Orthopnoa
Orthopnoa , noun
[Latin orthopnoea, Greek {not transcribed}; 'orqo`sstraight, right + pnei^n to breathe: compare French orthopnée.]
(Medicine) Specifically, a morbid condition in which respiration can be performed only in an erect posture; by extension, any difficulty of breathing.
Also: Orthopny, Orthopnoea