Which statement is true about orthopnoea and paroxysmal nocturnal dyspnoea?

Which statement is true about orthopnoea and paroxysmal nocturnal dyspnoea?

• A. Orthopnoea occurs when lying flat and is relieved by sitting; Paroxysmal nocturnal dyspnoea occurs 2-5 hours after sleep and is relieved by sitting upright.
• B. Orthopnoea occurs after meals; PND occurs during waking hours.
• C. Orthopnoea occurs during sleep; PND occurs during exercise.
• D. Orthopnoea lasts hours; PND lasts minutes.

Answer: (A)

The idea being tested is how these two forms of dyspnea present and why they occur. Orthopnoea is the difficulty breathing that happens when you lie flat. When you lie down, more blood returns to the heart, raising the pressure in the pulmonary circulation and causing fluid to shift into the lungs, which makes breathing hard. Sitting up or standing reduces that venous return and relieves the breathlessness. Paroxysmal nocturnal dyspnoea is a sudden breathlessness that awakens you 2–5 hours after you’ve fallen asleep. In the recumbent position, overnight fluid from the legs shifts into the central circulation, which can provoke pulmonary congestion and a rapid onset of dyspnea. Sitting upright relieves this by lowering venous return and easing the pulmonary pressures. These descriptions align with the true statement: orthopnoea is relieved by sitting when lying flat, and nocturnal episodes occur after several hours of sleep and improve with upright positioning. The other patterns described—dyspnea after meals, during waking hours, during exercise, or with different durations—don’t match these classic mechanisms.

The idea being tested is how these two forms of dyspnea present and why they occur. Orthopnoea is the difficulty breathing that happens when you lie flat. When you lie down, more blood returns to the heart, raising the pressure in the pulmonary circulation and causing fluid to shift into the lungs, which makes breathing hard. Sitting up or standing reduces that venous return and relieves the breathlessness. Paroxysmal nocturnal dyspnoea is a sudden breathlessness that awakens you 2–5 hours after you’ve fallen asleep. In the recumbent position, overnight fluid from the legs shifts into the central circulation, which can provoke pulmonary congestion and a rapid onset of dyspnea. Sitting upright relieves this by lowering venous return and easing the pulmonary pressures. These descriptions align with the true statement: orthopnoea is relieved by sitting when lying flat, and nocturnal episodes occur after several hours of sleep and improve with upright positioning. The other patterns described—dyspnea after meals, during waking hours, during exercise, or with different durations—don’t match these classic mechanisms.