[A Jehovah's Witness child with hemophilia B and factor IX inhibitors undergoing scoliosis surgery].

PURPOSE: To describe the successful perioperative hemostatic management of a Jehovah's Witness patient with hemophilia B and anaphylactic inhibitors to factor IX, undergoing scoliosis surgery. CLINICAL FEATURES: A 14 (1/2)-yr-old boy with severe hemophilia B who had a history of anaphylactic inhibitors to factor IX was scheduled to undergo corrective scoliosis surgery. He was initially started on epoetin alfa and iron supplementation to maximize preoperative red cell mass. Additionally, he was placed on a desensitization protocol of recombinant coagulation factor IX (rFIX) and was then treated with activated recombinant coagulation factor VII (rFVIIa) during the postoperative period. Tranexamic acid was given concomitantly. The intraoperative blood loss was approximately 350 mL. The nadir hemoglobin concentration was 111 g.L(-1) on postoperative days one and two. On postoperative day 11, the patient was stable and discharged home with a hemoglobin of 138 g.L(-1). He did not require blood transfusion and no adverse events were observed. CONCLUSIONS: The use of rFIX, rFVIIa, erythropoetin, iron, and tranexamic acid before, during and after scoliosis surgery may be a viable and safe option for hemophilia patients with inhibitors, who refuse blood products.

Current European practice in immune tolerance induction therapy in patients with haemophilia and inhibitors.

The management of patients with inhibitors is an important challenge in haemophilia care. The lack of randomized controlled trials means that clinical decisions are generally based on subjective opinions, and purchasers' attention is likely to focus on the costs of treatment. In order to assess the current management of inhibitor patients and use of immune tolerance induction therapy (ITI) in Europe, we performed a survey within a European network of 21 comprehensive care centres from 14 countries (the European Haemophilia Therapy Standardisation Board). The survey identified a total of 381 patients with inhibitors attending the centres, 211 (55.4%) of whom had never been exposed to ITI. Between 1998 and 2003, the centres performed 233 procedures and 114 (48.9%) were successful. The survey demonstrated that dosing, which is the time to start and stop the ITI, the type of concentrate to use and the definition of success varied among the centres. Well-designed trials are warranted to guide decision-making, but in the absence of these studies we have developed consensus guidance for the management of inhibitor patients based on current clinical practice, as identified by the survey, and review of the literature.

An inhibitory anti-factor IX antibody effectively reduces thrombus formation in a rat model of venous thrombosis.

An inhibitory anti-factor IX/IXa antibody (BC2) has been investigated as an anti-thrombotic agent in a rat venous thrombosis model. The treatment of rats post-injury with a single bolus dose of BC2 (3 mg/kg, i.v.) resulted in an approximately 4 fold reduction in venous thrombus mass (P = 0.043). This efficacy was matched by a minimal (<2.5 fold) prolongation of the aPTT and had no effect on the prothrombin time (PT). Heparin by comparison, given as a bolus followed by continuous infusion, at doses comparable in efficacy at reducing thrombus formation, prolonged the aPTT >50 fold. These results demonstrate that the anti-factor IX/IXa antibody (BC2), when compared to heparin, can effectively reduce venous thrombosis with less disruptive consequences on blood clotting.

Dose-dependent influence of acetylsalicyclic acid on platelet functions and plasmatic coagulation factors.

Lysine salt of acetylsalicylic acid (ASA) was given to ten patients by intravenous infusion. Blood samples taken at intervals during the infusion permitted the examination of the influence of the dose of ASA on platelet functions. Aggregation was significantly reduced when 50 mg ASA had entered circulation, while a diminution of PF3 and PF4 availability could only be demonstrated when the dose had reached 500 and 200 mg, respectively. In order to exclude a longer latency time for the diminution of PF3 and pf4 availability, a second series of ten patients received intravenous injections of 100 and 300 mg ASA, respectively. From these patients, blood was taken 1 h after the injection. The decrease of PF3 and PF4 availability in these cases was comparable to the results of the first group. In a third series of patients, a daily intravenous dose of 2,000 mg ASA was given. In these cases, a moderate decrease of factors II, VII, IX and X was observed. Since the appearance of a PIVKA effect could also be demonstrated, vitamin K antagonism was assumed when a high dose of AS