III-38. A 65-year-old man is brought to the emergency room by ambulance after his daughter found him to be incoherent earlier today. She last spoke with him yesterday, and at that time, he was complaining of 2 days of myalgias, headache,
and fever. He had attributed it to an upper respiratory tract infection and did not seek evaluation from his primary care physician. Today, he did not answer when she called his home, and she found him lying in his bed smelling
of urine. He was minimally arousable but appeared to be moving all of his extremities. His past medical history is significant for hypertension, hypercholesterolemia, and chronic obstructive pulmonary disease. He was evaluated 2 weeks previously for a transient ischemic attack after an
episode where he had numbness and weakness of his left arm and leg that resolved over 6 h without intervention. His current medications include aspirin, 81 mg daily, clopidogrel, 75 mg daily, atenolol, 100 mg daily, atorvastatin, 20 mg daily, and tiotropium, once daily. He is allergic to lisinopril,
which caused angioedema. He is a former smoker
and drinks alcohol rarely. On physical examination, he is obtunded and minimally arousable. He is febrile with a temperature of 38.9°C. His blood pressure is 159/96 mmHg, and heart rate is 98 beats/ min. He is breathing at a rate of 24 breaths/min with a room air oxygen saturation of 95%. He has minimal scleral icterus. The oropharynx reveals dry mucous membranes. His
cardiovascular, pulmonary, and abdominal examinations are normal. There are no rashes. His neurologic examination is difficult to obtain. There are no cranial nerve findings. He resists movement of his extremities but has normal strength. Deep tendon reflexes are brisk, 3+ and equal. The laboratory values are as follows: hemoglobin 9.3 g/
dL, hematocrit 29.1%, white blood cell count 14,000/μL, and platelets 42,000/μL. The differential demonstrates 83% neutrophils, 2% band forms, 6% lymphocytes, and 9% monocytes. The sodium is 145 meq/L, potassium 3.8 meq/L, chloride 113 meq/L, bicarbonate 19 meq/L, blood urea nitrogen 68 mg/dL, and creatinine 3.4 mg/dL. The bilirubin is 2.4 mg/dL, and lactate dehydrogenase is 450
U/L. A peripheral blood smear shows diminished platelets and many schistocytes.What is the next most appropriate step in this patient's care?
B. Discontinue clopidogrel and initiate plasmapheresis.