If orthopnea causes awakening during the night and is relieved by sitting, it is called paroxysmal nocturnal dyspnea.
如果端坐呼吸引起夜间觉醒，经坐起缓解，是为阵发性夜间呼吸困难。
英语百科
Paroxysmal nocturnal dyspnoea
（重定向自Paroxysmal Nocturnal Dyspnea）
Paroxysmal nocturnal dyspnea or paroxysmal nocturnal dyspnoea (PND) refers to attacks of severe shortness of breath and coughing that generally occur at night. It usually awakens the person from sleep, and may be quite frightening. Though simple orthopnea may be relieved by sitting upright at the side of the bed with legs dangling, in those with PND, coughing and wheezing often persist in this position.