Which of the following is not part of the five Hs?

• A. Hypoxia
• B. Hypovolemia
• C. Hydrogen Ion Imbalance
• D. Hyperthermia

Answer: (D)

In emergency care, we use the five Hs to remember common reversible causes of deterioration or cardiac arrest: Hypoxia, Hypovolemia, Hydrogen ion imbalance (acidosis), Electrolyte disturbances such as Hyperkalemia or Hypokalemia, and Hypothermia. These cover the main immediate threats to circulation and heart function that we can often fix quickly. Among the options, Hyperthermia does not belong to this list. While overheating can be dangerous in its own right, it isn’t one of the classic five Hs clinicians systematically check during rapid resuscitation. Hydrogen ion imbalance refers to acidosis, a state that disrupts cellular and cardiac function and is addressable by correcting ventilation and the underlying cause. Hypoxia is about insufficient oxygen delivery, hypovolemia about low circulating volume, and electrolyte disturbances about disorders in potassium that can precipitate dangerous rhythms. Hypothermia, a dangerously low body temperature, is the temperature-related H in the mnemonic. Hyperthermia is not part of that standard set.