The incidence and risk factors of hypofibrinogenemia in cardiovascular surgery

Effectiveness of the scheduled transfusion strategy for factor V deficiency with platelet dysfunction during coronary artery surgery

BACKGROUND

Factor V deficiency is a rare disease, with an incidence of one in a million. Symptoms are mostly scant, and it is often diagnosed by the presence of an abnormality on PT-INR or APTT. In addition, no established therapy exists and platelet dysfunction is seldom found to be concomitant with this disease CASE PRESENTATION: A 64-year-old man who had both factor V deficiency and platelet dysfunction had angina in the past year. Coronary surgery was required, and we successfully performed coronary artery bypass grafting under strategic planned platelet transfusion with additional adequate cryoprecipitates transfusion. No perioperative problems nor any postoperative major bleeding issues were observed. The postoperative course was also uneventful.

CONCLUSION

Strategic planned platelet transfusion with the additional transfusion of an adequate amount of cryoprecipitates is thus considered to be feasible for cases presenting with factor V deficiency and platelet dysfunction.

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.

Managing the coagulopathy associated with cardiopulmonary bypass

Cardiopulmonary bypass (CPB) has allowed for significant surgical advancements, but accompanying risks can be significant and must be expertly managed. One of the foremost risks is coagulopathic bleeding. Increasing levels of bleeding in cardiac surgical patients at the time of separation from CPB are associated with poor outcomes and mortality. CPB-associated coagulopathy is typically multifactorial and rarely due to inadequate reversal of systemic heparin alone. The components of the bypass circuit induce systemic inflammation and multiple disturbances of the coagulation and fibrinolytic systems. Anticipating coagulopathy is the first step in managing it, and specific patient and procedural risk factors have been identified as predictors of excessive bleeding. Medication management pre-procedure is critical, as patients undergoing cardiac surgery are commonly on anticoagulants or antiplatelet agents. Important adjuncts to avoid transfusion include antifibrinolytics, and perfusion practices such as red cell salvage, sequestration, and retrograde autologous priming of the bypass circuit have varying degrees of evidence supporting their use. Understanding the patient's coagulation status helps target product replacement and avoid larger volume transfusion. There is increasing recognition of the role of point-of-care viscoelastic and functional platelet testing. Common pitfalls in the management of post-CPB coagulopathy include overdosing protamine for heparin reversal, imperfect laboratory measures of thrombin generation that result in normal or near-normal laboratory results in the presence of continued bleeding, and delayed recognition of surgical bleeding. While challenging, the effective management of CPB-associated coagulopathy can significantly improve patient outcomes.

Viscoelastic Haemostatic Assays in Cardiovascular Critical Care

The initiation and management of anticoagulation is a fundamental practice for a wide variety of indications in cardiovascular critical care, including the management of patients with acute MI, stroke prevention in patients with AF or mechanical valves, as well as the prevention of device thrombosis and thromboembolic events with the use of mechanical circulatory support and ventricular assist devices. The frequent use of antiplatelet and anticoagulation therapy, in addition to the presence of concomitant conditions that may lead to a propensity to bleed, such as renal and liver dysfunction, present unique challenges. The use of viscoelastic haemostatic assays provides an additional tool allowing clinicians to strike a delicate balance of attaining adequate anticoagulation while minimising the risk of bleeding complications. In this review, the authors discuss the role that viscoelastic haemostatic assay plays in cardiac populations (including cardiac surgery, heart transplantation, extracorporeal membrane oxygenation, acute coronary syndrome and left ventricular assist devices), and identify areas in need of further study.

Hypofibrinogenemia can be estimated by the predictive formula in aortic surgery

OBJECTIVE

Aortic surgery often causes massive bleeding due to hypofibrinogenemia. Predicting hypofibrinogenemia is useful for developing a hemostasis strategy, including preparing for blood transfusion. We made a formula for predicting the serum fibrinogen level (SFL) at the termination of cardiopulmonary bypass (CPB) in aortic surgery and examined its validity.

METHODS

We performed a retrospective observational study that consisted of 267 patients (group A) who underwent aortic surgery from July 2013 to December 2016 and made a formula for predicting the SFL at the termination of CPB in group A by a multiple linear regression analysis. The validity of this formula was then examined in another 60 patients (group B) who underwent aortic surgery from January 2017 to December 2017.

RESULTS

We developed the following predictive formula: SFL at the termination of CPB (mg/dL) = 14.7 + 0.44 × preoperative SFL (mg/dL) + (- 0.14) × CPB time (min) + 0.64 × preoperative body weight (kg) + (- 17.3) × lateral thoracotomy (Yes/No, Yes: 1, No: 0). In group B, the predictive formula proved to be statistically valid in group B (R² = 0.531, p < 0.001).

CONCLUSION

The SFL at the termination of CPB in aortic surgery can be predicted by the preoperative SFL, body weight, CPB time and surgical approach. The predictive formula is useful for developing a hemostasis strategy, including preparing for blood transfusion.

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.