Which of the following is considered an Hs/Ts factor in cardiac arrest?

• A. Hypovolemia
• B. Hypertension
• C. Hypercalcemia
• D. Hypoventilation

Answer: (A)

In the Hs/Ts framework for reversible causes of cardiac arrest, hypovolemia fits as an Hs factor because a significant loss of circulating blood volume reduces preload and cardiac output, making CPR less effective and contributing to arrest. Restoring volume with fluids or blood products can reverse the underlying problem and improve chances of return of spontaneous circulation when appropriate. The other options aren’t part of the Hs/Ts list: hypertension isn’t a listed reversible arrest cause, hypercalcemia isn’t included in this mnemonic, and hypoventilation, while it can cause hypoxia, isn’t categorized as an Hs/Ts factor. Therefore, hypovolemia is the correct choice.