Evaluation of platelet function by Sonoclot analysis compared with other hemostatic variables in cardiac surgery

Establishment of reference intervals and transfusion criterion for Sonoclot analysis

Sonoclot analyzer has been widely used in many countries. But the reference intervals provided by the manufacturer were derived from only 45 participants, and there was no cut-off value for transfusion for Sonoclot analysis. This study aimed to establish reference intervals and transfusion criterion for Sonoclot analysis. Volunteers were recruited from healthy Chinese adults and patients undergoing cardiac surgery. Blood samples were withdrawn from forearm vein and measured for activated clotting time (ACT), clot rate (CR), platelet function (PF), activated partial thromboplastin time (APTT), fibrinogen concentration (FIB), and platelet count (PLT). The reference intervals were determined by the nonparametric method. Cut-off values were determined by the receiver operating characteristics curve. A total of 135 healthy volunteers and 281 patients were enrolled. The 95% reference intervals were 96-195 s, 22-51 signal U/min, >1.6 for ACT, CR, PF respectively. In the 281 patients, the results of APTT, FIB, PLT, ACT, CR, and PF ranged from 20.5-300.0 s, 0.28-4.11 g/L, (19.0-387.3)×109/L, 80-514 s, 2.9-74 signal U/min, and 0.1-5.1 respectively. The cut-off values for transfusion were >208, ≤14, and ≤1.3 for ACT, CR, PF respectively. The cut-off values of Sonoclot analysis were within the manufacturer's reference intervals, while they were outside the reference intervals established in this study. The results suggested that the manufacturer's reference intervals were not suitable for Chinese. The reference intervals and cut-off values established in this study will be helpful to Chinese patients.

Viscoelastic point-of-care testing to assist with the diagnosis, management and monitoring of haemostasis: a systematic review and cost-effectiveness analysis

BACKGROUND

Patients with substantive bleeding usually require transfusion and/or (re-)operation. Red blood cell (RBC) transfusion is independently associated with a greater risk of infection, morbidity, increased hospital stay and mortality. ROTEM (ROTEM® Delta, TEM International GmbH, Munich, Germany; www.rotem.de), TEG (TEG® 5000 analyser, Haemonetics Corporation, Niles, IL, USA; www.haemonetics.com) and Sonoclot (Sonoclot® coagulation and platelet function analyser, Sienco Inc., Arvada, CO) are point-of-care viscoelastic (VE) devices that use thromboelastometry to test for haemostasis in whole blood. They have a number of proposed advantages over standard laboratory tests (SLTs): they provide a result much quicker, are able to identify what part of the clotting process is disrupted, and provide information on clot formation over time and fibrinolysis.

OBJECTIVES

This assessment aimed to assess the clinical effectiveness and cost-effectiveness of VE devices to assist with the diagnosis, management and monitoring of haemostasis disorders during and after cardiac surgery, trauma-induced coagulopathy and post-partum haemorrhage (PPH).

METHODS

Sixteen databases were searched to December 2013: MEDLINE (OvidSP), MEDLINE In-Process and Other Non-Indexed Citations and Daily Update (OvidSP), EMBASE (OvidSP), BIOSIS Previews (Web of Knowledge), Science Citation Index (SCI) (Web of Science), Conference Proceedings Citation Index (CPCI-S) (Web of Science), Cochrane Database of Systematic Reviews (CDSR), Cochrane Central Register of Controlled Trials (CENTRAL), Database of Abstracts of Reviews of Effects (DARE), Health Technology Assessment (HTA) database, Latin American and Caribbean Health Sciences Literature (LILACS), International Network of Agencies for Health Technology Assessment (INAHTA), National Institute for Health Research (NIHR) HTA programme, Aggressive Research Intelligence Facility (ARIF), Medion, and the International Prospective Register of Systematic Reviews (PROSPERO). Randomised controlled trials (RCTs) were assessed for quality using the Cochrane Risk of Bias tool. Prediction studies were assessed using QUADAS-2. For RCTs, summary relative risks (RRs) were estimated using random-effects models. Continuous data were summarised narratively. For prediction studies, the odds ratio (OR) was selected as the primary effect estimate. The health-economic analysis considered the costs and quality-adjusted life-years of ROTEM, TEG and Sonoclot compared with SLTs in cardiac surgery and trauma patients. A decision tree was used to take into account short-term complications and longer-term side effects from transfusion. The model assumed a 1-year time horizon.

RESULTS

Thirty-one studies (39 publications) were included in the clinical effectiveness review. Eleven RCTs (n=1089) assessed VE devices in patients undergoing cardiac surgery; six assessed thromboelastography (TEG) and five assessed ROTEM. There was a significant reduction in RBC transfusion [RR 0.88, 95% confidence interval (CI) 0.80 to 0.96; six studies], platelet transfusion (RR 0.72, 95% CI 0.58 to 0.89; six studies) and fresh frozen plasma to transfusion (RR 0.47, 95% CI 0.35 to 0.65; five studies) in VE testing groups compared with control. There were no significant differences between groups in terms of other blood products transfused. Continuous data on blood product use supported these findings. Clinical outcomes did not differ significantly between groups. There were no apparent differences between ROTEM or TEG; none of the RCTs evaluated Sonoclot. There were no data on the clinical effectiveness of VE devices in trauma patients or women with PPH. VE testing was cost-saving and more effective than SLTs. For the cardiac surgery model, the cost-saving was £43 for ROTEM, £79 for TEG and £132 for Sonoclot. For the trauma population, the cost-savings owing to VE testing were more substantial, amounting to per-patient savings of £688 for ROTEM compared with SLTs, £721 for TEG, and £818 for Sonoclot. This finding was entirely dependent on material costs, which are slightly higher for ROTEM. VE testing remained cost-saving following various scenario analyses.

CONCLUSIONS

VE testing is cost-saving and more effective than SLTs, in both patients undergoing cardiac surgery and trauma patients. However, there were no data on the clinical effectiveness of Sonoclot or of VE devices in trauma patients.

STUDY REGISTRATION

This study is registered as PROSPERO CRD42013005623.

FUNDING

The NIHR Health Technology Assessment programme.

Diagnosis of overt disseminated intravascular coagulation in critically Ill adults by Sonoclot coagulation analysis

Disseminated intravascular coagulation (DIC) diagnosis is hampered by the limited availability of reliable clinical or laboratory tests. Currently available tests are time consuming and expensive. We investigated whether coagulation and platelet function analyses using the Sonoclot system were suitable for overt DIC diagnosis in critically ill adults. This was an observational diagnostic study performed in 498 patients presenting with an underlying disorder associated with DIC. Overt DIC patients were identified according to an International Society on Thrombosis and Hemostasis (ISTH) score of >5. Coagulation and platelet parameters were analyzed using the Sonoclot system, and compared with ISTH as the gold standard. Receiver operating characteristic curves and area under the curves were used to evaluate the value of the Sonoclot parameters. There were no differences for age or gender between the groups. Significant correlations were observed between activated clotting time (ACT) and ISTH score (r = 0.7; P < 0.001), clot rate (CR) and ISTH score (r = 0.5; P < 0.001), platelet function (PF) and ISTH score (r = -0.6; P < 0.001), and PF and platelet count (r = 0.5; P < 0.001). An ACT cut-off value of 213.5 s alone or combined with CR presented good sensitivity (76.7 and 86.8 %, respectively) and specificity (96.2 and 93.3 %, respectively). Sonoclot analysis can be performed using a point-of-care device that effectively discriminates low and high ISTH scores, and that effectively predicts coagulation dysfunction in patients with overt DIC.

Sonoclot signature analysis in patients with liver disease and its correlation with conventional coagulation studies

Introduction. Liver disease patients have complex hemostatic defects leading to a delicate, unstable balance between bleeding and thrombosis. Conventional tests such as PT and APTT are unable to depict these defects completely. Aims. This study aimed at analyzing the abnormal effects of liver disease on sonoclot signature by using sonoclot analyzer (which depicts the entire hemostatic pathway) and assessing the correlations between sonoclot variables and conventional coagulation tests. Material and Methods. Clinical and laboratory data from fifty inpatients of four subgroups of liver disease, including decompensated cirrhosis, chronic hepatitis, cirrhosis with HCC and acute-on-chronic liver failure were analyzed. All patients and controls were subjected to sonoclot analysis and correlated with routine coagulation parameters including platelet count, PT, APTT, fibrinogen, and D-dimer. Results. The sonoclot signatures demonstrated statistically significant abnormalities in patients with liver disease as compared to healthy controls. PT and APTT correlated positively with SONACT (P < 0.008 and <0.0015, resp.) while platelet count and fibrinogen levels depicted significant positive and negative correlations with clot rate and SONACT respectively. Conclusion. Sonoclot analysis may prove to be an efficient tool to assess coagulopathies in liver disease patients. Clot rate could emerge as a potential predictor of hypercoagulability in these patients.

cDNA cloning of a snake venom metalloproteinase from the eastern diamondback rattlesnake (Crotalus adamanteus), and the expression of its disintegrin domain with anti-platelet effects

A 5' truncated snake venom metalloproteinase was identified from a cDNA library constructed from venom glands of an eastern diamondback rattlesnake (Crotalus adamanteus). The 5'-rapid amplification of cDNA ends (RACE) was used to obtain the 1865 bp full-length cDNA sequence of a snake venom metalloproteinase (CamVMPII). CamVMPII encodes an open reading frame of 488 amino acids, which includes a signal peptide, a pro-domain, a metalloproteinase domain, a spacer, and an RGD-disintegrin domain. The predicted amino acid sequence of CamVMPII showed a 91%, 90%, 83%, and 82% sequence homology to the P-II class enzymes of C. adamanteus metalloproteinase 2, Crotalus atrox CaVMP-II, Gloydius halys agkistin, and Protobothrops jerdonii jerdonitin, respectively. Disintegrins are potent inhibitors of both platelet aggregation and integrin-dependent cell adhesion. Therefore, the disintegrin domain (Cam-dis) of CamVMPII was amplified by PCR, cloned into a pET-43.1a vector, and expressed in Escherichia coli BL21. Affinity purified recombinantly modified Cam-dis (r-Cam-dis) with a yield of 8.5 mg/L culture medium was cleaved from the fusion tags by enterokinase cleavage. r-Cam-dis was further purified by two-step chromatography consisting of HiTrap™ Benzamidine FF column, followed by Talon Metal affinity column with a final yield of 1 mg/L culture. r-Cam-dis was able to inhibit all three processes of platelet thrombus formation including platelet adhesion with an estimated IC(50) of 1 nM, collagen- and ADP-induced platelet aggregation with the estimated IC(50)s of 18 and 6 nM, respectively, and platelet function on clot retraction. It is a potent anti-platelet inhibitor, which should be further investigated for drug discovery to treat stroke patients or patients with thrombotic disorders.

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.

Impairment of coagulation by commonly used resuscitation fluids in human volunteers

BACKGROUND

This study compared the effects of two commonly used resuscitation fluids on whole blood coagulation.

METHODS

1000 ml of two resuscitation fluids each (saline and Gelofusine) were given to eight volunteers in a crossover design with a 2-week washout period. The effect on whole blood coagulation was assessed using the Sonoclot analyzer, a conventional coagulation screen and coagulation markers.

RESULTS

No significant effect was found on whole blood coagulation by giving saline (time to peak clot increased by a mean of 106 s; (95% confidence interval (CI) -140 to 354), whereas Gelofusine delayed the time to peak by a mean of 845 s (95% CI 435 to 1255). By contrast, there was no change in the conventional coagulation screen with either fluid.

CONCLUSION

It was concluded that some resuscitation fluids have an effect on clot formation that is not shown by the conventional coagulation screen, but is disclosed only if the whole coagulation process is studied.

The effects of commonly used resuscitation fluids on whole blood coagulation

OBJECTIVES

Evidence on the effect of crystalloid and colloid resuscitation fluids on coagulation is confusing, with contradictory results from previous studies. This study was performed to test the effect on whole blood coagulation of a range of resuscitation fluids in vitro using a single method at a single dilution.

METHODS

Seven resuscitation fluids were tested in vitro at a dilution of 40%. Whole blood coagulation was measured using a Sonoclot analyser.

RESULTS

A crystalloid/colloid split of effect on coagulation in vitro was not seen. The time to clot formation with Gelofusine, dextran and hydroxyethyl starch was a greatly increased, whereas saline and Haemaccel had little effect, or were slightly procoagulant.

CONCLUSIONS

Some resuscitation fluids have a profound effect on coagulation. The confusion in the literature may result from the effect on coagulation being both fluid and dilution dependent, with no simple crystalloid/colloid split.

Point-of-Care Testing of Hemostasis in Cardiac Surgery

An excessive perioperative blood loss, that requires transfusion of blood products, sometimes occurs in patients undergoing cardiopulmonary bypass for cardiac surgery. Blood loss and transfusion requirements in these patients may be reduced with a better control of heparin treatment and its reversal. Blood component administration in patients with excessive post-cardiopulmonary bypass bleeding has been empiric for a long time due to turnaround times of laboratory coagulation tests. Devices are now available for rapid, point-of-care assessment of hemostasis alterations to allow an appropriate, targeted therapy. In particular, a quick evaluation of platelet and coagulation defects with new point-of-care devices can optimize the administration of pharmacological and transfusion-based therapy in patients with excessive bleeding after cardiopulmonary bypass.

Cardiac surgery and the coagulation system

This review focuses on the activation of the haemostatic system during cardiopulmonary bypass. The interaction of different cascade systems are examined, in particular the relation of inflammation with haemostasis. Novel strategies to supplement or replace heparin for anticoagulation during cardiopulmonary bypass have recently been described. Drug approaches to reduce activation of haemostasis reported during the review period are already well established. Their influence on the inflammatory response may offer interesting perspectives for the future.