Dapsone Induced Methaemoglobinemia: Early Intraoperative Detection by Pulse Oximeter Desaturation

Abstract

Several drugs cause methaemoglobinemia which can lead to pulse oximeter desaturation and hypoxemia.Children with immune thrombocytopenic purpura are being treated with dapsone which is known to cause methaemoglobinemia and many of these can be planned for elective splenectomy. Preoperative knowledge of drug intake and their adverse effects is essential so is the early detection of the cause of intraoperative hypoxemia and the remedial measures taken. We present a child on dapsone therapy for treatment of immune thrombocytopenic purpura planned for elective splenec-tomy developed intraoperative pulseoximeter desaturation. The cause of desaturation was identified as methaemoglobinemia caused by dapsone therapy. Case signifies the importance of knowledge of any preoperative drug intake and its anaesthetic implications. Also patients on dapsone therapy especially children should be monitored for methaemoglobin levels. Since children with immune thrombocy-topenic purpura are being treated with dapsone these days and many of these patients would be planned for splenectomy, monitoring of preoperative methaemoglobin levels and methaemoglobinemia as a cause of intraoperative pulse oximeter desaturation should be kept in mind.

Keywords

• Methaemoglobinemia; Dapsone; Idiopathic thrombocytopenic purpura