Orthopnea

n. shortness of breath (except when in an upright position)

Orthopnea (Greek from ortho, straight + pnoia, breath) is dyspnea which occurs when lying flat, causing the person to have to sleep propped up in bed or sitting in a chair. Orthopnoea is a symptom of heart failure. It can also occur in those with asthma and chronic bronchitis, as well as those with sleep apnea or panic disorder. The condition is often due to left ventricular failure and/or pulmonary edema. It is also associated with Polycystic Liver Disease.
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Orthopnea /or·thop·nea/ dyspnea that is relieved in the upright position.orthopne´ic or·thop·ne·a n. [more]Orthopnea - Community and Resources

Noun
1. form of dyspnea in which the person can breathe comfortably only when standing or sitting erect; associated with asthma and emphysema and angina pectoris
(hypernym) dyspnea, dyspnoea

The plight of a person who can only breath easily when sitting straight or standing erect.