Artificial colloids impair haemostasis. An in vitro study using thromboelastometry coagulation analysis

Azolo[1,5-a]pyrimidines and Their Condensed Analogs with Anticoagulant Activity

Hypercytokinemia, or cytokine storm, is one of the severe complications of viral and bacterial infections, involving the release of abnormal amounts of cytokines, resulting in a massive inflammatory response. Cytokine storm is associated with COVID-19 and sepsis high mortality rate by developing epithelial dysfunction and coagulopathy, leading to thromboembolism and multiple organ dysfunction syndrome. Anticoagulant therapy is an important tactic to prevent thrombosis in sepsis and COVID-19, but recent data show the incompatibility of modern direct oral anticoagulants and antiviral agents. It seems relevant to develop dual-action drugs with antiviral and anticoagulant properties. At the same time, it was shown that azolo[1,5-a]pyrimidines are heterocycles with a broad spectrum of antiviral activity. We have synthesized a new family of azolo[1,5-a]pyrimidines and their condensed polycyclic analogs by cyclocondensation reactions and direct CH-functionalization and studied their anticoagulant properties. Five compounds among 1,2,4-triazolo[1,5-a]pyrimidin-7-ones and 5-alkyl-1,3,4-thiadiazolo[3,2-a]purin-8-ones demonstrated higher anticoagulant activity than the reference drug, dabigatran etexilate. Antithrombin activity of most active compounds was confirmed using lipopolysaccharide (LPS)-treated blood to mimic the conditions of cytokine release syndrome. The studied compounds affected only the thrombin time value, reliably increasing it 6.5–15.2 times as compared to LPS-treated blood.

Biodegradability of Novel Polylactide and Polycaprolactone Materials with Bacteriostatic Properties Due to Embedded Birch Tar in Different Environments

The microbial biodegradation of new PLA and PCL materials containing birch tar (1-10% v/v) was investigated. Product of dry distillation of birch bark (Betula pendula Roth) was added to polymeric materials to obtain films with antimicrobial properties. The subject of the study was the course of enzymatic degradation of a biodegradable polymer with antibacterial properties. The results show that the type of the material, tar concentration, and the environment influenced the hydrolytic activity of potential biofilm degraders. In the presence of PCL films, the enzyme activities were higher (except for α-D-glucosidase) compared to PLA films. The highest concentration of birch tar (10% v/v) decreased the activity of hydrolases produced by microorganisms to the most significant extent; however, SEM analysis showed the presence of a biofilm even on plastics with the highest tar content. Based on the results of the biological oxygen demand (BOD), the new materials can be classified as biodegradable but, the biodegradation process was less efficient when compared to plastics without the addition of birch tar.

A randomised controlled trial of succinylated gelatin (4%) fluid on urinary acute kidney injury biomarkers in cardiac surgical patients

Background

Fluid resuscitation is frequently required for cardiac surgical patients admitted to the intensive care unit. The ideal fluid of choice in regard to efficacy and safety remains uncertain. Compared with crystalloid fluid, colloid fluid may result in less positive fluid balance. However, some synthetic colloids are associated with increased risk of acute kidney injury (AKI). This study compared the effects of succinylated gelatin (4%) (GEL) with compound sodium lactate (CSL) on urinary AKI biomarkers in patients after cardiac surgery.

Methods

Cardiac surgical patients who required an intravenous fluid bolus of at least 500 mL postoperatively were randomly allocated to receive GEL or CSL as the resuscitation fluid of choice for the subsequent 24 h. Primary outcomes were serial urinary neutrophil gelatinase-associated lipocalin (NGAL) and cystatin C concentrations measured at baseline, 1 h, 5 h and 24 h after enrolment, with higher concentrations indicating greater kidney injury. Secondary biomarker outcomes included urinary clusterin, α1-microglobulin and F₂-isoprostanes concentrations. Differences in change of biomarker concentration between the two groups over time were compared with mixed-effects regression models. Statistical significance was set at P < 0.05.

Results

Forty cardiac surgical patients (n = 20 per group) with similar baseline characteristics were included. There was no significant difference in the median volume of fluid boluses administered over 24 h between the GEL (1250 mL, Q1–Q3 500–1750) and CSL group (1000 mL, Q1–Q3 500–1375) (P = 0.42). There was a significantly greater increase in urinary cystatin C (P < 0.001), clusterin (P < 0.001), α1-microglobulin (P < 0.001) and F₂-isoprostanes (P = 0.020) concentrations over time in the GEL group, compared to the CSL group. Change in urinary NGAL concentration (P = 0.68) over time was not significantly different between the groups. The results were not modified by adjustment for either urinary osmolality or EuroSCORE II predicted risk of mortality.

Conclusions

This preliminary randomised controlled trial showed that use of succinylated gelatin (4%) for fluid resuscitation after cardiac surgery was associated with increased biomarker concentrations of renal tubular injury and dysfunction, compared to crystalloid fluid. These results generate concern that use of intravenous gelatin fluid may contribute to clinically relevant postoperative AKI.

Trial registration ANZCTR.org.au, ACTRN12617001461381. Registered on 16th October, 2017, http://www.anzctr.org.au/Trial/Registration/TrialReview.aspx?id=373619&isReview=true.

Supplementary Information

The online version contains supplementary material available at 10.1186/s40635-021-00412-9.

The impact of crystalloid versus colloid on coagulation as measured by thromboelastometry in term parturients: an in vitro study

OBJECTIVE

A pilot study to examine the impact of crystalloid versus albumin hemodilution in vitro on coagulation using thromboelastometry in pregnant patients.

METHODS

This prospective, observational pilot study included seventy-six pregnant patients at term (≥37 weeks) without history of bleeding or clotting disorder or on anticoagulation. Blood was collected and diluted with either Plasma-Lyte or albumin at the following levels: 0%, 20%, 25%, 30%, 35%, 40%, 45%, 55%, 60%, 65%, 70%, 75%, 80%. Thromboelastometry was performed to assess for coagulation changes.

RESULTS

There was a small, statistically significant difference in the FIBTEM A5 between the Plasma-Lyte and albumin samples. However, the predicted probability of coagulopathy, using FIBTEM A5 less than 12 mm, was not different between the groups at any dilution. There was no difference in EXTEM clotting time at low-moderate levels of hemodilution. At dilutions above 40%, the albumin group had a significantly greater prolongation in clotting time compared to the Plasma-Lyte group.

CONCLUSION

When albumin is used at low-moderate levels of hemodilution in vitro in parturients there is no additional risk of coagulopathy compared to hemodilution with crystalloid. Given that colloids are frequently used to restore intravascular volume during massive hemorrhage, these results support that during early stages of hemorrhage, albumin may not contribute to additional coagulopathy beyond that of hemodilution, although further in vivo studies are needed.

Intravenous Fluid Administration and the Coagulation System

Intravenous fluid administration in veterinary patients can alter coagulation function by several mechanisms. Both crystalloid and colloid fluids cause hemodilution, reducing platelet count and plasma coagulation protein concentrations. Hemodilution is associated with a hypercoagulable effect at low dilutions and a hypocoagulable effect at higher dilutions. Composition of crystalloid fluids likely has a minor effect, primarily dependent on fluid ion composition. Hypertonic crystalloids may also cause hypocoagulability. Colloids, both synthetic and natural, can cause hypocoagulability by several mechanisms beyond the effects of hemodilution. These include impaired platelet function, decreased plasma coagulation factor activity, impaired fibrin formation and crosslinking, and accelerated fibrinolysis. The vast majority of the veterinary literature investigates the hypocoagulable effects of hydroxyethyl starch-containing fluids using in vitro, experimental, and clinical studies. However, results are inconsistent, likely due to the varying doses and physicochemical properties of the specific fluid products across studies. In addition, some evidence exists for hypocoagulable effects of gelatin and albumin solutions. There is also evidence that these colloids increase the risk of clinical bleeding in people. Limitations of the veterinary evidence for the hypocoagulable effects of colloid fluids include a predominance of in vitro studies and in vivo studies using healthy subjects, which exclude the interaction of the effects of illness. Therefore, clinical relevance of these effects, especially for low-molecular-weight hydroxyethyl starch, is unknown. Firm recommendations about the most appropriate fluid to use in clinical scenarios cannot be made, although it is prudent to limit the dose of synthetic colloid in at-risk patients. Clinicians should closely monitor relevant coagulation assays and for evidence of hemorrhage in at-risk patients receiving any type of fluid therapy, especially in large volumes.

The effects of hemodilution on coagulation in term parturients: an in vitro study utilizing rotational thromboelastometry

Objective: To examine the impact of hemodilution on components of blood coagulation using rotational thromboelastometry (ROTEM^®) in term parturientsMethods: This is a prospective, observational pilot study including 35 healthy, parturients at term (≥37 weeks) without history of bleeding or clotting disorder or on medication affecting coagulation. Venous blood samples were collected and divided into specimen tubes to generate varying degrees of hemodilution with Plasma-Lyte (0%, 20%, 25%, 30%, 35%, 40%, 45%, 55%, 60%, 65%, 70%, 75%, 80%). ROTEM^® was performed to assess for coagulation changes.Results: EXTEM (extrinsically activated assay) clotting time (CT) became prolonged at 65% hemodilution and above, and the median CT was in the coagulopathic range (>80 s) at a dilution of 80%. FIBTEM (extrinsically activated assay with platelet inhibitor) amplitude at 5 min (A5) began to diminish at 35% hemodilution, with the median A5 in the coagulopathic range (<12 mm) at 55% hemodilution. The area under the curve (AUC) for EXTEM and FIBTEM consistently declined as hemodilution increased. Greater decreases in FIBTEM AUC were seen compared to EXTEM AUC, with the ratio of FIBTEM:EXTEM AUC at each dilution demonstrating a statistically significant difference from baseline.Conclusion: All thromboelastometry values demonstrated a hypocoagulable trend as hemodilution increased. However, the samples analyzed by the FIBTEM assay trended toward a coagulopathy at a lower degree of hemodilution compared to the EXTEM assay. As FIBTEM tests analyze the role of fibrinogen in hemostasis and EXTEM tests analyze the role of platelets, our findings suggest that platelets may be able to withstand higher degrees of hemodilution before impairing hemostasis compared to fibrinogen. These findings support the growing body of literature that in early stages of severe obstetric hemorrhage, the prioritization of fibrinogen replacement may be critical in preventing further coagulopathy.

Mannitol and the Combination of Mannitol and Gelatin Impair Whole Blood Coagulation and the Platelet Function In Vitro

Objective

Mannitol 20% and succinylated gelatin 4% are routinely used in neurosurgical procedures. The aim of this in vitro study was to explore the influence of both agents on blood coagulation and platelet function.

Methods

Blood from 21 healthy volunteers was obtained and then diluted so as to form five groups: (1) 7% dilution with mannitol; (2) 10% dilution with gelatin; (3) 17% dilution with isotonic balanced electrolyte solution; (4) 17% dilution with mannitol+gelatin; and (5) undiluted blood. The extrinsic thrombelastometry (EXTEM) and fibrin thrombelastometry (FIBTEM) tests were examined by rotational thrombelastometry via ROTEM®, and thrombocyte aggregometry with the aspirin inhibiting- (ASPI), adenosine diphosphate- (ADP), and thrombin-activating protein (TRAP) tests performed by Multiplate.

Results

In the EXTEM test clot formation time, the alpha angle, and maximum clot firmness were significantly reduced by mannitol and the combination of mannitol with gelatin. The platelet function tested in the ADP test was also significantly reduced with this combination.

Conclusion

In this in vitro study, clinically relevant dilutions of mannitol and gelatin showed a significant inhibition of whole blood coagulation and the platelet function, which could be detrimental in neurosurgical settings.

Albumin combined with Mannitol impairs whole blood coagulation and platelet function in vitro

BACKGROUND

The indication of hydroxyethyl starch is currently under critical discussion and albumin 5% (ALB) has an increasing use in the operating theatre. Therefore, ALB is routinely used in neurosurgical procedures and often combined with mannitol 20% (MAN). Purpose of this in vitro study was to determine the influence of the combination of MAN and ALB on blood coagulation and platelet function.

METHODS

22 healthy volunteers were included into this study and 21 analysed. Blood was obtained and diluted into five groups: (1) 7% dilution with MAN, (2) 10% dilution with ALB (3) 17% dilution with isotonic balanced electrolyte solution, (4) 17% dilution with MAN + ALB and (5) undiluted blood as control group (CON). Rotational thrombelastometry via ROTEM® (EXTEM, FIBTEM-Test) and thrombocyte aggregometry via Multiplate® (ASPI, ADP and TRAP-test) were used to detect differences within the intervention groups and compared to the control group.

RESULTS

The maximum clot firmness in the FIBTEM test decreased under the normal range with the combination of MAN+ALB: 8mm (5.5-11) compared to CON: 15mm (12.5-20), p<0.05. Platelet function (ADP-test) showed significant decreases for ALB: 51 AUC (40-84) and MAN+ALB: 54 AUC (41-68) compared to CON: 92 AUC (75-101), p<0.05. Except in clotting time all other EXTEM tests of MAN+ALB subgroup showed significant impairment on blood coagulation compared to the control group.

CONCLUSIONS

In this in vitro study clinically relevant dilutions of MAN+ALB showed a significant inhibition of blood coagulation and platelet function. Further in vivo studies are necessary to confirm these results.

Hypocoagulability and Platelet Dysfunction Are Exacerbated by Synthetic Colloids in a Canine Hemorrhagic Shock Model

Background: Hemorrhagic shock and volume replacement can alter coagulation. Synthetic colloids, hydroxyethyl starch (HES), and gelatin, may enhance hypocoagulability. Our primary objective was to describe the effect of four fluid products on coagulation in canine hemorrhagic shock. Our secondary objective was to compare measurements of coagulation during shock to baseline in all dogs.

Methods: Anesthetized greyhounds subjected to atraumatic hemorrhage for 60 min were administered 20 mL kg⁻¹ of either fresh whole blood (FWB), 6% HES 130/0.4, 4% succinylated gelatin (GELO), or 80 mL kg⁻¹ of isotonic crystalloid over 20 min (n = 6 per group). Platelet closure time (PCT), rotational thromboelastometry (ROTEM) and plasma coagulation assays were measured at baseline, end of hemorrhage (shock), and 40 (T60), and 160 (T180) min after study fluid. ROTEM parameters included clotting time (CT), clot formation time (CFT), alpha angle, maximum clot firmness (MCF), lysis index at 60 min (LI60), and thrombodynamic potential index (TPI) for INTEM, EXTEM, FIBTEM (MCF only), and APTEM (LI60 only) profiles. Plasma coagulation assays included prothrombin time (PT), activated partial thromboplastin time (APTT), fibrinogen concentration and activities of factor VII (FVII), factor VIII (FVIII), and von Willebrand Factor antigen (vWF). Between-group differences were tested using linear mixed models with post-hoc between-group comparisons (Bonferroni-Holm corrected). Differences between baseline and shock were tested using paired t-tests. Significance was set at P < 0.05.

Results: GELO showed longer PCT at T60, compared with FWB and CRYST, and at T180, compared with all other groups. HES showed longer EXTEM CT at T60, compared with all other groups. HES showed lower INTEM and EXTEM MCF at T60 and lower INTEM MCF at T180, compared with FWB. Some plasma coagulation assays showed greater hypocoagulability with HES. Comparing shock to baseline, EXTEM CT, INTEM CFT, EXTEM CFT, PT, and FVIII significantly increased and PCT, INTEM CT, INTEM MCF, EXTEM MCF, EXTEM LI60, EXTEM TPI, FIBTEM MCF, APTT, fibrinogen, FVII, and vWF significantly decreased.

Conclusions: In dogs with hemorrhagic shock, volume replacement with GELO caused mild platelet dysfunction and HES was associated with coagulation changes consistent with hypocoagulability, beyond effects of hemodilution. Shock alone produced some evidence of hypocoagulability.

Synthetic colloid resuscitation in severely injured patients: analysis of a nationwide trauma registry (TraumaRegister DGU)

The purpose of this study was to investigate the efficacy and safety of synthetic colloid resuscitation among severely injured patients. Fluid resuscitation of trauma patients of a nationwide trauma registry was analysed between 2002 and 2015. Effects of synthetic colloid resuscitation in the pre-hospital setting and emergency department on renal failure, renal replacement therapy and multiple organ failure were analysed among patients with ≥2 days intensive care unit stay, and in-hospital mortality was analysed among all patients. 48,484 patients with mean age of 49 years and mean injury severity score of 23 points were included; 72.3% were male and 95.5% had blunt trauma. Risk-adjusted analyses revealed that patients receiving >1,000 ml synthetic colloids experienced an increase of renal failure and renal replacement therapy rates (OR 1.42 and 1.32, respectively, both p ≤ 0.006). Any synthetic colloid use was associated with an increased risk of multiple organ failure (p < 0.001), but there was no effect on hospital mortality (p = 0.594). Between 2002 and 2015 usage of synthetic colloids dropped, likewise did total fluid intake and usage of blood products. The data from this analysis suggests that synthetic colloid resuscitation provides no beneficial effects and might be harmful in patients with severe trauma.

The effects of haemodilution with succinylated gelatin solution on coagulation in vitro as assessed by thromboelastometry and impedance (multiple electrode) aggregometry

We investigated the in vitro viscoelastic changes of progressive haemodilution with succinylated gelatin (SG) solution compared with normal saline (NS) using rotational thromboelastometry (ROTEM®). Whole blood (WB) samples obtained from 20 healthy volunteers were diluted in vitro with SG solution or NS by 10%, 20% and 40%. Fibrinogen concentration and ROTEM (EXTEM, FIBTEM) variables including coagulation time (CT), clot formation time (CFT), α-angle, and maximum clot firmness (MCF) were measured in the undiluted sample and at each degree of haemodilution. Haemodilution with SG decreased FIBTEM MCF by 34.8% at 20% dilution (SG 20% haemodilution mean 9.1 [standard deviation, SD 2.7] mm versus WB, mean 13.9 [SD 3.4] mm) whereas this was observed only at 40% haemodilution with NS (mean 8.5 [SD 2.7] mm, 38.7% decrease). We found that 40% haemodilution with SG slowed clot formation (EXTEM CFT; SG 40%, mean 179 [SD 39] seconds versus WB mean 87.9 [SD 13.7] seconds; increased CFT by 103%), reduced clot strength by 23.5% (EXTEM MCF; SG 40% mean 47.7 [SD 3.4] mm versus WB mean 62.4 [SD 2.5] mm), and decreased fibrin formation (FIBTEM MCF; SG 40% mean 5.8 [SD 1.6] mm versus WB mean 13.9 [SD 3.4] mm); 58.4% decrease). The platelet contribution to clot strength (EXTEM MCF-FIBTEM MCF) was not changed by SG. We found that haemodilution of more than 20% with SG impaired coagulation greater than that observed with NS haemodilution in this in vitro study. This suggests that at 40% haemodilution with SG, a clinical scenario that could occur during resuscitation of a patient in grade IV haemorrhagic shock, impaired coagulation could occur. Frequent monitoring of coagulation is advised when SG solutions are administered rapidly during volume resuscitation.

Effects of Tranexamic Acid Based on its Population Pharmacokinetics in Pediatric Patients Undergoing Distraction Osteogenesis for Craniosynostosis: Rotational Thromboelastometry (ROTEMTM) Analysis

Background: Distraction osteogenesis for craniosynostosis is associated with significant hemorrhage. Additionally, patients usually require several transfusions. Tranexamic acid (TXA) is effective for reducing blood loss and the need for transfusions during surgeries. However, the significance of TXA infusion has not been thoroughly described yet. Methods: Forty-eight children undergoing distraction osteogenesis for craniosynostosis were administered intraoperative TXA infusion (loading dose of 10 mg/kg for 15 min, followed by continuous infusion at 5 mg/kg/h throughout surgery; n = 23) or normal saline (control, n = 25). Rotational thromboelastometry (ROTEM^TM) was conducted to monitor changes in coagulation perioperatively. Results: Blood loss during surgery was significantly lower in the TXA-treated group than it was in the control group (81 vs. 116 mL/kg, P = 0.003). Furthermore, significantly fewer transfusions of red blood cells and fresh frozen plasma were required in the TXA group. In the control group, clotting time during the postoperative period was longer than it was during the preoperative period. Similarly, clot strength was weaker during the postoperative period. D-dimer levels dramatically increased in the control group compared with the TXA group after surgery. The duration of mechanical ventilation and the number of postoperative respiratory-related complications were significantly greater in the control group than they were in the TXA group. Conclusions: TXA infusion based on population pharmacokinetic analysis is effective in reducing blood loss and the need for transfusions during the surgical treatment of craniosynostosis. It can also prevent the increase in D-dimer levels without affecting systemic hemostasis.

Non-oncotic properties of albumin. A multidisciplinary vision about the implications for critically ill patients

INTRODUCTION

Effective resuscitation with human albumin solutions is achieved with less fluid than with crystalloid solutions. However, the role of albumin in today's critical care unit is also linked to its multiple pharmacological effects. Areas covered: The potential clinical benefits of albumin in select populations of critically ill patients like sepsis seem related to immunomodulatory and anti-inflammatory effects, antibiotic transportation and endothelial stabilization. Albumin transports many drugs used in critically ill patients. Such binding to albumin is frequently lessened in critically ill patients with hypoalbuminemia. These changes could result in sub-optimal treatment. Albumin has immunomodulatory capacity by binding several bacterial products. Albumin also influences vascular integrity, contributing to the maintenance of the normal capillary permeability. Moreover, the albumin molecule encompasses several antioxidant properties, thereby significantly reducing re-oxygenation injury, which is especially important in sepsis. In fact, most studies of albumin administration are a combination of a degree of resuscitation with a degree of maintenance or supplementation of albumin. Expert commentary: The potential clinical benefits of the use of albumin in selected critically ill patients such as sepsis seem related to its immunomodulatory and anti-inflammatory effects, antioxidant properties, antibiotic transportation and endothelial stabilization. Additional studies are warranted to further elucidate the underlying physiologic and molecular rationale.

A Comparison of the Effects of 20% Mannitol and 3% NaCl on Coagulation Parameters In Vitro using ROTEM: A Prospective Randomized Crossover Study

OBJECTIVE

The aim of the present study is to compare the effect of 20% mannitol and 3% NaCl on blood coagulation in vitro using rotational thromboelastometry (ROTEM).

METHODS

Twenty-millilitre blood samples were obtained from 15 volunteers. In each group, 2 mL blood samples were collected into both polypropylene tubes and EDTA tubes for ROTEM and hemogram analysis. After sampling, blood samples were diluted with test solutions. Group C (control): Only blood, Group M (mannitol): 7% vol 20% mannitol concentration in the blood, Group hypertonic saline (HS): 7% vol 3% hypertonic saline (NaCl) in the blood, Group M/H (mannitol and hydroxyethyl starch solutions [HES]): 6% vol 20% mannitol concentration and 8% vol HES in the blood and Group HS/H (hypertonic saline and HES): 6% vol 3% hypertonic saline concentration and 8% vol HES in the blood. The following thromboelastometric parameters were measured automatically: clotting time (CT) and clot formation time (CFT) with intrinsic activation by tissue factor (InTEM), CT, CFT and maximum clot firmness (MCF) with extrinsic activation by tissue factor (ExTEM) and MCF with FibTEM.

RESULTS

The ExTEM CT value was found to be significantly longer in the M/H group than in the controls. The ExTEM CFT median and percentile values were: group C: 85 s (70-95 s), group M: 115 s (94-128 s), group HS: 102 s (84-114 s), group M/H: 128 s (110-144 s) and group HS/H: 118 s (107-132 s). In all the groups, FibTEM MCF values were significantly lower than the control and also there was a significant difference between groups M and HS according to FibTEM MCF values.

CONCLUSION

Whole-blood coagulation disorder induced by these solutions is mainly dependent on fibrinogen and fibrin interaction. However, 3% HS has much less negative effect on coagulation.

A single-centre study of haemostatic outcomes of joint replacement in von Willebrand disease and control patients and an analysis of the literature

INTRODUCTION

Haemostatic assessments of patients with von Willebrand disease (VWD) who undergo total knee arthroplasty (TKA) and total hip arthroplasty (THA) have mainly relied on subjective parameters.

AIMS

To compare objective haemostatic outcomes of TKA/THA in VWD patients and controls without bleeding disorders.

METHODS

We retrospectively analysed haemostatic outcomes in VWD patients undergoing TKA/THA from 1993 to 2011 and compared them with two matched controls per operation. Using one-way analysis of variance, we tested the effect of VWD on bleeding risk after TKA and THA.

RESULTS

Twelve VWD patients (6 type 1, 3 type 2M, 1 each of types 2A/2B/3) undergoing 19 operations (12 TKA, 7 THA) were matched to 38 controls. One (5%) of 19 operations in VWD patients and none of the control operations met clinical criteria for major bleeding. Baseline and postoperative day 1 haemoglobin levels, postoperative blood loss, transfused red blood cells (RBCs) and mean hospitalization days were not significantly different. More VWD patients than controls received RBC transfusions [12 (63%) vs. 12 (32%)]. Only 9 (47%) VWD patients vs. 38 (100%) controls received pharmacologic VTE prophylaxis. No postoperative symptomatic VTE occurred in either group.

CONCLUSION

In this largest, single-institutional study, von Willebrand factor replacement based on daily levels resulted in low frequency of major bleeding in VWD patients after TKA/THA. RBC transfusion was more frequent compared with matched controls, but other objective measures of haemostasis were similar. Lack of sufficient details in published reports precluded comparison of haemostatic outcomes.

The effect of tranexamic acid on blood coagulation in total hip replacement arthroplasty: rotational thromboelastographic (ROTEM®) analysis

We evaluated changes in rotational thromboelastometry (ROTEM(®) ) parameters and clinical outcomes in patients undergoing total hip replacement arthroplasty, with concomitant infusions of tranexamic acid and of 6% hydroxyethyl starch 130/0.4. Fifty-five patients were randomly assigned to either the tranexamic acid (n = 29) or the control (n = 26) group. Hydroxyethyl starch was administered in the range of 10-15 ml.kg(-1) during the operation in both groups. In the control group, the clot formation time and maximum clot firmness of APTEM showed significant differences when compared with those of EXTEM at one hour postoperatively, suggestive of fibrinolysis. In the tranexamic acid group, there was no significant difference between each postoperative EXTEM and APTEM parameter. In the tranexamic acid and control group, postoperative blood loss was 308 ml (210-420 [106-745]) and 488 ml (375-620 [170-910], p = 0.002), respectively, and total blood loss was 1168 ml (922-1470 [663-2107]) and 1563 ml (1276-1708 [887-1494], p = 0.003). Haemoglobin concentration was higher in the tranexamic acid group on the second postoperative day (10.5 (9.4-12.1 [7.9-14.0]) vs. 9.6 (8.9-10.5[7.3-16.0]) g.dl(-1) , p = 0.027). In patients undergoing total hip replacement arthroplasty, postoperative fibrinolysis aggravated by hydroxyethyl starch was attenuated by co-administration of 10 mg.kg(-1) tranexamic acid, which may have led to less postoperative blood loss.

Changes in blood coagulation after colloid administration in patients undergoing total hip arthroplasty: comparison between pentastarch and tetrastarches, a randomized trial

Background

Hydroxyethyl starch (HES) solutions are used as plasma expanders for correcting hypovolemia, but can lead to impaired coagulation. We evaluated the changes in hematological and hemostatic profiles with three types of HES.

Methods

Patients were randomized to receive volume replacement with 10% pentastarch 260/0.45 in 0.9% saline (Group-PEN, n = 25), 6% tetrastarch 130/0.4 in 0.9% saline (Group-TET_S, n = 25), or 6% tetrastarch 130/0.4 in a balanced electrolyte solution (Group-TET_B, n = 25). Coagulation was assessed using rotational thromboelastometry (ROTEM®) and other laboratory tests were performed, including measurements of hematological and hemostatic parameters and electrolytes.

Results

Post-operative ROTEM® parameters changed toward hypocoagulable states in all groups. The post-operative parameters of EXTEM and FIBTEM were more impaired in Group-PEN than in Group-TET_B. The percentage change in INTEM clot formation time (P = 0.004) and α-angle (P = 0.003) were smaller in Group-TET_S and Group-TET_B than in Group-PEN. The percentage change in the FIBTEM maximum clot firmness was greatest in Group-PEN (P = 0.011). The international normalized ratio of prothrombin time (P < 0.001) and the activated partial thromboplastin time (P < 0.001) were significantly prolonged in Group-PEN compared to those of Group-TET_B.

Conclusions

The 6% HES 130/0.4 in a balanced electrolyte solution seemed to have less of an impact on blood coagulation than the 10% HES 260/0.45. No differences in hemostatic profile were observed between the balanced electrolyte and saline-based 6% HES 130/0.4.

The Effects of Haemodilution with Albumin on Coagulation in Vitro as Assessed by Rotational Thromboelastometry

We investigated the in vitro viscoelastic changes of progressive haemodilution with 4% albumin compared with normal saline (NS) using rotational thromboelastometry (ROTEM®, Pentapharm Co., Munich, Germany). Whole blood samples obtained from 20 healthy volunteers were diluted in vitro with 4% albumin or NS by 10%, 20% and 40%. Fibrinogen concentration and ROTEM® (EXTEM [screening test for the extrinsic haemostasis system], FIBTEM [EXTEM-based assay for the fibrin part of the clot]) variables including coagulation time, clot formation time (CFT), α-angle, maximum clot firmness and lysis index were measured in the undiluted sample and at each degree of haemodilution. There was no significant difference in fibrinogen concentration at equivalent haemodilutions with normal saline and 4% albumin solutions. Forty percent haemodilution with albumin significantly prolonged coagulation time (EXTEM P=0.007, FIBTEM P=0.0001) and significantly decreased lysis index (FIBTEM P=0.009) compared with NS. A significant decrease in maximum clot firmness from undiluted measurements ( P=0.05) was observed at lower haemodilutions with albumin (20% with EXTEM, 10% with FIBTEM) compared with NS (40% with EXTEM and FIBTEM). The adverse effects of large degrees of haemodilution with 4% albumin solution are in excess of what can be explained by haemodilution alone. This study suggests that large degrees of haemodilution with albumin impair fibrinogen activity to a greater extent than equivalent degrees of haemodilution with NS.

Effect of priming solution and ultrafiltration on post-operative bleeding and blood transfusion in cardiac surgery. Randomized controlled trial

OBJECTIVE

Assess the effectiveness of priming the extracorporeal circulation system with albumin-mannitol combined with ultrafiltration during extracorporeal circulation to reduce post-operative bleeding and transfusion requirements in heart surgery, as well as its impact on the fluid balance, coagulation and hematocrit parameters, re-operation for bleeding, ICU, and hospital length of stay.

MATERIAL AND METHODS

A total of 134 patients scheduled for heart surgery were randomized to receive Ringer's lactate 1,500mL in the priming reservoir (group C), or mannitol 20% 250mL, albumin 20% 150mL and Ringer's lactate 1,100mL combined with ultrafiltration (group T). Bleeding volume, transfusions, fluid balance, coagulation, and hematology parameters were determined until 48h in the post-operative period.

RESULTS

There was a reduction of postoperative bleeding in group T, 1,165±789mL vs 992±662mL (P=.17), and red blood cell concentrate transfusions, 694±843mL vs 413±605mL (P=.03). Intra-operative and post-operative fluid balance was significantly less positive in group T, with an overall balance of 2,292±2,152mL vs 5,388±2,834mL (P<.001). There were higher values of hemoglobin and hematocrit, intraoperative (P<.001), on admission to ICU (P=.001), and at 6h (P=.05) in group T, and lower INR at 6h (P=.01) and 24h (P=.02). Re-operation rate and length of stay in ICU were higher in group C, but not statiscally significant.

CONCLUSIONS

The priming of extracorporeal reservoir with mannitol, albumin, and Ringer's lactate, combined with ultrafiltration, significantly improves intra- and post-operative fluid balance, resulting in a reduction in blood transfusions, with no significant decrease in post-operative bleeding, re-operation bleeding rate, and length of stay in the ICU.

Albumin—Beyond Fluid Replacement in Cardiopulmonary Bypass Surgery

Maintaining vascular barrier competence, preventing interstitial edema, and keeping microcirculation intact is crucial to achieve an optimal outcome in cardiopulmonary bypass surgery (CPB). Blood contact with roller pumps and foreign surfaces during CPB induces shear stress and a pressure drop across the pump boot that leads to transient systemic activation of the inflammatory and hemostatic systems. Moreover, patients after CPB often need volume resuscitation using the smallest possible amount of colloid solution because of fluid overload. For this purpose, human-derived albumin may be preferred over synthetic colloids because CPB priming with albumin preserves oncotic pressure, prevents platelet adhesion, and likely induces less consumption of coagulation factors. In patients with increased bleeding or renal failure, albumin is a safe alternative because of its minimal side effects. Large, randomized clinical trials comparing the benefit of albumin versus other fluids are warranted in the future to define albumin’s distinct role in select high-risk surgical populations.

Effect of 6% hydroxyethyl starch 130/0.4 as a priming solution on coagulation and inflammation following complex heart surgery

PURPOSE

Prolonged duration of cardiopulmonary bypass aggravates the degree of inflammation and coagulopathy. We investigated the influence of 6% hydroxyethyl starch (HES) 130/0.4 on coagulation and inflammation compared with albumin when used for both cardiopulmonary bypass priming and perioperative fluid therapy in patients undergoing complex valvular heart surgery.

MATERIALS AND METHODS

Fifty four patients were randomly allocated into albumin-HES, albumin-nonHES, and HES-HES groups. The cardiopulmonary bypass circuit was primed with 5% albumin in the albumin-HES and albumin-nonHES group, and with HES in the HES-HES group. As perioperative fluid, only plasmalyte was used in the albumin-nonHES group whereas HES was used up to 20 mL/kg in the albumin-HES and albumin-HES group. Serial assessments of coagulation profiles using the rotational thromboelastometry and inflammatory markers (tissue necrosis factor-α, interleukin-6, and interleukin-8) were performed.

RESULTS

Patients' characteristics and the duration of cardiopulmonary bypass (albumin-HES; 137±34 min, HES-HES; 136±47 min, albumin-nonHES; 132±39 min) were all similar among the groups. Postoperative coagulation profiles demonstrated sporadic increases in clot formation time and coagulation time, without any differences in the actual amount of perioperative bleeding and transfusion requirements among the groups. Also, inflammatory markers showed significant activation after cardiopulmonary bypass without any differences among the groups.

CONCLUSION

Even in the presence of prolonged duration of cardiopulmonary bypass, HES seemed to yield similar influence on the ensuing coagulopathy and inflammatory response when used for priming and perioperative fluid therapy following complex valvular heart surgery compared with conventional fluid regimen including albumin and plasmalyte.

Impact of different types of resuscitation fluids on coagulation and continuous venovenous hemofiltration hemocompatibility in a porcine model

Intensive therapy demanding diseases (organ failure or sepsis) are assumed to be the etiology behind a decreased biocompatibility of extracorporeal systems for renal replacement therapy (RRT). There are also potential interactions between different components of the overall therapy. Volume substitutes are known to influence hemorheology and coagulation. To define a potential net effect of volume substitutes on the hemocompatibility of an RRT, we chose an animal model without interfering pathophysiologies. According to the problem of early filter failure and coagulation disorders in critically ill patients, we focused on the hypothesized interaction between RRT and different volume substitutes with respect to blood cell counts, coagulation parameters and required heparin dose. Forty-eight pigs were assigned to four groups of fluid therapy with either normal saline (NaCl), 6%HES130kD/0.4 (HES130), 6%HES200kD/0.5 (HES200) or 4%gelatin (GEL). Six pigs of each fluid group underwent continuous venovenous hemofiltration (CVVH), the remaining six served as the control group. Anticoagulation was performed with continuous heparin infusion. CVVH was run in a recirculation-mode for 4.5 h to force hemocompatibility reactions, thereafter in a standard-mode for 2 h. During the CVVH-treatment GEL reduced platelet counts and fibrinogen concentration and additionally lowered ATIII levels. Heparin requirements did not differ between different volume substitutes or CVVH and control groups. Severe pathophysiologies are not the only reason for a reduced hemocompatibility of CVVH treatment. Interaction of a particular volume substitute with CVVH should be considered when interpreting study results and evolving new strategies.

Assessment of hemostatic changes after crystalloid and colloid fluid preloading in trauma patients using standard coagulation parameters and thromboelastography

Background:

The choice of an ideal fluid administered post trauma and its subsequent influence on coagulation still poses a clinical dilemma. Hence, this study was designed to assess the influence of in vivo hemodilution with various fluid preparations (4% gelatin, 6% hydoxyethyl starch (HES), Ringer's lactate, 0.9% normal saline) on coagulation using standard coagulation parameters and real-time thromboelastography (TEG) in patients undergoing elective surgery post trauma.

Methods:

In a randomized, double-blind study, 100 patients of either sex and age, belonging to ASA Grades I and II, scheduled for elective surgeries were allocated into four groups of 25 each according to the type of fluid infused. Group G (4% gelatin), Group N (0.9% normal saline), Group R (Ringer's lactate), and Group H (6% HES) received preloading with 1 L of fluid according to the group. The coagulation status of the patients was assessed during perioperative period (before surgery, after fluid preloading, and at the end of the surgery) using both conventional coagulation analysis and TEG.

Statistical Analysis:

Analysis of variance (ANOVA), post hoc and Pearson Chi-square test were used.

Results:

In all the patients preloaded with gelatin, there was a significant increase in prothrombin time index (PTI; 14.88±0.90 vs. 13.78±3.01, P<0.001) and international normalized ratio (INR; 1.12±0.09 vs. 1.09±0.19, P<0.05) compared to the baseline value. An increase was observed in these parameters in the postoperative period also. In the HES group, there was statistically significant increase in PT time (15.70±1.51 vs. 13.74±0.75, P=0.01) and INR (1.20±0.15 vs. 1.03±0.17, P<0.001) as compared to the baseline. In the intergroup comparisons, the patients preloaded with HES had a significant increase in INR (1.20±0.15 vs. 1.12±0.09, P=0.04) and reaction time (R time; 6.84±2.55 min vs. 4.79±1.77 min, P=0.02) as compared to the gelatin group. The fall in coagulation time (k time; 2.16±0.98 vs. 3.94±2.6, P=0.02), rise in maximum amplitude (MA; 61.94±14.08 vs. 50.11±14.10, P=0.04), and rise in A20 (56.17±14.66 vs. 43.11±14.24, P=0.05) were more in patients preloaded with RL as compared to the HES group. 100% patients in the gelatin group, 84.2% patients in the NS group, 94.4% patients in the RL group, and 66.7% patients in the HES group had hypocoagulable (R time > 14 min) state in the postoperative period.

Conclusion:

Crystalloids are optimal volume expanders in trauma, with RL having beneficial effects on coagulation system (decrease in k time and increase in MA and A20). Among the colloids, HES 6% (130/0.4) affects coagulation parameters (increase in PTI, INR, R time, k time) more than gelatin. Trial registration (protocol number-IEC/NP-189/2011).

The effect of fibrinogen concentrate and factor XIII on thromboelastometry in 33% diluted blood with albumin, gelatine, hydroxyethyl starch or saline in vitro

BACKGROUND

Fluid replacement results in dilutional coagulopathy. We investigated the potential role of fibrinogen, factor XIII and a combination of both to reverse dilutional coagulopathy, assessed by thromboelastometry (ROTEM(®)).

MATERIAL AND METHODS

Blood samples from healthy volunteers were analysed undiluted and after 33% dilution in vitro with albumin, gelatine, 130/0.4 hydroxyethyl starch or saline. Diluted samples were incubated with fibrinogen (3 g/70 kg bodyweight equivalent), factor XIII (10,000 IU/70 kg bodyweight equivalent), or a combination of both. Measurements were performed using an extrinsic activated assay (EXTEM(®)) and a functional fibrin polymerisation test (FIBTEM(®)).

RESULTS

Compared with baseline, EXTEM clotting time increased with hydroxyethyl starch, exceeding the upper limit of the reference value. Albumin prolonged clotting time within normal limits. Gelatine did not change clotting time, and saline reduced clotting time. Clot formation time increased in colloids only. Maximum clot firmness of both EXTEM and FIBTEM decreased with all fluids, but was less pronounced in saline. Incubation with fibrinogen had no effect on EXTEM maximum clot firmness but improved FIBTEM maximum clot firmness in saline (P <0.001) and albumin (P <0.05), but not gelatine and hydroxyethyl starch). Factor XIII had no effect on any EXTEM and FIBTEM maximum clot firmness results. Fibrinogen and factor XIII combined did not improve EXTEM maximum clot firmness. Fibrinogen and factor XIII did not change FIBTEM maximum clot firmness in hydroxyethyl starch but improved FIBTEM maximum clot firmness in albumin (P <0.001), gelatine (P <0.01) and saline (P <0.001).

DISCUSSION

ROTEM parameters in dilutional coagulopathy in vitro cannot be improved with factor XIII alone in any tested diluent. The combination of fibrinogen and factor XIII is highly effective in raising FIBTEM maximum clot firmness after dilution with albumin, gelatine and saline back to normal values, but is ineffective in 130/0.4 hydroxyethyl starch.

Evaluation of hemostatic changes using n thromboelastography after crystalloid or colloid fluid administration during major orthopedic surgery

The effects of Ringer lactate, 6% hydroxyethyl starch (130/0.4) or 4% succinylated gelatin solutions on perioperative coagulability were measured by thromboelastography (TEG). Seventy-five patients (ASA I-III) who were to undergo major orthopedic procedures performed under epidural anesthesia were included in the study. Patients were randomly divided into three groups of 25 each for the administration of maintenance fluids: group RL (Ringer lactate), group HES (6% hydroxyethyl starch 130/0.4), and group JEL (4% gelofusine solution). Blood samples were obtained during the perioperative period before epidural anesthesia (t1, baseline), at the end of the surgery (t2), and 24 h after the operation (t3). TEG data, reaction time (R), coagulation time (K), angle value (α), and maximum amplitude (MA) were recorded. TEG parameters changed from normal values in all patients. In group RL, R and K times decreased compared to perioperative values while the α angle and MA increased (P < 0.05). In group HES, R and K times increased, however, the α angle and MA decreased (P < 0.05). In group JEL, R time increased (P < 0.05), but K time, α angle and MA did not change significantly. In the present study, RL, 6% HES (130/0.4) and 4% JEL solutions caused changes in the coagulation system of all patients as measured by TEG, but these changes remained within normal limits.

Isovolaemic hemodilution with gelatin and hydroxyethylstarch 130/0.42: effects on hemostasis in piglets

OBJECTIVES

Artificial colloids, frequently used to prevent hemorrhagic shock in children, impair blood coagulation. To determine the impact of acute isovolaemic hemodilution with artificial colloids on clot formation, we conducted an experimental study in a pediatric animal model.

METHODS

Fifteen piglets underwent hemorrhage by withdrawing 40 ml·kg(-1) of blood volume in steps of 10 ml·kg(-1) each within 1 hour. After each withdrawal, the blood loss was randomly compensated by administering 4% gelatin (GEL) or hydroxylethyl starch 130/0.42 (HES) in a ratio of 1 : 1, or isotonic crystalloid solution (ICS) in a ratio of 1 : 4 for isovolaemic hemodilution. Quality of clot formation and platelet function was measured using Thrombelastometry (ROTEM(®)) and Multiple electrode impedance aggregometry (Multiplate(®)) after 10, 20, and 40 ml·kg(-1) blood replacement.

RESULTS

Moderate hemodilution (10-20 ml·kg(-1) blood replacement) caused no significant differences among groups (e.g. INTEM(®)-MCF after 20 ml·kg(-1) blood replacement (ICS vs GEL vs HES, P > 0.05). Profound hemodilution with 40 ml·kg(-1) blood replacement showed a significant difference between ICS and both colloids (P < 0.05), but no significant differences between GEL and HES.

CONCLUSIONS

Impairment of clot formation by moderate isovolaemic hemodilution did not significantly differ between ICS, GEL, and HES. Profound hemodilution of more than 50% of the estimated blood volume with GEL and HES caused significant impairment of clot formation in comparison to ICS and has to be considered when using high amounts of these synthetic colloids.

Emerging treatment strategies for trauma-induced coagulopathy

Background

Trauma-induced coagulopathy has a multifactorial aetiology. Coagulopathy is related to blood loss including consumption of clotting factors and platelets and haemodilution. Additionally hyperfibrinolysis, hypothermia, acidosis and metabolic changes affect the coagulation system.

Methods

This is a review of pathophysiology and new treatment strategies for trauma-induced coagulopathy.

Results

Paradigms are actively changing and there is still a shortage of data. The aim of any haemostatic therapy is to control bleeding and minimize blood loss and transfusion requirements. Transfusion of allogeneic blood products as well as trauma-induced coagulopathy cause increased morbidity and mortality. Current opinion is based on present studies and results from small case series, combined with findings from experimental studies in animals, in vitro studies and expert opinions, as opposed to large, randomized, placebo-controlled studies. A summary of new and emerging strategies, including medical infusion and blood products, to beneficially manipulate the coagulation system in the critically injured patient is suggested.

Conclusion

Future treatment of trauma-induced coagulopathy may be based on systemic antifibrinolytics, local haemostatics and individualized point-of-care-guided rational use of coagulation factor concentrates such as fibrinogen, prothrombin complex concentrate, recombinant factor VIIa and factor XIII. The authors speculate that timely and rational use of coagulation factor concentrates will be more efficacious and safer than ratio-driven use of transfusion packages of allogeneic blood products.

Influence of hydroxyethyl starch (HES) 130/0.4 on hemostasis as measured by viscoelastic device analysis: a systematic review

PURPOSE

Hydroxyethyl starch solutions (HES) are plasma volume expanders which affect hemostasis. Newer HES 130/0.4 is said to be safer. Reevaluation of published evidence is necessary after the recent retraction of studies.

METHODS

Systematic review of studies assessing HES 130/0.4 effects on hemostasis by thrombelastography (TEG, ROTEM) or Sonoclot (SCR) in comparison with crystalloid or albumin control fluids was performed. Only studies which provided statistical comparisons between study fluids were analyzed. Studies were divided into in vitro or in vivo hemodilution studies. We assessed study quality, HES effects which differed significantly from controls, values outside normal range, degree of hemodilution, and cumulative HES dose.

RESULTS

Seventeen in vitro and seven in vivo hemodilution studies were analyzed. Four studies reported quality control measures. Nineteen studies (all 15 ROTEM studies, 3 of 5 in vitro TEG, and 1 of 2 SCR studies) showed a significant hypocoagulatory effect of HES 130/0.4 on clot formation, while clotting time was not uniformly affected. Three in vivo TEG studies with low HES doses or cancer patients found mixed or nonsignificant results. In studies which provided normal ranges (n = 9), more values were outside normal ranges in the HES than in the control groups (87/122 vs. 58/122, p < 0.001). Dose effects were apparent in the in vitro studies, which investigated higher dilutions up to 80%. In vivo studies were fewer and did not investigate doses >40 ml/kg.

CONCLUSIONS

HES 130/0.4 administration results in a weaker and smaller clot. Until results from well-designed clinical trials are available, safer fluids should be chosen for patients with impaired coagulation.

Comparison of hypertonic saline and mannitol on whole blood coagulation in vitro assessed by thromboelastometry

BACKGROUND

Hypertonic saline (HS) is an alternative to mannitol for decreasing intracranial pressure in traumatic brain injury and before craniotomy. Both HS and mannitol may interfere with blood coagulation but their influence on coagulation has not been compared in controlled situations. Therefore, we evaluated different strengths of HS and 15% mannitol on blood coagulation in vitro.

METHODS

Citrated fresh whole blood, withdrawn from 10 volunteers, was diluted with 0.9%, 2.5%, or 3.5% HS or 15% mannitol to make 10 vol.% and 20 vol.% hemodilution in vitro. The diluted blood and undiluted control samples were analyzed with thromboelastometry (ROTEM(®)) using two activators, tissue thromboplastin without (ExTEM(®)) or with cytochalasin (FibTEM(®)).

RESULTS

In the FibTEM(®) analysis, maximum clot firmness (MCF) was stronger in the 2.5% HS group than in the mannitol group after both dilutions (P < 0.05). In the ExTEM(®) analysis, clot formation time (CFT) was more delayed in the mannitol group than in the 0.9%, 2.5%, or 3.5% HS groups in 20 vol.% hemodilution (P < 0.05). MCF was weaker in the mannitol group than in the other groups after 20 vol.% dilution (P < 0.05). MCF was also weaker in the 3.5% than in the 0.9% saline group after 20 vol.% dilution (P < 0.05).

CONCLUSIONS

Blood coagulation is disturbed more by 15% mannitol than by equiosmolar 2.5% saline. This disturbance seems to be attributed to overall clot formation and strength but also to pure fibrin clot firmness. This saline solution might be more favorable than mannitol before craniotomy in patients with a high risk of bleeding.

Hydroxyethyl starches and dextran during hip replacement surgery: effects on blood volume and coagulation

BACKGROUND

Colloid fluids influence the coagulation system by diluting the plasma and, potentially, by exerting other effects that are unique for each fluid product. We hypothesised that changes in the coagulation measured at the end of surgery would be mainly governed by differences in half-life between the colloid fluids.

METHODS

Eighty-four patients were randomised to receive one of four colloids: HES 130/0.42/6:1 (Venofundin(®)), 130/0.4/9:1 (Voluven(®)), 200/0.5/5:1 (Haes-steril(®)) and 6% dextran 70 (Macrodex(®)). Blood samples were taken just before and after a preoperative 500 ml bolus, and also after subsequent elective hip replacement surgery. Volume expansion was estimated from the blood dilution and coagulation assessed by ROTEM, activated partial thromboplastin time, prothrombin international normalised ratio (PT-INR), D-dimer and thrombin-antithrombin complex (TAT).

RESULTS

The blood volume expansion amounted to approximately 600 ml for all four colloids directly after infusion. Voluven(®) and Haes-steril(®) prolonged the aPT time and Venofundin(®) increased TAT. Although all colloids increased PT-INR and D-dimer, the ROTEM analyses showed that they consistently shortened the clotting time and weakened the clot strength. These effects were mainly unchanged after surgery, during which the haemorrhage averaged 500-600 ml. Macrodex(®) produced a stronger volume support at the end of the surgery (91% of infused volume; P<0.001) than the three starch solutions (42-60%).

CONCLUSIONS

All tested colloid fluids induced a mild hypercoagulable state with faster clotting, but with weaker clot strength. The additive influence of surgery was relatively small, and postoperative changes in coagulation were mainly due to differences in the half-life of each colloid.

Effects of combined balanced colloid and crystalloid on rotational thromboelastometry in vitro

Our objective was to investigate the in vitro effects of a totally balanced fluid concept on whole blood coagulation. Venous blood from 12 healthy volunteers was diluted by 20% and 40% with a combination of an equal amount of colloid (balanced or unbalanced 6% HES 130/0.4, or 4% gelatin) and crystalloid (balanced or unbalanced Ringer's acetate). Blood samples were analyzed with rotational thromboelastometry (ROTEM®). The initiation of coagulation was delayed in all dilutions except for the 20 vol% gelatin-dilution. In the extrinsic activation test, maximum clot firmness was decreased and clot formation time prolonged after 40 vol% hemodilution with a balanced Ringer's/unbalanced HES combination, more than in the corresponding gelatin hemodilution. In the fibrin-based test, after both 20- and 40 vol% hemodilution with unbalanced Ringer's/gelatin solution, maximum clot firmness was significantly stronger than in the Ringer's/HES-combinations. The combination of balanced colloid and crystalloid has similar coagulation effects in vitro as their respective combination of unbalanced solutions.

The Effects of Colloid Pre-Loading on Thromboelastography Prior to Caesarean Delivery: Hydroxyethyl Starch 130/0.4 versus Succinylated Gelatine

This prospective, randomized, double-blind study compared the effects on thromboelastography (TEG) of preloading with two different colloid fluids prior to spinal anaesthesia for caesarean section. Healthy full-term parturients received either 500 ml 6% hydroxyethyl starch 130/0.4 (HES, n = 25) or 500 ml 4% succinylated gelatine (GEL, n = 25) prior to spinal anaesthesia. TEG parameters including reaction time (r-time), clot formation time (k-time), clot formation rate (α-angle) and maximum amplitude (MA) were measured immediately before and after pre-loading. Both groups had significantly shorter r-time and lower MA after pre-loading. The α-angle was significantly decreased after pre-loading with HES but not with GEL. No significant differences in k-time were induced pre-loading. In conclusion, preloading with HES or GEL was associated with a mild hypocoagulable effect in healthy parturients presenting for elective caesarean section; however, all TEG parameters in both groups remained within or very close to the normal range after pre-loading.

The impact of balanced hydroxylethyl starch cardiopulmonary bypass priming solution on the fibrin part of clot formation: ex vivo rotation thromboelastometry

Introduction: Balanced colloidal priming solutions are supposed to further minimize the effects of cardiopulmonary bypass (CPB) on haemostasis as compared to gelatin-based preparations. This exploratory study investigated whether clot formation, in particular the fibrin part of the clot, is less altered by a modern balanced HES solution as compared to a gelatin-based priming solution.

Methods: CPB priming solutions containing 60% gelatin (Gelofusin®) or balanced HES starch (100% or 60% Tetraspan®) were mixed with blood samples from healthy volunteers and compared with respect to their impact on clotting time (CT), alpha angle, maximum clot firmness (MCF), and fibrinogen, using thromboelastometry.

Results: The 100% and 60% HES priming solutions significantly increased the EXTEM CT from 66 ± 9 s to 82 ± 19 and 83 ± 13, respectively (both P<0.05 vs. baseline). The speed of solid clot formation decreased significantly for all priming solutions compared with baseline values. The INTEM MCF decreased from 59 ± 4 mm to 47 ± 4, 44 ± 4 and 43 ± 3 mm, whereas the EXTEM MCF decreased from 57 ± 4 mm to 51 ± 4, 51 ± 4 and 50 ± 4 mm after dilution with 60% gelatin, 100% HES or 60% HES priming solution, respectively (all P<0.01 vs. baseline). The priming solutions containing HES induced the largest decrease in MCF attributed to fibrinogen from 12 ± 3 mm to 4 ± 4 mm and 3 ± 2 mm (both P<0.05) for the 100% and mixed priming solution, respectively.

Conclusions: Ex vivo rotation thromboelastometry did not reveal the expected preservation of coagulation parameters, in particular the fibrin part of clot formation, by a balanced HES priming solution.

Coagulation status in coronary artery disease patients with type II diabetes mellitus compared with non-diabetic coronary artery disease patients using the PFA-100® and ROTEM®

Previous investigations in patients with coronary artery disease (CAD) revealed differences in thromboelastographic parameters indicating different states of coagulability. The aim of the present study was to investigate the coagulation status of patients with documented CAD and type II diabetes mellitus (DM) and non-diabetic patients with coronary artery disease with the PFA-100® and the ROTEM®. No differences were found in platelet function as measured with collagen/epinephrine (263.6 ± 70.6 s vs. 254.6 ± 65.3 s) and collagen/ADP cartridges (105.3 ± 63.2 s vs. 90.6 ± 47.3 s) in CAD patients with DM and CAD patients without DM. Measured with the EXTEM reagent of the ROTEM®, mean maximum clot elasticity (MCE) in patients with CAD and DM (233.6 ± 86.9) was significantly longer than in CAD patients without DM (186.7 ± 54.5), (p = 0.03). A similar result was seen using the INTEM reagent; patients with CAD and DM (234.4 ± 83.9) showed a higher value for MCE than CAD patients without DM (190.8 ± 57.8) which was of borderline significance (p = 0.053). Moreover, a weak trend for higher maximum clot firmness (MCF) was seen in CAD patients with DM compared with CAD patients without DM with the EXTEM reagent (68.1 ± 7.5 vs. 63.6 ± 8.6, p = 0.08) and the INTEM reagent (68.4 ± 7.2 vs. 64.1 ± 8.2, p = 0.09). The ROTEM® analysis indicates increased coagulability in patients with coronary artery disease and diabetes mellitus compared to non-diabetic CAD patients. Moreover, the ROTEM® device seems to be an appropriate and easy-to-use tool to describe the coagulation status in these patients groups.