An unresponsive 62-year-old man is brought to the emergency department after sustaining multiple injuries in a major motor vehicle accident. He is obtunded but responds to painful stimuli. His blood pressure is 160/90 mm Hg, pulse is 72/min, and respirations are 10/min. A few hours after initial treatment and stabilization, he develops severe tachypnea and decreased oxygenation. His chest x-ray shows evidence of pulmonary edema. He is rapidly intubated and given oxygen but acutely worsens and dies a few hours later, despite aggressive measures. Which of the following drugs could have caused this patient's condition?

Question

An unresponsive 62-year-old man is brought to the emergency department after sustaining multiple injuries in a major motor vehicle accident.  He is obtunded but responds to painful stimuli.  His blood pressure is 160/90 mm Hg, pulse is 72/min, and respirations are 10/min.  A few hours after initial treatment and stabilization, he develops severe tachypnea and decreased oxygenation.  His chest x-ray shows evidence of pulmonary edema.  He is rapidly intubated and given oxygen but acutely worsens and dies a few hours later, despite aggressive measures.  Which of the following drugs could have caused this patient's condition?

Quizplus · Accepted Answer

This patient presents after trauma and was likely treated with mannitol, an osmotic diuretic often used in the management of cerebral edema and increased intracranial pressure. Mannitol works by rapidly increasing plasma or tubular fluid osmolality, which causes water to move from the interstitial space into the vascular space or tubular lumen. In the kidneys, osmotic diuretics primarily work in the proximal tubule and the loop of Henle to produce diuresis. In the brain, water redistribution from the tissues into the plasma helps to reduce cerebral edema and intracranial pressure. Common side effects of osmotic diuretics include headache, nausea, and vomiting. Overaggressive treatment with osmotic diuretics can lead to excessive volume depletion and eventual hypernatremia in certain patients. One of the more severe toxicities of aggressive osmotic diuretic therapy is pulmonary edema, caused by the rapid rise in volume that can also increase the overall hydrostatic pressure in the vasculature. The continued rise in plasma osmolality causes more water and potassium to move out of the cells and brain. This leads to further volume expansion (and possibly worsening pulmonary edema), dilutional hyponatremia and metabolic acidosis, and hyperkalemia. Therefore, osmotic diuretics should be cautiously used in high-risk patients, such as those with congestive heart failure (CHF) or preexisting pulmonary edema. (Choice A) Thiazide diuretics are used to treat edema secondary to heart failure, renal disease, and liver disease. Common side effects include hypokalemia and hypomagnesemia. Less common side effects include hypotension, volume depletion, hypercalcemia, and hyponatremia. (Choice B) Bumetanide is a loop diuretic that works by inhibiting NaK2Cl symporters in the ascending limb of the loop of Henle to block Na and Cl transport and increase Na, Cl, and fluid excretion. Loop diuretics are commonly used to treat pulmonary edema, venous and pulmonary congestion secondary to CHF, and peripheral edema. Common side effects include hypokalemia, hypomagnesemia, and hypocalcemia. (Choice C) Spironolactone is an aldosterone antagonist with mild diuretic effects. It has a potassium-sparing effect and some endocrine effects and can cause significant hyperkalemia, gynecomastia, decreased libido, and erectile dysfunction. (Choice D) Triamterene is a potassium-sparing diuretic that works by blocking sodium channels in the distal tubule and collecting duct, leading to increased sodium and fluid excretion. Educational objective: Mannitol is an osmotic diuretic that works by increasing plasma or tubular fluid osmolality. Increased plasma and fluid osmolality causes extraction of water from the interstitial space into the vascular space or tubular lumen, with subsequent diuresis. In the brain, water redistribution from the tissues into the plasma helps reduce edema and intracranial pressure in the setting of cerebral edema. One of the more severe toxicities of aggressive osmotic diuretics is pulmonary edema. __________ References: Mannitol revisited (http://www.ncbi.nlm.nih.gov/pubmed/7963823)

An Unresponsive 62-Year-Old Man Is Brought to the Emergency Department