Thrombelastographic whole blood clot formation after ex vivo addition of plasma substitutes: improvements of the induced coagulopathy with fibrinogen concentrate

Variations in emergency hemorrhage panel turnaround times in 2 major medical centers using the same laboratory methods

OBJECTIVES

Demand for rapid coagulation testing for massive transfusion events led to development of an emergency hemorrhage panel (EHP; hemoglobin, platelet count, prothrombin time/international normalized ratio, and fibrinogen), with laboratory turnaround time (TAT) of less than 20 minutes. Ten years on, we asked if current laboratory practices were meeting that TAT goal and differences were evident in TAT between the 2 major institutions in our system.

METHODS

We identified EHPs ordered at our 2 largest hospitals, February 2, 2021, to July 17, 2022, comparing order to specimen draw time, specimen draw to specimen received time, laboratory analytic time, and total TAT results from emergency department and operating room. Site 1 houses a level I trauma center; site 2 includes tertiary care, transplant, and obstetrics services.

RESULTS

In total, 1137 EHPs were recorded in our study period. Laboratory TAT was significantly faster at site 1 (~14 vs ~27 minutes, P < .01). Average laboratory TAT was under 20 minutes at site 1 but only for 50% of specimens at site 2. Outlier specimens were collection delays at site 1 and specimen processing delays at site 2.

CONCLUSIONS

The EHP can be performed as rapidly as described. However, compromises in laboratory location, available personnel, and processing differences can degrade performance.

Principles of minimize bleeding and the transfusion of blood and its components in operated patients - surgical aspects

One of the target of perioperative tratment in surgery is decreasing intraoperative bleeding, which increases the number of perioperative procedures, mortality and treatment costs, and also causes the risk of transfusion of blood and its components. Trying to minimize the blood loss(mainly during the operation) as well as the need to transfuse blood and its components (broadly understood perioperative period) should be standard treatment for a patient undergoing a procedure. In the case of this method, the following steps should be taken: 1) in the preoperative period: identyfication of risk groups as quickly as possible, detecting and treating anemia, applying prehabilitation, modyfying anticoagulant treatment, considering donating one's own blood in some patients and in selected cases erythropoietin preparations; 2) in the perioperative period: aim for normothermia, normovolemia and normoglycemia, use of surgical methods that reduce bleeding, such as minimally invasive surgery, high-energy coagulation, local hemostatics, prevention of surgical site infection, proper transfusion of blood and its components if it occurs; 3) in the postoperative period: monitor the condition of patients, primarily for the detection of bleeding, rapid reoperation if required, suplementation (oral administration preferred) nutrition with microelements (iron) and vitamins, updating its general condition. All these activities, comprehensively and in surgical cooperation with the anesthesiologist, should reduce the blood loss and transfusion of blood and its components.

Lidocaine effects on coagulation assessed by whole blood rotational thromboelastometry

Lidocaine may be beneficial when added in solutions for the preservation of vascular grafts or solid organs as it has anti-inflammatory, endothelial protective, and antithrombotic effects. However, the mechanisms of lidocaine-induced changes in hemostasis were not elucidated until now. The aim of the study was to examine the effect of increasing concentrations of lidocaine on coagulation parameters and blood-clotting kinetics using velocity curves of clot formation assessed by rotational thromboelastometry. Ex-vivo blood coagulation using whole blood from healthy volunteers was studied with rotational thromboelastometry. For each volunteer, four assays were performed: saline control and samples with lidocaine end blood concentrations of 0.3, 0.6, and 0.9%. In this in-vitro study, whole blood from 15 healthy volunteers was used. Lidocaine concentration of 0.3% prolonged the initiation phase of clotting without significant differences in the propagation phase or clot stability and inhibited clot lysis compared with the control group. Higher lidocaine concentrations (0.6 and 0.9%) resulted in prolongation of both initiation and propagation phases and decreased clot firmness compared with the control group. Lysis was significantly increased only in the 0.6% lidocaine group compared with control. Although lidocaine concentration of 0.3% only delays coagulation initiation, the 0.6% concentration inhibits all phases of hemostasis and increases clot lysis compared with control. Higher lidocaine concentration results in very weak clot formation with very low lysis visible on thromboelastometry. More research is needed to explain the effects of lidocaine on clotting kinetics.

Standard and derived rotational thromboelastometry parameters for prediction of disseminated intravascular coagulation in septic patients

: Waiting for lab tests results for the calculation of disseminated intravascular coagulation (DIC) scores leads to unwanted delays in diagnosis. The use of rotational thromboelastometry (ROTEM) for this purpose would allow for a more rapid DIC diagnosis at the bedside. The aim of this study was to assess the ability of standard ROTEM parameters and calculated parameters from the ROTEM velocity curve to predict DIC. The retrospective observational study included 97 septic patients. Japanese Association for Acute Medicine score was used for DIC diagnosis and whole-blood ROTEM was performed at study inclusion. Univariate analysis revealed delayed coagulation initiation and propagation and reduced clot firmness and maximum elasticity in DIC patients compared with patients without DIC. To adjust for confounders, multivariable logistic regression models were created and fibrinogen levels, prothrombin time and ROTEM parameters such as maximum clot firmness, maximum clot elasticity (MCE) and total thrombus formation [area under the curve (AUC)] were identified as significant predictors of DIC. According to receiver operating characteristics analysis, MCE and total thrombus formation (AUC) were the most useful ROTEM parameters for DIC prediction. MCE less than 158 (73% sensitive, 80% specific) and AUC less than 6175 mm × 100 (73% sensitive, 76% specific) predicted DIC in septic patients. Both standard and derived ROTEM parameters are useful for rapid DIC prediction in septic patients, allowing the timely identification of patients with higher mortality risk which might benefit from additional therapies. Further studies are needed to assess the clinical relevance of these findings.

Haemotherapy with Fibrinogen for Perioperative Bleeding Prevention-A View on Arterial Thrombogenesis and Myocardial Infarction in the Rat In Vivo

Major blood loss during cardiac surgery is associated with increased morbidity and mortality. Clinical pilot studies indicated that preoperative fibrinogen supplementation reduces postoperative blood loss without increasing thrombotic complications. However, an increase in fibrinogen concentration might rather aggravate pre-existing thrombosis than increase the incidence of thrombotic events. Therefore, we investigated, in the present study, whether fibrinogen supplementation influences (1) arterial thrombus formation, (2) the extent of myocardial infarction and (3) the cardioprotective effect of ischaemic preconditioning. Arterial thrombogenesis of the femoral artery was induced by topic FeCl₃ treatment in anaesthetised Wistar rats after pretreatment with 60 mg/kg (Fib_low), 120 mg/kg (Fib_high) or vehicle (Con). Vessel blood flow was monitored, and time to vessel occlusion was analysed as a marker for arterial thrombogenesis. In addition, regional myocardial I/R injury was induced by temporary left coronary artery occlusion in rats pretreated with or without fibrinogen supplementation. In additional groups, ischaemic preconditioning (IPC) was induced by 3 cycles of 5 min of ischaemia/reperfusion. In all groups, myocardial infarct size was determined by triphenyltetrazoliumchlorid staining. Arterial thrombogenesis was not affected by fibrinogen pretreatment. No differences in time until vessel occlusion between Con, Fib_low and Fib_high groups were observed. In addition, fibrinogen supplementation in low and high concentrations had no effect on infarct size after regional myocardial ischaemia and reperfusion (Fib_low: 66 ± 10%, Fib_high: 62 ± 9%; each ns vs. Con). IPC reduced infarct size from 62 ± 14% to 34 ± 12% (p < 0.05 vs. Con). Furthermore, both fibrinogen concentrations did not affect cardioprotection by ischaemic preconditioning (Fib_low + IPC: 34 ± 11%, Fib_high + IPC: 31 ± 13%; each ns vs. IPC). Haemotherapy with fibrinogen did not affect arterial thrombogenesis, myocardial infarction and the cardioprotective effect of ischaemic preconditioning.

Thromboelastography and Thromboelastometry in Assessment of Fibrinogen Deficiency and Prediction for Transfusion Requirement: A Descriptive Review

Fibrinogen is crucial for the formation of blood clot and clinical outcomes in major bleeding. Both Thromboelastography (TEG) and Rotational Thromboelastometry (ROTEM) have been increasingly used to diagnose fibrinogen deficiency and guide fibrinogen transfusion in trauma and surgical bleeding patients. We conducted a comprehensive and comparative review on the technologies and clinical applications of two typical functional fibrinogen assays using TEG (FF TEG) and ROTEM (FIBTEM) for assessment of fibrinogen level and deficiency, and prediction of transfusion requirement. Clot strength and firmness of FF TEG and ROTEM FIBTEM were the most used parameters, and their associations with fibrinogen levels as measured by Clauss method ranged from 0 to 0.9 for FF TEG and 0.27 to 0.94 for FIBTEM. A comparison of the interchangeability and clinical performance of the functional fibrinogen assays using the two systems showed that the results were correlated, but are not interchangeable between the two systems. It appears that ROTEM FIBTEM showed better associations with the Clauss method and more clinical use for monitoring fibrinogen deficiency and predicting transfusion requirements including fibrinogen replacement than FF TEG. TEG and ROTEM functional fibrinogen tests play important roles in the diagnosis of fibrinogen-related coagulopathy and guidance of transfusion requirements. Despite the fact that high-quality evidence is still needed, the two systems are likely to remain popular for the hemostatic management of bleeding patients.

Thromboelastometric prediction of mortality using the kinetics of clot growth in critically ill septic patients

: Sepsis induces alterations in blood coagulation which are associated with mortality. Using rotational thromboelastometry (ROTEM), these states are often characterized by changes in parameters representing terminal clot lysis. However, the ROTEM changes are often subtle, making them difficult to recognize and interpret. The objective of this study is to evaluate a new ROTEM clot velocity parameter representing clot formation kinetics in septic ICU patients. We hypothesized that this time-based parameter was significantly different in critically ill septic survivors vs. nonsurvivors. This retrospective observational study included severe sepsis and septic shock patients having a minimum of two organ dysfunctions by Sequential Organ Failure Assessment criteria (study group), and a control group of healthy adults without infection . ROTEM with EXTEM activation was performed in all groups. The time from maximal clot formation velocity to zero velocity, representing the latter portion of time during active clot formation prior to achieving maximal clot firmness (t-AUCi) was calculated along with other ROTEM parameters and compared between septic survivors, nonsurvivors and healthy controls. A total of 76 septic patients, of which 26.3%, survived, were included in the study group, and 26 healthy control individuals were included in the control group. t-AUCi correlated with terminal clot lysis (P < 0.001), and was significantly prolonged in septic nonsurvivors compared with survivors and healthy controls (P < 0.001). t-AUCi also differentiated nonsurvivors vs. survivors among those patients having similar ROTEM lysis indices. t-AUCi was useful to differentiate critically ill septic patients, and could be useful to identify septic patients with high-risk of ICU mortality.

The role of fibrinogen in trauma-induced coagulopathy

Fibrinogen plays an essential role in clot formation and stability. Importantly it seems to be the most vulnerable coagulation factor, reaching critical levels earlier than the others during the course of severe injury. A variety of causes of fibrinogen depletion in major trauma have been identified, such as blood loss, dilution, consumption, hyperfibrinolysis, hypothermia and acidosis. Low concentrations of fibrinogen are associated with an increased risk of diffuse microvascular bleeding. Therefore, repeated measurements of plasma fibrinogen concentration are strongly recommended in trauma patients with major bleeding. Recent guidelines recommend maintaining plasma fibrinogen concentration at 1.5–2 g/l in coagulopathic patients. It has been shown that early fibrinogen substitution is associated with improved outcome.

Hemostatic Therapy Using Tranexamic Acid and Coagulation Factor Concentrates in a Model of Traumatic Liver Injury

BACKGROUND

The potential clinical benefits of targeted therapy with coagulation factor concentrates (e.g., fibrinogen) and antifibrinolytic agents (e.g., tranexamic acid [TXA]) for the treatment of trauma-induced coagulopathy are increasingly recognized. We hypothesized that human fibrinogen concentrate (FC) and prothrombin complex concentrate (PCC), administered as combined therapy with TXA, would provide additive effects for reducing blood loss in an animal trauma model.

METHODS

Thirty-six pigs were subjected to 2 consecutive blunt liver injuries, resulting in severe hemorrhagic shock and coagulopathy. Intervention comprised saline (control group); TXA (15 mg kg, TXA group); TXA and FC (90 mg kg, TXA-FC); or TXA, FC, and PCC (20 U kg, TXA-FC-PCC). Blood loss, thromboelastometry (ROTEM), measures of thrombin generation, platelet activation, and global coagulation variables were monitored for 4 hours. Tissue sections were examined to determine the occurrence of thromboembolic events.

RESULTS

Total blood loss was similar in the TXA-FC and TXA-FC-PCC groups (mean ± SD: 1012 ± 86 mL and 1037 ± 118 mL, respectively; P = 1.000). These values were both lower (P < 0.001) than the TXA group (1579 ± 306 mL). Blood loss in all 3 intervention groups was lower (P < 0.001) than in the control group (2376 ± 478 mL). After trauma and resuscitation, but before study intervention, plasma fibrinogen levels were severely depleted (median for the whole study population: 66 mg dL; interquartile range: 51-108 mg dL) and clot strength was decreased (EXTEM whole-blood maximum clot firmness [MCF]: 53 ± 5 mm). Compared with controls, TXA inhibited fibrinolysis and stabilized MCF and clotting time. The addition of FC restored and stabilized hemostasis to a greater extent than TXA alone; the addition of PCC had no statistically significant impact on blood loss, clot strength (MCF), or clotting time, but it increased thrombin generation. There were no significant differences among the study groups regarding platelet activation. No thrombi or microthrombi were observed in any group at necropsy.

CONCLUSIONS

The early use of TXA and FC reduced blood loss and improved coagulation measurements in a porcine model of blunt liver injury and hemorrhagic shock. FC, administered in addition to TXA, was highly effective in reducing blood loss. The lack of statistically significant reduction in blood loss when PCC was added to TXA and FC may be attributable to the absence of thrombin generation impairment in this model.

Relative effects of plasma, fibrinogen concentrate, and factor XIII on ROTEM coagulation profiles in an in vitro model of massive transfusion in trauma

Massive traumatic haemorrhage is aggravated through the development of trauma-induced coagulopathy, which is managed by plasma transfusion and/or fibrinogen concentrate administration. It is yet unclear whether these treatments are equally potent in ensuring adequate haemostasis, and whether additional factor XIII (FXIII) administration provides further benefits. In this study, we compared ROTEM whole blood coagulation profiles after experimental massive transfusion with different transfusion regimens in an in vitro model of dilution- and transfusion-related coagulopathy. Healthy donor blood was mixed 1 + 1 with six different transfusion regimens. Each regimen contained RBC, platelet concentrate, and either fresh frozen plasma (FFP) or Ringer's acetate (RA). The regimens were further augmented through addition of a low- or medium-dose fibrinogen concentrate and FXIII. Transfusion with FFP alone was insufficient to maintain tissue-factor activated clot strength, coincidental with a deficiency in fibrin-based clot strength. Fibrinogen concentrate conserved, but did not improve coagulation kinetics and overall clot strength. Only combination therapy with FFP and low-dose fibrinogen concentrate improved both coagulation kinetics and fibrin-based clot strength. Administration of FXIII did not result in an improvement of clot strength. In conclusion, combination therapy with both FFP and low-dose fibrinogen concentrate improved clotting time and produced firm clots, representing a possible preferred first-line regimen to manage trauma-induced coagulopathy when RBC and platelets are also transfused. Further research is required to identify optimal first-line transfusion fluids for massive traumatic haemorrhage.

Management of postpartum haemorrhage

Postpartum Haemorrhage (PPH) is a major cause of maternal morbidity and mortality. Treatment of acquired coagulopathy observed in severe PPH is an important part of PPH management, but is mainly based on literature in trauma patients, and data thus should be interpreted with caution. This review describes recent advances in transfusion strategy and in the use of tranexamic acid and fibrinogen concentrates in women with PPH.

Interventional Algorithms for the Control of Coagulopathic Bleeding in Surgical, Trauma, and Postpartum Settings: Recommendations From the Share Network Group

Several clinical settings are associated with specific coagulopathies that predispose to uncontrolled bleeding. With the growing concern about the need for optimizing transfusion practices and improving treatment of the bleeding patient, a group of 9 Portuguese specialists (Share Network Group) was created to discuss and develop algorithms for the clinical evaluation and control of coagulopathic bleeding in the following perioperative clinical settings: surgery, trauma, and postpartum hemorrhage. The 3 algorithms developed by the group were presented at the VIII National Congress of the Associação Portuguesa de Imuno-hemoterapia in October 2013. They aim to provide a structured approach for clinicians to rapidly diagnose the status of coagulopathy in order to achieve an earlier and more effective bleeding control, reduce transfusion requirements, and improve patient outcomes. The group highlights the importance of communication between different specialties involved in the care of bleeding patients in order to achieve better results.

The effects of haemodilution with hydroxyethyl starch 130/0.4 solution on coagulation as assessed by thromboelastography and platelet receptor function studies in vitro

This study evaluated the effects of haemodilution with either 6% hydroxyethyl starch (HES) 130/0.4 (Voluven(®)) or 0.9% normal saline (NS) on blood coagulation in vitro. Haemodilution with 6% HES 130/0.4 impaired coagulation, as indicated by the changes in thromboelastographic parameters k-time, α-angle and maximum amplitude. Light transmission aggregometry and multiple electrode aggregometry demonstrated that impaired platelet receptor function occurred only at high levels of haemodilution (40%) with both fluids, but there was no significant difference between the two fluids (P=0.05). The thromboelastographic functional fibrinogen assay showed that the fibrinogen component of clot strength was significantly impaired with haemodilution with HES 130/0.4 compared with haemodilution with NS (whole blood [14.4 ± 4.6 mm] versus 40% HES dilution [3.7 ± 1.9], [P=0.001]; versus 40% NS dilution [10.4 ± 4.6], [P=0.129]). These findings suggest that there is little difference between HES or NS in relation to coagulation or platelet function during minor or moderate haemodilution, but at high levels of haemodilution with HES, fibrinogen activity is more impaired compared with NS.

Ex vivo addition of fibrinogen concentrate improves the fibrin network structure in plasma samples taken during liver transplantation

BACKGROUND

Optimal hemostatic management during orthotopic liver transplantation (OLT) remains a challenge. The cause of bleeding during OLT is multifactorial, and may include hemostatic imbalance. Fibrinogen concentrates are increasingly being used to control perioperative bleeding during OLT. However, administration is based on arbitrary thresholds of fibrinogen levels. Importantly, studies on fibrin clot structure during OLT are lacking.

OBJECTIVE

We determined the hemostatic efficacy of fibrinogen concentrate in correcting the fibrin structure.

METHODS

Plasma samples taken at various times during OLT from 15 patients and 15 healthy controls were spiked with 1 g L(-1) fibrinogen concentrate or saline. Turbidity, fibrin fiber density and permeability of the fibrin clots were assessed.

RESULTS

Clotting rate and turbidity were significantly decreased at the start of surgery, and decreased even further during surgery. Addition of fibrinogen significantly increased the clotting rate and turbidity at all time points, but did not normalize it. Fibrin density was significantly reduced after reperfusion as compared with the density at the start of surgery and in healthy controls. Fibrin density improved significantly after addition of fibrinogen in samples taken at the start of surgery and after reperfusion. The severely impaired polymerization and decreased density after reperfusion were accompanied by significantly increased permeability of the clot as compared with the start of surgery and in controls, which was completely restored after addition of fibrinogen.

CONCLUSIONS

Ex vivo addition of fibrinogen concentrate during OLT substantially improves the structural properties of the fibrin clot, which, particularly after reperfusion, shows hypocoagulable features. These data support the use of fibrinogen concentrate to control bleeding complications during OLT.

Over 50 Years of Fibrinogen Concentrate

March 2013 represented the 50th anniversary of the first license granted for a fibrinogen concentrate. In this review, we look at the history of bleeding management that led to the development of fibrinogen concentrate, discuss its current use, and consider future developments for this product.

Effects of in vitro hemodilution with crystalloids, colloids, and plasma on canine whole blood coagulation as determined by kaolin-activated thromboelastography

OBJECTIVE

To investigate the effects of in vitro hemodilution with lactated Ringers solution (LRS), hetastarch (HES), and fresh frozen plasma (FFP) on whole blood coagulation in dogs as assessed by kaolin-activated thromboelastography.

DESIGN

In vitro experimental study.

SETTING

University teaching hospital.

ANIMALS

Six healthy client-owned dogs.

INTERVENTIONS

Whole blood was collected and diluted in vitro at a 33% and 67% dilution with either LRS, HES, or FFP.

MEASUREMENTS AND MAIN RESULTS

Kaolin-activated thromboelastography was performed on each sample as well as a control. Thromboelastographic parameters R (min), alpha (deg), K (min), and MA (mm) were measured and compared to the sample control for each dilution using mixed model methodology. Prolongation in coagulation times were seen at both dilutions with LRS and HES. There was no significant difference in R times at the 33% dilution, but R time was significantly prolonged at the 67% dilution with HES (P = 0.004). MA was significantly decreased for LRS at both dilutions (P = 0.013, P < 0.001) and more profoundly decreased for HES (P < 0.001, P = 0.006). No significant difference in any parameter was found for FFP.

CONCLUSIONS

In vitro hemodilution of whole blood with both LRS and HES but not FFP resulted in significant effects on coagulation with HES having a more profound effect. In vivo evaluation of changes in coagulation with various resuscitation fluids is warranted and may be clinically relevant.

Effect of fibrinogen on blood coagulation detected by optical coherence tomography

Our previous work demonstrated that an optical coherence tomography (OCT) technique and the parameter 1/e light penetration depth (d1/e) were able to characterize the whole blood coagulation process in contrast to existing optical tests that are performed on plasma samples. To evaluate the feasibility of the technique for quantifying the effect of fibrinogen (Fbg) on blood coagulation, a dynamic study of d1/e of blood in various Fbg concentrations was performed in static state. Two groups of blood samples of hematocrit (HCT) in 35, 45, and 55% were reconstituted of red blood cells with: 1) treated plasma with its intrinsic Fbg removed and commercial Fbg added (0-8 g L(-1)); and 2) native plasma with commercial Fbg added (0-8 g L(-1)). The results revealed a typical behavior due to coagulation induced by calcium ions and the clotting time is Fbg concentration-dependent. The clotting time was decreased by the increasing amount of Fbg in both groups. Besides, the blood of lower HCT with various levels of Fbg took shorter time to coagulate than that of higher HCT. Consequently, the OCT method is a useful and promising tool for the detection of blood-coagulation processes induced with different Fbg levels.

Massive transfusion and massive transfusion protocol

Haemorrhage remains a major cause of potentially preventable deaths. Rapid transfusion of large volumes of blood products is required in patients with haemorrhagic shock which may lead to a unique set of complications. Recently, protocol based management of these patients using massive transfusion protocol have shown improved outcomes. This section discusses in detail both management and complications of massive blood transfusion.

Hydroxyethyl starch: a review of pharmacokinetics, pharmacodynamics, current products, and potential clinical risks, benefits, and use

OBJECTIVE

To review and summarize the pharmacokinetics and pharmacodynamics of hydroxyethyl starch (HES), as well as reported risks and benefits of HES infusion, and to provide administration and monitoring recommendations for HES use in dogs and cats.

DATA SOURCES

Veterinary and human peer-reviewed medical literature, including scientific reviews, clinical and laboratory research articles, and authors' clinical experience.

SUMMARY

HES solutions are the most frequently used synthetic colloid plasma volume expanders in human and veterinary medicine. The majority of research in human medicine has focused on the adverse effects of HES infusion, with emphasis on acute kidney injury and coagulation derangements. The studies often differ in or fail to report factors, such as the type, amount, interval, and concentration of HES administered; the patient population studied; or concurrent fluids administered. Currently, there is no definitive clinical evidence that the reported adverse effects of HES use in human medicine occur in veterinary species. There is little information available on HES administration techniques or simultaneous administration of additional fluids in human and veterinary medicine. The rationale for HES use in small animals has been largely extrapolated from human medical studies and guidelines. A controlled approach to intravenous fluid resuscitation using crystalloid and HES volumes titrated to reach desired resuscitation end point parameters is outlined for small animal practitioners.

CONCLUSION

The extrapolation of data from human studies directly to small animals should be done with the knowledge that there may be species variations and different pharmacokinetics with different HES solutions. Veterinary reports indicate that bolus and continuous rate infusions of 6% hetastarch solutions at moderate doses are well tolerated in feline and canine subjects. Further research in domesticated species is necessary to better define and expand the knowledge regarding use of HES solutions in small animal medicine.

Bleeding management for pediatric craniotomies and craniofacial surgery

Pediatric patients when undergoing craniotomies and craniofacial surgery may potentially have significant blood loss. The amount and extent will be dictated by the nature of the surgical procedure, the proximity to major blood vessels, and the age, and weight of the patient. The goals should be to maintain hemodynamic stability and oxygen carrying capacity and to prevent and treat hyperfibrinolysis and dilutional coagulopathy. Over transfusion and transfusion-related side effects should be minimized. This article will highlight the pertinent considerations for managing massive blood loss in pediatric patients undergoing craniotomies and craniofacial surgery. North American and European guidelines for intraoperative administration of fluid and blood products will be discussed.

Noninvasive measurement of glucose in artificial plasma with near-infrared and Raman spectroscopy

The goal of this research was to develop a method for noninvasive blood glucose assay. Near-infrared (NIR) spectroscopy and Raman spectroscopy, two more promising techniques compared to other methods, were investigated in two kinds of artificial plasma (AP). Calibration models were generated by performing partial least squares (PLS) regression and optimized individually by considering spectral range, spectral pretreatment methods, and number of model factors. The two spectroscopic models were validated for the determination of glucose, and the results show that the two spectroscopic models established are robust, accurate, and repeatable. Compared to Raman spectroscopy, the performance of NIR spectroscopy was much better, with lower root mean square errors of cross-validation (RMSECV) of 0.128 and 0.094 mg/ml, lower root mean square errors of validation (RMSEP) of 0.061 and 0.046 mg/ml, higher correlation coefficients (R) of 99.15% and 99.55%, and higher residual predictive deviations (RPD) of 10.8 and 15.0 for artificial plasma I and II, respectively.

Fibrinogen concentrate in bleeding patients

BACKGROUND

Hypofibrinogenaemia is associated with increased morbidity and mortality, but the optimal treatment level, the use of preemptive treatment and the preferred source of fibrinogen remain disputed. Fibrinogen concentrate is increasingly used and recommended for bleeding with acquired haemostatic deficiencies in several countries, but evidence is lacking regarding indications, dosing, efficacy and safety.

OBJECTIVES

We assessed the benefits and harms of fibrinogen concentrate compared with placebo or usual treatment for bleeding patients.

SEARCH METHODS

We searched the following electronic databases: the Cochrane Central Register of Controlled Trials (CENTRAL) (The Cochrane Library 2013, Issue 8); MEDLINE (1950 to 9 August 2013); EMBASE (1980 to 9 August 2013); International Web of Science (1964 to 9 August 2013); CINAHL (1980 to 9 August 2013); LILACS (1982 to 9 August 2013); and the Chinese Biomedical Literature Database (up to 10 November 2011), together with databases of ongoing trials. We contacted trial authors, authors of previous reviews and manufacturers in the field.

SELECTION CRITERIA

We included all randomized controlled trials (RCTs), irrespective of blinding or language, that compared fibrinogen concentrate with placebo/other treatment or no treatment in bleeding patients, excluding neonates and patients with hereditary bleeding disorders.

DATA COLLECTION AND ANALYSIS

Three review authors independently abstracted data; we resolved any disagreements by discussion. Our primary outcome measure was all-cause mortality. We performed subgroup and sensitivity analyses to assess the effects of fibrinogen concentrate in adults and children in terms of various clinical and physiological outcomes. We presented pooled estimates of the effects of intervention on dichotomous outcomes as risk ratios (RRs) and on continuous outcomes as mean differences, with 95% confidence intervals (CIs). We assessed the risk of bias through assessment of trial methodological components and the risk of random error through trial sequential analysis.

MAIN RESULTS

We included six RCTs with a total of 248 participants; none of the trials were determined to have overall low risk of bias. We found 12 ongoing trials, from which we were unable to retrieve any data. Only two trials provided data on mortality, and one was a zero event study; thus the meta-analysis showed no statistically significant effect on overall mortality (2.6% vs 9.5%, RR 0.28, 95% CI 0.03 to 2.33). Our analyses on blood transfusion data suggest a beneficial effect of fibrinogen concentrate in reducing the incidence of allogenic transfusions (RR 0.47, 95% CI 0.31 to 0.72) but show no effect on other predefined outcomes, including adverse events such as thrombotic episodes.

AUTHORS' CONCLUSIONS

In the six available RCTs of elective surgery, fibrinogen concentrate appears to reduce transfusion requirements, but the included trials are of low quality with high risk of bias and are underpowered to detect mortality, benefit or harm. Furthermore, data on mortality are lacking, heterogeneity is high and acute or severe bleeding in a non-elective surgical setting remains unexplored. Currently, weak evidence supports the use of fibrinogen concentrate in bleeding patients, as tested here in primarily elective cardiac surgery. More research is urgently needed.

Free oscillation rheometry monitoring of haemodilution and hypothermia and correction with fibrinogen and factor XIII concentrates

Background

Haemodilution and hypothermia induce coagulopathy separately, but their combined effect on coagulation has not been widely studied. Fibrinogen concentrate can correct dilutional coagulopathy and has an additional effect when combined with factor XIII concentrate. However, their effect on dilutional coagulopathy concomitant with hypothermia has not been studied previously. Free oscillation rheometry – FOR (Reorox®) – is a novel viscoelastic haemostatic assay that has not been studied in this context before.

Methods

Blood from 10 healthy volunteers was diluted by 33% with hydroxyethyl starch or Ringer’s acetate solutions. Effects of fibrinogen added in vitro with and without factor XIII were studied at 33°C and 37°C. Coagulation velocity (coagulation time) and clot strength (elasticity) were assessed with FOR. Coagulation was initiated in vitro with thromboplastin alone, or thromboplastin plus a platelet inhibitor.

Results

Hydroxyethyl starch increased the coagulation time and decreased clot strength significantly more than Ringer’s acetate solution, both in the presence and absence of a platelet inhibitor. There was a significant interaction between haemodilution with hydroxyethyl starch and hypothermia, resulting in increased coagulation time. After addition of fibrinogen, coagulation time shortened and elasticity increased, with the exception of fibrinogen-dependent clot strength (i.e., elasticity in the presence of a platelet inhibitor) after hydroxyethyl starch haemodilution. Factor XIII had an additional effect with fibrinogen on fibrinogen-dependent clot strength in blood diluted with Ringer’s acetate solution. Hypothermia did not influence any of the coagulation factor effects.

Conclusions

Both haemodilution and mild hypothermia impaired coagulation. Coagulopathy was more pronounced after haemodilution with hydroxyethyl starch than with Ringer’s acetate. Addition of fibrinogen with factor XIII was unable to reverse hydroxyethyl starch induced clot instability, but improved coagulation in blood diluted with Ringer’s acetate solution. Fibrinogen improved coagulation irrespective of hypothermia.

The early use of fibrinogen, prothrombin complex concentrate, and recombinant-activated factor VIIa in massive bleeding

BACKGROUND

Coagulopathy related to massive bleeding has a multifactorial aetiology. Coagulopathy is related to shock and blood loss including consumption of clotting factors and platelets and hemodilution. Additionally hyperfibrinolysis, hypothermia, acidosis, and metabolic changes affect the coagulation system. The aim of any hemostatic therapy is to control bleeding and minimize blood loss and transfusion requirements. Transfusion of allogeneic blood products as well as the presence of coagulopathy cause increased morbidity and mortality.

STUDY DESIGN AND METHODS

This paper presents a short review on new treatment strategies of coagulopathy, related to massive blood loss.

RESULTS

Paradigms are actively changing and there is still shortage of data. However, there is increasing experience and evidence that "target controlled algorithms" using point-of-care monitoring devices and coagulation factor concentrates are more effective compared to transfusion of fresh frozen plasma, independently of the individual clinical situation.

CONCLUSION

Future treatment of coagulopathy associated with massive bleeding can be based on an individualized point-of-care guided rational use of coagulation factor concentrates such as fibrinogen, prothrombin complex concentrate, and recombinant factor VIIa. The timely and rational use of coagulation factor concentrates may be more efficacious and safer than ratio-driven use of transfusion packages of allogeneic blood products.

Nonsurgical techniques to control massive bleeding

Significant advancements in nonsurgical and surgical approaches to control bleeding in severely injured patients have also improved the treatment of critical trauma-related coagulopathy. Nonsurgical procedures such as angiographic embolization are progressively considered to terminate arterial bleeding from pelvic fractures. The disturbance of coagulation may aggravate bleeding and hamper surgical procedures. The administration of coagulation factors and factor concentrates may be useful for correcting systemic coagulopathy and reducing the need for fresh frozen plasma, platelet, and red blood cell transfusions, which are associated with various adverse outcomes. In this review, nonsurgical management of critical trauma bleeding is discussed.

Observational study of fibrinogen concentrate in massive hemorrhage: evaluation of a multicenter register

In acute hemorrhage, a critical decrease in fibrinogen often induces acquired coagulopathy. Fibrinogen concentrate has been used to supplement fibrinogen during massive hemorrhage. However, there are limited data on the utilization of fibrinogen concentrate in this setting. This prospective, multicenter observational study analyzed clinical treatment with fibrinogen concentrate in acute bleeding. A prospective multicenter web-based register was developed to document closed cases of massive hemorrhage treated with fibrinogen concentrate perioperatively. Anonymized data including the cause and kinetics of the bleeding, coagulation parameters, coagulation therapy, clinical effects and adverse events were recorded. Two hundred and twenty-three cases entered between September 2008 and August 2009 were eligible for analysis. According to patient needs, additional common blood and coagulation products were administered. Fibrinogen substitution by fibrinogen concentrate and fresh frozen plasma (FFP) was initiated at a median blood loss of 2.0 l and plasma fibrinogen of 1.45 g/l. After a median dose of 12.0 g fibrinogen (4 g in fibrinogen concentrate and 8 g in FFP), plasma fibrinogen rose to 2.19 g/l at the end of surgery; corresponding to a median increment of 0.045 g/l per gram of fibrinogen administered. After substitution, 6% of patients had supra-physiological plasma fibrinogen levels. Three percent of patients sustained thromboembolic complications perioperatively. Logistic regression analysis showed positive correlation of postoperative plasma fibrinogen and survival (P < 0.05). Clinical application of fibrinogen concentrate in bleeding patients is included within a multimodal therapeutic concept. High levels of fibrinogen are necessary in order to reach therapeutic goals. In bleeding patients, higher plasma fibrinogen might be associated with higher rates of survival.

The in vivo effect of fibrinogen and factor XIII on clot formation and fibrinolysis in Glanzmann's thrombasthenia

Glanzmann's thrombasthenia (GT) is characterized by increased bleeding risk. The treatment options in GT are limited. The aim of this study was to test the effect of GT blood supplementation with fibrinogen and factor XIII on thrombin generation, blood clotting, and fibrinolysis. Whole blood samples of GT patients and normal donors treated with eptifibatide (GT model) were subjected to clotting by CaCl(2) and tissue factor. Thrombin generation was measured in platelet-rich plasma. Clot formation and tPA-induced fibrinolysis were evaluated in whole blood by rotation thromboelastometry (ROTEM). Blood was supplemented with fibrinogen (3 g/L) and/or FXIII (2 IU/mL). Thrombin generation analysis of blood derived from GT model and GT patients revealed decreased endogenous thrombin potential and peak height and extended lag time compared to control. However, this method was not sensitive to blood spiking with fibrinogen and FXIII. ROTEM revealed lower maximum clot firmness (MCF) and area under curve (AUC) in the blood of GT model and GT patients. In the absence of exogenous tPA, blood spiking with fibrinogen markedly enhanced clot quality while FXIII had no effect. Combination of fibrinogen and FXIII did not add to the effect of fibrinogen. In contrast, by the addition of tPA, both fibrinogen and FXIII separately and, to more extent, in combination enhanced clot quality as well as resistance against tPA-induced fibrinolysis (increasing MCF, AUC, and lysis onset time). In conclusion, fibrinogen and FXIII exerted stimulation of blood clotting and inhibition of fibrinolysis. Treating normal blood with eptifibatide mimics the changes of coagulopathy in GT blood.

Critical role of factors II and X during coumarin anticoagulation and their combined measurement with a new Fiix-prothrombin time

Vitamin K antagonists (VKA) are monitored with prothrombin time (PT) based assays that are equally sensitive to reductions in factors II, VII or X. We compared the effect of vitamin K dependent (VKD) coagulation factors on PT and also on rotational thromboelastometric (ROTEM) parameters. The PT was equally sensitive to reductions in factors II, VII or X but ROTEM parameters correlated poorly with the PT in anticoagulated patients´ plasmas. ROTEM parameters were more affected by mild and moderate reductions in FII or FX than by FVII or FIX which had little influence except at very low coagulant activity. We developed a modified PT that was sensitive only to reductions in factors II and X. The Fiix-PT (Fiix-INR) correlated well with PT (INR) but the Fiix-INR fluctuated less than the INR in an anticoagulated patient reflecting its insensitivity to FVII. The ROTEM results suggest that mild to moderate reductions in factors II or X are more important during clot formation than factors VII or IX. Reductions in FII and X may better reflect anticoagulation with VKA than FVII or IX. The new Fiix-PT may more accurately reflect the degree of therapeutic anticoagulation in patients treated with VKA than the current PT which is subject to a confounding variation caused by FVII.

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.

Can RoTEM® analysis be applied for haemostatic monitoring in paediatric congenital heart surgery?

BACKGROUND

Successful management of bleeding disorders after congenital heart surgery requires detection of specific coagulation disturbances. Whole-blood rotation thromboelastometry (RoTEM®) provides continuous qualitative haemostatic profiles, and the technique has shown promising results in adult cardiac surgery.

SETTING

To compare the performance of RoTEM® with that of conventional coagulation tests in children, we conducted a descriptive study in children undergoing congenital cardiac surgery. For that purpose, 60 children were enrolled and had blood samples taken before, immediately after, and 1 day after surgery. Conventional coagulation tests included: activated partial thromboplastin time, prothrombin time, fibrinogen, fibrin D-dimer, thrombin clotting time, factor XIII, and platelet count.

RESULTS

Post-surgical haemostatic impairment was present to some degree in all children, as seen by pronounced changes in activated partial thromboplastin time, prothrombin time, thrombin clotting time, and platelet count, as well as RoTEM® analysis. RoTEM® showed marked changes in clotting time - prolonged by 7-18% - clot formation time - prolonged by 46-71% - maximum clot firmness - reduced by 10-19%, and maximum velocity - reduced by 29-39%. Comparison of the two techniques showed that conventional coagulation tests and RoTEM® performed equally well with regard to negative predictive values for excessive post-operative drain production - more than 20 millilitres per kilogram per 24 hours after surgery - with an area under the curve of approximately 0.65.

CONCLUSION

RoTEM® can detect haemostatic impairments in children undergoing cardiac surgery and the method should be considered as a supplement in the perioperative care of the children where targeted transfusion therapy is necessary to avoid volume overload.

Clinical effectiveness of fresh frozen plasma compared with fibrinogen concentrate: a systematic review

Introduction

Haemostatic therapy in surgical and/or massive trauma patients typically involves transfusion of fresh frozen plasma (FFP). Purified human fibrinogen concentrate may offer an alternative to FFP in some instances. In this systematic review, we investigated the current evidence for the use of FFP and fibrinogen concentrate in the perioperative or massive trauma setting.

Methods

Studies reporting the outcome (blood loss, transfusion requirement, length of stay, survival and plasma fibrinogen level) of FFP or fibrinogen concentrate administration to patients in a perioperative or massive trauma setting were identified in electronic databases (1995 to 2010). Studies were included regardless of type, patient age, sample size or duration of patient follow-up. Studies of patients with congenital clotting factor deficiencies or other haematological disorders were excluded. Studies were assessed for eligibility, and data were extracted and tabulated.

Results

Ninety-one eligible studies (70 FFP and 21 fibrinogen concentrate) reported outcomes of interest. Few were high-quality prospective studies. Evidence for the efficacy of FFP was inconsistent across all assessed outcomes. Overall, FFP showed a positive effect for 28% of outcomes and a negative effect for 22% of outcomes. There was limited evidence that FFP reduced mortality: 50% of outcomes associated FFP with reduced mortality (typically trauma and/or massive bleeding), and 20% were associated with increased mortality (typically surgical and/or nonmassive bleeding). Five studies reported the outcome of fibrinogen concentrate versus a comparator. The evidence was consistently positive (70% of all outcomes), with no negative effects reported (0% of all outcomes). Fibrinogen concentrate was compared directly with FFP in three high-quality studies and was found to be superior for > 50% of outcomes in terms of reducing blood loss, allogeneic transfusion requirements, length of intensive care unit and hospital stay and increasing plasma fibrinogen levels. We found no fibrinogen concentrate comparator studies in patients with haemorrhage due to massive trauma, although efficacy across all assessed outcomes was reported in a number of noncomparator trauma studies.

Conclusions

The weight of evidence does not appear to support the clinical effectiveness of FFP for surgical and/or massive trauma patients and suggests it can be detrimental. Perioperatively, fibrinogen concentrate was generally associated with improved outcome measures, although more high-quality, prospective studies are required before any definitive conclusions can be drawn.

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.

Fibrinogen concentrates for bleeding trauma patients: what is the evidence?

INTRODUCTION

A balanced transfusion of red blood cells, fresh frozen plasma and platelets are recommended for massively bleeding trauma patients. Fibrinogen concentrates could potentially lessen or replace the need for fresh frozen plasma and/or platelet transfusions.

OBJECTIVE

To provide a review of the literature covering the application of fibrinogen concentrates in trauma care.

METHODS

PubMed and Cochrane database search, 'fibrinogen' and ('concentrate' or 'trauma'), not 'congenital', 10 years.

RESULTS

Only four papers were identified. None were randomized controlled trials. The main conclusion of these papers was that administration of fibrinogen sometimes together with prothrombin complex concentrate might improve haemostasis in trauma patients resuscitated with synthetic colloids.

CONCLUSION

Evidence for the use of fibrinogen concentrate to trauma patients with massive bleeding is lacking. Well-designed prospective, randomized, double-blinded studies evaluating the effect of fibrinogen concentrate, as the only intervention, are urgently needed.