The Resuscitative Fluid You Choose May Potentiate Bleeding

A balancing act: drifting away from the reflexive use of "ab"normal saline

Maintenance intravenous fluids are the most frequently ordered medications for hospitalized children. Since the American Association of Pediatrics published national guidelines, there has been an increased reflexive use of isotonic solutions, especially 0.9% saline, as a prophylaxis against hyponatremia. In this educational review, we discuss the potential deleterious effects of using 0.9% saline, including the development of hyperchloremia, metabolic acidosis, acute kidney injury, hyperkalemia, and a proinflammatory state. Balanced solutions with anion buffers cause relatively minimal harm when used in most children. While the literature supporting one fluid choice over the other is variable, we highlight the benefits of balanced solutions over saline and the importance of prescribing fluid therapy that is individualized for each patient.

Effect of hyperchloremia on mortality of pediatric trauma patients: a retrospective cohort study

BACKGROUND

Hyperchloremia is often encountered due to the frequent administration of intravenous fluids in critically ill patients with conditions such as shock or hypotension in the pediatric intensive care unit, and high serum levels of chloride are associated with poor clinical outcomes.

OBJECTIVES

This study aimed to determine the association between hyperchloremia and in-hospital mortality in pediatric patients with major trauma.

DESIGN AND SETTING

This retrospective cohort study was conducted at a tertiary university hospital in Turkey.

METHODS

Data were collected between March 2020 and April 2022. Patients aged 1 month to 18 years with major trauma who received intravenous fluids with a concentration > 0.9% sodium chloride were enrolled. Hyperchloremia was defined as a serum chloride level > 110 mmol/L. Clinical and laboratory data were compared between the survivors and nonsurvivors.

RESULTS

The mortality rate was 23% (n = 20). The incidence of hyperchloremia was significantly higher in nonsurvivors than in survivors (P = 0.05). In multivariate logistic analysis, hyperchloremia at 48 h was found to be an independent risk factor for mortality in pediatric patients with major trauma.

CONCLUSIONS

In pediatric patients with major trauma, hyperchloremia at 48-h postadmission was associated with 28-day mortality. This parameter might be a beneficial prognostic indicator.

CAPILLARY LEAK AND EDEMA AFTER RESUSCITATION: THE POTENTIAL CONTRIBUTION OF REDUCED ENDOTHELIAL SHEAR STRESS CAUSED BY HEMODILUTION

ABSTRACT

Normal shear stress is essential for the normal structure and functions of the microcirculation. Hemorrhagic shock leads to reduced shear stress due to reduced tissue perfusion. Although essential for the urgent restoration of cardiac output and systemic blood pressure, large volume resuscitation with currently available solutions causes hemodilution, further reducing endothelial shear stress. In this narrative review, we consider how the use of currently available resuscitation solutions results in persistent reduction in endothelial shear stress, despite successfully increasing cardiac output and systemic blood pressure. We consider how this reduced shear stress causes (1) a failure to restore normal vasomotor function and normal tissue perfusion thus leading to persistent tissue hypoxia and (2) increased microvascular endothelial permeability resulting in edema formation and impaired organ function. We discuss the need for clinical research into resuscitation strategies and solutions that aim to quickly restore endothelial shear stress in the microcirculation to normal.

Validation of the relationship between coagulopathy and localization of hydroxyethyl starch on the vascular endothelium in a rat hemodilution model

Various anticoagulant properties have been associated with hydroxyethyl starch (HES). However, the mechanism remains unclear and it has not been fully considered whether these properties are beyond the dilutional effect itself. The aim of this study was to reproduce the coagulopathy induced by HES and to test the hypothesis that the coagulopathy is caused by endothelial or glycocalyx damage due to localization of HES on the endothelium, which is caused by the high shear viscosity of dilutional blood. Using a rat model, we compared blood coagulability measured by Sonoclot, levels of endothelial and glycocalyx damage markers and coagulation factors, and blood shear viscosity when hemodilution was performed with physiological saline (PS), 6% HES 130/0.4 in PS, and 10% HES 200/0.5 in PS. We also evaluated the localization rates of fluorescently labeled HES on endothelium in the isolated aorta. HES decreased the fibrin gel formation rate more than did PS. HES was shown to cover the endothelium, possibly due to its high shear viscosity, and this mechanism potentially acted to protect, rather than damage, the endothelium and glycocalyx. However, this covering effect may be the cause of coagulopathy due to inhibition of von Willebrand factor secretion from the endothelium.

Controlled Multifactorial Coagulopathy: Effects of Dilution, Hypothermia, and Acidosis on Thrombin Generation In Vitro

BACKGROUND

Coagulopathy and hemostatic abnormalities remain a challenge in patients following trauma and major surgery. Coagulopathy in this setting has a multifactorial nature due to tissue injury, hemodilution, hypothermia, and acidosis, the severity of which may vary. In this study, we combined computational kinetic modeling and in vitro experimentation to investigate the effects of multifactorial coagulopathy on thrombin, the central enzyme in the coagulation system.

METHODS

We measured thrombin generation in platelet-poor plasma from 10 healthy volunteers using the calibrated automated thrombogram assay (CAT). We considered 3 temperature levels (31°C, 34°C, and 37°C), 3 pH levels (6.9, 7.1, and 7.4), and 3 degrees of dilution with normal saline (no dilution, 3-fold dilution, and 5-fold dilution). We measured thrombin-generation time courses for all possible combinations of these conditions. For each combination, we analyzed 2 scenarios: without and with (15 nM) supplementation of thrombomodulin, a key natural regulator of thrombin generation. For each measured thrombin time course, we recorded 5 quantitative parameters and analyzed them using multivariable regression. Moreover, for multiple combinations of coagulopathic conditions, we performed routine coagulation tests: prothrombin time (PT) and activated partial thromboplastin time (aPTT). We compared the experimental results with simulations using a newly developed version of our computational kinetic model of blood coagulation.

RESULTS

Regression analysis allowed us to identify trends in our data (P < 10). In both model simulations and experiments, dilution progressively reduced the peak of thrombin generation. However, we did not experimentally detect the model-predicted delay in the onset of thrombin generation. In accord with the model predictions, hypothermia delayed the onset of thrombin generation; it also increased the thrombin peak time (up to 1.30-fold). Moreover, as predicted by the kinetic model, the experiments showed that hypothermia increased the area under the thrombin curve (up to 1.97-fold); it also increased the height of the thrombin peak (up to 1.48-fold). Progressive acidosis reduced the velocity index by up to 24%; acidosis-induced changes in other thrombin generation parameters were much smaller or none. Acidosis increased PT by 14% but did not influence aPTT. In contrast, dilution markedly prolonged both PT and aPTT. In our experiments, thrombomodulin affected thrombin-generation parameters mainly in undiluted plasma.

CONCLUSIONS

Dilution with normal saline reduced the amount of generated thrombin, whereas hypothermia increased it and delayed the time of thrombin accumulation. In contrast, acidosis in vitro had little effect on thrombin generation.

Hemodilution and Endothelial Cell Regulation of Whole Blood Coagulation

Background

Beyond localized damage to the circulatory system and surrounding tissue, trauma stresses endothelial cells throughout the vasculature, potentially leading to hemorrhagic or thrombotic complications away from the injury site.

Objective

Use a whole blood endothelial cell model to define the effects of crystalloid fluid therapy on protein C pathway regulation of tissue factor-initiated coagulation.

Methods

Tissue factor-initiated coagulation was studied in the presence of EA.hy926 cells. Blood was diluted to 70% or 40% using normal saline or lactated ringers. Analyses of coagulation dynamics included clot times, thrombin formation (thrombin-antithrombin complex), FV activation/inactivation, fibrinogen consumption, FXIII activation, and platelet activation.

Results

In all donors, the onset of thrombin generation was not altered in 70% blood using either diluent; with the blood component reduced to 40%, clot time was prolonged two-fold when normal saline was utilized but was unchanged with lactated ringers. The timing of the activations of FV, fibrinogen, and platelets paralleled the effects of dilution on clot times. Extensive inactivation of FVa was observed in undiluted blood and where lactated ringers was the diluent but not in trials with 40% blood/60% normal saline.

Conclusion

Feedback inhibition of tissue factor-initiated coagulation by the protein C pathway is not compromised by hemodilution with crystalloids.

An Investigation Into the Effects of In Vitro Dilution With Different Colloid Resuscitation Fluids on Clot Microstructure Formation

BACKGROUND

Balancing the beneficial effects of resuscitation fluids against their detrimental effect on hemostasis is an important clinical issue. We aim to compare the in vitro effects of 3 different colloid resuscitation fluids (4.5% albumin, hydroxyethyl starch [Voluven 6%], and gelatin [Geloplasma]) on clot microstructure formation using a novel viscoelastic technique, the gel point. This novel hemorheologic technique measures the biophysical properties of the clot and provides an assessment of clot microstructure from its viscoelastic properties. Importantly, in contrast to many assays in routine clinical use, the measurement is performed using unadulterated whole blood in a near-patient setting and provides rapid assessment of coagulation. We hypothesized that different colloids will have a lesser or greater detrimental effect on clot microstructure formation when compared against each other.

METHODS

Healthy volunteers were recruited into the study (n = 104), and a 20-mL sample of whole blood was obtained. Each volunteer was assigned to 1 of the 3 fluids, and the sample was diluted to 1 of 5 different dilutions (baseline, 10%, 20%, 40%, and 60%). The blood was tested using the gel point technique, which measures clot mechanical strength and quantifies clot microstructure (df) at the incipient stages of fibrin formation.

RESULTS

df and clot mechanical strength decrease with progressive dilution for all 3 fluids. A significant reduction in df from baseline was recorded at dilutions of 20% for albumin (P < .0001), 40% for starch (P < .0001), and 60% for gelatin (P < .0001). We also observed significant differences, in terms of df, when comparing the different types of colloid (P < .0001). We found that albumin dilution produced the largest changes in clot microstructure, providing the lowest values of df (= 1.41 ± 0.061 at 60% dilution) compared with starch (1.52 ± 0.081) and gelatin (1.58 ± 0.063).

CONCLUSIONS

We show that dilution with all 3 fluids has a significant effect on coagulation at even relatively low dilution volumes (20% and 40%). Furthermore, we quantify, using a novel viscoelastic technique, how the physiochemical properties of the 3 colloids exert individual changes on clot microstructure.

Effects of Different Crystalloid Solutions on Hemodynamics, Peripheral Perfusion, and the Microcirculation in Experimental Abdominal Sepsis

BACKGROUND

Crystalloid solutions are used to restore intravascular volume in septic patients, but each solution has limitations. The authors compared the effects of three crystalloid solutions on hemodynamics, organ function, microcirculation, and survival in a sepsis model.

METHODS

Peritonitis was induced by injection of autologous feces in 21 anesthetized, mechanically ventilated adult sheep. After baseline measurements, animals were randomized to lactated Ringer's (LR), normal saline (NS), or PlasmaLyte as resuscitation fluid. The sublingual microcirculation was assessed using sidestream dark field videomicroscopy and muscle tissue oxygen saturation with near-infrared spectroscopy.

RESULTS

NS administration was associated with hyperchloremic acidosis. NS-treated animals had lower cardiac index and left ventricular stroke work index than LR-treated animals from 8 h and lower mean arterial pressure than LR-treated animals from 12 h. NS-treated animals had a lower proportion of perfused vessels than LR-treated animals after 12 h (median, 82 [71 to 83] vs. 85 [82 to 89], P = 0.04) and greater heterogeneity of proportion of perfused vessels than PlasmaLyte or LR groups at 18 h. Muscle tissue oxygen saturation was lower at 16 h in the NS group than in the other groups. The survival time of NS-treated animals was shorter than that of the LR group (17 [14 to 20] vs. 26 [23 to 29] h, P < 0.01) but similar to that of the PlasmaLyte group (20 [12 to 28] h, P = 0.74).

CONCLUSIONS

In this abdominal sepsis model, resuscitation with NS was associated with hyperchloremic acidosis, greater hemodynamic instability, a more altered microcirculation, and more severe organ dysfunction than with balanced fluids. Survival time was shorter than in the LR group.

Crystalloid fluid therapy

This article is one of ten reviews selected from the Annual Update in Intensive Care and Emergency medicine 2016. Other selected articles can be found online at http://www.biomedcentral.com/collections/annualupdate2016. Further information about the Annual Update in Intensive Care and Emergency Medicine is available from http://www.springer.com/series/8901.

Prehospital Resuscitation of Traumatic Hemorrhagic Shock with Hypertonic Solutions Worsens Hypocoagulation and Hyperfibrinolysis

Impaired hemostasis frequently occurs after traumatic shock and resuscitation. The prehospital fluid administered can exacerbate subsequent bleeding and coagulopathy. Hypertonic solutions are recommended as first-line treatment of traumatic shock; however, their effects on coagulation are unclear. This study explores the impact of resuscitation with various hypertonic solutions on early coagulopathy after trauma. We conducted a prospective observational subgroup analysis of large clinical trial on out-of-hospital single-bolus (250 mL) hypertonic fluid resuscitation of hemorrhagic shock trauma patients (systolic blood pressure, ≤70 mmHg). Patients received 7.5% NaCl (HS), 7.5% NaCl/6% Dextran 70 (HSD), or 0.9% NaCl (normal saline [NS]) in the prehospital setting. Thirty-four patients were included: 9 HS, 8 HSD, 17 NS. Treatment with HS/HSD led to higher admission systolic blood pressure, sodium, chloride, and osmolarity, whereas lactate, base deficit, fluid requirement, and hemoglobin levels were similar in all groups. The HSD-resuscitated patients had higher admission international normalized ratio values and more hypocoagulable patients, 62% (vs. 55% HS, 47% NS; P < 0.05). Prothrombotic tissue factor was elevated in shock treated with NS but depressed in both HS and HSD groups. Fibrinolytic tissue plasminogen activator and anti-fibrinolytic plasminogen activator inhibitor type 1 were increased by shock but not thrombin-activatable fibrinolysis inhibitor. The HSD patients had the worst imbalance between procoagulation/anticoagulation and profibrinolysis/antifibrinolysis, resulting in more hypocoagulability and hyperfibrinolysis. We concluded that resuscitation with hypertonic solutions, particularly HSD, worsens hypocoagulability and hyperfibrinolysis after hemorrhagic shock in trauma through imbalances in both procoagulants and anticoagulants and both profibrinolytic and antifibrinolytic activities.

Comparison of fibrin-based clot elasticity parameters measured by free oscillation rheometry (ReoRox ®) versus thromboelastometry (ROTEM ®)

Background. Whole blood viscoelastic tests such as the fibrin-based thromboelastometry (ROTEM^®) test FIBTEM are increasingly used in the perioperative setting to quickly identify deficits in fibrin quality, and to guide hemostatic therapy. The recently developed FibScreen2 test of the ReoRox^® method, based on free oscillation rheometry, also provides an evaluation of fibrin clot quality. To date, little information is available on the performance of this test in hemodiluted blood, by comparison to FIBTEM. Methods. Whole blood samples from eight healthy volunteers were analyzed using FIBTEM and Fibscreen2. Native and diluted (to 33% and 50% using saline, gelatin or hydroxyethyl starch [HES]) samples were analyzed. Clot strength parameters, including FIBTEM maximum clot firmness (MCF), FIBTEM maximum clot elasticity (MCE) and Fibscreen2 maximum elasticity (G'max), were measured. Results. In repeatedly measured samples from two volunteers, FIBTEM MCF and Fibscreen2 G'max revealed a coefficient of variation (CV) of 5.3 vs. 16.3% and 5.6 vs. 31.7% for each volunteer, respectively. Hemodilution decreased clot strength. Both Fibscreen2 G'max and FIBTEM parameters decreased proportionally to the dilution ratio when saline was used. The observed reductions in FIBTEM and Fibscreen2 parameters were more severe in samples diluted with gelatin and HES, compared to saline. Finally, a regression analysis between FIBTEM MCE and Fibscreen2 G'max revealed a poor goodness of fit (r² = 0.37, p < 0.0001). Conclusions. ReoRox^® Fibscreen2 test has a high coefficient of variation, and its application in various hemodilution conditions showed limited comparability with the ROTEM^® FIBTEM test.

Limited volume resuscitation in hypotensive elderly multiple trauma is safe and prevents early clinical dilutive coagulopathy -- a matched-pair analysis from TraumaRegister DGU(®)

BACKGROUND

The use of permissive hypotension includes a restrained volume preclinical therapy. However, in the elderly patients, this approach has raised concerns because of the increased cardiovascular risk profile and a higher incidence of hypertension under normal conditions. The aim of the study was to examine whether preclinical administration of restrictive volume therapy in the elderly patient can be safe.

PATIENTS AND METHODS

A retrospective matched-pair analysis with the data set of the TraumaRegister DGU(®) (TR-DGU) was performed based on data of 176 pairs of totally 67,000 patients. To address elderly potentially bleeding patients without major brain injury the following inclusion criteria were chosen: patients ≥ 60 years, ISS ≥ 16, AIS head<4, preclinical blood pressure between 60 and 100 mmHg and recorded preclinical volume administration. Patients that met the inclusion criteria (908) were divided into two groups: pre-clinical volume resuscitation ≤ 1000 ml (=low volume) and >1000 ml (high volume). Patients with high- and low-volume fluid replacement were matched according to the following criteria: age group, gender, date of the accident ± 5 years, ISS, GCS, preclinical intubation, ground-/air-transport, pre-clinical blood pressure.

RESULTS

Preclinical volume resuscitation showed a difference of about 1000 ml between the "low volume" and "high volume" group. The "low volume" group showed a significantly elongated prothrombin time. The amount of blood products given in the emergency department was not significantly different. The ventilation was 2 days shorter in the "low volume", although the number of patients with severe thoracic trauma was greater in this group. The length of stay in the ICU differed by 3 days in favour of the "low volume" group. The overall mortality was almost the same in both groups.

CONCLUSIONS

Based on these data it can be assumed that the lower preclinical volume administration has a positive effect on the initial coagulation status in elderly patients. In spite of some limitations such as low number of matched pairs, we draw the cautious conclusion that a restrictive preclinical volume therapy is safe and also indicated in elderly patients.

Isotonic crystalloid solutions: a structured review of the literature

BACKGROUND

Several different crystalloid solutions are available for i.v. fluid administration but there is little information about their specific advantages and disadvantages.

METHODS

We performed a systematic search of MEDLINE, EMBASE, and CENTRAL up until May 17, 2012, selecting all prospective human studies that directly compared any near-isotonic crystalloids and reported any outcome.

RESULTS

From the 5060 articles retrieved in the search, only 28 met the selection criteria. There was considerable heterogeneity among the studies. Several articles reported an increased incidence of hyperchloraemic acidosis with the use of normal saline, and others an increase in blood lactate levels when large amounts of Ringer's lactate solutions were infused. From the limited data available, normal saline administration appears to be associated with increased blood loss and greater red blood cell transfusion volumes in high-risk populations compared to Ringer's lactate. Possible effects of the different solutions on renal function, inflammatory response, temperature, hepatic function, glucose metabolism, and splanchnic perfusion are also reported. The haemodynamic profiles of all the solutions were similar.

CONCLUSIONS

Different solutions have different effects on acid-base status, electrolyte levels, coagulation, renal, and hepatic function. Whether these differences have clinical consequences remains unclear.

Volume replacement with Ringer-lactate is detrimental in severe hemorrhagic shock but protective in moderate hemorrhagic shock: studies in a rat model

INTRODUCTION

To date, there are insufficient data demonstrating the benefits of preclinically administered Ringer-lactate (RL) for the treatment of hemorrhagic shock following trauma. Recent animal experiments have shown that lactate tends to have toxic effects in severe hemorrhagic shock. This study aimed to compare the effects of RL administered in a rat model of severe hemorrhagic shock (mean arterial blood pressure (MAP): 25 to 30 mmHg) and moderate hemorrhagic shock (MAP: 40 to 45 mmHg).

METHODS

Four experimental groups of eight male Wistar rats each (moderate shock with Ringer-saline (RS), moderate shock with RL, severe shock with RS, severe shock with RL) were established. After achieving the specified depth of shock, animals were maintained under the shock conditions for 60 minutes. Subsequently, reperfusion with RS or RL was performed for 30 minutes, and the animals were observed for an additional 150 minutes.

RESULTS

All animals with moderate shock that received RL survived the entire study period, while six animals with moderate shock that received RS died before the end of the experiment. Furthermore, animals with moderate shock that received RL exhibited considerable improvements in their acid-base parameters and reduced organ damage.

CONCLUSIONS

The preclinical use of RL for volume replacement has different effects depending on the severity of hemorrhagic shock. RL exhibits detrimental effects in cases of severe shock, whereas it has pronounced protective effects in cases of moderate shock.

Hyperosmolar reconstituted lyophilized plasma is an effective low-volume hemostatic resuscitation fluid for trauma

BACKGROUND

We performed this study to optimize reconstituted lyophilized plasma (LP) into a minimal volume fluid that provides effective hemostatic resuscitation for trauma while minimizing logistical limitations.

METHODS

We performed a prospective, blinded animal study. Plasma was lyophilized following whole blood collection from anesthetized swine. The minimal volume needed for reconstitution was determined, and this solution was evaluated for safe infusion into the swine. Reconstituted LP was analyzed for electrolyte content, osmolarity, and coagulation factor activity. Twenty swine were anesthetized and subjected to a validated model of polytrauma and hemorrhagic shock (including a Grade V liver injury), then randomized to resuscitation with LP reconstituted to either 100% of the original plasma volume (100%LP) or the minimal volume LP fluid. Physiologic data were monitored, and blood loss and hematocrit were measured. Coagulation status was evaluated using thrombelastography.

RESULTS

The minimal volume of reconstituted LP safe for infusion in swine was 50% of the original plasma volume (50%LP). The 50%LP had higher electrolyte concentrations, osmolarity, and increased coagulation factor activity levels by volume compared with 100%LP (p < 0.05). Blood loss, hematocrit, mean arterial pressure, and heart rate did not differ between animals receiving 100%LP (n = 10) or 50%LP (n = 10) at any time point (p > 0.05). International normalized ratio and thrombelastography parameters were not different between groups (R time, α angle, or maximal amplitude, p > 0.05).

CONCLUSION

Resuscitation with 50%LP fluid was well tolerated and equally effective compared with 100%LP, with respect to physiologic and hemostatic properties. The smaller volume of fluid necessary to reconstitute hypertonic LP makes it logistically superior to 100%LP for first responders and may reduce adverse effects of large-volume resuscitation.

Hemodilution as a result of aggressive fluid resuscitation aggravates coagulopathy in a rat model of uncontrolled hemorrhagic shock

BACKGROUND

The relationship between dilution caused by fluid resuscitation and blood coagulability during ongoing, uncontrolled hemorrhagic shock (UHS) remains unclear. We hypothesized that dilution caused by fluid resuscitation may impair blood coagulability in UHS.

METHODS

Eighteen rats underwent under halothane anesthesia. The UHS model consisted of the following phases: (1) an initial blood withdrawal of 2.5 mL per 100 g during 15 minutes, followed by UHS via tail amputation and fluid resuscitation with lactated Ringer's (LR) solution (0-60 minutes); (2) hemostasis and reinfusion of withdrawn blood and additional LR solution (60-100 minutes); and (3) observation of awake rats for 72 hours. Rats were randomized into three resuscitation regimens (n = 6 per group) during Phase I. LR solution was infused at a rate of 0.1 mL/min in Group 1, 0.25 mL/min in Group 2, and 0.75 mL/min in Group 3. Blood coagulability was assessed with a Sonoclot analysis, and survival to 72 hours were compared between groups.

RESULTS

Both resuscitation regimens of Groups 2 and 3 increased the blood pressure and bleeding volume from the tail stump compared with Group 1 (p < 0.05). At the end of Phase I, the hematocrit decreased to 29% (3%) in Group 1, 23% (3%) in Group 2, and 12% (3%) in Group 3 (p < 0.05). Sonoclot analysis revealed a decreased clot rate of 16 (9) clot signal per minute in Group 2 and 14 (10) clot signal per minute in Group 3 compared with Group 1 (40 [10] clot signal per minute; p < 0.01). There was a significant correlation between clot rate and hematocrit values (r = +0.67, p < 0.01). Compared with Group 1, survival improved in Groups 2 and 3 (p < 0.05).

CONCLUSION

In a rat model of UHS, aggressive fluid resuscitation aggravated hemodilution and blood coagulability as well as and bleeding but improved the hemodynamics and survival. There was a positive correlation between hemodilution and coagulation indexes. Hemodilution, as part of fluid therapy, may affect coagulopathy in UHS.

Postoperatives Management der Gerinnung

<b><i>Hintergrund: </i></b>Das Gerinnungsmanagement in der postoperativen Phase stellt eine komplexe Herausforderung dar. Einerseits führt eine bereits präoperativ vorbestehende oder intraoperativ erworbene Beeinträchtigung der Blutgerinnung zu einem erhöhten Risiko für Nachblutungen. Andererseits sind Patienten in der postoperativen Phase einem erhöhten Risiko für thromboembolische Komplikationen ausgesetzt. Zudem drängen vermehrt neue orale Antikoagulanzien und Thrombozytenaggregationshemmer auf den Markt, für deren perioperativen Einsatz noch wenig Erfahrung besteht. <b><i>Methode: </i></b>Literaturübersicht. <b><i>Ergebnisse: </i></b>Das postoperative Gerinnungsmanagement sollte individualisiert nach einer Diagnostik mit klassischen Gerinnungstests und Point-of-Care(POC)-Diagnoseverfahren erfolgen. Verglichen mit dem intraoperativen Gerinnungsmanagement bestehen Unterschiede. <b><i>Schlussfolgerungen: </i></b>Das Ziel des postoperativen Gerinnungsmanagements ist eine Gerinnungsaktivität, die eine suffiziente Wundheilung zulässt, ohne thromboembolische Ereignisse zu begünstigen. Im Falle einer postoperativen Blutung sollte zur Diagnostik neben den klassischen Gerinnungstests auf viskoelastische POC-Verfahren zurückgegriffen werden. Neben der bedarfsadaptierten Substitution von Gerinnungsfaktoren ist die Aufrechterhaltung der Rahmenbedingungen der Gerinnung von entscheidender Bedeutung (Normothermie, physiologischer pH-Wert, Normokalziämie). Die Fortführung einer bestehenden Antikoagulation mit neuen oralen Antikoagulanzien ist eine Einzelfallentscheidung. Für ihren perioperativen Einsatz gib es noch keine Leitlinien.

Factor IX complex for the correction of traumatic coagulopathy

BACKGROUND

Damage control resuscitation advocates correction of coagulopathy; however, options are limited and expensive. The use of prothrombin complex concentrate (PCC), also known as factor IX complex, can quickly accelerate reversal of coagulopathy at relatively low cost. The purpose of this study is to describe our experience in the use of factor IX complex in coagulopathic trauma patients.

METHODS

All patients receiving PCC at our Level I trauma center over a two-year period (2008-2010) were reviewed. PCC was used at the discretion of the trauma attending for treatment of coagulopathy, reversal of coumadin, and when recombinant factor VIIa was indicated.

RESULTS

Forty-five trauma patients received 51 doses of PCC. Sixty-two per cent were male and mean Injury Severity Score was 23 (± 14.87). Standard dose was 25 units per kg and mean cost per patient was $1,022 ($504-3,484). Fifty-eight per cent of patients were on warfarin before admission. Mean international normalized ratio (INR) was decreased after PCC administration (p = 0.001). Packed red blood cell transfusion was also reduced after factor IX complex (p = 0.018). Mean INR was reduced in both the nonwarfarin (p = 0.001) and warfarin (p = 0.001) groups. Packed red blood cell transfusion was less in the nonwarfarin group (p = 0.002) however was not significant in the warfarin group. Subsequent thromboembolic events were observed in 3 of the 45 patients (7%). Mortality was 16 of 45 (36%).

CONCLUSION

PCC rapidly and effectively treats coagulopathy after traumatic injury. PCC therapy leads to a significant correction in INR in all trauma patients, regardless of coumadin use, and concomitant reduction in blood product transfusion. PCC should be considered as an effective tool to treat acute coagulopathy of trauma. Further prospective studies examining the safety, efficacy, cost, and outcomes comparing PCC and recombinant factor VIIa are needed.

Computational analysis of intersubject variability and thrombin generation in dilutional coagulopathy

BACKGROUND

Blood dilution is a frequent complication of massive transfusion during trauma and surgery. This article investigates the quantitative effects of blood plasma dilution on thrombin generation in the context of intersubject variability.

STUDY DESIGN AND METHODS

A thoroughly validated computational model was used to simulate thrombin generation curves for 472 healthy subjects in the Leiden Thrombophilia Study. Individual thrombin curves were calculated for undiluted blood and for different dilution scenarios. For every such curve, five standard quantitative parameters of thrombin generation were calculated and analyzed.

RESULTS

Thrombin generation parameters in diluted blood plasma displayed significant intersubject variability (with a coefficient of variation up to approx. 28%). Nevertheless, dilutional effects in the majority (or all) of the subjects in the study group were characterized by persistent patterns. In particular, the largest dilution-induced change typically occurred in the maximum slope (MS) of the thrombin curve, followed by a change in thrombin peak height (PH), whereas the smallest change often occurred in the area under the curve. The identified patterns demonstrated considerable robustness to variations in dilution scenario and tissue factor concentration.

CONCLUSION

Dilutional effects on thrombin generation in a human population can be predicted from trends identified for the "average" subject and then refined by performing an analysis of actual subjects in the study group. The MS and PH are dilution indicators that are both sensitive and reliable across a large subject group and could potentially be used as disease markers in the diagnosis of coagulopathic conditions.

Factor VII-activating protease is activated in multiple trauma patients and generates anaphylatoxin C5a

Severe tissue injury results in early activation of serine protease systems including the coagulation and complement cascade. In this context, little is known about factor VII-activating protease (FSAP), which is activated by substances released from damaged cells such as histones and nucleosomes. Therefore, we have measured FSAP activation in trauma patients and have identified novel FSAP substrates in human plasma. Mass spectrometry-based methods were used to identify FSAP binding proteins in plasma. Anaphylatoxin generation was measured by ELISA, Western blotting, protein sequencing, and chemotaxis assays. Plasma samples from trauma patients were analyzed for FSAP Ag and activity, nucleosomes, C5a, and C3a. Among others, we found complement components C3 and C5 in FSAP coimmunoprecipitates. C3 and C5 were cleaved by FSAP in a dose- and time-dependent manner generating functional C3a and C5a anaphylatoxins. Activation of endogenous FSAP in plasma led to increased C5a generation, but this was not the case in plasma of a homozygous carrier of Marburg I single nucleotide polymorphism with lower FSAP activity. In multiple trauma patients there was a large increase in circulating FSAP activity and nucleosomes immediately after the injury. A high correlation between FSAP activity and C5a was found. These data suggest that activation of FSAP by tissue injury triggers anaphylatoxin generation and thereby modulates the posttraumatic inflammatory response in vivo. A strong link between C5a, nucleosomes, and FSAP activity indicates that this new principle might be important in the regulation of inflammation.

The treatment of traumatic shock: recent advances and unresolved questions

Uncontrolled bleeding remains a leading cause of potentially preventable death after trauma. Timely, adequate resuscitation in traumatic shock is an essential, lifesaving aspect of polytrauma care. Whilst basic principles in the treatment of traumatic shock remain the same-achieving hemorrhage control and replacing lost volume, the way this is achieved has changed significantly in the last five years. The abandonment of blood pressure driven uncontrolled fluid resuscitation, the introduction of the concept of hemostatic resuscitation, and the increasing use of massive transfusion protocols have all contributed to an improvement in timely access to various blood products. The increase in knowledge regarding the pathophysiology of trauma, the availability of adjuncts, and the array of resuscitation monitoring options available have all contributed to a potentially improved approach to resuscitation. The purpose of this report is to review the most important advances in traumatic shock therapy in the last five years.

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.

Fibrinogen estimates are influenced by methods of measurement and hemodilution with colloid plasma expanders

BACKGROUND

Measurement of plasma fibrinogen is often required in critically ill patients or massively bleeding patients being resuscitated with colloid plasma expander. This study aimed at evaluating different assays of plasma fibrinogen after in vitro dilution with commonly used plasma expanders and challenged the hypothesis that levels of fibrinogen are estimated significantly higher in plasma diluted with colloid plasma expander compared with isotonic saline.

STUDY DESIGN AND METHODS

Fibrinogen measurements were established in plasma samples each diluted in vitro to 30 or 50% with isotonic saline, hydroxyethyl starch (HES) 130/0.4, and human albumin. Fibrinogen levels were assessed using an antigen determination, three photo-optical Clauss methods, one mechanical Clauss method, a prothrombin-derived method, and viscoelastic measurement through thromboelastometry.

RESULTS

Measurement of fibrinogen levels was significantly different when performed on alternate analytical platforms. By 30 and 50% dilution with HES 130/0.4 coagulation analyzers using the photo-optical Clauss methods significantly overestimated levels of fibrinogen. Dilution with human albumin did not affect fibrinogen levels except from one analyzer by 50% dilution level. Viscoelastic measurement of fibrin polymerization was reduced at both dilution levels and appeared to reflect the impairment of fibrin polymerization induced by HES 130/0.4 and to a lesser extent human albumin.

CONCLUSION

This study demonstrated that different automated coagulation analyzers revealed significantly different levels of fibrinogen. The presence of colloid plasma expander gave rise to erroneous high levels of fibrinogen returned from some coagulation analyzers employing the method of Clauss.

New approaches to the management of traumatic external haemorrhage

Uncontrolled external haemorrhage, though rare in civilian practice, is responsible for up to 80% of pre-hospital deaths in military trauma. Data from recent conflicts shows that exsanguination before evacuation accounts for 50% of deaths. Severe haemorrhage leads to the lethal triad of acidosis, hypothermia and coagulopathy. A new treatment paradigm, <C>ABC (where <C> stands for ‘Control of catastrophic haemorrhage) has been used to prioritise management of external haemorrhage. This approach has been augmented by the use of elastic field dressings, tourniquets and haemostatic agents. A ‘ladder’ approach is used to ensure basic wound management techniques are adopted before more sophisticated ones. Early fluid replacement via intraosseous needles and using blood and other blood products in the pre-hospital environment are other strategies used to achieve early haemostasis.

Posttraumatic massive bleeding: a challenging multidisciplinary task

Massive bleeding is a key issue in the treatment of trauma and surgery. It does in fact account for more than 50% of all trauma-related deaths within the first 48 h following hospital admission, and it can significantly raise the mortality rate of any kind of surgery. Despite this great clinical relevance, evidence on the management of massive bleeding is surprisingly scarce, and its treatment is often based on empirical grounds. Successful treatment of massive haemorrhage depends on better understanding of the associated physiological changes as well as on good team work between the different specialists involved in the management of such a complex condition. The aim of this article is to provide an overview of the pathophysiology as well as of current treatment options of such a condition, including the new concept of "damage control resuscitation", which integrates permissive hypotension, haemostatic resuscitation and damage control surgery.

New developments in massive transfusion in trauma

PURPOSE OF REVIEW

Trauma patients requiring massive transfusion represent a population at high risk for potentially preventable death. This review describes recent advances in the early recognition and treatment of the coagulopathy of trauma, as well as ongoing work to define optimal resuscitation strategies.

RECENT FINDINGS

Damage control resuscitation involves the rapid correction of hypothermia and acidosis, direct treatment of coagulopathy, and early transfusion in trauma patients. Recent evidence demonstrates improved mortality and lower overall blood product usage with higher ratios of plasma and platelets to red blood cells transfused. Adjuncts to damage control resuscitation such as factor VIIa may also be beneficial. Thrombelastography and advances in point-of-care testing may provide timely measurements to help guide massive transfusion in patients based on their individual needs.

SUMMARY

As optimal resuscitation strategies continue to evolve, recent efforts have focused on early and aggressive treatment of coagulopathy, with higher ratios of plasma and platelets to red blood cells transfused. Early evidence suggests that such strategies have a beneficial outcome in regards to trauma-related mortality.

New insights into acute coagulopathy in trauma patients

Abnormal coagulation parameters can be found in 25% of trauma patients with major injuries. Furthermore, trauma patients presenting with coagulopathy on admission have worse clinical outcome. Tissue trauma and systemic hypoperfusion appear to be the primary factors responsible for the development of acute traumatic coagulopathy immediately after injury. As a result of overt activation of the protein C pathway, the acute traumatic coagulopathy is characterised by coagulopathy in conjunction with hyperfibrinolysis. This coagulopathy can then be exacerbated by subsequent physiologic and physical derangements such as consumption of coagulation factors, haemodilution, hypothermia, acidemia and inflammation, all factors being associated with ongoing haemorrhage and inadequate resuscitation or transfusion therapies. Knowledge of the different mechanisms involved in the pathogenesis of acute traumatic coagulopathy is essential for successful management of bleeding trauma patients. Therefore, early evidence suggests that treatment directed at aggressive and targeted haemostatic resuscitation can lead to reductions in mortality of severely injured patients.

The acute coagulopathy of trauma shock: clinical relevance

Recent observational studies have identified an acute coagulopathy in trauma victims that is present on arrival in the emergency room. It has been associated with a four-fold increase in mortality and increased incidence of organ failure. Conventional trauma resuscitation and transfusion protocols are designed for dilutional coagulopathy and appear inadequate in the management of acute traumatic coagulopathy and massive transfusion. Acute Coagulopathy of Trauma Shock (ACoTS) is caused by a combination of tissue injury and shock, and may occur without significant fluid administration, clotting factor depletion or hypothermia. The mechanism through which acute coagulopathy develops is unclear but activation of the protein C pathway has been implicated. Standard coagulation tests do not identify cases in a timely fashion and ACoTS should be suspected in any trauma patient with a significant magnitude of injury and shock, as evidenced by an abnormal admission base deficit on blood gas. Development of point of care coagulometers and whole blood coagulation analysers, such as rotational thromboelastometry, may enable earlier laboratory identification of this group. Retrospective studies performed by the American military indicate that resuscitation of severely injured patients with higher ratios of plasma given early may improve outcome and reduce overall blood product use. The place of adjunctive pharmaceutical agents within this strategy remains unclear. There is an acute coagulopathy associated with trauma and shock that is an independent predictor of outcomes. Delineation of this entity, with directed management protocols should lead to a reduction in avoidable deaths from haemorrhage after trauma.

Optimal fluid resuscitation: timing and composition of intravenous fluids

BACKGROUND

Recent data suggest that the timing of fluid resuscitation and the type of fluid used to treat hemorrhagic shock contribute to the inflammatory response as well as cell death.

METHODS

Rats were bled of 40% of their total blood volume and then resuscitated in either early or delayed fashion. Treatment was assigned randomly and consisted of lactated Ringer's solution, normal saline, bicarbonate Ringer's solution, hypertonic saline, or no resuscitation. The first four groups were subdivided into early and late resuscitation. After a 5-h observation period, lung and liver samples were evaluated for apoptosis, and blood was collected for measurements of the cytokines interleukin (IL)-6, IL-10, and IL-1beta.

RESULTS

The rats that were not resuscitated had significantly more apoptosis in liver tissue. In the lung, bicarbonate Ringer's solution, when given early, was associated with significantly less apoptosis. Non-resuscitated rats had significantly higher IL-6 concentrations than all other groups. Animals receiving hypertonic saline early had significantly higher IL-6 concentrations than those given any other fluid. The concentration of IL-1beta was significantly higher in the non-resuscitated rats than in those receiving bicarbonate Ringer's, lactated Ringer's, or normal saline for early resuscitation. Interleukin-10 was elevated significantly in non-resuscitated rats.

CONCLUSIONS

Cellular destruction and a pro-inflammatory response follow hemorrhagic shock. Early resuscitation with isotonic crystalloid fluids decreases these responses.

Prehospital resuscitation with hypertonic saline-dextran modulates inflammatory, coagulation and endothelial activation marker profiles in severe traumatic brain injured patients

Background

Traumatic brain injury (TBI) initiates interrelated inflammatory and coagulation cascades characterized by wide-spread cellular activation, induction of leukocyte and endothelial cell adhesion molecules and release of soluble pro/antiinflammatory cytokines and thrombotic mediators. Resuscitative care is focused on optimizing cerebral perfusion and reducing secondary injury processes. Hypertonic saline is an effective osmotherapeutic agent for the treatment of intracranial hypertension and has immunomodulatory properties that may confer neuroprotection. This study examined the impact of hypertonic fluids on inflammatory/coagulation cascades in isolated head injury.

Methods

Using a prospective, randomized controlled trial we investigated the impact of prehospital resuscitation of severe TBI (GCS < 8) patients using 7.5% hypertonic saline in combination with 6% dextran-70 (HSD) vs 0.9% normal saline (NS), on selected cellular and soluble inflammatory/coagulation markers. Serial blood samples were drawn from 65 patients (30 HSD, 35 NS) at the time of hospital admission and at 12, 24, and 48-h post-resuscitation. Flow cytometry was used to analyze leukocyte cell-surface adhesion (CD62L, CD11b) and degranulation (CD63, CD66b) molecules. Circulating concentrations of soluble (s)L- and sE-selectins (sL-, sE-selectins), vascular and intercellular adhesion molecules (sVCAM-1, sICAM-1), pro/antiinflammatory cytokines [tumor necrosis factor (TNF)-α and interleukin (IL-10)], tissue factor (sTF), thrombomodulin (sTM) and D-dimers (D-D) were assessed by enzyme immunoassay. Twenty-five healthy subjects were studied as a control group.

Results

TBI provoked marked alterations in a majority of the inflammatory/coagulation markers assessed in all patients. Relative to control, NS patients showed up to a 2-fold higher surface expression of CD62L, CD11b and CD66b on polymorphonuclear neutrophils (PMNs) and monocytes that persisted for 48-h. HSD blunted the expression of these cell-surface activation/adhesion molecules at all time-points to levels approaching control values. Admission concentrations of endothelial-derived sVCAM-1 and sE-selectin were generally reduced in HSD patients. Circulating sL-selectin levels were significantly elevated at 12 and 48, but not 24 h post-resuscitation with HSD. TNF-α and IL-10 levels were elevated above control throughout the study period in all patients, but were reduced in HSD patients. Plasma sTF and D-D levels were also significantly lower in HSD patients, whereas sTM levels remained at control levels.

Conclusions

These findings support an important modulatory role of HSD resuscitation in attenuating the upregulation of leukocyte/endothelial cell proinflammatory/prothrombotic mediators, which may help ameliorate secondary brain injury after TBI.

Trial registration

NCT00878631.

Influence of fluid therapy on the haemostatic system of intensive care patients

Haemostatic alterations associated with the use of fluids are related to non-specific dilutional effects and colloid-specific effects, such as acquired von Willebrand syndrome, inhibition of platelet function and fibrin polymerization. Judging by currently available evidence, dextran, hetastarch and pentastarch have a more pronounced impact than tetrastarch, gelatin and albumin. In patients with hypocoagulability, tetrastarch appears to be a suitable volume expander due to its high safety index and volume efficacy. Gelatins have lower inhibitory effects on clot strength compared with tetrastarch, but their volume efficacy is also lower. Dextrans are potent anticoagulants with a high risk for adverse reactions. Albumin has negligible effects on haemostasis, but low volume efficacy and costs limit the use of a blood product as a routine volume replacement fluid. To avoid potential acidosis-induced changes in haemostasis, plasma-adapted carrier solutions may be used instead of saline-based solutions.

Hemostatic and hemorrhagic problems in neurosurgical patients

BACKGROUND

Abnormalities of the hemostasis can lead to hemorrhage, and on the other hand to thrombosis. Intracranial neoplasms, complex surgical procedures, and head injury have a specific impact on coagulation and fibrinolysis. Moreover, the number of neurosurgical patients on medication (which interferes with platelet function and/or the coagulation systems) has increased over the past years.

METHOD

The objective of this review is to recall common hemostatic disorders in neurosurgical patients on the basis of the "new concept of hemostasis". Therefore the pertinent literature was searched to provide a structured and up to date manuscript about hemostasis in Neurosurgery.

FINDINGS

According to recent scientific publications abnormalities of the coagulation system are discussed. Pathophysiological background and the rational for specific (cost)-effective perioperative hemostatic therapy is provided.

CONCLUSIONS

Perturbations of hemostasis can be multifactorial and maybe encountered in the daily practice of neurosurgery. Early diagnosis and specific treatment is the prerequisite for successful treatment and good patients outcome.

Fluid management in traumatic shock: a practical approach for mountain rescue. Official recommendations of the International Commission for Mountain Emergency Medicine (ICAR MEDCOM)

Sumann, Günther, Peter Paal, Peter Mair, John Ellerton, Tore Dahlberg, Gregoire Zen-Ruffinen, Ken Zafren, and Hermann Brugger. Fluid management in traumatic shock: a practical approach for mountain rescue. High Alt. Med. Biol. 10:71-75, 2009.-The management of severe injuries leading to traumatic shock in mountains and remote areas is a great challenge for emergency physicians and rescuers. Traumatic brain injury may further aggravate outcome. A mountain rescue mission may face severe limitations from the terrain and required rescue technique. The mission may be characterized by a prolonged prehospital care time, where urban traumatic shock protocols may not apply. Yet optimal treatment is of utmost importance. The aim of this study is to establish scientifically supported recommendations for fluid management that are feasible for the physician or paramedic attending such an emergency. A nonsystematic literature search was performed; the results and recommendations were discussed among the authors and accepted by the International Commission for Mountain Emergency Medicine (ICAR MEDCOM). Diagnostic and therapeutic strategies are discussed, as well as limitations on therapy in mountain rescue. An algorithm for fluid resuscitation, derived from the recommendations, is presented in Fig. 1. Focused on the key criterion of traumatic brain injury, different levels of blood pressure are presented as a goal of therapy, and the practical means for achieving these are given.

Empirical and theoretical phenotypic discrimination

We have developed an integrated approach that combines empirical and computational methodologies to define an individual's thrombin phenotype. We have evaluated the process of thrombin generation in healthy individuals and individuals with defined pathologies in order to develop general criteria relevant to assess an individual's propensity for hemorrhage or thrombosis. Three complementary hypotheses have emerged from our work: (i) compensation by the ensemble of other coagulation proteins in individuals with specific factor deficiencies can 'normalize' an individual's thrombin generation process and represents a rationale for their unexpected phenotype; (ii) individuals with clinically unremarkable factor levels may present thrombin generation profiles typical of individuals with hemostatic complications; and (iii) in some hemostatic disorders a specific pattern of expression of a small ensemble of coagulation factors may be sufficient to explain the overall phenotype.

Mechanisms of hydroxyethyl starch-induced dilutional coagulopathy

BACKGROUND

The biochemical mechanisms causing dilutional coagulopathy following infusion of hydroxyethyl starch 130/0.4 (HES) are not known in detail.

OBJECTIVES

To give a detailed biochemical description of the mechanism of coagulopathy following 30%in vivo dilution with HES, to present a systematic ex vivo test of various hemostatic agents, and to investigate the hypothesis that acquired fibrinogen deficiency constitutes the most important determinant of the coagulopathy.

METHODS

Dynamic whole blood clot formation assessed by thromboelastometry, platelet count, thrombin generation, and the activities of von Willebrand factor, coagulation factor II, FVII, FVIII, FIX, FX and FXIII were measured in 20 bleeding patients enrolled in a prospective clinical study investigating in vivo substitution of blood loss with HES up to a target level of 30%. Thromboelastometry parameters were further evaluated after ex vivo spiking experiments with fibrinogen, prothrombin complex concentrate (PCC), FXIII, activated recombinant FVIIa (rFVIIa), fresh frozen plasma, and platelets.

RESULTS

Hemodilution reduced maximum clot firmness (MCF), whereas whole blood clotting time (CT) and maximum velocity remained unaffected. All coagulation factor activities were reduced. Fibrinogen, FII, FXIII and FX activities decreased significantly below the levels expected from dilution. The endogenous thrombin potential was unchanged. Ex vivo addition of fibrinogen normalized the reduced MCF and increased the maximum velocity, whereas PCC, rFVIIa and platelets shortened the CT but showed no effect on the reduced MCF.

CONCLUSIONS

Acquired fibrinogen deficiency seems to be the leading determinant in dilutional coagulopathy, and ex vivo addition corrected the coagulopathy completely.

Thrombin generation and bleeding in haemophilia A

Haemophilia A displays phenotypic heterogeneity with respect to clinical severity. The aim of this study was to determine if tissue factor (TF)-initiated thrombin generation profiles in whole blood in the presence of corn trypsin inhibitor (CTI) are predictive of bleeding risk in haemophilia A. We studied factor(F) VIII deficient individuals (11 mild, 4 moderate and 12 severe) with a well-characterized 5-year bleeding history that included haemarthrosis, soft tissue haematoma and annual FVIII concentrate usage. This clinical information was used to generate a bleeding score. The bleeding scores (range 0-32) were separated into three groups (bleeding score groupings: 0, 0 and < or = 9.6, >9.6), with the higher bleeding tendency having a higher score. Whole blood collected by phlebotomy and contact pathway suppressed by 100 microg mL(-1) CTI was stimulated to react by the addition of 5 pM TF. Reactions were quenched at 20 min by inhibitors. Thrombin generation, determined by enzyme-linked immunosorbent assay for thrombin-antithrombin was evaluated in terms of clot time (CT), maximum level (MaxL) and maximum rate (MaxR) and compared to the bleeding score. Data are shown as the mean+/-SD. MaxL was significantly different (P < 0.001) between the groups: 504 +/- 114, 315 +/- 117 and 194 +/- 91 nM; with higher thrombin concentrations in the groups with lower bleeding scores. MaxR was higher in the groups with a lower bleeding score; 97 +/- 51, 86 +/- 60 and 39 +/- 16 nM min(-1) (P = 0.09). No significant difference was detected in CT among the groups, 5.6 +/- 1.3, 4.7 +/- 0.7 and 5.6 +/- 1.3 min. Our empirical study in CTI-inhibited whole blood shows that the MaxL of thrombin generation appears to correlate with the bleeding phenotype of haemophilia A.

Fibrinogen substitution improves whole blood clot firmness after dilution with hydroxyethyl starch in bleeding patients undergoing radical cystectomy: a randomized, placebo-controlled clinical trial

SUMMARY BACKGROUND

Infusion of artificial colloids such as hydroxyethyl starch (HES) induces coagulopathy to a greater extent than simple dilution. Several studies have suggested that the coagulopathy could be corrected by substitution with a fibrinogen concentrate.

OBJECTIVES

The aims of the present prospective, randomized, placebo-controlled trial were to investigate the hemostatic effect of a fibrinogen concentrate after coagulopathy induced by hydroxyethyl starch in patients experiencing sudden excessive bleeding during elective cystectomy.

METHODS

Twenty patients were included. Blood loss was substituted 1:1 with HES 130/0.4. At a dilution level of 30%, patients were randomly selected for intra-operative administration of a fibrinogen concentrate or placebo. The primary endpoint was maximum clot firmness (MCF), as assessed by thromboelastometry. Secondary endpoints were blood loss and transfusion requirements, other thromboelastometry parameters, thrombin generation and platelet function.

RESULTS

Whole-blood MCF was significantly reduced after 30% dilution in vivo with HES. The placebo resulted in a further decline of the MCF, whereas randomized administration of fibrinogen significantly increased the MCF. Furthermore, only 2 out of 10 patients randomly chosen to receive fibrinogen substitution required postoperative red blood cell transfusions, compared with 8 out of 10 in the placebo group (P = 0.023). Platelet function and thrombin generation were reduced after 30% hemodilution in vivo, and fibrinogen administration caused no significant changes.

CONCLUSIONS

During cystectomy, fluid resuscitation with HES 130/0.4 during sudden excessive bleeding induces coagulopathy that shows reduced whole-blood maximum clot firmness. Randomized administration of fibrinogen concentrate significantly improved maximum clot firmness and reduced the requirement for postoperative transfusion.