Fibrinogen Levels After Cardiac Surgical Procedures: Association With Postoperative Bleeding, Trigger Values, and Target Values

How do I implement pathogen reduced Cryoprecipitated fibrinogen complex in a tertiary Hospital's blood Bank

BACKGROUND

Kaiser-Permanente Los Angeles Medical Center (LAMC) is a 560 licensed bed facility that provides regional cardiovascular services, including 1200 open heart surgeries annually. In 2021, LAMC explored alternative therapies to offset the impact of pandemic-driven cryo AHF shortages, and implemented Pathogen Reduced Cryoprecipitated Fibrinogen Complex (also known as INTERCEPT Fibrinogen Complex or IFC). IFC is approved to treat and control bleeding associated with fibrinogen deficiency. Unlike cryo AHF, IFC has 5-day post-thaw shelf life with potential operational and clinical benefits. The implementation steps and the operational advantages to the LAMC Blood Bank are described.

STUDY DESIGN AND METHODS

Eighteen months post-implementation, the institution reviewed their product implementation experience and compared IFC with cryo AHF with a retrospective review of transfusion service and cardiac post-op data.

RESULTS

IFC significantly decreased product wastage rates and order-to-issue time. It did not significantly impact post-op product utilization or hospital length of stay (LOS) in cardiac surgery patients when compared with cryo AHF.

DISCUSSION

Implementation of IFC provides improved product supply stability, shorter turnaround times, and reduced wastage.

Analyzing and modeling massive transfusion strategies and the role of fibrinogen-How much is the patient actually receiving?

BACKGROUND

Hemorrhage is a leading cause of preventable death in trauma, cardiac surgery, liver transplant, and childbirth. While emphasis on protocolization and ratio of blood product transfusion improves ability to treat hemorrhage rapidly, tools to facilitate understanding of the overall content of a specific transfusion strategy are lacking. Medical modeling can provide insights into where deficits in treatment could arise and key areas for clinical study. By using a transfusion model to gain insight into the aggregate content of massive transfusion protocols (MTPs), clinicians can optimize protocols and create opportunities for future studies of precision transfusion medicine in hemorrhage treatment.

METHODS

The transfusion model describes the individual round and aggregate content provided by four rounds of MTP, illustrating that the total content of blood elements and coagulation factor changes over time, independent of the patient's condition. The configurable model calculates the aggregate hematocrit, platelet concentration, percent volume plasma, total grams and concentration of citrate, percent volume anticoagulant and additive solution, and concentration of clotting factors: fibrinogen, factor XIII, factor VIII, and von Willebrand factor, provided by the MTP strategy.

RESULTS

Transfusion strategies based on a 1:1:1 or whole blood foundation provide between 13.7 and 17.2 L of blood products over four rounds. Content of strategies varies widely across all measurements based on base strategy and addition of concentrated sources of fibrinogen and other key clotting factors.

DISCUSSION

Differences observed between modeled transfusion strategies provide key insights into potential opportunities to provide patients with precision transfusion strategy.

Fresh frozen plasma transfusion after cardiac surgery

INTRODUCTION

Fresh frozen plasma (FFP) transfusion in the intensive care unit (ICU) is commonly used to treat coagulopathy and bleeding in cardiac surgery, despite suggestion that it may increase the risk of morbidity and mortality through mechanisms such as fluid overload and infection.

METHODS

We retrospectively studied consecutive adults undergoing cardiac surgery from the Medical Information Mart for Intensive Care III and IV databases. We applied propensity score matching to investigate the independent association of within-ICU FFP transfusion with mortality and other key clinical outcomes.

RESULTS

Of our 12,043 adults who met inclusion criteria, 1585 (13.2%) received perioperative FFP with a median of 2.48 units per recipient (interquartile range [IQR]: 2.04, 4.33) at a median time of 1.83 h (IQR: 0.75, 3.75) after ICU admission. After propensity matching of 952 FFP recipients to 952 controls, we found no significant association between FFP use and hospital mortality (odds ratio (OR): 1.58; 99% confidence interval (CI): 0.57, 3.71), suspected infection (OR: 0.72; 99% CI: 0.49, 1.08), or acute kidney injury (OR: 1.23; 99% CI: 0.91, 1.67). However, FFP was associated with increased days in hospital (adjusted mean difference (AMD): 1.28; 99% CI: 0.27, 2.41; p = .0050), days in intensive care (AMD: 1.28; 99% CI: 0.27, 2.28; p = .0011), and chest tube output in millilitres up to 8 h after transfusion (AMD: 92.98; 99% CI: 52.22, 133.74; p < .0001).

CONCLUSIONS

After propensity matching, FFP transfusion was not associated with increased hospital mortality, but was associated with increased length of stay and no decrease in bleeding in the early post-transfusion period.

Basic Principles of Rotational Thromboelastometry (ROTEM®) and the Role of ROTEM-Guided Fibrinogen Replacement Therapy in the Management of Coagulopathies

Rotational thromboelastometry (ROTEM) is a viscoelastic method, which provides a graphical and numerical representation of induced hemostasis in whole blood samples. Its ability to quickly assess the state of hemostasis is used in the management of bleeding from a variety of causes. The separate activation of particular parts of hemocoagulation in INTEM, EXTEM, and FIBTEM tests allows for a more comprehensive and faster evaluation of the missing component of hemostasis followed by targeted therapy. One of the most common cause of coagulopathy is trauma-induced coagulopathy. Fibrinogen replacement therapy by ROTEM allows for the use of a standard dosage of fibrinogen, which has been shown to be successful in preventing dilutional coagulopathy following colloid and crystalloid replacement and excessive amount of allogeneic blood transfusions. The best reflection of fibrinogen activity is observed in the FIBTEM assay, where fibrinogen replacement therapy is recommended at an MCF (maximum clot firmness) of FIBTEM < 10 mm and FIBTEM A10 < 7 mm. ROTEM also plays an important role in the diagnostic and management of inherited fibrinogen disorders. These can be manifested by bleeding complications, where changes in the MCF parameter are the most useful tool for assessing the effectiveness of fibrinogen replacement therapy. ROTEM-guided bleeding management algorithms effectively reduce the number of transfusions, healthcare costs, and complications, leading to the improvement of patient safety and overall health.

Comparison of Bacterial Risk in Cryo AHF and Pathogen Reduced Cryoprecipitated Fibrinogen Complex

Until November 2020, cryoprecipitated antihaemophilic factor (cryo AHF) was the only United States Food and Drug Administration (FDA)-approved fibrinogen source to treat acquired bleeding. The post-thaw shelf life of cryo AHF is limited, in part, by infectious disease risk. Concerns over product wastage demand that cryo AHF is thawed as needed, with thawing times delaying the treatment of coagulopathic patients. In November 2020, the FDA approved Pathogen Reduced Cryoprecipitated Fibrinogen Complex for the treatment and control of bleeding, including massive hemorrhage, associated with fibrinogen deficiency. Pathogen Reduced Cryoprecipitated Fibrinogen Complex (also known as INTERCEPT^® Fibrinogen Complex, IFC) has a five-day post-thaw room-temperature shelf life. Unlike cryo AHF, manufacturing of IFC includes broad spectrum pathogen reduction (Amotosalen + UVA), enabling this extended post-thaw shelf life. In this study, we investigated the risk of bacterial contamination persisting through the cryoprecipitation manufacturing process of cryo AHF and IFC. Experiments were performed which included spiking plasma with bacteria prior to cryoprecipitation, and bacterial survival was analyzed at each step of the manufacturing process. The results show that while bacteria survive cryo AHF manufacturing, IFC remains sterile through to the end of shelf life and beyond. IFC, with a five-day post-thaw shelf life, allows the product to be sustainably thawed in advance, facilitating immediate access to concentrated fibrinogen and other key clotting factors for the treatment of bleeding patients.

An audit of the diagnostic accuracy of the ROTEM®sigma for the identification of hypofibrinogenaemia in cardiac surgical patients

The ROTEM®delta (TEM Innovations GmbH, Munich, Germany) has been used extensively worldwide for the assessment of coagulation in cardiac surgical patients. Recently, a new cartridge-based ROTEM device (ROTEM®sigma, TEM Innovations GmbH, Munich, Germany) has become available. In this paper we report an audit of the diagnostic accuracy of the ROTEM sigma for the identification of hypofibrinogenaemia in cardiac surgical patients. We hypothesised that the diagnostic accuracy of the ROTEMsigma for the identification of hypofibrinogenaemia would be in a similar range to that previously reported for the ROTEMdelta. Simultaneous blood samples for Clauss laboratory fibrinogen and ROTEMsigma FIBTEM measurements were obtained immediately after heparin reversal post-cardiopulmonary bypass in 200 adult cardiac surgical patients. The sensitivity, specificity, and positive and negative predictive values for FIBTEM A5 and A10 for the identification of hypofibrinogenaemia (Clauss fibrinogen <1.5 g/l) were calculated. The prevalence of hypofibrinogenaemia across the 200 patients was 8%. The mean sensitivity and specificity of FIBTEM A10 ≤8 mm for the identification of hypofibrinogenaemia were 0.75 and 0.90 respectively, which are in a similar range to that reported in several previous studies using the ROTEMdelta. For FIBTEM A5 ≤6 mm the values were 0.63 and 0.98 respectively. The predictive values were also in a similar range to those previously reported for the ROTEMdelta, with low false negative rates (2% for A10 ≤8 mm; 3% for A5 ≤6 mm). These findings support the use of the ROTEMsigma as an alternative to the ROTEMdelta for the identification of hypofibrinogenaemia post-cardiopulmonary bypass in cardiac surgical patients. However, further studies are required in other settings.

Clinical evaluation of the novel Capiox NX19 adult oxygenator-a multicenter study

INTRODUCTION

The novel Capiox NX19 adult oxygenator is, compared to its predecessors, improved with enhanced air removal technology, a polymer heat exchanger and smaller, innovative hollow fibers resulting in a surface area reduction and a lower priming volume. The aim of this study was to evaluate the NX19 oxygenator performance in a clinical setting.

METHODS

A prospective multicenter study was performed involving three large European university hospitals. The Capiox NX19 (n = 150) performance was assessed during adult cardiopulmonary bypass and involved gaseous microemboli handling and gas transfer efficiency. The heat exchanger performance was evaluated separately in vitro.

RESULTS

The heat exchanger performance factors were 0.80 ± 0.03 and 0.58 ± 0.04 at pump flow rates of 3 L/min and 6 L/min, respectively. After priming, residual post-oxygenator gaseous microemboli count and volume were decreased by 91% and 93.7%, respectively. The gas compartment pressure was 6.0 ± 2.5 mmHg, while the O₂ transfer was 69 ± 30 mL/min/m² and the CO₂ transfer 73 ± 34 mL/min/m². The O₂ gradient was 44 ± 19 mmHg/LPM and the O₂ diffusing capacity 0.38 ± 0.14 mL/min/mmHg. The shunt fraction was 0.19 ± 0.13, whereas oxygenator resistance and shear stress were 10.5 ± 3.7 mmHg/LPM and 5.1 ± 3.1 dyn/cm², respectively.

CONCLUSION

This multicenter study displayed good clinical safety and performance of the NX19 oxygenator.

Comparison of coagulation monitoring using ROTEM and Sonoclot devices in cardiac surgery. A single-centre prospective observational study

BACKGROUND

Viscoelastic tests (VETs) are recommended during cardiac surgery to monitor coagulation status and guide transfusion. We compared the results of two VETs, the Sonoclot Analyzer and the ROTEM Sigma. Agreement between viscoelastic tests' subdiagnoses and overall diagnosis severity was assessed. Correlations with conventional coagulation tests (CCT) and the discriminatory potential of numerical VET outputs for transfusion thresholds was determined.

METHODS

Single-centre, prospective observational study in a tertiary academic centre. In fifty adult patients undergoing elective cardiac surgery, parallel Sonoclot, ROTEM and CCT analysis was performed before heparin, or after protamine or coagulation product administration. All patients completed the study, resulting in 139 data points.

RESULTS

Agreement on the severity of coagulation disorders was acceptable (83%), but poor (27%) on the differentiation of the underlying causes. Correlations between ROTEM parameters and CCT were good (post-protamine: FIBTEM A5 (r2 = 0.90 vs fibrinogen) and EXTEM-FIBTEM A5 difference (r2 = 0.81 vs platelet count) ). Sonoclot correlated less (Clot Rate (r2 = 0.25 vs fibrinogen) and Platelet Function (r2 = 0.43 vs platelet count)). This was reflected in the discriminatory potential of these parameters as found by linear mixed modelling. We suggest clinically useful grey zones for VET cutoff interpretation.

CONCLUSIONS

ROTEM and Sonoclot accord well on the detection of severity of coagulation dysfunction, but not on the diagnosis of the underlying cause. ROTEM correlated more closely with CCT then Sonoclot. We propose a testing strategy that could lead to a cost-effective approach to the bleeding cardiac surgery patient.

Evaluation of plasma fibrinogen levels before and after coronary artery bypass graft surgery and its association with the need for blood products

Background:

The present study investigated the plasma level of fibrinogen before and after removing the pump in coronary artery bypass graft (CABG) surgery and its relationship with the need for blood products.

Materials and Methods:

The present study was performed on 60 patients who were candidates for CABG surgery. The fibrinogen level of these patients was assessed and recorded before surgery and immediately after removing the pump. In addition, their hemoglobin level was recorded before the operation and 2 h after. In addition, the number and type of blood products transfusion were recorded intraoperatively and postoperatively and also at the intensive care unit.

Results:

Patients’ fibrinogen level after removing the pump with the mean of 130.53 ± 122.01 mg/dl decreased significantly compared to before surgery with the mean of mg/dl 224.95 ± 132.88 mg/dl (P < 0.001). In addition, the prognostic value of fibrinogen after removing the pump in determining the postoperative need of blood transfusion showed that the cut-off value of fibrinogen was < 196 mg/dl with a sensitivity of 16.82% and specificity of 80%, but it was not statistically significant (area under the curve [95% confidence interval]: 0.519 [0.350–0.689]; P = 0.825).

Conclusion:

According to the results of the present study, due to significant changes in fibrinogen levels after removing the pump compared to preoperation, it seems that this factor can play an important role in prognosis of the need to postoperative blood transfusion, although the prognostic value and the critical point mentioned in our study was not significant and it is required to do further studies.

Fibrinogen and Bleeding in Adult Cardiac Surgery: A Review of the Literature

Background: Fibrinogen is a substrate for blood clots formation. In cardiac surgery, a number of different mechanisms lead to a decrease in fibrinogen levels and consequent impaired haemostasis. Patients undergoing cardiac surgery are therefore frequently exposed to blood loss and allogeneic blood transfusion, which are risk factors associated with morbidity and mortality. Thus, particular efforts in fibrinogen management should be made to decrease bleeding and the need for blood transfusion. Therefore, fibrinogen remains an active focus of investigations from basic science to clinical practice. This review aims to summarise the latest evidence regarding the role of fibrinogen and current practices in fibrinogen management in adult cardiac surgery. Methods: The PubMed database was systematically searched for literature investigating the role and disorders of fibrinogen in cardiac surgery and diagnostic and therapeutic procedures related to fibrinogen deficiency aimed at reducing blood loss and transfusion requirements. Clinical trials and reviews from the last 10 years were included. Results: In total, 146 articles were analysed. Conclusion: The early diagnosis and treatment of fibrinogen deficiency is crucial in maintaining haemostasis in bleeding patients. Further studies are needed to better understand the association between fibrinogen levels, bleeding, and fibrinogen supplementation and their impacts on patient outcomes in different clinical settings.

Association of Plasma Fibrinogen and Thromboelastography With Blood Loss in Complex Cardiac Surgery

Postoperative coagulopathic bleeding is common in cardiac surgery and is associated with increased morbidity and mortality. Ideally, real-time information on in-vivo coagulation should be available. However, up to now it is unclear which perioperative coagulation parameters can be used best to accurately identify patients at increased risk of bleeding. The present study analyzed the associations of perioperative fibrinogen concentrations and whole blood viscoelastic tests with postoperative bleeding in 89 patients undergoing combined cardiac surgery procedures. Postoperative bleeding was recorded until 24 hours after surgery. Regression analyses were performed to establish associations between blood loss and coagulation parameters after cardiopulmonary bypass including a prediction model with known confounding factors for bleeding. Coagulation tests show large changes over the perioperative course with the strongest coagulopathic deviations from baseline after cardiopulmonary bypass. After adjustment for multiple confounders, viscoelastic clot strength instead of fibrinogen concentration showed a similar performance for 24 hour blood loss and a better performance for 6 hour blood loss. This makes intraoperative viscoelastic testing a useful tool to strengthen early clinical decision-making with the potential to reduce perioperative blood transfusions.

Individual variation in unfractionated heparin dosing after pediatric cardiac surgery

We aimed to identify attributing factors to the interindividual variabilities of the infusion rates in unfractionated heparin therapy. We included patients who required unfractionated heparin therapy to achieve the target APTT after cardiac surgery between May 2014 and February 2018. Fifty-nine patients were included, of whom 8 underwent Blalock-Taussig shunt; 27, Glenn procedure; 19, Fontan procedure; 3, mechanical valve replacement; and 2, Rastelli procedure. Previously reported variables that influenced the response to unfractionated heparin treatment were initially compared, which included age; weight; sex; type of surgery; platelet count; fibrinogen, antithrombin III, total protein, albumin, alanine transaminase, and creatinine levels; and use of fresh frozen plasma. The type of surgical procedure was found to be significantly associated with the differences in heparin infusion rate (P = 0.00073). Subsequently, the variance explained by these factors was estimated through a selection based on the minimum Akaike information criterion value; models constructed by various combinations of the surgery types were compared. The model including the Blalock-Taussig shunt, Glenn procedure, and mechanical valve replacement showed the highest summed variance explained (29.1%). More than 70% of the interindividual variability in initial heparin maintenance dosing was unexplained.

Detection of hypofibrinogenemia during cardiac surgery: a comparison of resonance-based thrombelastography with the traditional Clauss method

: Bleeding after cardiac surgery is associated with significant morbidity and mortality. Hypofibrinogenemia is a crucial factor for bleeding in this setting and may be rapidly detected using point-of-care viscoelastic tests (POC-VET). However, the correlation of POC-VET with conventional coagulation assays is still unclear. The current study aimed to correlate resonance-based POC-VET assays (Haemonetics TEG 6s) with the traditional nonrapid Clauss method. Another aim was to identify a cut-off value for the detection of hypofibrinogenemia (fibrinogen plasma level below 150 mg/dl) focusing on the maximum amplitude of the TEG 6s citrated functional fibrinogen (CFF) assay. Adult patients undergoing cardiac surgery were screened for inclusion in this single-centre retrospective cohort study. Inclusion criteria were the availability of a TEG assay and timely corresponding laboratory results. Calculation of a CFF-maximum amplitude (CFF-MA) cut-off value was performed using receiver operating curve analysis in the baseline cohort and validated in the control cohort. The best correlation with the Clauss method was observed for the CFF-MA (r = 0.77; P < 0.0001) compared with the citrate kaolin maximum amplitude assay (r = 0.57; P < 0.0001) and the citrate kaolin heparinase maximum amplitude assay (r = 0.67; P < 0.0001). A cut-off value of 19.9 mm for the CFF-MA was calculated [area under the curve 0.87 (95% confidence interval: 0.82-0.92; P < 0.0001)]. This cut-off value had a sensitivity of 81.8% and a specificity of 71.1% for identification of hypofibrinogenemia in the control cohort. The resonance-based thrombelastography analyser can identify hypofibrinogenemia. Future clinical studies should investigate whether cut-off value guided coagulation therapy with POC-VET may improve patient outcomes in patients who suffer from bleeding complications.

Diagnostic accuracy of viscoelastic point-of-care identification of hypofibrinogenaemia in cardiac surgical patients: A systematic review

Hypofibrinogenaemia during cardiac surgery may increase blood loss and bleeding complications. Viscoelastic point-of-care tests provide more rapid diagnosis than laboratory measurement, allowing earlier treatment. However, their diagnostic test accuracy for hypofibrinogenaemia has never been reviewed systematically. We aimed to systematically review their diagnostic test accuracy for the identification of hypofibrinogenaemia during cardiac surgery. Two reviewers assessed relevant articles from seven electronic databases, extracted data from eligible articles and assessed quality. The primary outcomes were sensitivity, specificity and positive and negative predictive values. A total of 576 articles were screened and 81 full texts were assessed, most of which were clinical agreement or outcome studies. Only 10 diagnostic test accuracy studies were identified and only nine were eligible (ROTEM delta 7; TEG5000 1; TEG6S 1, n = 1820 patients) (ROTEM, TEM International GmbH, Munich, Germany; TEG, Haemonetics, Braintree, MA, USA). None had a low risk of bias. Four ROTEM studies with a fibrinogen threshold less than 1.5–1.6 g/l and FIBTEM threshold A10 less than 7.5–8 mm had point estimates for sensitivity of 0.61–0.88; specificity 0.54–0.94; positive predictive value 0.42–0.70; and negative predictive value 0.74–0.98 (i.e. false positive rate 30%–58%; false negative rate 2%–26%). Two ROTEM studies with higher thresholds for both fibrinogen (<2 g/l) and FIBTEM A10 (<9.5 mm) had similar false positive rates (25%–46%), as did the two TEG studies (15%–48%). This review demonstrates that there have been few diagnostic test accuracy studies of viscoelastic point-of-care identification of hypofibrinogenaemia in cardiac surgical patients. The studies performed so far report false positive rates of up to 58%, but low false negative rates. Further diagnostic test accuracy studies of viscoelastic point-of-care identification of hypofibrinogenaemia are required to guide their better use during cardiac surgery.

Factor XIII activity in patients requiring surgical re-exploration for bleeding after elective cardiac surgery - A prospective case control study

PURPOSE

Surgical re-exploration due to postoperative bleeding is associated with increased morbidity and mortality. The aim of our study was to assess a potential association between the level of postoperative FXIII activity and need for re-exploration due to bleeding in patients undergoing cardiothoracic surgery.

MATERIALS AND METHODS

In our prospective single center observational cohort study, we enrolled patients who underwent elective cardiothoracic surgery. Patients who required re-exploration (RE group) were matched to patients from the study population (non-RE group).

RESULTS

The study included 64 patients, out of a cohort of 678 patients, of whom 32 required surgical re-exploration due to bleeding within the first 24 h. Between patients of the RE and non-RE group, a significantly reduced FXIII activity was observed postoperatively (59.0 vs 71.1; p = .014). Multivariable analysis revealed reduced FXIII activity (p = .048) as a parameter independently associated with surgical re-exploration. Further, reduced FXIII activity (p = .037) and surgical re-exploration (p = .01) were significantly associated with increased 30 day mortality. In multivariable analysis re-exploration was independently associated with increased risk of 30 day mortality (p = .004, HR 9.68).

CONCLUSIONS

Reduced postoperative FXIII activity may be associated with the need for surgical re-exploration. Postoperative assessment of FXIII activity should therefore be considered in patients undergoing elective cardiothoracic surgery.

Review of current transfusion therapy and blood banking practices

Transfusion Medicine is a dynamically evolving field. Recent high-quality research has reshaped the paradigms guiding blood transfusion. As increasing evidence supports the benefit of limiting transfusion, guidelines have been developed and disseminated into clinical practice governing optimal transfusion of red cells, platelets, plasma and cryoprecipitate. Concepts ranging from transfusion thresholds to prophylactic use to maximal storage time are addressed in guidelines. Patient blood management programs have developed to implement principles of patient safety through limiting transfusion in clinical practice. Data from National Hemovigilance Surveys showing dramatic declines in blood utilization over the past decade demonstrate the practical uptake of current principles guiding patient safety. In parallel with decreasing use of traditional blood products, the development of new technologies for blood transfusion such as freeze drying and cold storage has accelerated. Approaches to policy decision making to augment blood safety have also changed. Drivers of these changes include a deeper understanding of emerging threats and adverse events based on hemovigilance, and an increasing healthcare system expectation to align blood safety decision making with approaches used in other healthcare disciplines.

The role of evidence-based algorithms for rotational thromboelastometry-guided bleeding management

Rotational thromboelastometry (ROTEM) is a point-of-care viscoelastic method and enables to assess viscoelastic profiles of whole blood in various clinical settings. ROTEM-guided bleeding management has become an essential part of patient blood management (PBM) which is an important concept in improving patient safety. Here, ROTEM testing and hemostatic interventions should be linked by evidence-based, setting-specific algorithms adapted to the specific patient population of the hospitals and the local availability of hemostatic interventions. Accordingly, ROTEM-guided algorithms implement the concept of personalized or precision medicine in perioperative bleeding management (‘theranostic’ approach). ROTEM-guided PBM has been shown to be effective in reducing bleeding, transfusion requirements, complication rates, and health care costs. Accordingly, several randomized-controlled trials, meta-analyses, and health technology assessments provided evidence that using ROTEM-guided algorithms in bleeding patients resulted in improved patient’s safety and outcomes including perioperative morbidity and mortality. However, the implementation of ROTEM in the PBM concept requires adequate technical and interpretation training, education and logistics, as well as interdisciplinary communication and collaboration.

The velocity curve of the clotting waveform of rotational thromboelastometry predicts bleeding after cardiac surgery but conventional rotational thromboelastometric parameters do not

BACKGROUND

Early detection of a risk of postoperative bleeding is essential in cardiac surgery patients. The aim of the present study was to evaluate the utility of the first derivative curve (the V-curve) of the clotting waveform of rotational thromboelastometry (ROTEM) in terms of predicting bleeding after cardiac surgery.

METHODS

We retrospectively analysed 534 cardiac surgery patients. We used the chest tube output during the stay in the intensive care unit to divide patients into a higher blood loss group (HBL group; the fourth quartile) and a lower blood loss group (LBL group; the lower quartiles). We performed multivariable logistic regression using the V-curve parameters and potential confounders including conventional ROTEM parameters.

RESULTS

In the multivariable model, the adjusted odds ratios for HBL of patients with a lower maximum clotting velocity (MaxVel ≤9 mm*100 s-1) as revealed by extrinsically activated ROTEM (EXTEM), and the area under the velocity curve (AUC ≤988 mm*100) of the fibrin-based extrinsically activated ROTEM (FIBTEM), both measured at skin closure in the end of surgery, were 1.78 (95% CI 1.03 to 3.07) and 2.14 (95% CI 1.20 to 3.82), respectively. However, conventional ROTEM parameters were not included in the final model. Additionally, lower EXTEM MaxVel and FIBTEM AUC values were associated with the need for a higher transfusion volume, longer postoperative intensive care unit and hospital stays, and more frequent re-exploration to control bleeding.

CONCLUSIONS

The ROTEM V-curve parameters can predict postoperative bleeding and clinical outcomes after cardiac surgery.

Platelet function after cardiac surgery and its association with severe postoperative bleeding: the PLATFORM study

Platelet dysfunction after cardiac surgery is a determinant of postoperative bleeding. The existing guidelines suggest the use of desmopressin and/or platelet concentrate transfusions in case of platelet dysfunction in bleeding patients, but no cut-off values for platelet activity exist in the literature. The Platelet Function in the Operating Room (PLATFORM) study aims to identify the relationship between platelet function after cardiopulmonary bypass and severe bleeding, finding adequate predictive values of platelet function for severe bleeding. The PLATFORM is a prospective cohort study on 490 adult patients receiving cardiac surgery with cardiopulmonary bypass. Patients received platelet function tests (multiple electrode aggregometry ADPtest and TRAPtest) before surgery and after cardiopulmonary bypass, and routine coagulation tests before surgery and at the arrival in the intensive care unit. The post-cardiopulmonary bypass ADPtest and TRAPtest were significantly (P = 0.001) associated with severe bleeding, as well as the post-cardiopulmonary bypass activated partial thromboplastin time, the international normalized ratio, and the fibrinogen concentration. At a multivariable analysis, the ADPtest (odds ratio 0.962, 95% confidence interval 0.936-0.989, P = 0.005) and the activated partial thromboplastin time (odds ratio 1.097, 95% confidence interval 1.016-1.185, P = 0.017) remained independently associated with severe bleeding. The post-cardiopulmonary bypass ADPtest had the best discrimination, with an area under the curve of 0.712. The best positive predictive value (42%) was found at a cut-off ≤8 U. In conclusion, platelet function tests after cardiopulmonary bypass are significantly associated with postoperative bleeding. However, postoperative bleeding has a multifactorial nature, and the measure of platelet function alone does not provide a high positive predictive value for severe bleeding.

Factors associated with the increased bleeding in the postoperative period of cardiac surgery: A cohort study

AIMS AND OBJECTIVES

To identify factors associated with the increased bleeding in patients during the postoperative period after cardiac surgery.

BACKGROUND

Bleeding is among the most frequent complications that occur in the postoperative period after cardiac surgery, representing one of the major factors in morbidity and mortality. Understanding the factors associated with the increased bleeding may allow nurses to anticipate and prioritise care, thus reducing the mortality associated with this complication.

DESIGN

Prospective cohort study.

METHODS

Adult patients in a cardiac hospital who were in the postoperative period following cardiac surgery were included. Factors associated with the increased bleeding were investigated by means of linear regression, considering time intervals of 6 and 12 hr.

RESULTS

The sample comprised 391 participants. The factors associated with the increased bleeding in the first 6 hr were male sex, body mass index, cardiopulmonary bypass duration, anoxia duration, metabolic acidosis, higher heart rate, platelets and the activated partial thromboplastin time in the postoperative period. Predictors in the first 12 hr were body mass index, cardiopulmonary bypass duration, metabolic acidosis, higher heart rate, platelets and the activated partial thromboplastin time in the postoperative.

CONCLUSIONS

This study identified factors associated with the increased postoperative bleeding from cardiac surgery that have not been reported in previous studies. The nurse is important in the vigilance, evaluation and registry of chest tube drainage and modifiable factors associated with the increased bleeding, such as metabolic acidosis and postoperative heart rate, and in discussions with the multiprofessional team.

RELEVANCE TO CLINICAL PRACTICE

Knowledge of the factors associated with the increased bleeding is critical for nurses so they can provide prophylactic interventions and early postoperative treatment when needed.

Short-term recovery pattern of plasma fibrinogen after cardiac surgery: A prospective observational study

Low plasma fibrinogen level is common after cardiopulmonary bypass (CPB). Current substitution practice with fibrinogen concentrate generally follows a single measurement and cut-off values from the literature, whereas early postoperative endogenous fibrinogen kinetics is incompletely described and widely disregarded. The aim of this study was to determine the short-term recovery pattern of plasma fibrinogen after CPB weaning. Our hypothesis was that in the absence of surgical bleeding, CPB-induced hypofibrinogenemia would resolve spontaneously and predictably within a few hours. In a prospective, observational study of 26 patients undergoing conventional CPB (cCPB) or minimally invasive extracorporeal circulation (MiECC), Clauss fibrinogen level (C-FIB) was determined at 10 closely spaced time points after protamine administration. Primary endpoint was the time to recovery of post-CPB fibrinogen levels to ≥1.5 g/L. C-FIB reached its nadir after protamine administration corresponding to 62 ± 5% (mean ± SD) of the baseline level after cCPB and 68 ± 7% after MiECC (p = 0.027 vs. cCPB). C-FIB recovered spontaneously at a nearly constant rate of approximately 0.08 g/L per hour. In all patients, C-FIB was ≥1.5 g/L at 4 hours and ≥2.0 g/L at 13 hours after CPB weaning. Following cardiac surgery with CPB and in the absence of surgical bleeding, spontaneous recovery of normal endogenous fibrinogen levels can be expected at a rate of 0.08 g/L per hour. Administration of fibrinogen concentrate triggered solely by a single-point measurement of low plasma fibrinogen some time after CPB is not justified.