Which condition is commonly caused by inability to equalize pressure in air-filled spaces during descent?

Which condition is commonly caused by inability to equalize pressure in air-filled spaces during descent?

• A. Ear squeeze
• B. Nitrogen narcosis
• C. Decompression sickness
• D. Hypercapnia

Answer: (A)

During descent, ambient pressure increases and air-filled spaces in the head must be equalized to match that pressure. The middle ear relies on the Eustachian tube to vent air in or out; if it can’t open, a pressure difference builds across the tympanic membrane. That mismatch compresses the ear structures and causes pain and fullness—the classic ear squeeze. This happens specifically because the air in the middle ear can’t be equalized as you go deeper. Nitrogen narcosis isn’t about pressure equalization in the ear; it’s a narcotic effect from high nitrogen partial pressures. Decompression sickness arises on ascent when dissolved gases form bubbles in tissues, not from failing to equalize during descent. Hypercapnia is high carbon dioxide from inadequate ventilation, not a pressure-equalization issue.

During descent, ambient pressure increases and air-filled spaces in the head must be equalized to match that pressure. The middle ear relies on the Eustachian tube to vent air in or out; if it can’t open, a pressure difference builds across the tympanic membrane. That mismatch compresses the ear structures and causes pain and fullness—the classic ear squeeze. This happens specifically because the air in the middle ear can’t be equalized as you go deeper.

Nitrogen narcosis isn’t about pressure equalization in the ear; it’s a narcotic effect from high nitrogen partial pressures. Decompression sickness arises on ascent when dissolved gases form bubbles in tissues, not from failing to equalize during descent. Hypercapnia is high carbon dioxide from inadequate ventilation, not a pressure-equalization issue.