A 45-year-old man comes to the emergency department with progressive dyspnea. The patient has a history of uncontrolled hypertension. Blood pressure is 210/115 mm Hg and pulse is 105/min. Chest examination demonstrates bibasilar crackles. There are no heart murmurs. Serum creatinine is 1.6 mg/dL. Intravenous furosemide and continuous nitroprusside infusion are started, along with noninvasive positive pressure ventilation, and he experiences improvement in his symptoms. The next morning, the patient is confused and lethargic, and he suffers a generalized tonic-clonic seizure. The skin appears flushed, and serum lactic acid level is elevated. The nitroprusside infusion rate is found to be higher than recommended. Which of the following mechanisms is most likely responsible for the drug toxicity seen in this patient?

Question

A 45-year-old man comes to the emergency department with progressive dyspnea.  The patient has a history of uncontrolled hypertension.  Blood pressure is 210/115 mm Hg and pulse is 105/min.  Chest examination demonstrates bibasilar crackles.  There are no heart murmurs.  Serum creatinine is 1.6 mg/dL.  Intravenous furosemide and continuous nitroprusside infusion are started, along with noninvasive positive pressure ventilation, and he experiences improvement in his symptoms.  The next morning, the patient is confused and lethargic, and he suffers a generalized tonic-clonic seizure.  The skin appears flushed, and serum lactic acid level is elevated.  The nitroprusside infusion rate is found to be higher than recommended.  Which of the following mechanisms is most likely responsible for the drug toxicity seen in this patient?

Quizplus · Accepted Answer

Eductional Objective: Cyanide toxicity is an important adverse effect of nitroprusside.  Blockage of mitochondrial electron transport leads to impaired oxygen utilization, causing lactic acidosis, neurologic dysfunction, and cardiovascular collapse.

A 45-Year-Old Man Comes to the Emergency Department with Progressive