第VIII因子インヒビターを有する血友病A患者の麻酔経験

Abstract

第VIII因子(FVIII)インヒビターすなわちFVIII中和抗体を有する血友病A患者の人工膝関節置換術において, 遺伝子組換え活性型凝固第VII因子(recombinant activated factor VII: rFVIIa)を使用し, 安全に周術期管理を行えた症例を経験したので報告する. 「1. 症例」41歳, 男性, 身長168cm, 体重75.9kg 10歳時に血友病Aと診断され, 定期的に輸血あるいはFVIII製剤による治療を行ってきた. 28歳ごろより膝関節痛のために徐々に歩行困難となってきたため, 32歳時に当院で全身麻酔下に右膝人工膝関節置換術を施行し, 周術期にはFVIII製剤を使用した. その後も頻回に関節内の出血を来し, FVIII製剤投与を繰り返した. しかし, 36歳時よりFVIIIインヒビターが高力価となり, 止血療法としてrFVIIaの使用を開始し, その後プレドニゾロンによる免疫寛容療法を行ってインヒビター値は低力価で推移するようになった.

Occurrence of factor VIII (FVIII) inhibitor is a serious problem for hemophilia A patients. Recombinant activated factor VII (rFVIIa) has successfully been used for hemophilia A patients with FVIII inhibitor, but its perioperative effect on them needs still to be fully elucidated. We treated a 41-year-old male patient with hemophilia A scheduled for total knee arthroplasty (TKA) using FVIII inhibitor. The level of FVIII inhibitor was reduced to less than 5 BU • ml⁻¹ by immune tolerance therapy. We administered rFVIIa 120 μg • kg⁻¹ 2 hours before the surgery and every 2 hours during and after surgery. The amount of bleeding during TKA was small. After the 3rd postoperative day, the dosing interval of rFVIIa was gradually extended. He was discharged without rFVIIa administration on the 29th postoperative day, but further rFVIIa administration was needed because of rebleeding on the 49th postoperative day. No other hemorrhage occurred until the 241st postoperative day. Shortness of half-life period of rFVIIa needs its frequent administration, but rFVIIa interacts with thrombin- activated platelets to produce a thrombin burst : leading to accelerated fibrin clot formation localized to damaged sites of blood vessels. Moreover, the occurrences of the side effects such as DIC and thrombosis are rare. We conclude FVIII inhibitor, rFVIIa as a bypassing agent, is useful for perioperative management of a hemophilia A patient.