Sonoclot Coagulation Research Articles

Influence of Storage on Red Blood Cell Rheological Properties

Background. It is known that the age of transfused blood is a risk factor for the development of multiple organ failure in surgical patients. However, the character of hemorrheological changes in stored blood as well as the time when they appear remains disputable. We assumed that blood storage was accompanied by a progressive decrease of RBC deformability and rheological disorders. The degree of rheological disturbances should be directly proportional to the number of RBC with altered geometry.Materials and methods. Nine packages of RBC kept in adenine saline solution were examined from the 5th to the 42nd day of storage. RBC deformability index (DI) was determined by micropore filtration technique. RBC shape was estimated by means of scanning electron microscopy. Blood clotting time was measured by Sonoclot coagulation analyzer.Results. Significant alterations of RBC shape started at the second week of storage and progressed during the rest of the storage period. RBC shape changes were accompanied by progressive decrease in DI and increase in hemolysis and acidosis. The correlation index between the percentage of abnormally shaped RBC and DI was −0.81 (P = 0.0258). Blood clotting progressively decreased after 2 weeks of storage, probably due to the exhaustion of some procoagulant plasma factors.Conclusions. Serious hemorrheological disorders, including the decrease in RBC deformability secondary to shape abnormalities, acidosis, and the decrease of blood clotting, start already at the second week of storage and progress up to the end of the storage period. Transfusion of packed RBC older than 7 days may contribute to hemorrheological disorders in critically ill patients.

Analysis of the information content in Sonoclot data and reconstruction of coagulation test variables.

The Sonoclot Coagulation Analyzer is a viscoelastometer used for in vitro analysis of the coagulation process from the start of fibrin formation, through polymerization of the fibrin monomer, platelet interaction, and eventually to clot retraction and lysis. In this paper, we have analyzed series of Sonoclot curves and simultaneously obtained coagulation tests (APT, PT, Fibrinogen, Platelet Count, and D-dimer) from patients who underwent total hip replacements (THA). By using the Principal Component Analysis method (PCA), we found that the most important coagulation test variables as reflected in the Sonoclot signature, are Platelet Count, PT, and Fibrinogen. Also, by using a Back-Propagation Neural Network (BP), we were able to reconstruct the coagulation variables Platelet Count, PT, and Fibrinogen from the Sonoclot curve with a reasonable accuracy. This would also indicate that these three coagulation test variables are most important in determining the appearance of the Sonoclot signature.

Sonoclot coagulation analysis of in-vitro haemodilution with resuscitation solutions.

The colloid and crystalloid solutions used for resuscitation should preferably be free from effects on coagulation. In 10 volunteers, the effects of haemodilution with various concentrations of 0.9% sodium chloride and 4% succinylated gelatin were assessed by Sonoclot analysis, which describes the whole coagulation process. Small and moderate haemodilution (up to 40%) with 0.9% sodium chloride promoted coagulation. Similar haemodilution with 4% succinylated gelatin impaired coagulation, and at 60% haemodilution coagulation was very poor. These findings need to be confirmed in vivo and their clinical relevance determined.

Sonoclot coagulation analysis: A study of test variability

Objective: To test the reproducibility of Sonoclot coagulation analysis (SCA; Sienco Inc, Morrison, CO). The authors wished to determine if the mix/release of the preloaded celite activator in standard Sono-cuvettes could be responsible for the high variation coefficients for SCA parameters with citrated whole blood and if citrated whole blood is optimal for SCA. Design: A prospective trial. Setting: A large academic teaching medical center. Participants: Eight healthy volunteers. Interventions: Repeated blood sampling was performed through indwelling radial artery catheters. Seven different Sonoclot analyzers were used to test seven different types of analysis procedures in the volunteers, involving activators of different types and amounts and in different forms, and the use of citrated or native whole blood. Measurements and Main Results: Two-way and one-way ANOVA, variance, variance analysis, and Tukey's test were used to evaluate differences in SCA methods and volunteer influence. A high variance, with SDs up to 200% of the median values of the SCA parameters with recalcified citrated blood and the standard Sono-cuvette, was confirmed. SCA with native blood and/or the use of other types of preloaded activators, ie, kaolin, significantly ( p < 0.05) reduced this variance. Repeated SCAs further reduced the variance to 10% to 35% of the variance for a single analysis (standard cuvette and native blood). Conclusion: Improvement of the activator in the Sonocuvette, use of native whole blood, and repeated Sonoclot analyses reduced the previously reported high variability of this instrument.

Evaluation of Platelet Function by Sonoclot Analysis Compared with Other Hemostatic Variables in Cardiac Surgery

Platelet function can be easily measured as time to peak (TP) by Sonoclot Coagulation & Platelet Function Analyzer (Sienco Inc., Morrison, CO) analysis. However a correlation between Sonoclot analysis and platelet aggregation, which is accepted as a test of platelet function, has not been established. In this study, we compared TP and collagen-induced whole blood platelet aggregation in 15 patients undergoing cardiac surgery. Two or three blood samples were randomly obtained from each patient before and after cardiopulmonary bypass (CPB). Sonoclot analysis, collagen-induced whole blood aggregation, and laboratory measurement (including platelet count and coagulation profile) were measured. Seventy-two samples were obtained (35 before CPB and 37 after CPB). TP was correlated with collagen-induced whole blood aggregation (r = -0.652), platelet count (r = -0.671), fibrinogen level (r = -0.598), prothrombin time (r = 0.394), activated partial thromboplastin time (r = 0.486), and use of CPB (r = 0.380). Significant predictors of TP for multiple linear regression modeling were collagen-induced whole blood aggregation, platelet count, and fibrinogen level (r = 0.742). In conclusion, Sonoclot analysis TP predicts approximate platelet function in patients undergoing cardiac surgery. Implications: Approximate platelet function can be easily measured as time to peak by Sonoclot analysis. In this study, time to peak was predicted by platelet count, whole blood platelet aggregation, and fibrinogen level for multiple linear regression modeling. (Anesth Analg 1998;87:1228-33)

Effect of Age, Gender, and Platelet Count on Sonoclot Coagulation Analysis in Patients Undergoing Orthopedic Operations

To assess the relationship between Sonoclot coagulation variables and age, gender, or platelet count in surgical patients without coagulation disorders. This study included 136 patients undergoing orthopedic surgical procedures under spinal or epidural anesthesia. Whole blood was withdrawn preoperatively from each patient, and a Sonoclot analysis was performed within 2 minutes after the sample was obtained. The Sonoclot results were considered investigational and not used in the perioperative management of the patients. Variables from the Sonoclot graphs were analyzed statistically to determine any associations with age, gender, or platelet count. The Sonoclot baseline height was decreased in patients with lower hemoglobin levels, older age, and female gender. The upward slope from baseline to inflection (R1) was increased in female patients and older patients. In comparison with patients who had lower platelet counts, patients with higher platelet counts exhibited a shorter time to inflection, increased upward slope from inflection to peak (R2), shorter time to peak, increased downward slope from peak to plateau (R3), decreased time to plateau, and lower plateau height (P < or = 0.01 for all relationships). Sonoclot coagulation analysis reliably evaluates platelet count as an indicator of platelet function. Controlled studies are needed to examine the clinical usefulness of Sonoclot coagulation analysis in the diagnosis and treatment of perioperative coagulopathies and hemorrhagic complications.

A.322 Sonoclot coagulation analysis as a rapid guideline in the HELLP syndrome

A.322 Sonoclot coagulation analysis as a rapid guideline in the HELLP syndrome

Perioperative autotransfusion and functional coagulation analysis in total hip replacement

Functional coagulation analyses like Sonoclot and thromboelastography have not been evaluated during perioperative autotransfusion. We have prospectively studied three different transfusion regimes in 45 patients undergoing total hip arthroplasty. Blood losses were replaced either with heterologous erythrocyte concentrate (group I), intra- and postoperative autotransfusion of blood salvaged with cellsaver technique (group II) or predonated autologous erythrocyte concentrates together with salvaged blood (group III). Routine and functional coagulation analyses with a Sonoclot were performed preoperatively, 6 hours postoperatively (6 h), day 1-5 and 10. An early postoperative hypo- and late postoperative hypercoagulative phase could be detected with Sonoclot signs of platelet function and fibrin deposition in all groups. Sonoclot coagulation analyses better correlated to both blood loss and dextran dosage than APTT and platelet count in the routine coagulation analyses. Functional coagulation analysis has a potential use in individualizing plasmasubstitution and thromboprophylaxis regimes during autotransfusion in THR.

Do Sonoclot Coagulation Parameters Correlate with Thrombelastograph Parameters?

Postoperative hemorrhage is a major cause of morbidity after cardiopulmonary bypass. Timely coagulation test results may aid the clinician in diagnosing and treating coagulopathy. The purpose of this study is to determine if there is any correlation between parameters obtained from two viscoelastic coagulation monitors (Thrombelastograph and Sonoclot). Fifty non-heparinized blood samples were obtained from cardiac surgery patients pre-skin incision or post-Protamine. Each blood sample was placed in the Celite-activated Sonoclot cuvette and native, as well as Celitc-activatcd TEG wells. The parameters compared were: native and Celite TEG split point, r, k, alpha angle, MA, MA60 vs. Sonoclot immersion point, SonACT, R1, shoulder point, time to shoulder, R2, peak, time to peak, R3, retraction point and time to retraction. All viscoelastic parameters were correlated with routine coagulation tests including: ACT, PT, PTT, platelet count, fibrinogen concentration, bleeding time and hematocrit. Simple and multiple regressions were performed on these Thromhelastograph and Sonoclot parameters to determine correlation, if any. Correlations were considered significant if p&lt;0.01 and R2 &gt; 0.6. The Sonoclot R1 correlated significantly with the Thromhelastograph Celite-activated k-time and alpha angle. The Sonoclot shoulder point correlated with the Thrombelastograph Celite-activated MA and Coagulation Index. The Sonoclot R1 and shoulder point correlated with fibrinogen and platelet counts. The Sonoclot time to peak and time to retraction correlated with the PTT. The Sonoclot coagulation parameters generally do not correlate with the Thrombelastograph parameters. The lack of better correlation among all parameters suggests that there are aspects of coagulation that arc detected differently by each monitor. Therefore, the two viscoelastic monitors cannot be substituted for each other.

Persistent hypercoagulation associated with heterotopic ossification in patients with spinal cord injury long after injury has occurred.

Three patients are presented with traumatic spinal cord injury (SCI) complicated by acute heterotopic ossification (HO), and concurrent deep vein thrombosis 15 months, 18 months and 22 years after SCI, accompanied by persistent hypercoagulation. The diagnosis of HO preceded deep vein thrombosis in all three patients. All were treated with etidronate disodium and therapeutic heparin followed by oral anticoagulation. As these patients were not acutely injured, the questions arose as to what predisposed them to deep vein thrombosis and when was the appropriate time to discontinue anticoagulation. Over a course of 3 years following deep vein thrombosis, these patients were monitored for evidence of hypercoagulation by D-dimer assay, plasma fibrinogen estimation, and rate of whole blood clotting by Sonoclot coagulation analyzer. The activity of acute HO was assessed by three-phase bone scan. A steady state of hypercoagulation, reflected by an increase in all three parameters, ran parallel to the extent of acute HO for the entire observation period. Moreover, hypercoagulation was persistently greater during increased acute HO activity even when the warfarin-induced prothrombin time ratio was 1.2-1.5. In addition, as acute heterotopic ossification activity decreased, the test values returned to near normal during warfarin therapy.(ABSTRACT TRUNCATED AT 250 WORDS)

Effect of Methylprednisolone on Intravascular Coagulation and Edema Formation Induced by Venous Occlusion

Cause and effect relations between Intravascular coagulation and increased vascular endothelial permeability have recently been recognized. The purpose of this study was to investigate the effect of high dose methylprednisolone on tissue edema formation and coagulation in canine legs subjected to venous occlusion. Eight mongrel dogs received 30mg/kg methylprednisolone administration intravenously. Eight additional days received normal saline as controls. Hind leg venous pressure was raised to 75mmHg continuously for 5 hours by a tourniquet around the thigh. Venous blood was sampled before tourniquet inflation, six times during tourniquet inflation, and 60 min after tourniquet ination. The sample blood was used for measurement of Sonoclot coagulation analysis, prothrombin time, and activated partial thromboplastin time. At each time of venous blood sampling, circumferences of 3 points of the distal part of the hind leg were measured to assess edema. Coagulation studies indicated initial hypercoagulability, and later hypocoagulability during venous occlusion in the control group. In the methylprednisolone-treated group, coagulation parameters remained unchanged throughout the study. Percent increases in circumferences as indices of edema formation were significantly less in the methylprednisolone-treated group than in the control group. The results suggest that inhibitory action of methylprednisolone on activation of the coagulation system secondary to venous occlusion may be a key factor in maintaining the integrity of endothelial permeability, resulting in less edema formation.

Ｓｏｎｏｃｌｏｔ Ｃｏａｇｕｌａｔｉｏｎ Ａｎａｌｙｚｅｒを用いた凝血学的検査の臨床 Ｉ 正常値と基礎的検討

Basic study on normal and abnormal tracings of sonoclot coagulation analyzer (SCA) was performed. Beginning of fibrinogenesis can be detected earlier by SCA than by thromboelastgram. Recalcified citrated whole blood or plasma can be used. Reproductibility of the tracing was good. Not only the concentrations of hemostatic factors and platelet counts but also Ca2+ concentration, the concentrations of F XII activators, hematocrit value affect the tracing. Normal value of the onset time of Japanese adults, which is said to show the interval between the initiation and the beginning of fibrinogenesis was male: X±2SD=124.5±44.2sec, female: X±2SD=96.6±37sec. The sexual difference is statistically significant (p<0.001). SCA is considered to be applicable to clinical investigation of hemostasis.

Activated Clotting Time (ACT): The Reproducibility of Three Techniques

(J. Extra-Corpor. Technol. 19[3] p. 265-267 Fall 1987, 6 ref.) The ACT has routinely been used to monitor anticoagulation during surgical procedures, including open heart surgery. Since there is no laboratory substrate that can serve as a control for the test, it is important to know the reproducibility of the ACT. This study examined the reproducibility of three ACT techniques using the single syringe method. Before heparinization, a 7cc sample of blood was collected from each of 50 open heart surgery patients. From this sample two Hemochron ACTs (H-ACT), two Sonoclot Coagulation ACTs (SonACT), and two manual ACTs (M-ACT) were simultaneously performed. The mean ± S.D. (seconds) was found to be 105.6 ± 31.8 for the SonACT, 109.7 ± 27.2 for the H-ACT, and 126.8 ± 15.4 for theM-ACT. Five minutes after heparinization the ACTs showed means of 485.5 ± 93.3 for the Son ACT, 455.6 ± 1 01.9 for the HACT, and 471.2 ± 84.9 for the M-ACT. The absolute value of the difference between the paired observations, a function of the reproducibility, was seen to have a mean of 8.8 ± 13.4 for the SonACT, 6.1 ± 7.0 for the H-ACT, and 8.3 ± 7.6 for theM-ACT. Post heparinization, the absolute difference between the paired observations gave means of 90.7 ± 99.7 for the SonACT, 56.7 ± 59.8 for the HACT, and 40.4 ± 45.4 for the M-ACT. Before heparinization, all three techniques gave acceptable results. With heparinization the M-ACT showed the most reproducibility, followed by the H-ACT, while the SonACT provided the least consistent results.

Evaluation of a new dynamic viscometer for measuring the viscosity of whole blood and plasma.

We evaluated a new type of dynamic viscometer, the Sonoclot Coagulation Analyzer, for use in measuring the viscosity of whole-blood and plasma. Such information can be useful in monitoring patients with hyperviscosity syndromes, e.g., from multiple myeloma. A vibrating Teflon or plastic probe continuously measures dynamic viscosity. The instrument can be calibrated to measure a range of viscosities from 0.69 to 23 cP (mN X s X m-2) or more. The coefficient of variation at 0.69 cP was 3-4% for measurements with the Teflon probe, 7-9% with the plastic probe. Viscosity measured at 37 degrees C for plasma and whole-blood samples from 20 normal patients was 1.22 (SD 0.05) cP and 3.63 (SD 0.52) cP, respectively. Dynamic viscosity measured in blood samples from a single source, with contrived hematocrits ranging from 0 to 89%, increased exponentially as a function of hematocrit, confirming previous studies. Overall, we found this instrument simple and quick to operate, producing accurate, precise viscosity measurements over at least a 40-fold range of viscosity.