同济医学院诊断学—呼吸障碍.ppt

Etiology Respiratory dyspnea Caused by abnormal ventilation and gas exchange, reduction in ventilatory capacity, hypercapnia and hypoxemia resulting from respiratory disease. Three clininal types: Inspiratory dyspnea Expiratory dyspnea Mixed dyspnea Inspiratory dyspnea Tends to occur primarily when there is obstruction ( such as inflammation, edema, tumor and foreign body) in larynx, trachea and major bronchi. Characterized by the depression sigh, in which visible indrawing over the sternal notch, the supraclavioular spaces, the intercostal spaces and the epigastrium in the inspiration can be seen. Often accompanied by a coarse, low pitched inspiratory wheezing and dry cough. Expiratory dyspnea Expiratory dyspnea is due to the decrease of lung elasticity and spasm narrowing of the bronchioles and smaller bronchi as in emphysema, bronchial asthma and asthmatic bronchitis. Expiration is prolonged and laboured with wheezing. Mixed dyspnea Occurs with the extensive lung disease, such as severe pneumonia, pulmonary fibrosis, massive atelectasis, pleural effusion and pneumothorax. Results in the decrease of ventilators and gas exchange capacity. Breathing is difficult during both inspiration and expiration. Cardiac dyspnea Cardiac dyspnea is usually attributable to pulmonary vascular congestion resulting from the left and/or right heart failure. Cardiac dyspnea In Left-sided heart failure, compliance is reduced, and therefore, ventilation is decreased to the edematous lung regions and vital capacity reduced. Alveoli are stiff and more work is needed to overcome elastic recoil, the high alveolar pressure will stimulate stretch receptor and initiate the inflation reflex resulting in early turning off of inspiration and an increase in respiratory rate. Cardiac dyspnea The dyspnea caused by right-sided heart failure is less severe than that one caused by left-sided. Mechanism: (1)