indidoc1
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41.
A 72-year-old man with a known history of diverticular disease is admitted to the intensive care unit for a presumed diverticular bleed. Urgent colonoscopy is unable to find the source of bleeding because of poor visualization of the colonic mucosa caused by the large amounts of blood obscuring the field. Interventional radiology is called. Attempts to stop the bleeding using angiography and sclerotherapy fail. Finally the patient is brought to surgery and he receives a hemicolectomy that stops the bleeding. The patient’s hematocrit has steadily decreased throughout this time, from a high of 38% to a low of 21%, necessitating repeated transfusions. The patient eventually receives a total of 15 units of packed red blood cells, 8 units of platelets, and 8 units of fresh frozen plasma before being stabilized. While being brought back to the intensive care unit, the patient suffers a 2-minute seizure characterized by muscle contractions, jerking, and full body convulsions. An electrocardiogram (EKG) shows normal sinus rhythm, with the exception of a prolonged QT interval. An electroencephalogram (EEG) is performed that reveals both spikes and bursts of high-voltage slow waves. Which of the following is the most likely underlying cause of this patient’s tonic-clonic seizure?
A. Citrate infusion
B. Hypercalcemia
C. Hyperkalemia
D. Hypokalemia
E. Metabolic alkalosis
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| neuroblastoma
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D hypokalemia
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| cool doctor
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C??
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| me007
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A.
prolonged QT and muscle contraction and seizure - due to hypocalcemia, which is due to citrate toxicity
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| Vietnamese
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D- He had Torsade de Points, then the imminent hypotension.
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| doyoudig
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E - change in ph binds ca binding to OH causing hypocalcemia
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| indidoc1
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The correct answer is A. One of the complications of a massive blood transfusion is that large amounts of citrate used to anticoagulate stored blood are also infused. Citrate, before it can be converted to lactate, binds calcium, resulting in hypocalcemia, which is the cause of this patient’s seizure and classic EKG and EEG findings.
Hypocalcemia, not hypercalcemia (choice B), is a common complication of massive blood transfusions.
Hyperkalemia (choice C) is a complication of blood transfusion, but does not explain this patient's symptoms. The older the blood used (greater than 5 days), the greater the risk for hyperkalemia. As the blood sits, red blood cells leak potassium or lyse, releasing intracellular potassium. Blood can be "rinsed" of potassium by the blood bank before transfusion, if there is concern of hyperkalemia.
Hypokalemia (choice D) is not a complication of blood transfusion.
Metabolic alkalosis (choice E) is a complication of massive blood transfusions. Citrate is converted to bicarbonate at a ratio of 1 mmol of citrate generating 3 mmol of bicarbonate. If there is renal ischemia or underlying renal disease, this excess bicarbonate can rapidly cause a metabolic alkalosis. Severe alkalosis may worsen hypocalcemia by increasing the bound ionic form of calcium, but is not the main culprit responsible for this patient's seizure.
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| tamerbashir
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A A A A A A
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| Vietnamese
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Good explanation. Thank You indiloc1.
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