addition, bleeding time did not correlate with the number of units of platelet concentrate (r = 0.12) or packed red cells (r = 0.2) infused. The bleeding time, which has been recommended as an essential screening test before all cardiopulmonary bypass procedures, need not be performed as a preoperative screen in otherwise healthy patients with no history of bleeding abnormalities and a normal coagulation profile.     

Platelet-activated clotting time does not measure platelet reactivity during cardiac surgery.

BACKGROUND: Platelet dysfunction is a major contributor to bleeding after cardiopulmonary bypass (CPB), yet it remains difficult to diagnose. A point-of-care monitor, the platelet-activated clotting time (PACT), measures accelerated shortening of the kaolin-activated clotting time by addition of platelet activating factor. The authors sought to evaluate the clinical utility of the PACT by conducting serial measurements of PACT during cardiac surgery and correlating postoperative measurements with blood loss. METHODS: In 50 cardiac surgical patients, blood was sampled at 10 time points to measure PACT. Simultaneously, platelet reactivity was measured by the thrombin receptor agonist peptide-induced expression of P-selectin, using flow cytometry. These tests were temporally analyzed. PACT values, P-selectin expression, and other coagulation tests were analyzed for correlation with postoperative chest tube drainage. RESULTS: PACT and P-selectin expression were maximally reduced after protamine administration. Changes in PACT did not correlate with changes in P-selectin expression at any time interval. Total 8-h chest tube drainage did not correlate with any coagulation test at any time point except with P-selectin expression after protamine administration (r = -0.4; P = 0.03). CONCLUSIONS: The platelet dysfunction associated with CPB may be a result of depressed platelet reactivity, as shown by thrombin receptor activating peptide-induced P-selectin expression. Changes in PACT did not correlate with blood loss or with changes in P-selectin expression suggesting that PACT is not a specific measure of platelet reactivity.     

Major obstetric haemorrhage: monitoring with thromboelastography,laboratory analyses or both?

BackgroundHaemorrhage is a common cause of morbidity and mortality in the obstetric population. The aim of this study was to compare the use of thromboelastography and laboratory analyses to evaluate haemostasis during major obstetric haemorrhage. A secondary aim was to evaluate correlations between the results of thromboelastography, laboratory analyses and estimated blood loss.MethodsForty-five women with major obstetric haemorrhage and 49 women with blood loss <600 mL were included. The following thromboelastography analyses were performed: time to start of clotting (TEG-R), time to 20 mm of clot firmness (TEG-K), rate of clot growth (TEG-Angle), maximum amplitude of clot (TEG-MA) and lysis after 30 min (TEG-LY30). In addition, platelet count, activated partial thromboplastin time, prothrombin time, fibrinogen, antithrombin and D-dimer were measured.ResultsThromboelastography variables reflecting clot stability and fibrinolysis were decreased in women with massive obstetric haemorrhage compared to women with normal bleeding, while clot initiation was accelerated. Laboratory analyses also showed impaired haemostasis with the most pronounced differences in platelet count, fibrinogen concentration and antithrombin activity. The strongest correlations existed between fibrinogen and TEG-MA and between estimated blood loss and TEG-MA, fibrinogen and antithrombin, respectively.ConclusionsImpaired haemostasis, demonstrated by thromboelastography and laboratory analyses, was found after an estimated blood loss of 2000 mL. Thromboelastography provides faster results than standard laboratory testing which is advantageous in the setting of on-going obstetric haemorrhage. However, laboratory analyses found greater differences in coagulation variables, which correlated better with estimated blood loss.     

Reproductibilité et interchangeabilité du Thromboélastographe®, Sonoclot® et du temps de coagulation activé (Hémochron®), en chirurgie cardiaque

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.