Effects of fibrinogen supplementation on clot formation in blood samples from cardiac surgery patients before and after tranexamic acid administration

Abstract

Summary Objectives To investigate if supplementation with fibrinogen concentrate to blood samples collected after tranexamic acid administration improve clot formation more than what can be achieved with fibrinogen in the absence of tranexamic acid. Background It is not known if the combination of fibrinogen and tranexamic acid has additional effects than what can be achieved individually. Methods Four blood samples were collected from 15 coronary artery bypass patients. Two samples were collected before surgery, before and after 2 g tranexamic acid was administered. The preoperative samples were diluted to haematocrit 21%. Two samples were collected after surgery, before and after a second dose of 2 g tranexamic acid. Fibrinogen concentrate corresponding to a dose of 3 g in a 70‐kg patient was added to the samples. Platelet‐independent clotting time and maximum clot firmness assessed by thromboelastometry (ROTEM‐FIBTEM®) were compared between the samples. Results Administration of tranexamic acid shortened clotting time marginally (−6%) before surgery, P = 0·029) but did not influence clot firmness. Fibrinogen concentrate shortened clotting time (−14% before and −12% after surgery, both P = 0·003) and increased clot firmness (+51 and +39%, both P < 0·001). The effects of fibrinogen did not differ before and after tranexamic acid administration. Fibrinolysis was not detected in any sample. Conclusions The results of this in vitro study suggest that the enhancing effects of fibrinogen on clot firmness in blood samples from cardiac surgery patients are not further increased in the presence of tranexamic acid. Further studies on patients with ongoing bleeding and/or hyperfibrinolysis are necessary to validate the results.

A randomised controlled trial of fibrinogen concentrate during scoliosis surgery

“…We could not determine the specific contribution of fibrinogen to haemostatic tests due to its interaction with tranexamic acid. A recent in‐vitro study suggested that tranexamic acid does not enhance the effects of fibrinogen on clot firmness in cardiac surgery, leaving it possible that tranexamic acid might interfere with fibrinogen’s effect [30]. Further research can help determine whether our results are replicable in general populations undergoing scoliosis surgery.…”

Altered Fibrinolysis during and after Surgery

“…17,25 The direct effect of TXA administration measured by thromboelastometry (ROTEM, Pentapharm GmBh Munich, Germany) resulted in a small reduction in median CT but there was no significant difference in MCF. 53 Monaco et al, 54 in a randomized controlled trial involving 100 patients undergoing elective open abdominal aortic aneurysm repair, reported a 20% reduction in intraoperative blood loss and a 33% reduction in postoperative blood loss during the first 24 hours, without any apparent increases in adverse events including thromboembolism and death caused by TXA treatment.…”