Pathophysiology–Pharmacology (Pathopharm) Practice Exam

In cases of severe diarrhea, the primary concern is dehydration and the loss of both water and electrolytes, particularly sodium. 0.9% sodium chloride, also known as normal saline, is the most appropriate intravenous solution because it effectively replaces extracellular fluid volume and restores sodium levels without introducing additional glucose that could potentially worsen dehydration.

Normal saline is isotonic, meaning it has a similar osmolarity to blood plasma, making it suitable for rehydration in situations of hypovolemia, such as severe diarrhea. It helps maintain electrolyte balance and replenish lost fluids efficiently.

Other options, while they have their uses, do not address the patient's immediate needs as effectively. For instance, 5% dextrose in water provides calories but not adequate electrolytes, which can lead to further complications in a dehydrated state. 0.45% sodium chloride is a hypotonic solution and could dilute serum sodium levels further, thus not suitable in acute management of dehydration from diarrhea. Normal saline with dextrose involves the addition of glucose, which may not be beneficial in the acute scenario of dehydration due to diarrhea, as the primary concern is restoring fluid and electrolyte balance rather than providing calories at that moment.