Preoperative hemostatic testing and the risk of postoperative bleeding in coronary artery bypass surgery patients

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.

The use of point-of-care testing in detecting platelet function recovery in a patient treated with prasugrel undergoing urgent surgical revascularization

A recent administration of potent P2Y₁₂ receptor inhibitor such as prasugrel in patients undergoing cardiac surgery remains a dilemma and little is known about its impact on platelet function recovery. Guidelines recommend discontinuation of prasugrel 7 days before surgery to reduce the risk of surgery-related bleeding. Patients at risk may benefit from preoperative platelet function testing to guide individualized preoperative waiting time. We present a rare case of complete function recovery in a patient treated with prasugrel revealed by preoperative platelet function monitoring before urgent coronary artery bypass surgery (CABG). A complete platelet function recovery was revealed by platelet function testing after discontinuation of prasugrel for four days and patient underwent urgent CABG without increased risk of postoperative bleeding. Our case with a review of literature emphasized that the decision to proceed with urgent CABG in a patient recently treated with prasugrel should be based on a personalized risk assessment and might be supported by preoperative platelet function monitoring to shorten the waiting time.

The routine use of platelet function tests in elective coronary artery bypass grafting: A prospective observational trial

BACKGROUND

Preoperative use of platelet function tests contributes to the decrease of re-intervention rate due to bleeding and the necessity of transfusion in coronary artery bypass grafting (CABG) patients. The aim was to investigate the predictive value and to justify routine preoperative use of multiple electrode aggregometry in these patients.

METHODS

A prospective observational trial which included 416 consecutive patients subjected to elective isolated CABG was conducted. The Multiplate® test was used to assess platelet function. Platelet function test results, postoperative blood loss, and transfusion requirements were compared between high and low bleeding risk patients. Receiver operating characteristic analysis was performed to assess the sensitivity and specificity of the arachidonic acid (ASPI) and adenosine di-phosphate high sensitive (ADPHS) tests.

RESULTS

ADPHS and ASPI test results significantly predicted total bleeding > 1000 ml (AUC, 0.685, p < .001; 0.695, p = .039). Sensitivity and specificity were 62.9% and 40.0%, for ADPHS ≤602, and 70.8% and 41.8%, for ASPI ≤ 453. The sensitivity and specificity of cut-off values recommended by the manufacturer were 84.2% and 40.0% for ADPHS ≤ 500, while for ASPI < 600 the values were 54.7% and 62.2%. More platelets and cryoprecipitate were transfused in patients with ADPHS ≤ 602.5 (p < .001; p = .035). Patients with ADPHS ≤ 500 had a higher rate of red blood count, platelet and cryoprecipitate transfusion (p<.001p<.001; p = .013). The manufacturer's ASPI test cut-off values showed no statistically significant prediction for a higher transfusion rate.

CONCLUSION

Preoperative platelet function tests should be conducted systematically for all elective CABG patients who were on dual antiplatelet therapy after adjusting test cut-off values for each population.

Implementation of Perioperative Point-of-Care Platelet Function Analyses Reduces Transfusion Requirements in Cardiac Surgery: A Retrospective Cohort Study

Background Platelet dysfunction is a common cause of bleeding, perioperative blood transfusion, and surgical re-exploration in cardiac surgical patients. We evaluated the effect of incorporating a platelet function analyzer utilizing impedance aggregometry (Multiplate, Roche, Munich, Germany) into our local transfusion algorithm on the rate of platelet transfusion and postoperative blood loss in patients undergoing coronary artery bypass grafting (CABG) surgery.

Methods Data were collected on patients undergoing CABG surgery from January 2015 to April 2017. Patients who underwent surgery before and after introduction of this algorithm were classified into prealgorithm and postalgorithm groups, respectively. The primary outcome was the rate of platelet transfusion before and after implementation of the Multiplate-based transfusion algorithm. Secondary outcomes included transfusion rate of packed red blood cells, postoperative blood loss at 12 and 24 hours, length of stay in the intensive care unit, and the hospital and mortality.

Results A total of 726 patients were included in this analysis with 360 and 366 patients in the pre- and postalgorithm groups, respectively. Transfusion rates of platelets (p = 0.01) and packed red blood cells (p = 0.0004) were significantly lower following introduction of the algorithm in patients (n = 257) who had insufficient time to withhold antiplatelet agents. Receiver operating characteristic curves defined optimal cutoff points of arachidonic acid and adenosine diphosphate assays on the Multiplate to predict future platelet transfusion were 23AU and 43AU, respectively.

Conclusions The introduction of a Multiplate-based platelet transfusion algorithm showed a statistically significant reduction in the administration of platelets to patients undergoing urgent CABG surgery.

Postoperative complications associated with coronary artery bypass graft surgery and their therapeutic interventions

Coronary artery disease is one of the commonest surgery demanding cardiovascular diseases. Coronary artery bypass graft surgery is practiced all over the world for the treatment of coronary artery disease. Systemic trauma during the surgery is associated with a wide range of complications, some of which are fatal. Preoperative risk factors such as age, previous illness and obesity are common predictors of these adverse events. Advances in therapeutic medicine have allowed timely treatment of these adverse events and co-morbidities. This review summarizes some of the most occurring complications associated with coronary artery bypass graft and corresponding treatment options.

Thromboelastography and rotational thromboelastometry for the surgical intensivist: A narrative review

BACKGROUND

Viscoelastic tests (VETs), specifically thromboelastography (TEG) and rotational thromboelastometry (ROTEM), are gaining popularity in the management of critically ill surgical patients with hemorrhage or thrombosis due to their comprehensive characterization of the coagulation process and point-of-care availability in comparison to conventional coagulation tests (CCTs). We review current evidence for VET use in patients in the surgical intensive care unit (SICU).

METHODS

We searched PUBMED, EMBASE and the Cochrane Library through May 30, 2018 for articles that evaluated the use of VETs in patient populations and clinical scenarios germane to the surgical intensivist. Individual articles were critically evaluated for relevance and appropriate methodology using a structured technique. Information on patient characteristics, timing and methods of CCTs/VETs, and outcomes was collected and summarized in narrative form.

RESULTS

Of 2,589 identified articles, 36 were included. Five (14%) were interventional studies and 31 (86%) were observational. Twenty-five (69%) evaluated TEG, 11 (31%) ROTEM and 18 (50%) CCTs. Investigated outcomes included quantitative blood loss (13 (36%)), blood product transfusion (9 (25%)), thromboembolic events (9 (25%)) and mortality (6 (17%)). We identified 12 clinical scenarios with sufficient available evidence, much of which was of limited quantity and poor methodological quality. Nonetheless, research supports the use of VETs for guiding early blood product administration in severe traumatic hemorrhage and for the prediction of abstract excess bleeding following routine cardiac surgery. In contrast, evidence suggests VET-based heparin dosing strategies for venous thromboembolism prophylaxis are not superior to standard dosing in SICU patients.

CONCLUSION

While VETs have the potential to impact the care of critically ill surgical patients in many ways, current evidence for their use is limited, mainly because of poor methodological quality of most available studies. Further high-quality research, including several ongoing randomized controlled trials, is needed to elucidate the role of TEG/ROTEM in the SICU population.

LEVEL OF EVIDENCE

Systematic review, level IV.

Transfusion requirements in elective cardiopulmonary bypass surgery patients: predictive value of Multiplate and Thromboelastography (TEG) Platelet Mapping Assay

Managing haemostasis in patients undergoing cardiopulmonary bypass (CPB) surgery remains a challenge. There is no established laboratory test to predict transfusion requirements in cardiac surgery. We investigated whether preoperative Thromboelastography (TEG) with Platelet Mapping Assay (PMA) or Multiple Electrode Aggrometry (MEA) could predict transfusion requirements in patients undergoing elective coronary artery bypass grafting (CABG) or combined CABG with aortic or mitral valve replacement. We prospectively investigated 199 patients undergoing elective CABG or combined procedures. PMA and MEA were performed at baseline (after anaesthesia induction), upon arrival at the intensive care unit and on the first postoperative day. Patients receiving fresh frozen plasma and/or platelets (FFP/PLT) had a lower PMA maximum amplitude (MA) for adenosine diphosphate (PMA-ADP) and arachidonic acid (PMA-AA) at baseline, at arrival in the intensive care unit and the first postoperative day compared to non-transfused patients. Receiver operating characteristic curves on PMA showed that lower values predicted FFP/PLT transfusion: PMA-ActF 0.64 (p = 0.04), PMA-ADP 0.69 (p = 0.01) and PMA-AA 0.71 (p = 0.002). In contrast, MEA values were not able to predict FFP/PLT transfusions. This study shows that preoperative PMA potentially is a better screening tool for platelet inhibition associated with transfusion requirements in patients undergoing CABG or combined procedures.