We have read with great interest the article by Okonta and colleagues [1]. The recombinant activated factor VII (rFVIIa) was applied for treatment of the postoperative bleeding in children at our centre for the first time in 2003. We prospectively reviewed the results of its application in 70 patients aged 0-14 years who received rFVIIa at dose ranging from 90 to 120 mcg/kg. Haemostasis was achieved in 59 (84.2%) patients after rFVIIa administration [2]. We received the evidences of the high haemostatic potential of this drug, but it cannot be considered a panacea. While accumulating the experience, some unclarified issues appeared. Firstly, what are the reasons of a non-effective administration rFVIIa in the achievement of haemostasis? The second point is whether we can use rFVIIa within the prevention of the hemorrhage? And, lastly, what is the rate of the thrombotic complications? Should we perform laboratory control of the rFVIIa application?
The idea of the rFVIIa administration in patients after cardiac surgery procedure consists of “bypassing” most of the coagulation reactions by creating an excess concentration of FVIIa. Therefore, its application is appropriate when coagulation factors are insufficient. But it will not be reasonable and effective under the circumstances of an excessive activation of natural anticoagulants or a deficiency in the final-stage components of the clot formation, e.g., fibrinogen, FXIII. The rFVIIa can be used as part of the complex therapy only after overcoming the above mentioned coagulation disorders.
The administration of the rFVIIa with preventive goals should be excluded. First of all, rFVIIa does not have a replacement function in contrast to the prothrombin complex concentrates. Secondly, there is a risk of thrombosis in the background of the minimal changes of the haemostasis. The rate of this complication in the off-label usage of rFVIIa reaches 10.9% [3]. Due to this we recommend an application of rFVIIa only for treatment of patients with an International Normalized Ratio (INR) higher than 1.5 under the laboratory control of this parameter. The rFVIIa dosage should be titrated closely according the degree of coagulation disorders to achieve the target INR values of 1-1.2.
So we consider that, the main indication for rFVIIa administration is the excessive bleeding due to the severe impairments of the thrombin generation. It can be used as a monotherapy or in combination with other drugs under the laboratory control of its efficacy.
Conflict of Interest: None declared
REFERENCES
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