Clinical significance of coagulation studies in predicting response to activated recombinant Factor VII in cardiac surgery patients

Outcomes associated with absent blood product utilization in Jehovah's witness patients compared to the standard of care in cardiac surgery: A ten-year experience

INTRODUCTION

For Jehovah's Witness (JW) patients requiring cardiac surgery, various strategies such as preoperative use of erythropoietin stimulating agents (ESAs), intravenous iron (IVI), and non-pharmacologic interventions have emerged to prevent complications from blood loss given transfusion is not acceptable in this population.

METHODS

Retrospective case-control of cardiac surgeries performed by the same surgeon between 1/1/2011 and 8/30/2021. JW patients were matched to non-JW who received blood products and non-JW who did not receive blood products on a 1:2:2 basis. Patients were matched on procedure, age, gender, and Society of Thoracic Surgeons morbidity score. Eligible patients were aged >18 years and had a sternotomy procedure. The primary efficacy and safety outcomes included mean hematocrit values perioperatively and thrombotic events.

RESULTS

A total of 27 JW, 52 non-JW transfused, and 53 non-JW not transfused patients were included in the analysis. JW patients had significantly higher mean hematocrits at every time point when compared to non-JW transfused patients and at all time points except clinic and the last recorded operating room value when compared to non-JW not transfused patients. No significant differences in thrombotic rates were found between groups, however there was a numerically higher incidence in the JW population (JW: 7.4%; non-JW transfused: 0%; non-JW not transfused: 1.9%; p = .106).

CONCLUSION

A blood conservation protocol in a JW population was associated with higher perioperative hematocrit values when compared to matched controls. Further prospective study is warranted before applying similar protocols to other populations given the possibility for an increased rate of venous thromboembolism.

Perioperative management of the bleeding patient

Perioperative bleeding remains a major complication during and after surgery, resulting in increased morbidity and mortality. The principal causes of non-vascular sources of haemostatic perioperative bleeding are a preexisting undetected bleeding disorder, the nature of the operation itself, or acquired coagulation abnormalities secondary to haemorrhage, haemodilution, or haemostatic factor consumption. In the bleeding patient, standard therapeutic approaches include allogeneic blood product administration, concomitant pharmacologic agents, and increasing application of purified and recombinant haemostatic factors. Multiple haemostatic changes occur perioperatively after trauma and complex surgical procedures including cardiac surgery and liver transplantation. Novel strategies for both prophylaxis and therapy of perioperative bleeding include tranexamic acid, desmopressin, fibrinogen and prothrombin complex concentrates. Point-of-care patient testing using thromboelastography, rotational thromboelastometry, and platelet function assays has allowed for more detailed assessment of specific targeted therapy for haemostasis. Strategic multimodal management is needed to improve management, reduce allogeneic blood product administration, and minimize associated risks related to transfusion.

Prothrombin Complex Concentrates for Bleeding in the Perioperative Setting

Prothrombin complex concentrates (PCCs) contain vitamin K-dependent clotting factors (II, VII, IX, and X) and are marketed as 3 or 4 factor-PCC formulations depending on the concentrations of factor VII. PCCs rapidly restore deficient coagulation factor concentrations to achieve hemostasis, but like with all procoagulants, the effect is balanced against thromboembolic risk. The latter is dependent on both the dose of PCCs and the individual patient prothrombotic predisposition. PCCs are approved by the US Food and Drug Administration for the reversal of vitamin K antagonists in the setting of coagulopathy or bleeding and, therefore, can be administered when urgent surgery is required in patients taking warfarin. However, there is growing experience with the off-label use of PCCs to treat patients with surgical coagulopathic bleeding. Despite their increasing use, there are limited prospective data related to the safety, efficacy, and dosing of PCCs for this indication. PCC administration in the perioperative setting may be tailored to the individual patient based on the laboratory and clinical variables, including point-of-care coagulation testing, to balance hemostatic benefits while minimizing the prothrombotic risk. Importantly, in patients with perioperative bleeding, other considerations should include treating additional sources of coagulopathy such as hypofibrinogenemia, thrombocytopenia, and platelet disorders or surgical sources of bleeding. Thromboembolic risk from excessive PCC dosing may be present well into the postoperative period after hemostasis is achieved owing to the relatively long half-life of prothrombin (factor II, 60-72 hours). The integration of PCCs into comprehensive perioperative coagulation treatment algorithms for refractory bleeding is increasingly reported, but further studies are needed to better evaluate the safe and effective administration of these factor concentrates.