A 67-year-old man with mild chronic obstructive pulmonary disease is brought to the emergency department by his daughter with the chief complaint of seizure. The patient has had episodes of confusion and lethargy over the past week. He complains of some exertional shortness of breath and nonproductive cough. His daughter believes that he is losing weight and has decreased appetite. His temperature is 37.2 C (99 F), blood pressure is 134/88 mm Hg, and pulse is 104/min and irregular. The mucous membranes are moist and there is no peripheral edema. Neurologic examination is unremarkable. Laboratory results are as follows: Rapid correction of this patient's metabolic abnormalities puts him at highest risk of which of the following?

Question

A 67-year-old man with mild chronic obstructive pulmonary disease is brought to the emergency department by his daughter with the chief complaint of seizure.  The patient has had episodes of confusion and lethargy over the past week.  He complains of some exertional shortness of breath and nonproductive cough.  His daughter believes that he is losing weight and has decreased appetite.  His temperature is 37.2 C (99 F), blood pressure is 134/88 mm Hg, and pulse is 104/min and irregular.  The mucous membranes are moist and there is no peripheral edema.  Neurologic examination is unremarkable.  Laboratory results are as follows:  Rapid correction of this patient's metabolic abnormalities puts him at highest risk of which of the following?

Quizplus · Accepted Answer

This patient presents with a provoked seizure in the setting of severe hyponatremia. This is considered a medical emergency and requires prompt correction of the serum sodium concentration with 3% saline solution. However, correction of the serum sodium should not exceed 0.5 mEq/L/hr to avoid causing irreversible brain damage from osmotic demyelination or central pontine myelinolysis. Rapid correction of serum sodium in the setting of hyponatremia results in excess water being moved by osmosis from the intracellular compartment (neurons and glia) into the extracellular compartment. This in turn leads to disruption of cellular metabolic activity and subsequent cell damage. The opposite is true when rapidly correcting a patient with hypernatremia, when cerebral edema can occur (Choice A). This patient's hyponatremia could be from lung cancer-associated syndrome of inappropriate antidiuretic hormone given his euvolemic status, recent weight loss, and smoking history. (Choice B) This patient has an irregular heart rhythm, which may be secondary to atrial fibrillation, and therefore is at increased risk of an embolic stroke. However, rapid correction of his hyponatremia will not contribute to that risk. (Choice C) Rapid correction of hyponatremia results in increased water movement out of brain tissue and so would not contribute to the formation of hydrocephalus. Hydrocephalus can be either obstructive (noncommunicating) or nonobstructive (communicating), resulting from excess cerebrospinal fluid production or impaired cerebrospinal fluid absorption. (Choice E) Electrolyte abnormalities can result in cardiac arrhythmias. However, rapid correction of hyponatremia is more likely to result in osmotic demyelination in the central nervous system than to cause a ventricular arrhythmia. Educational objective: Acute, symptomatic hyponatremia (impaired mental status/seizures) is a medical emergency. It requires a prompt increase in the serum sodium concentration with 3% or hypertonic saline at a rate of no more than 0.5 mEq/L/hr to avoid causing central nervous system osmotic demyelination syndrome.

A 67-Year-Old Man with Mild Chronic Obstructive Pulmonary Disease Is