呼吸困难的鉴别诊断.doc

Step-by-step diagnostic approach of dyspnea. Clinical history Careful history-taking is the most useful first step in elucidating the aetiology of dyspnoea. Several factors need to be addressed in the clinical history when constructing the initial differential diagnosis. Time course Acute dyspnoea appears suddenly or in a matter of minutes. It typically indicates acute and severe conditions that may be life-threatening. Examples of conditions causing sudden-onset dyspnoea include acute pulmonary embolism, myocardial infarction, acute heart valve insufficiency, pneumothorax, anaphylaxis, foreign body aspiration, pulmonary oedema, or cardiac tamponade. [16] Subacute dyspnoea develops over hours to days. Common causes include acute asthma, exacerbation of COPD, or pulmonary oedema. Less common causes include myocarditis, superior vena cava syndrome, acute eosinophilic pneumonia, or cardiac tamponade. [16] [17] [18] Chronic dyspnoea develops over weeks to months. It is associated with chronic pathology, such as congestive heart failure, COPD, cardiomyopathy, idiopathic pulmonary fibrosis, pulmonary vascular disease, pulmonary hypertension, valvular heart disease, or anaemia. [19] Less common causes include muscular dystrophies, kyphoscoliosis, amyotrophic lateral sclerosis, pulmonary alveolar proteinosis, chronic eosinophilic pneumonia, uraemia, or constrictive pericarditis. [18] [20] [21] [22] [23] Recurrent dyspnoea may indicate paroxysmal tachycardias or intermittent complete heart block. Severity There is no universally agreed measure of dyspnoea; several scales are available in both research and clinical practice. [24] Dyspnoea is highly subjective, and, for a given level of functional impairment, severity varies widely. Severe dyspnoea is typically accompanied by associated symptoms and is more likely to be life-threatening. It may be associated with acute asthma, tension pneumothorax, acute upper airway obstruction, massive pulmonary embolism, or myocardial