同济医学院诊断学—呼吸障碍

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.
Etiology
Respiratory diseases Circulatory diseases Poisoning Hematology Neuropsychogenic factors
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.
Dyspnea
Definition:
Dyspnea is defined as an awareness of difficulty in breathing It is therefore a symptom, usually described by the patient as “short of breath,” whether the sensation is due to actual difficulty in breathing or is essentially an awareness of hyperventilation. If the symptom becomes striking, it always companies with dilatation of nares, cyanosis, use of accessory muscles of respiration and abnormalities of respiratory rate, depth or rhythm.
Cardiac dyspnea
The dyspnea caused by right-sided heart failure is less severe than that one caused by left-sided.
Mechanism: (1) The pressure of right atrial and superior vena cava is the natural stimulus of respiratory center. (2) The decrease of oxygen content and the accumulation of the acid metabolites, such as lactic, stimulate respiratory center. (3) The restriction of the respiratory movement caused by enlargement of liver resulting from congestion, ascites and pleural effusion.
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.
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.
Results in the decrease of ventilators and gas exchange capacity.
Breathing is difficult during both inspiration and expiration.
CardiLeabharlann c dyspneaCardiac 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.