プロテインC 活性低下を背景とし，オートマチック車への変更を契機に肺血栓塞栓症を発症したタクシー運転手の一例

A ６２-year-old man, who was a taxi-driver, presented to our hospital for further examination and treatment of deep venous thrombosis（DVT）suspected in another clinic. Before ３ months of consultation, he had changed his taxi from manual transmission car to automatic transmission car. Around the same time, he had complained progressively worsening left pedal edema and pain. When he consulted our hospital, blood examination showed elevated D-dimer and deficiency of protein C. A venous ultrasound showed an occlusive DVT in left lower extremity through an external iliac vein. A contrast-enhanced computed tomography showed bilateral pulmonary embolism（PE） and extensive thrombus in the left lower extremity. Following hospitalization, an inferior vena cava （IVC）filter was placed in an infrarenal IVC position, and anticoagulant therapy was initiated with heparin and warfarin. His DVT and PE were managed successfully with anticoagulant therapy, and pedal edema was improved. Besides some risk factors of thrombogenicity such as age and deficiency of protein C, sitting position for long hours and decreased motion of left leg might have triggered off the thrombus formation in the left lower extremity. This report demonstrates the importance of careful follow-ups to long-distance drivers with risk factors of thrombus formation, especially about clutch operation.