Hyperventilation occurs when emotional stress, fright, or pain causes which physiological change?

• A. Breathing rate and depth increase, while CO2 in the blood is reduced.
• B. Breathing rate and depth decrease.
• C. Breathing rate becomes erratic with no CO2 change.
• D. Breathing rate and depth increase, and CO2 increases.

Answer: (A)

When emotional stress, fright, or pain hits, the body's response is to over-breathe. This means the breathing rate and depth both increase. As you exhale more air, you remove carbon dioxide from the blood faster than it’s produced, so the CO2 level in the blood drops. That reduction in CO2 shifts the blood toward alkalinity (respiratory alkalosis) and causes cerebral vessels to constrict, which can lead to dizziness, tingling, or lightheadedness. In flight, this is why a stressed pilot may feel faint or dizzy even though oxygen levels may still be adequate. Restoring a normal breathing rate and CO2 level helps resolve the symptoms.