Dyspnea(redirected from paroxysmal nocturnal dyspnea)
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disruption of the rate and depth of respiration, accompanied by the sensation of shortness of breath.
Cardiac patients experience dyspnea both while physically exerting themselves and while subsequently resting in the horizontal position. Their condition is complicated by orthopnea, the inability to breathe except in a sitting position. In patients with cardiac diseases, attacks of severe dyspnea, which usually occur at night, are a symptom of cardiac asthma. In such cases, the dyspnea is inspiratory; that is, the patient finds it difficult to inhale. Expiratory dyspnea, difficulty in exhaling, arises when the lumina of the small bronchi and bronchioles are narrowed, as in bronchial asthma. It also arises when the elasticity of the lung tissue is lost, as in chronic emphysema of the lungs. Cerebral dyspnea is a result of direct irritation of the cerebral respiratory center by such abnormalities as tumors and hemorrhages.