Which of the following is an emergency treatment for cyanide poisoning?

The correct treatment for cyanide poisoning is amyl nitrate. Amyl nitrate acts as a cyanide antidote by providing a source of nitrates that convert hemoglobin to methemoglobin. Methemoglobin has a higher affinity for cyanide, allowing it to bind with cyanide molecules and thereby reducing the amount of free cyanide in the bloodstream, which can help prevent cellular hypoxia and damage.

This mechanism of action makes amyl nitrate a key emergency response in cases of cyanide poisoning, supporting vital cellular functions in the context of an otherwise life-threatening condition. Along with other treatment options, such as hydroxocobalamin or sodium thiosulfate, amyl nitrate plays an important role in the emergency management of cyanide exposure.

While other substances listed have their uses in different contexts—fomepizole is primarily an antidote for methanol or ethylene glycol poisoning; calcium chloride is used for calcium deficiency or severe hyperkalemia; and sodium bicarbonate is often utilized to treat metabolic acidosis or as an alkalinizing agent—none of them serve as effective emergency treatments for cyanide poisoning. Understanding the specific actions and appropriate contexts for each of these agents is critical for effective emergency practice.