Which of the following is NOT considered a reversible cause of PEA?

Severe dehydration is not typically classified as a reversible cause of pulseless electrical activity (PEA) because it does not directly lead to a mechanical or electrical obstruction of the heart or major vessels that can be immediately corrected in an emergency setting. PEA arises from multiple potential causes, many of which involve acute and potentially reversible conditions that result in inadequate cardiac output or ineffective circulation.

In contrast, conditions like tension pneumothorax and upper airway obstruction involve immediate physical problems that can be quickly remedied, restoring normal circulatory function. Tension pneumothorax compresses the heart and great vessels, and when it is relieved, circulation can often be restored. Similarly, resolving upper airway obstruction can restore adequate oxygenation and blood flow. Anaphylaxis also represents a reversible cause, as it can lead to vasodilation and severe allergic reactions that can be treated effectively with appropriate interventions, such as epinephrine.

While severe dehydration affects overall fluid balance and can impact circulation, it is not an acute event that can be addressed on the spot like the other conditions mentioned. In an emergency context, the immediate focus is usually on addressing causes that directly impede hemodynamic stability.