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Keywords:

  • abciximab;
  • cytochalasin D;
  • glycoprotein IIb/IIIa;
  • thrombelastography

Abstract

  1. Top of page
  2. Abstract
  3. Introduction
  4. Materials and methods
  5. Results
  6. Discussion
  7. Acknowledgements
  8. References

Summary.  Maximum amplitude (MA) in thrombelastography (TEG) consists of a plasmatic and a platelet component. To assess the magnitude of the plasmatic component, pharmacological approaches have been proposed to eliminate the platelet component. We evaluated the individual and combined effects of abciximab and cytochalasin D on the MA of TEG. Whole blood, platelet-rich plasma (PRP) and homologous platelet-poor plasma (PPP) from 20 healthy volunteers were spiked with abciximab or cytochalasin D or a combination of both and TEGs performed. Abciximab and cytochalasin D decreased MA in all samples. MA of whole blood (18.6 ± 3.1 mm) and PRP (33.7 ± 3.5 mm) spiked with abciximab or cytochalasin D alone (15.0 ± 2.9 mm and 25.0 ± 4.0 mm) were significantly higher when compared with abciximab and cytochalasin D combined (10.4 ± 3.0 and 20.2 ± 3.5 mm). While MA of PRP and homologous PPP were significantly (P < 0.001) different after individual administration of abciximab and cytochalasin D, combination of both abolished this difference (20.2 ± 3.5 mm and 20.4 ± 3.7 mm, P = 0.372). In whole blood of critically ill patients or patients undergoing major surgery there was also a significant difference of MA between abciximab alone and in combination with cytochalasin D (16.5 ± 11.3 mm and 11.3 ± 7.7 mm, P < 0.001). This indicates that in contrast to individual administration of abciximab or cytochalasin D, a combination of both compounds eliminates the platelet-specific effect on MA of TEG tracings.


Introduction

  1. Top of page
  2. Abstract
  3. Introduction
  4. Materials and methods
  5. Results
  6. Discussion
  7. Acknowledgements
  8. References

Blood coagulation is the result of a dynamic interaction between soluble coagulation factors, platelets and the vessel wall [1,2]. Bleeding problems in the perioperative setting are caused by a combination of hemodilution, consumption of platelets and coagulation factors, alterations of platelet function, fibrinolysis, hypothermia, drug effects, e.g. heparin, aprotinin and protamine, and other effects of surgery [3–5]. Routine coagulation tests such as activated partial thromboplastin time (APTT) or prothrombin time (PT) are performed in citrated plasma and provide information about the coagulation time. However, clot quality and the impact of platelets on coagulation, which are strongly altered in the perioperative setting [6,7], are not assessed by these assays. Thrombelastography (TEG) provides information about both coagulation time, represented by the r-time, and clot strength, represented by the maximum amplitude (MA), when it is performed in whole blood and therefore allows the global assessment of the effects of all blood components on the coagulation process [8–11].

The MA in TEG reflects both a plasmatic and a platelet component [9]. In ‘abciximab-modified TEG’ the effect of platelets on MA has been assumed to be completely eliminated by addition of the monoclonal Fab-fragment abciximab (c7E3, ReoPro®), which blocks binding of fibrin and fibrinogen to GPIIb/IIIa receptors of platelets [12]. Recent literature describes differentiation of these two components of MA by comparing ‘standard TEG’ with ‘abciximab-modified TEG’[13–18], allowing a more specific perioperative treatment [17].

Abciximab-mediated inhibition of the platelet component on MA, however, has recently been demonstrated to be incomplete, although MA values decreased to < 30% of control [15]. Experiments using platelet aggregometry also indicate incomplete inhibition of platelet aggregation by abciximab [16,19,20].

Alternatively, cytochalasin D [16,21,22] has been proposed as a tool to eliminate platelet influence on MA by inhibition of platelet cytoskeletal reorganization [23]. There are few data comparing the effects of cytochalasin D and abciximab on MA in TEG, but none that examines whether a combination of these substances would have additional, synergistic effects and thereby enhance the diagnostic significance of TEG tracings.

For this reason, we evaluated the individual and combined effects of abciximab and cytochalasin D on MA in TEG of human samples.

Materials and methods

  1. Top of page
  2. Abstract
  3. Introduction
  4. Materials and methods
  5. Results
  6. Discussion
  7. Acknowledgements
  8. References

Subjects

Healthy volunteers from our medical staff, who had not taken non-steroidal anti-inflammatory agents for at least 2 weeks, gave written informed consent before blood sampling. Blood was collected in 4.5-mL silicone-coated glass tubes containing 0.5 mL of 0.129 m buffered sodium citrate (VACUTAINER®; Becton Dickinson, Meylan, France). Samples were divided into three aliquots. To assess the influence of hematocrit on TEG tracing, the first part was used for whole blood measurements. The other aliquots were centrifuged at 500 × g or 3500 × g for 10 min to obtain platelet-rich plasma (PRP) and platelet-poor plasma (PPP). Platelet count was determined in whole blood, PRP and PPP (Sysmex SF-3000).

Thrombelastographic measurements

TEG was performed on the ROTEG® Coagulation Analyzer (Pentapharm GmbH, Munich, Germany). Clot formation was induced by activation of the intrinsic coagulation pathway as previously described [24,25] using 20 µL 0.2 mol L−1 calcium chloride solution (StartTEG®; NOBIS, Endingen, Germany) and 20 µL intrinsic activator (INTEG-LS Activator®; NOBIS). TEG tracing was automatically started after injection of 300 µL sample by an automatic pipette.

TEG traces were interpreted using standard parameters. These included the reaction time (r), which represents the time delay from activation of the sample to the point where the trace is 1 mm wide; the k-value, which represents the time between the 1 mm wide point to the 20 mm wide point; and maximum amplitude (MA), which represents the widest point of the tracing.

Recent evaluations of MA have revealed, however, that physical and biological properties of clot strength are better reflected by the arbitrary elastic shear modulus (MCE) [26], a parameter that can be derived mathematically from the MA by MCE = (100 × MA)/(100 − MA) (arbitrary units) [27]. MCE is automatically calculated by the ROTEG® device. Since the correlation between MA and MCE is non-linear, it has been proposed that the clot strength of different TEG tracings be compared with MCE rather than MA [13,21,22]. As most previous investigations reported MA as a reflection of clot strength, in the present study we chose to report clot strength using both MA and MCE.

Other measurements

Standard coagulation measurements (PT, APTT and fibrinogen) were performed with the Behring Coagulation System® (BCS). Multifibren U® was used for fibrinogen determination, Thromborel S® for prothrombin time (PT), and Pathrombin SL® for APTT. All reagents were purchased from Dade Behring (Marburg, Germany).

Reproducibility To determine the precision of the method, a blood sample was collected from a healthy volunteer as described above. The sample was analyzed by TEG 10 times consecutively, using the intrinsic pathway for triggering clot formation in citrated whole blood.

Dose–response curve of abciximab on TEG tracing The effect of abciximab on the TEG tracing was determined in four samples of whole blood and homologous PRP from healthy volunteers.

The monoclonal antibody fragment abciximab, stock solution (2 mg mL−1, c7E3-Fab, ReoPro®; Centocor B.V., CB Leiden, The Netherlands), was diluted serially using sterile isotonic saline. Abciximab solution (20 µL) was placed in the measurement cup followed by 20 µL StartTEG®, 20 µL InTEG-LS Aktivator® and 300 µL sample. The resulting final concentrations of abciximab were: 111 µg mL−1; 55.6 µg mL−1; 27.8 µg mL−1; 13.9 µg mL−1; 6.9 µg mL−1; 3.5 µg mL−1; 1.7 µg mL−1; 0.9 µg mL−1. For control experiments, 20 µL isotonic saline were used instead of abciximab solution. TEG tracing was started immediately after addition of the sample without preincubation with abciximab.

Dose–response curve of cytochalasin D on TEG tracing Stock solution of cytochalasin D (Sigma Aldrich, Vienna, Austria) was prepared by dissolving 1 mg cytochalasin D in 1 mL human albumin (Octapharma® 5%; Pharmaceutica, Vienna, Austria). Cytochalasin D stock solution was serially diluted with human albumin resulting in final concentrations of cytochalasin D as follows: 55.6 µg mL−1; 27.8 µg mL−1; 13.9 µg mL−1; 6.9 µg mL−1; 3.5 µg mL−1; 1.7 µg mL−1; 0.9 µg mL−1; 0.4 µg mL−1. TEG tracings were performed using 20 µL cytochalasin D solution as described for abciximab.

Evaluation of the individual and combined effects of abciximab and cytochalasin D on MA and MCE on TEG tracings To evaluate the effects of platelet count on MA and MCE, we used samples from 20 healthy volunteers. TEG traces were performed in whole blood, homologous PRP and homologous PPP. Four measurements were performed in each sample: in the first measurement 10 µL abciximab (final abciximab concentration 55.6 µg mL−1) and in the second measurement 10 µL cytochalasin D (final cytochalasin D concentration 6.9 µg mL−1) were added to 10 µL isotonic saline, reagents and 300 µL sample. In the third measurement 10 µL abciximab and 10 µL cytochalasin D were added to reagents and 300 µL sample. In the fourth measurement 20 µL isotonic saline were added to reagents and 300 µL sample for control.

Effects of abciximab alone and in combination with cytochalasin D in patient samples To evaluate the benefit of the combination of abciximab and cytochalasin D compared with abciximab alone, 28 samples from critically ill patients (mainly undergoing major surgery, Table 1) were investigated. TEGs were performed in whole blood. Three measurements were performed with each sample: in the first measurement 10 µL abciximab (final abciximab concentration 55.6 µg mL−1) were added to10 µL isotonic saline, reagents and 300 µL sample. In the second measurement 10 µL abciximab (final concentration 55.6 µg mL−1) and 10 µL cytochalasin D (final concentration 6.9 µg mL−1) were added to reagents and 300 µL sample. In the third measurement 20 µL isotonic saline were added to reagents and 300 µL sample to provide control values.

Table 1.  Clinical data and basic laboratory findings of patient samples (n = 28)
  • *

    One sample was excluded from the calculation as no clot was detectable.

  • st. p., status post.

Male (%)64
Female (%)36
Cardiac surgery (intraoperative) (%)11
Cardiac surgery (postoperative) (%)57
Bleeding (st. p. sectio) (ausschreiben) (%)4
Polytrauma (%)7
Aneurisma abdominalis (%)4
Thrombopenia (st. p. heart-lung transplantation, CMV infection) (%)4
Abdominal subcutaneous hematoma (oral anticoagulation) (%)4
Essential thrombocythemia (%)4
Mamma reduction (%)4
Bougierauge (esophageal carcinoma) (%)4
Age (years), mean ± SD56 ± 25
Platelets ( × 103 µL−1), mean ± SD116 ± 94
Hematocrit (%), mean ± SD28.5 ± 4.6
Prothrombin rime (%), mean ± SD66 ± 27
Activated partial thromboplastin time (s), mean ± SD68 ± 36*
Thrombin time (s), mean ± SD25 ± 16*

Statistical analysis

Data calculations were performed with MS Excel. Data groups were compared with a paired t-test. P < 0.05 was considered statistically significant.

Results

  1. Top of page
  2. Abstract
  3. Introduction
  4. Materials and methods
  5. Results
  6. Discussion
  7. Acknowledgements
  8. References

In citrated whole blood from 20 healthy donors, median platelet count was 2.07 × 105 µL−1 (range 1.36 × 105 µL−1 to 3.14 × 105 µL−1), median hematocrit was 36.6% (range 29.5–42.5%), median PT was 98% (range 85–118%), median APTT was 32.6 s (range 27.6–38.3 s) and median fibrinogen was 241 mg dL−1 (range 189 mg dL−1 to 411 mg dL−1).

In PRP median platelet count was 3.96 × 105 µL−1 (range 3.62 × 105 µL−1 to 6.50 × 105 µL−1) and in PPP median platelet count was 0.028 × 105 µL−1 (range < 0.01 × 105 µL−1 to 0.66 × 105 µL−1). Compared with homologous PRP, platelet count in PPP was decreased by > 80% in all samples.

Reproducibility

TEG with intrinsic activation demonstrated a coefficient of variation (CV) for MA and MCE of 2.3% (mean ± SD 62.0 ± 1.4 mm) and 5.8% (mean ± SD 162.0 ± 9.9 U), respectively.

Dose–response curve of abciximab on TEG tracing

Increasing concentrations of abciximab significantly reduced clot strength in whole blood. A concentration of 3.5 µg mL−1 abciximab reduced clot strength to 50%, a concentration of 13.9 µg mL−1 reduced clot strength to 15%. Higher concentrations of abciximab did not further reduce clot strength (Fig. 1, Table 2).

image

Figure 1. Dose–response curve of abciximab from four samples of whole blood from healthy volunteers. Relative reduction of clot strength was calculated on the basis of the arbitrary elastic shear modulus (MCE). Platelet count and fibrinogen values for each sample were: sample 1, platelets 237 × 103 µL−1, fibrinogen 240 mg dL−1; sample 2, platelets 191 × 103 µL−1, fibrinogen 257 mg dL−1; sample 3, platelets 176 × 103 µL−1, fibrinogen 295 mg dL−1; sample 4, platelets 273 × 103 µL−1, fibrinogen 304 mg dL−1.

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Table 2.  Medium and standard deviation of maximum amplitude (MA) and arbitrary elastic shear modulus (MCE) values of dose–response curve of abciximab or cytochalasin D (n = 4)
Final concentration of abciximab, µg mL−1013.927.8111
 MA in mm (MCE in units)
Whole blood64 ± 2.521 ± 1.222 ± 2.520 ± 1.1
(181 ± 16.8)(27 ± 1.9)(29 ± 3.9)(25 ± 1.9)
PRP71 ± 2.231 ± 0.830 ± 1.328 ± 1.9
(239 ± 25)(44 ± 2.3)(44 ± 2.4)(38 ± 3.6)
Final concentration of cytochalsin D, µg mL−106.913.955.6
 MA in mm (MCE in units)
Whole blood64 ± 2.512 ± 2.312 ± 1.911 ± 1.0
(181 ± 16.8)(14 ± 2.9)(13 ± 3.0)(13 ± 1.1)
PRP71 ± 2.223 ± 1.724 ± 1.523 ± 2.0
(239 ± 25)(30 ± 2.9)(31 ± 2.4)(29 ± 3.1)

When we used PRP instead of whole blood, the dose–response curve of abciximab was similar to whole blood. Again, increasing concentrations of abciximab to 13.9 µg mL−1 significantly reduced clot strength with no further inhibition at higher concentrations (Fig. 2A).

image

Figure 2. Dose–response curves of abciximab (A) and cytochalasin D (B) in a representative sample from a normal volunteer. Relative reduction of clot strength was calculated by the arbitrary elastic shear modulus (MCE). Addition of cytochalasin D to the sample resulted in a marked reduction of MCE in whole blood and in homologous platelet-rich plasma (PRP). Addition of abciximab produced a sigmoid dose–response curve. The dose–response curve of abciximab (A) and cytochalasin D (B) in homologous PRP was similar to that of whole blood; however, MCE values of homologous PRP were in all cases higher than corresponding MCE values in whole blood.

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Dose–response curve of cytochalasin D on TEG tracing

Increasing concentrations of cytochalasin D significantly reduced clot strength in whole blood. At a cytochalasin D concentration of 6.9 µg mL−1, clot strength reached a plateau and subsequent increases of cytochalasin D concentration did not further reduce clot strength (Table 2).

The dose–response curve of cytochalsin D in PRP was similar to whole blood. Again, a plateau effect was observed at a cytochalasin D concentration of 6.9 µg mL−1 and, similar to abciximab, increases of the concentration of cytochalasin D did not further reduce clot strength (Fig. 2B).

Evaluation of the individual and combined effects of abciximab and cytochalasin D on MA and MCE on TEG tracing

Addition of abciximab or cytochalasin D alone or in combination significantly reduced MA and MCE in whole blood, PRP and PPP.

In whole blood and PRP, the inhibitory effect of the combination of cytochalasin D and abciximab was greater than the effect of each of the two components alone (P < 0.001). In PPP, however, cytochalasin D and abciximab and the combination of both were equally effective (Table 3).

Table 3.  Effect of abciximab and cytochalasin D on maximum amplitude (MA) and arbitrary elastic shear modulus (MCE) alone or in combination on thrombelastography (TEG) tracing of 20 healthy volunteers
 WB (n = 20)PRP (n = 20)PPP (n = 20)
  1. MA (mm) and MCE (units in parenthesis) of all samples spiked with abciximab and cytochalasin D alone or in combination are significantly (P < 0.001) lower than control. *P < 0.001 vs. abciximab-spiked samples; **P < 0.001 vs. cytochalasin D-spiked samples; ***P < 0.001 vs. homologous PPP; ****P = 0.372 vs. homologous PPP; *****P = 0.45 vs. homologous PPP. WB, Whole blood; PRP, platelet-rich plasma; PPP, platelet-poor plasma; n = 20.

Control60.4 ± 3.976.8 ± 3.2***35.0 ± 10.9
(155.1 ± 26.5)(338.6 ± 59.6)(58.5 ± 29.5)
Abciximab (55.6 µg mL−1)18.6 ± 3.133.7 ± 3.5***21.6 ± 4.1
(23.2 ± 5.0)(51.2 ± 8.5)(28.0 ± 7.2)
Cytochalasin D (6.9 µg mL−1)15.0 ± 2.9*25.0 ± 4.0*,***20.9 ± 4.0
(17.7 ± 4.2)(33.8 ± 7.7)(26.6 ± 6.6)
Abciximab (55.6 µg mL−1) +10.4 ± 3.0*,**20.2 ± 3.5*,**,****20.4 ± 3.7
 cytochalasin D (6.9 µg mL−1)(11.8 ± 4.0)(25.6 ± 6.0)*****(26.1 ± 7.1)

Notably, MA and MCE were similar in PRP and PPP (P = 0.45) when the combination of cytochalasin D and abciximab was used, indicating that the influence of platelets was completely eliminated.

TEG tracings from PRP and whole blood from one typical sample are shown in Fig. 3.

image

Figure 3. Typical thrombelastographic tracings of one sample using abciximab and cytochalasin D alone or in combination in whole blood, platelet-rich plasma (PRP) and platelet-poor plasma (PPP). Platelet count was 228 × 103 µL−1 in whole blood and 641 × 103 µL−1 in PRP. Standard coagulation values were within normal limits: fibrinogen 339 mg dL−1; prothrombin time (PT) 109%; activated partial thromboplastin time (APTT) 30 s. Maximum amplitude (MA) and arbitrary elastic shear modulus (MCE) values decrease after addition of abciximab (55.6 µg mL−1) compared with MA and MCE of PRP control and whole-blood control. When abciximab (55.6 µg mL−1) and cytochalasin D (6.9 µg mL−1) were both added to the sample, MA and MCE values further decreased compared with the TEG tracing when abciximab was added alone. WB, Whole blood; CD, cytochalasin D.

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Effects of abciximab alone and in combination with cytochalasin D in patient samples

Patient characteristics and basic laboratory data are given in Table 1. In standard TEG, mean MA and MCE were 52.4 mm (±12.7 mm) and 129 U (±85.1 U), respectively. When abciximab alone was added to whole blood, mean MA and MCE were 16.5 mm (±11.3 mm) and 19.5 U (±11.5 U), respectively. However, when abciximab and cytochalasin D were used in combination, MA and MCE were 11.3 mm (±7.7 mm) and 13.5 U (±10.1 U). The reduction of MCE by abciximab alone or in combination with cytochalasin D was similar to that seen in healthy volunteers; MA and MCE were significantly lower when abciximab and cytochalasin D were combined compared with samples spiked with abciximab alone (P < 0.001, Fig. 4). There was no correlation between platelet count and the difference in MCE between samples spiked with abciximab alone and samples spiked with abciximab and cytochalasin D in combination (r = 0.09).

image

Figure 4. Relative reduction of clot strength by abciximab alone or abciximab and cytochalasin D in combination in samples from healthy volunteers (n = 20) and critically ill patients (n = 28). Relative reduction of clot strength was calculated using the arbitrary elastic shear modulus (MCE). In samples of healthy volunteers and patients, the combination of abciximab and cytochalasin D caused a significantly greater reduction of clot strength compared with abciximab alone. However, there was a greater variability in samples of patients compared with healthy volunteers. *P < 0.001.

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Discussion

  1. Top of page
  2. Abstract
  3. Introduction
  4. Materials and methods
  5. Results
  6. Discussion
  7. Acknowledgements
  8. References

Unlike common routine coagulation tests, TEG provides estimates of both coagulation time and clot strength [8–11,26,27]. Clot strength has been broken down into a platelet and a plasmatic component by comparing standard TEG and abciximab-modified TEG [13–18]. Addition of abciximab has been suggested to eliminate completely the platelet component of MA [16]. As MA and MCE in PRP spiked with abciximab alone were significantly higher compared with homologous PPP spiked with abciximab, our results demonstrate that abciximab only incompletely eliminates platelet influence on MA and MCE. Although abciximab dose-dependently reduced MA and MCE, a plateau was reached at a concentration of 16 µg mL−1 without further effects at higher doses, and a similar saturation phenomenon was observed for cytochalasin D.

In dose–response curves performed in whole blood as well as in PRP, MA and MCE were lower in samples spiked with high concentrations of cytochalasin D than in those with abciximab. The greater effect of cytochalasin D alone thus supports the hypothesis that the platelet component of MA and MCE cannot be completely eliminated with abciximab.

Several mechanisms may be responsible for the residual influence of platelets on MA and MCE in the presence of high concentrations of abciximab. GPIIb/IIIa receptors are localized in both platelet membrane and intracelluar granula [28]. In resting platelets, intracellular GPIIb/IIIa receptors reversibly bind to intracellular fibrinogen [29,30].

Stimulation of platelets by different agonists induces multiple effects, including activation of intracellular GPIIb/IIIa receptors by reorganization of the cytoskeleton [31] and subsequent irreversible binding of fibrinogen [32,33]. Once translocated to the cell surface, these complexes remain functional as they are not accessible to abciximab [34]. By light transmission aggregometry, Gawaz et al. [19] demonstrated a strong association between the expression of ligand-bound GPIIb/IIIa on the platelet surface and residual platelet aggregation despite high concentrations of abciximab. In TEG, a similar mechanism might explain the incomplete inhibition of the platelet component by abciximab, in particular as we used fairly high concentrations of abciximab, sufficient to saturate all GPIIb/IIIa receptors.

Stimulation of platelets results in reorganization of the cytoskeleton [31]. Cytochalasin D inhibits the reorganization of the cytoskeleton and prevents irreversible binding of fibrinogen to GPIIb/IIIa receptors [23,29,30]. As, in contrast to abciximab, cytochalasin D affects both surface and intracellular GPIIb/IIIa receptors, we hypothesized that a combination of cytochalasin D and abciximab would reinforce reduction of MA and MCE. In fact, in whole blood and PRP, the lowest MA and MCE were achieved by combining cytochalasin D and abciximab, compared with cytochalasin D and abciximab used alone.

Further, the effectiveness of the combination of cytochalasin D and abciximab in eliminating the influence of platelets on clot strength was shown by the comparison of MA of PRP and homologous PPP, both spiked with abciximab and cytochalasin D. No difference was seen when the MA and MCE of PRP and PPP were compared.

To evaluate the practical implications of these findings, samples from patients undergoing major surgery were analyzed. As expected, MA and MCE were significantly lower when abciximab and cytochalasin D were combined than when abciximab was used alone. Compared with healthy volunteers, there was a greater variation in MA and MCE in patient samples, which reflects the variability of hemostatic conditions in these patients. However, the effects on MA and MCE of abciximab, and the combination of abciximab and cytochalasin D, were similar to those seen in healthy volunteers. Surprisingly, this difference in MCE was independent of platelet count and also emerged in samples with low platelet count. Hence, if one assumes that abciximab-modified TEG represents the plasmatic component of maximum amplitude, the platelet component of clot strength will be underestimated and the plasmatic component of clot strength will be overestimated.

While several studies demonstrated the usefulness of standard TEG in transfusion management [35–37], it was beyond the scope of this study to evaluate the clinical utility of the modified TEG. Thus prospective clinical trials are now required to evaluate the clinical relevance of the modified TEG using abciximab and cytochalasin D in combination rather than abciximab alone.

We suggest that a combination of abciximab and cytochalasin D eliminates the influence of platelets on MA and MCE in TEG more effectively than the individual compounds alone. This allows a better estimation of platelet and plasmatic components of clot strength and may ultimately improve transfusion management in major surgery.

Acknowledgements

  1. Top of page
  2. Abstract
  3. Introduction
  4. Materials and methods
  5. Results
  6. Discussion
  7. Acknowledgements
  8. References

We thank Eugenia Lamont for editing the manuscript.

References

  1. Top of page
  2. Abstract
  3. Introduction
  4. Materials and methods
  5. Results
  6. Discussion
  7. Acknowledgements
  8. References
  • 1
    Hoffman M, Monroe DM. A cell-based model of hemostasis. Thromb Haemost 2001; 85: 95865.
  • 2
    Hogan KA, Weiler H, Lord ST. Mouse models in coagulation. Thromb Haemost 2002; 87: 56374.
  • 3
    Ozier Y, Steib A, Ickx B, Nathan N, Derlon A, Guay J, De Moerloose P. Haemostatic disorders during liver transplantation. Eur J Anaesthesiol 2001; 18: 20818.
  • 4
    Raymond PD, Marsh NA. Alterations to haemostasis following cardiopulmonary bypass and the relationship of these changes to neurocognitive morbidity. Blood Coagul Fibrinolysis 2001; 12: 60118.
  • 5
    Spiess BD. Maintenance of homeostasis in coagulation during cardiopulmonary bypass. J Cardiothorac Vasc Anesth 1999; 13: 25.
  • 6
    Kestin AS, Valeri CR, Khuri SF, Loscalzo J, Ellis PA, MacGregor H, Birjiniuk V, Ouimet H, Pasche B, Nelson MJ. The platelet function defect of cardiopulmonary bypass. Blood 1993; 82: 10717.
  • 7
    Kralisz U, Mussur M, Jegier B, Pawlicki L, Majewska E, Iwaszkiewicz A, Ligocka A, Kowalski J, Zaslonka J, Cierniewski C. Activation of blood platelets after percutaneous transluminal coronary angioplasty and coronary artery bypass graft surgery. J Thromb Thrombolysis 2000; 10: 25564.
  • 8
    Srinivasa V, Gilbertson LI, Bhavani-Shankar K. Thromboelastography: where is it and where is it heading? Int Anesthesiol Clin 2001; 39: 3549.
  • 9
    Vig S, Chitolie A, Bevan DH, Halliday A, Dormandy J. Thromboelastography: a reliable test? Blood Coagul Fibrinolysis 2001; 12: 55561.
  • 10
    Mallett SV, Cox DJ. Thrombelastography. Br J Anaesth 1992; 69: 30713.
  • 11
    Salooja N, Perry DJ. Thrombelastography. Blood Coagul Fibrinolysis 2001; 12: 32737.
  • 12
    Coller BS, Peerschke EI, Scudder LE, Sullivan CA. A murine monoclonal antibody that completely blocks the binding of fibrinogen to platelets produces a thrombasthenic-like state in normal platelets and binds to glycoproteins IIb and/or IIIa. J Clin Invest 1983; 72: 32538.
  • 13
    Kettner SC, Panzer OP, Kozek SA, Seibt FA, Stoiser B, Kofler J, Locker GJ, Zimpfer M. Use of abciximab-modified thrombelastography in patients undergoing cardiac surgery. Anesth Analg 1999; 89: 5804.
  • 14
    Reid TJ, Snider R, Hartman K, Greilich PE, Carr ME, Alving BM. A method for the quantitative assessment of platelet-induced clot retraction and clot strength in fresh and stored platelets. Vox Sang 1998; 75: 2707.
  • 15
    Greilich PE, Alving BM, O'Neill KL, Chang AS, Reid TJ. A modified thromboelastographic method for monitoring c7E3 Fab in heparinized patients. Anesth Analg 1997; 84: 318.
  • 16
    Khurana S, Mattson JC, Westley S, O'Neill WW, Timmis GC, Safian RD. Monitoring platelet glycoprotein IIb/IIIa–fibrin interaction with tissue factor-activated thromboelastography. J Lab Clin Med 1997; 130: 40111.
  • 17
    Koster A, Kukucka M, Fischer T, Hetzer R, Kuppe H. Evaluation of post-cardiopulmonary bypass coagulation disorders by differential diagnosis with a multichannel modified thromboelastogram: a pilot investigation. J Extra Corpor Technol 2001; 33: 1538.
  • 18
    Calatzis AN, Haas S, Gödje O, Calatzis AL, Hipp R, Walenga JM. Thrombelastographic coagulation monitoring during cardiovascular surgery with the roTEG coagulation analyzer. In: PifarréR, ed. Management of Bleeding in Cardiovascular Surgery. Philadelphia: Hanley and Belfus, Inc., 2000: 21526.
  • 19
    Gawaz M, Ruf A, Pogatsa-Murray G, Dickfeld T, Rudiger S, Taubitz W, Fischer J, Muller I, Meier D, Patscheke H, Schomig A. Incomplete inhibition of platelet aggregation and glycoprotein IIb-IIIa receptor blockade by abciximab: importance of internal pool of glycoprotein IIb-IIIa receptors. Thromb Haemost 2000; 83: 91522.
  • 20
    Kleiman NS, Raizner AE, Jordan R, Wang AL, Norton D, Mace KF, Joshi A, Coller BS, Weisman HF. Differential inhibition of platelet aggregation induced by adenosine diphosphate or a thrombin receptor-activating peptide in patients treated with bolus chimeric 7E3 Fab: implications for inhibition of the internal pool of GPIIb/IIIa receptors. J Am Coll Cardiol 1995; 26: 166571.
  • 21
    Nielsen VG, Geary BT. Thoracic aorta occlusion-reperfusion decreases hemostasis as assessed by thromboelastography in rabbits. Anesth Analg 2000; 91: 51721.
  • 22
    Nielsen VG, Geary BT, Baird MS. Evaluation of the contribution of platelets to clot strength by thromboelastography in rabbits: the role of tissue factor and cytochalasin D. Anesth Analg 2000; 91: 359.
  • 23
    Olorundare OE, Simmons SR, Albrecht RM. Cytochalasin D and E: effects on fibrinogen receptor movement and cytoskeletal reorganization in fully spread, surface-activated platelets: a correlative light and electron microscopic investigation. Blood 1992; 79: 99109.
  • 24
    Boldt J, Haisch G, Suttner S, Kumle B, Schellhase F. Are lactated Ringer's solution and normal saline solution equal with regard to coagulation? Anesth Analg 2002; 94: 37884.
  • 25
    Fries D, Innerhofer P, Klingler A, Berresheim U, Mittermayr M, Calatzis A, Schobersberger W. The effect of the combined administration of colloids and lactated Ringer's solution on the coagulation system. An in vitro study using Thrombelastograph® Coagulation Analysis (ROTEG®). Anesth Analg 2002; 94: 12807.
  • 26
    Chandler WL. The thromboelastography and the thromboelastograph technique. Semin Thromb Hemost 1995; 21 (Suppl. 4): 16.
  • 27
    Hartert H, Schaeder JA. The physical and biological constants of thrombelastography. Biorheology 1962; 1: 319.
  • 28
    Phillips DR, Charo IF, Parise LV, Fitzgerald LA. The platelet membrane glycoprotein IIb-IIIa complex. Blood 1988; 71: 83143.
  • 29
    Bennett JS, Zigmond S, Vilaire G, Cunningham ME, Bednar B. The platelet cytoskeleton regulates the affinity of the integrin alpha(IIb)beta(3) for fibrinogen. J Biol Chem 1999; 274: 253017.
  • 30
    Fox JE, Shattil SJ, Kinlough-Rathbone RL, Richardson M, Packham MA, Sanan DA. The platelet cytoskeleton stabilizes the interaction between alphaIIbbeta3 and its ligand and induces selective movements of ligand-occupied integrin. J Biol Chem 1996; 271: 700411.
  • 31
    Torti M, Festetics ET, Bertoni A, Sinigaglia F, Balduini C. Agonist-induced actin polymerization is required for the irreversibility of platelet aggregation. Thromb Haemost 1996; 76: 4449.
  • 32
    Shattil SJ, Kashiwagi H, Pampori N. Integrin signaling: the platelet paradigm. Blood 1998; 91: 264557.
  • 33
    Plow EF, Haas TA, Zhang L, Loftus J, Smith JW. Ligand binding to integrins. J Biol Chem 2000; 275: 217858.
  • 34
    Legrand C, Dubernard V, Nurden AT. Studies on the mechanism of expression of secreted fibrinogen on the surface of activated human platelets. Blood 1989; 73: 122634.
  • 35
    Royston D, Von Kier S. Reduced haemostatic factor transfusion using heparinase-modified thrombelastography during cardiopulmonary bypass. Br J Anaesth 2001; 86: 5758.
  • 36
    Shore-Lesserson L, Manspeizer HE, DePerio M, Francis S, Vela-Cantos F, Ergin MA. Thromboelastography-guided transfusion algorithm reduces transfusions in complex cardiac surgery. Anesth Analg 1999; 88: 3129.
  • 37
    Spiess BD, Gillies BS, Chandler W, Verrier E. Changes in transfusion therapy and reexploration rate after institution of a blood management program in cardiac surgical patients. J Cardiothorac Vasc Anesth 1995; 9: 16873.