Fibrinogen measurements in plasma and whole blood: a performance evaluation study of the dry-hematology system

CG02N Analyzer Accurately Measures Fibrinogen Level in Whole Blood in the Presence of Low- or High-Dose Heparin

Rapid fibrinogen (Fbg) evaluation is important in patients with massive bleeding during severe trauma and those undergoing major surgery. However, there are only a few studies on the point-of-care Fbg analyzer. In this study, we aimed to investigate the accuracy of Fbg level measured using CG02N, with whole blood contained in lithium-heparinized syringes with two different concentrations of heparin. Blood samples were collected in lithium-heparinized tubes, namely PREZA-PAK®II (low-dose heparin group [LG], 7 IU/mL) and Pro-Vent® Plus (high-dose heparin group [HG], 70.5 IU/mL). The Fbg levels in LG and HG were compared with those of citrated plasma Fbg (standard-Fbg). Strong correlations with respect to the Fbg level were observed between standard-Fbg and LG or HG (r = 0.968, p < 0.0001; r = 0.970, p < 0.0001, respectively). We demonstrated that the Fbg level in whole-blood samples was accurately assessed by CG02N and not affected by low- or high-dose heparin.

The qLabs® FIB system, a novel point-of-care technology for a rapid and accurate quantification of functional fibrinogen concentration from a single drop of citrated whole blood

Hypofibrinogenemia is often associated with excessive bleeding and requires immediate treatment. The qLabs FIB® is a handheld and easy-to-use point-of-care (POC) device designed for the rapid measurement of functional fibrinogen concentration from a single drop of citrated whole blood. The aim of this study was to evaluate the analytical performances of the qLabs FIB system. Fibrinogen concentrations from 110 citrated whole blood specimen were measured by both the qLabs FIB and the Clauss laboratory reference methods (STA®-Liquid Fib assay on STA-R® Max from Stago). A three-laboratories comparison study was conducted to assess reproducibility and repeatability of the qLabs FIB using plasma quality control material. In addition, single-site assays were conducted to assess the repeatability from citrated whole blood specimen covering the qLabs FIB reportable range. A very strong correlation between the qLabs FIB and the Clauss laboratory reference method was observed (r = 0.95). Using a clinical cut-off value of 2.0 g/L, the area under the receiver operating characteristic curve (ROC) of citrated whole blood was 0.99 and sensibility and specificity were 100 % and 93.5 %, respectively. Percent CVs for reproducibility and repeatability assessed from quality control material, were both <5 %. Repeatability assessed from citrated whole blood specimen showed a CV of 2.6 to 6.5 %. In conclusion, the qLabs FIB system enables a rapid and reliable measurement of functional fibrinogen levels from citrated whole blood and exhibits a strong prediction power at the 2 g/L clinical cut-off when compared to the Clauss laboratory reference. Further clinical studies should demonstrate its ability to quickly confirm the diagnosis of acquired hypofibrinogenemia and help identify patients who may benefit from targeted hemostatic treatment.

Restrictive blood transfusion and 1-year mortality in patients undergoing open abdominal surgery: A retrospective propensity score-matched cohort study

BACKGROUND

The importance of patient blood management is increasingly recognized in surgery patients. This study aimed to examine the effect of perioperative restrictive blood transfusion on 1-year mortality and blood transfusion rate in open abdominal surgery.

METHODS

We retrospectively studied 452 consecutive patients who underwent open abdominal surgery before (liberal group: 233 patients) and after (restrictive group: 219 patients) implementing intraoperative restrictive transfusion of red blood cell. The trigger levels of hemoglobin were less than 9-10 g/dL in the liberal group and less than 7-8 g/dL in the restrictive group. All-cause mortality at 1-year as the primary outcome and the transfusion rate of any allogeneic blood products as secondary outcome were compared between the liberal group and the restrictive group by the propensity-score matching.

RESULTS

Among a total of 452 patients (69 ± 11 yr., 70.5 % men), overall mortality at 1 year was 8.4 % and the proportion of patients who received any allogeneic blood products was 19.6 %. Compared with 155 propensity-score matched patients of the liberal group, 155 matched patients of the restrictive group had significantly lower 1-year mortality (4 [2.5 %] versus 18 [11.6 %], p = 0.003, percent absolute risk reduction [%ARR]; 9.0, 95 % confidential interval [CI], 3.1-14.7) and had significantly lower proportion of patients who received any allogeneic blood products (21 [13.5 %] versus 41 [26.4 %], p = 0.006, %ARR; 12.9, 95 % CI, 3.9-21.5).

CONCLUSIONS

The results of this study indicate that intraoperative restrictive blood transfusion reduces 1-year mortality and the transfusion rate of allogeneic blood products.

Comparative retrospective study on the validity of point-of-care testing device for massive obstetrical hemorrhage: dry hematology vs thromboelastography

BACKGROUND

Early recognition of hypofibrinogenemia and prompt initiation of transfusion therapy in patients with massive obstetrical hemorrhage can improve prognosis. There are reports on the usefulness of point-of-care testing, which provides quicker test results compared with fibrinogen measurements using the conventional Clauss method.

OBJECTIVE

This study aimed to compare and investigate the diagnostic accuracy of dry hematology and thromboelastography in point-of-care testing for the diagnosis of hypofibrinogenemia.

STUDY DESIGN

A single-center, retrospective study of 126 massive obstetrical hemorrhage cases with point-of-care testing before treatment was initiated. The correlation of fibrinogen values with the Clauss method and the diagnostic accuracy for hypofibrinogenemia were compared between dry hematology and thromboelastography.

RESULTS

Fibrinogen value in dry hematology showed a strong positive correlation with values measured by the Clauss method, and the diagnostic accuracy for hypofibrinogenemia was high, but there were many residuals above 100 mg/dL, and the distribution of these residuals was not uniform. Although thromboelastography cannot be used to directly measure fibrinogen values, maximum amplitude citrated functional fibrinogen, amplitude-10 citrated rapid thromboelastography, and amplitude-10 citrated functional fibrinogen showed a strong positive correlation with fibrinogen values using the Clauss method, and no significant difference in correlation or diagnostic accuracy was observed relative to dry hematology.

CONCLUSION

Dry hematology and thromboelastography were equally accurate in diagnosing hypofibrinogenemia, with results correlating well with fibrinogen values measured by the Clauss method.

Comparison of Fibrinogen Concentrations Determined by the Clauss Method with Prothrombin-Derived Measurements on an Automated Coagulometer

Background

This research aims to compare fibrinogen results, obtained from the Clauss and PT-derived method on the Cobas t511 analyzer, in patients with specific categories of disease. A second aim was to determine the reference range for these 2 methods.

Methods

We retrospectively compared fibrinogen concentrations of 914 patients obtained by the Clauss and PT-derived methods on the Cobas t511 coagulation analyzer from the laboratory information system. Fibrinogen data was segregated into a healthy outpatient population and those populations with possible fibrinogen abnormalities including pregnancy, chronic illness, liver disease, heart and vascular diseases, and clinical suspicion of COVID-19. All data were analyzed using Passing–Bablok regression and Bland–Altman analysis. Reference ranges were determined from fibrinogen results of the healthy outpatient population who presented for a clinic check-up.

Results

All fibrinogen results were grouped and compared according to fibrinogen values (low, normal, and high), international normalized ratio (INR) values (<1.2, 1.2–2.0, and >2.0), and diagnosis. There were statistically significant positive correlations in all groups (P < 0.05), except for low fibrinogen values (P = 0.96). Results with INR value <1.2 had the highest correlation between 2 methods.

Conclusion

The PT-derived method can be used alone in the Cobas t511 analyzer, especially in patients with an INR <1.2. Reported new reference ranges of the PT-derived method could help to determine and compare the clinical significance of fibrinogen methods. Further studies must be focused on the conditions in which PT-derived fibrinogen results should be directed to the Clauss test.

Effect of cryoprecipitate on an increase in fibrinogen level in patients with excessive intraoperative blood loss: a single-center retrospective study

Background

Cryoprecipitate, which contains fibrinogen and factor VIII in large quantities, is concentrated from fresh frozen plasma, and it has hemostatic effects in severe bleeding. We retrospectively examined the effects of cryoprecipitate on the increase in fibrinogen levels in patients with excessive intraoperative blood loss.

Methods

Ninety-seven patients who were administered cryoprecipitate during surgery between June 2014 and May 2019 were enrolled in our study and categorized according to the volume of intraoperative blood loss as follows: group A, 2000–5000 mL; group B, 5000–10,000 mL; group C, > 10,000 mL. Data were extracted from electronic medical records and electronic anesthesia records. The primary endpoint was an increase in the fibrinogen level after the administration of cryoprecipitate.

Results

Nine patients with no fibrinogen data and four patients with a bleeding volume of less than 2000 mL were excluded; thus, 84 patients (A: n = 36, B: n = 37, C: n = 11) were evaluated. The mean intraoperative blood loss (mL) in groups A, B, and C were 3348 ± 791, 6688 ± 1225, and 14,281 ± 5142, respectively. The fibrinogen levels (mg/dL) before cryoprecipitate administration in groups A, B, and C were 189 ± 94, 113 ± 42, and 83 ± 29, respectively (p < 0.05 among the groups). The increase in fibrinogen level (mg/dL) after cryoprecipitate administration in group C was significantly greater than that in group A (84 ± 34 versus 50 ± 36, p < 0.01).

Conclusions

The results of this study indicate that the effect of cryoprecipitate on the increase in fibrinogen level was most apparent in patients with excessive intraoperative blood loss ≥ 10,000 mL. In addition, most patients with intraoperative blood loss ≥ 5000 mL had fibrinogen levels < 150 mg/dL which improved to ≥ 150 mg/dL after cryoprecipitate administration in approximately 70% of patients. Therefore, cryoprecipitate administration should be considered for patients with hypofibrinogenemia (≤ 150 mg/dL) experiencing severe bleeding (e.g., ≥ 5000 mL) and rapid administration of cryoprecipitate is necessary to maximize the hemostatic effect, especially when the bleeding volume exceeds 10,000 ml.

Paper-Based Lateral Flow Device for the Sustainable Measurement of Human Plasma Fibrinogen in Low-Resource Settings

Fibrinogen concentration is a major determinant of both clotting and bleeding risk. Clotting and bleeding disorders cause extensive morbidity and mortality, particularly in resource-poor and emergency settings. This is exacerbated by a lack of timely intervention informed by measurement of fibrinogen levels under conditions such as thrombosis or postpartum haemorrhage. There is an absence of simple, rapid, low-cost, and sustainable diagnostic devices for fibrinogen measurement that can be deployed in such environments. Paper-based analytical devices are of significant interest due to their potential for low-cost production, ease of use, and environmental sustainability. In this work, a device for measuring blood plasma fibrinogen using chromatography paper was developed. Wax printing was used to create hydrophobic structures to define the test channel and sample application zone. Test strips were modified with bovine thrombin. Plasma samples (22 μL) were applied, and the flow rate was monitored over 5 min. As the sample traversed the strip, clotting was induced by the conversion of soluble fibrinogen to insoluble fibrin. The flow rate and distance travelled by the sample were dependent on fibrinogen concentration. The device was able to measure fibrinogen concentration in the range of 0.5–7.0 ± 0.3 mg/mL (p < 0.05, n = 24) and had excellent correlation with laboratory coagulometry in artificial samples (r² = 0.9582, n = 60). Devices were also stable at 4–6 °C for up to 3 weeks.

Fibrinogen measurement by a novel point-of-care device with whole blood: comparison of values against Clauss method

Timely fibrinogen replacement is key to treating critical hemorrhage. Measuring fibrinogen concentration by conventional laboratory tests requires centrifugation of blood samples and is often time-consuming. A point-of-care testing device (A&T, Yokohama, Japan), CG02N, has been available in Japan since 2011 to measure fibrinogen concentration without centrifugation. However, it has not been widely used as it requires dilution of blood samples using manual micropipetting. To further speed up and simplify the fibrinogen measurement, an improved device called FibCare (Atom Medical, Tokyo, Japan) was developed to avoid diluting blood samples. The purpose of this study is to verify the reliability of FibCare against laboratory measurement using the Clauss method. Fibrinogen concentrations with 60 sodium citrated whole blood samples were measured by both FibCare and Clauss methods in the laboratory. Measured values with the Clauss method were distributed in the 88-300 mg/dL range. By comparing these results, a significant positive correlation was observed between the FibCare and Clauss method (Y = 12.402 + 0.982 X; R = 0.891; P < 0.01). The study indicated that FibCare allows accurate measurement of fibrinogen concentration and shows a possibility to contribute to optimal fibrinogen replacement therapy during critical hemorrhage.

Effect of an assessment of fibrin-based rotational thromboelastometry on blood transfusion and clinical outcomes in cardiovascular surgery: A cohort study

The clinical importance of viscoelastic testing in patient blood management when performing cardiovascular surgery is increasing. We aimed to examine the effect of a blood transfusion protocol including an assessment of fibrin-based rotational thromboelastometry on transfusion volume, mortality, and bleeding complications in patients undergoing cardiac or thoracic aortic surgery. We retrospectively studied a cohort of 376 consecutive patients who underwent cardiopulmonary bypass before (control group: 150 cardiac and 35 thoracic aortic surgeries) and after (assessment group: 154 cardiac and 37 thoracic aortic surgeries) introducing the fibrin polymerization assessment with thromboelastometry in the blood transfusion protocol. The transfusion volume and clinical outcomes were compared between the control and assessment groups, and the standardized (mean) difference (S[M]D) was calculated as an indicator of statistical effect size. Compared with the control group, the assessment group had a lower total blood transfusion volume (mL) in cardiac (2720 ± 1282 vs. 2034 ± 1330, p < 0.0001, [SMD] = 0.68) and thoracic aortic surgeries (5236 ± 2732 vs. 3714 ± 1768, p < 0.0001, SMD = 0.67). The 1-year mortality rates were 1.9 % and 2.7 % in cardiac and thoracic aortic surgeries, respectively. Significant differences were not observed in the 1-year mortality (3.2 % vs. 1.0 %, p = 0.16, relative risk [RR] = 0.32 with 95 % confidence intervals [CI] = 0.06-1.57, SD = 0.15), re-exploration for bleeding (4.8 % vs. 2.6 %, p = 0.28, RR = 0.53 with 95 % CI = 0.18-1.57, SD = 0.12), and major bleeding (17.3 % vs. 13.0 %, p = 0.31, RR = 0.75 with 95 % CI = 0.46-1.22, SD = 0.12) rates between the control and assessment groups. The assessment of fibrin polymerization with thromboelastometry using the blood transfusion protocol reduced the blood transfusion volume in cardiovascular surgery.

The value of the portable fibrinogen measuring device-a case report of severe postpartum hemorrhage with obstetric disseminated intravascular coagulation

Background

Fibrinogen concentration is an important indicator of the treatment for obstetric disseminated intravascular coagulation (DIC). We present how using the fibrinogen measuring device could solve problems in the treatment of postpartum hemorrhage with complicated DIC.

Case presentation

A 32-year-old woman with monochorionic diamniotic twins at 22 weeks of pregnancy was diagnosed with placental abruption and underwent emergent cesarean section. The estimated blood loss was 8375 g. She was transferred to our hospital for further treatment. Compressive uterine sutures and balloon tamponade were performed. We transfused fibrinogen and fresh frozen plasma actively during the operation to maintain plasma fibrinogen above 200 mg/dL by using a point-of-care fibrinogen measuring device. In spite of massive hemorrhage exceeding 10 L, she was extubated at the end of the operation and discharged on the 7th day after the operation.

Conclusion

The portable fibrinogen measuring device was useful for point-of-care assessment of obstetric DIC.

Supplementary Information

The online version contains supplementary material available at 10.1186/s40981-021-00426-y.

Clinical Simulation Model of Fibrinogen Decline During Hemorrhage in Major Noncardiac Surgery

BACKGROUND

Monitoring of decrease in fibrinogen levels with surgical blood loss is crucial for timely transfusion of fresh frozen plasma (FFP) to avoid coagulopathic bleeding. Here, we validated a simulation model to predict hemorrhagic reductions in fibrinogen levels during major noncardiac surgery.

METHODS

We retrospectively performed exponential regression analysis of intraoperative blood loss and fibrinogen levels to develop a simulation model in the initial 50 patients and applied the model to another 59 patients to compare the measured and simulated fibrinogen levels. We examined the relationship between FFP transfusion and the measured fibrinogen levels or blood loss. The fibrinogen trigger level of FFP transfusion was below 130 mg/dL, although the decision of a perioperative blood transfusion was at the discretion of the anesthesiologists and surgeons.

RESULTS

Application of the simulation model based on the initial 50 patients to another 59 patients showed no difference between the measured and estimated fibrinogen levels (189 ± 61 versus 186 ± 62, P = 0.60, mean difference: -2.28, limits of agreement: -69.42 to 64.84). The estimated fibrinogen level (mg/dL) = preoperative fibrinogen × exp (-1.90 × [blood loss/estimated circulation volume]), in which the estimated circulation volume = (70 [mL/kg] × body weight [kg]). FFP transfusion was significantly related to the measured fibrinogen level (cutoff: 145; 95% confidence intervals: 124-168; P = 0.0003) but not blood loss (P = 0.12).

CONCLUSIONS

Fibrinogen level simulation predicted a hemorrhagic fibrinogen decline, thereby guiding FFP transfusion during active surgical bleeding. Further studies on the usefulness of fibrinogen level simulation are warranted.

Pediatric Fibrinogen PART I-Pitfalls in Fibrinogen Evaluation and Use of Fibrinogen Replacement Products in Children

Fibrinogen is a key coagulation protein, playing a critical role in hemostasis. It is the first factor to decrease to critical levels during bleeding. Hypofibrinogenemia is an important risk factor for bleeding in clinical settings, including pediatric surgery. Yet, the optimal measurement of fibrinogen levels is subject to debate, as is the critical threshold for intervention. Fibrinogen replacement may be provided by cryoprecipitate and fibrinogen concentrate. Whilst both products contain fibrinogen, they are not equivalent, each has its own advantages and disadvantages, especially for pediatric use. Unfortunately, medical literature to support fibrinogen replacement in children is limited. In this article we review the current diagnostic tools to measure fibrinogen, with respect to their use in the pediatric critical care setting. Secondly, we evaluate the different fibrinogen replacement therapies, focusing on cryoprecipitate and fibrinogen concentrate and examine their individual product characteristics, associated risks and benefits, different dosing strategies and specific pitfalls for use in children. We summarize by highlighting current knowledge gaps and areas for future research.

Paper Diagnostic for Direct Measurement of Fibrinogen Concentration in Whole Blood

The ability to diagnose and treat critically bleeding patients can save more than 2 million lives a year. Diagnosing hypofibrinogenemia is essential in these patients. Recently, with the development of new handheld diagnostics, fibrinogen concentration can be measured rapidly at the point of care. However, these diagnostics can only work with plasma and hence need blood cells to be separated before use. In this study, we demonstrate a handheld fibrinogen diagnostic that works with whole blood. The test works by (1) forming a premixed droplet of a whole blood sample and thrombin solution on a solid surface, (2) allowing it to clot, and (3) dropping a paper strip on top. The further that blood moves down the strip, the lower the fibrinogen concentration. The diagnostic can easily measure plasma fibrinogen concentrations below 1.6 g/L for blood samples with hematocrits between 40 and 50%. Furthermore, diluting blood samples not only increases the test's sensitivity but also eliminates the effect of hematocrit and thrombin inhibitors. The test can be completed in 3-4 min, making it suitable for diagnosing early hypofibrinogenemia and allowing for fibrinogen replacement therapy in critically bleeding patients.

Interaction of fibrinogen-magnetic nanoparticle bioconjugates with integrin reconstituted into artificial membranes

Magnetic nanoparticles have a broad spectrum of biomedical applications including cell separation, diagnostics and therapy. One key issue is little explored: how do the engineered nanoparticles interact with blood components after injection? The formation of bioconjugates in the bloodstream and subsequent reactions are potentially toxic due to the ability to induce an immune response. The understanding of the underlying processes is of major relevance to design not only efficient, but also safe nanoparticles for e.g. targeted drug delivery applications. In this study, we report on maghemite nanoparticles functionalized with citrate-, dextran- and polyethylene glycol coatings and their interaction with the clotting protein fibrinogen. Further, we investigate using biophysical tools (e.g. dynamic light scattering, circular dichroism spectroscopy and quartz crystal microbalance) the interaction of the magnetic nanoparticles-fibrinogen bioconjugates with artificial cell membranes as a model system for blood platelets. We found that fibrinogen corona formation provides colloidal stability to maghemite nanoparticles. In addition, bioconjugates of fibrinogen with dextran- and citrate-coated NPs interact with integrin-containing lipid bilayer, especially upon treatment with divalent ions, whereas PEG-coating reveals minor interaction. Our study at the interface of protein-conjugated nanoparticles and artificial cell membranes is essential for engineering safe nanoparticles for drug delivery applications.

An integrated platform for fibrinogen quantification on a microfluidic paper-based analytical device

Fibrinogen (FIB) plays a key role in blood coagulation and thrombosis and its concentration in blood can directly reflect health conditions, thus efficient detection of FIB would benefit the treatments of certain diseases such as liver and heart diseases. However, there is a lack of sensitive, simple, rapid and cheap FIB detection device currently, in lieu of expensive and sophisticated approaches in laboratories. Here, we propose a novel plasma separation and FIB detection platform based on a microfluidic paper-based analytical device (μPAD). It is the first time that dielectrophoretic (DEP) force is combined with capillary force on paper for plasma separation, and the separation efficiency of plasma reaches about 95%, ensuring reliable downstream FIB detection, for which we also propose a new method called the resistance-fibrinogen detection (RFD) method. It not only avoids the use of large-scale instruments for detection, but also possesses high precision and simplicity. The method is found to be reliable in FIB detection for various concentrations ranging from 127.0 to 508.0 mg dL^-1. Moreover, the results obtained from the proposed μPAD show an excellent agreement (R² = 0.9985) with those obtained from an automatic coagulation analyzer with natural human blood samples. Overall, the proposed platform provides a low-cost and reliable approach for FIB detection, especially for clinical use in resource-limited areas.

Fibrinogen Diagnostics in Major Hemorrhage

Fibrinogen is one of the first factors to fall to critically low levels in the blood in many coagulopathic events. Patients with hypofibrinogenemia are at a significantly greater risk of major hemorrhage and death. The rapid replacement of fibrinogen early on in hypofibrinogenemia may significantly improve outcomes for patients. Fibrinogen is present at concentrations between 2 and 4 g/L in the plasma of healthy people. However, hypofibrinogenemia is diagnosed when the fibrinogen level drops below 1.5-2 g/L. This review analyses different types of fibrinogen assays that can be used for diagnosing hypofibrinogenemia. The scientific mechanisms and limitations behind these tests are then presented. Additionally, the current state of clinical major hemorrhage protocols (MHPs) is presented and the structure, function and physiological role of fibrinogen is summarized.

Fibrinogen levels measured by the dry hematology method are lower than those measured by the Clauss method under a high concentration of heparin

The activity of fibrinogen has been reported to decrease soon after the onset of major bleeding and to be an important determinant of the final extent of bleeding and postoperative outcome. A device that measures the perioperative fibrinogen level using the dry hematology (DH) method has recently become available. The aim of this study was to compare perioperative fibrinogen levels measured by the DH method with those measured by the conventional Clauss method and to assess the effects of heparin on these measurements. The study included 206 samples from 36 patients undergoing major surgery who received high-dose heparin (HH group, 23 samples), low-dose heparin (LH group, 57 samples), or no heparin (C group, 126 control samples). Each sample was measured using the DH and Clauss methods. After excluding samples outside the effective measurement range, the three study groups (HH group, n=23; LH group, n=49; C group, n=115) were compared. The mean fibrinogen level measured by the DH method in the HH group (87.9 ± 3.1%) was significantly lower than that measured by the Clauss method. There were no significant differences between the fibrinogen measurements obtained by the two methods between the LH and C groups. In patients on high-dose heparin, the mean fibrinogen level measured by the DH method was significantly lower than that measured by the Clauss method. When hemorrhage requires emergency treatment, a method that can measure the fibrinogen level rapidly is important. The DH method may be useful for decision-making with regard to perioperative coagulation factor replacement.

Rapid paper diagnostic for plasma fibrinogen concentration

Fibrinogen is one of the first proteins to be depleted in heavily bleeding patients. In this study, we have developed a new paper-based diagnostic to quantify the fibrinogen concentration in blood at room temperature.

Fibrinogen for the management of critical obstetric hemorrhage

AIM

In cases of critical obstetric hemorrhage leading to extreme hypofibrinogenemia, fibrinogen is the marker that indicates the critical severity, and early fibrinogen supplementation centering on hemostatic resuscitation is a vital treatment to stabilize a catastrophic condition. In this review, we investigated the effect of fibrinogen level on hemostasis and what we can do to treat hypofibrinogenemia efficiently and improve patients' outcome.

METHODS

We reviewed numerous articles related to hypofibrinogenemia in critical obstetric hemorrhage. Especially, we performed a systematic review on target value of fibrinogen for hemostasis and effectiveness of fibrinogen concentrate. We also reviewed the articles about the methods for early normalization of fibrinogen level such as tranexamic acid, massive transfusion protocol, and point-of-care testing.

RESULTS

The target value of fibrinogen calculated by needs for massive transfusion was 200 mg/dL or 10 mm of A5_FIBTEM . Although fibrinogen concentrate worked poorly on fibrinogen levels within the normal range, it improved the blood fibrinogen levels rapidly when it was administered to critical obstetric hemorrhage patients with serious hypofibrinogenemia. Hence, the volume of FFP transfused could be reduced along with a reduction in the frequency of pulmonary edema due to volume overload.

CONCLUSION

The patient group for which fibrinogen concentrate works most effectively is cases with severe hypofibrinogenemia. Further research is required in the light of evidence. The essence of the transfusion algorithm in critical obstetric hemorrhage is to approach the target value for obtaining hemostasis, ensure an accurate and prompt grasp of the severity using point-of-care testing, introduce a massive transfusion protocol and use tranexamic acid.

Introduction of thromboelastometry-guided administration of fresh-frozen plasma is associated with decreased allogeneic blood transfusions and post-operative blood loss in cardiopulmonary-bypass surgery

BACKGROUND

Cardiac surgery is frequently associated with excessive blood loss requiring multiple blood transfusions which are, in turn, associated with increased morbidity and mortality. We evaluated the effectiveness of rotational thromboelastometry (ROTEM^®)-guided administration of fresh-frozen plasma (FFP) with regards to blood loss, transfusion requirements, and major post-operative complications.

MATERIALS AND METHODS

Coagulation management in 68 prospective patients undergoing cardiac surgery with cardiopulmonary bypass was based on a treatment algorithm guided by ROTEM^® measurements. The primary end-point was blood loss at 24 hours after surgery. Secondary end-points were: (i) need for allogeneic blood products after cardiopulmonary bypass and 24 hours post-operatively, and (ii) post-operative complications until discharge. The results were compared with those of a retrospective, control group of 69 patients who received empirical coagulation management before implementation of the ROTEM^®-guided algorithm.

RESULTS

Although patients with significantly lower haemoglobin levels received less packed red blood cells (PRBC) (840 vs 1,120 mL; p=0.031) and FFP (480 vs 720 mL; p=0.007) after introduction of the ROTEM^® algorithm, the intra-operative blood loss and post-operative haemoglobin levels were similar in the ROTEM^® and the retrospective control groups. In addition to significantly reduced blood loss and decreased requirements for PRBC (30.8 vs 62.3%; p<0.001) and FFP (25.0 vs 56.5%; p<0.001), the amounts of PRBC (315 vs 840 mL; p<0.001) and FFP (480 vs 840 mL; p=0.001) received during the first 24 hours after surgery were significantly reduced in the ROTEM^® group, as was the duration of post-operative hospitalisation.

DISCUSSION

Compared with empirical treatment, timely ROTEM^®-guided FFP administration during cardiac surgery can reduce not only overall blood product use and blood loss but also the duration of hospitalisation.

Dynamics of fibrinogen in acute phases of trauma

Fibrinogen is a unique precursor of fibrin and cannot be compensated for by other coagulation factors. If plasma fibrinogen concentrations are insufficient, hemostatic clots cannot be formed with the appropriate firmness. In severe trauma patients, plasma fibrinogen concentrations decrease earlier and more frequently than other coagulation factors, predicting massive bleeding and death. We review the mechanisms of plasma fibrinogen concentration decrease, which include coagulation activation-induced consumption, hyper-fibrino(geno)lysis-induced degradation, and dilution by infusion/transfusion. Understanding the mechanisms of plasma fibrinogen concentration decrease in severe trauma patients is crucial.

Four-Group Classification Based on Fibrinogen Level and Fibrin Polymerization Associated With Postoperative Bleeding in Cardiac Surgery

Fibrinogen and fibrin formation have a key role in perioperative hemostasis. The aim of this study is to examine the association of postoperative hemostasis with a combined evaluation of the fibrinogen level and fibrin polymerization in cardiac surgery. We retrospectively classified 215 consecutive cardiac surgery patients into 4 groups (Fuji-san classification) that were divided by fibrinogen level <150 mg/dL (ie, hypofibrinogenemia) and fibrinogen thromboelastometry value at 10 minutes with rotational thromboelastometry <6 mm (ie, low fibrin polymerization) at the warming of cardiopulmonary bypass. Four groups resulted; group I, the acceptable range (n = 85); group II, only hypofibrinogenemia (<150 mg/dL, ≥6 mm, n = 63); group III, hypofibrinogenemia and low fibrin polymerization (<150 mg/dL, <6 mm, n = 60); and group IV, only low fibrin polymerization (≥150 mg/dL, <6 mm, n = 7). The risk of chest tube drainage volume greater than 500 mL within the first 24 hours after surgery (with group I as the reference) was increased in group II (odds ratio [OR], 3.3; 95% confidence interval [CI], 1.5-7.4; P < .01) and group III (OR, 8.5; 95% CI, 3.5-21.7; P < .01), and the risk greater than 1000 mL (with group I as the reference) was increased in group III (OR, 4.0; 95% CI, 1.1-17.3; P = .03) and group IV (OR, 23.1; 95% CI, 3.2-201.0; P < .01). Intraoperative blood transfusions were decreased by 24.5%, after stratifying the starting amount of fresh frozen plasma by the 4-group classification in the recent consecutive 65 (30.2%) patients ( P < .01). The 4-group classification is associated with postoperative bleeding and may improve the quality of perioperative blood transfusion in cardiac surgery.

Rapid measurement of fibrinogen concentration in whole blood using a steel ball coagulometer

Supplemental digital content is available in the text.

BACKGROUND

Fibrinogen plays a key role in hemostasis and is the first coagulation factor to reach critical levels in bleeding patients. Current European guidelines on the management of traumatic or perioperative bleeding recommend fibrinogen supplementation at specific threshold levels. Whole blood viscoelastic tests provide fast evaluation of fibrin deficits. Fast measurement of plasma fibrinogen concentration is not yet available. We investigated a method to rapidly determine whole blood fibrinogen concentration using standard Clauss assays and a steel ball coagulometer and provide an estimate of the “plasma-equivalent” fibrinogen concentration within minutes by adjustment of the measured whole blood fibrinogen concentration with a quickly measureable hemoglobin-derived hematocrit.

METHODS

The feasibility of this approach was tested with a Clauss assay using multiple porcine fresh blood samples obtained during in vivo bleeding, hemodilution, and after treatment with hemostatic therapy. Two different Clauss assays were then tested using multiple human volunteers’ blood samples diluted in vitro and supplemented with fibrinogen concentrate. Comparative measurements with fibrin-based thromboelastometry tests were performed.

RESULTS

Regression and Bland-Altman analyses of derived “plasma-equivalent” fibrinogen and measured plasma fibrinogen concentration was excellent in porcine and human blood samples, especially in the ranges relevant to traumatic or perioperative bleeding.

CONCLUSION

Fast whole blood fibrinogen measurements could be considered as an alternative to plasma fibrinogen measurement for acute bleeding management in trauma and perioperative care settings. Further studies are needed to prove this concept and determine the turnaround times for its clinical application in emergency departments and operating theaters.