Which symptom is specifically noted in individuals with orthopnea?

Individuals with orthopnea experience significant difficulty in breathing when lying flat. This symptom is often associated with specific medical conditions such as heart failure, where the supine position can exacerbate pulmonary congestion due to increased venous return to the heart. When the patient lies down, fluid may accumulate in the lungs, leading to shortness of breath. As a result, many individuals with orthopnea find relief when they sit up or prop themselves on pillows, allowing for better lung expansion and alleviation of respiratory distress.

The other symptoms listed, such as intense back pain, nausea and vomiting, and abdominal discomfort, are not characteristic of orthopnea. While these symptoms can be associated with various medical conditions, they do not specifically relate to the respiratory difficulties experienced when changing position to lying down. Thus, recognizing orthopnea as difficulty in breathing while lying flat is key in understanding this condition's implications for patient management and care.