Clinical features of pulmonary embolism. Doubts and certainties

The diagnosis of pulmonary embolism (PE) can be accurately made by perfusion lung scan and pulmonary angiography; however, when these diagnostic techniques are not promptly available, simple clinical procedures may be useful to identify patients with high probability PE. To this end, collection of clinical data through a standardized questionnaire and the use of findings from chest radiograph, ECG, and blood gas analysis may raise clinical suspicion and decide on therapeutic management. By reviewing published literature and our own experience, we found that unexplained dyspnea and chest pain are the most frequent symptoms, and sudden onset dyspnea and pleuritic chest pain are the most typical. Chest radiograph is abnormal in more than 80% of patients with PE, showing typical signs such as "sausage-like" descending pulmonary artery, Westermark sign, etc. The ECG may show findings characteristic of PE, such as tachycardia, T wave inversion in V1-V2, and PR displacement. Arterial blood gas data frequently demonstrate hypoxia and hypocapnia, being helpful in suspecting or excluding PE. Recent statistical techniques, such as discriminant or logistic analysis, may be applied to the above clinical assessment to refine and improve the noninvasive diagnosis of PE.