Heart failure or lung disease, worsening dyspnea may be the only symptom suggestive of pulmonary embolism. Chest pain is a common symptom of pulmonary embolism and is usually caused by pleural irritation in the event of a distal embolism causing pulmonary infarction. In massive pulmonary embolism with involvement of large branches of the pulmonary artery, chest pain may be typical of angina pectoris, possibly reflecting pancreatic ischemia, and requires a differential diagnosis with acute coronary syndrome or aortic dissection.
In addition to assessing symptoms to determine the clinical likelihood of venous thromboembolism (VTE), it is important to identify predisposing factors, the presence of which increases the likelihood of the disease. However, in 40% of patients with pulmonary embolism, there are no predisposing factors.
Hypoxemia is common, with <40% of patients having normal arterial oxygen saturation and 20% having an abnormal alveolar-arterial oxygen gradient. Hypocapnia is also often present. Changes frequently identified on chest x-ray are usually nonspecific for pulmonary embolism, but the examination itself may be useful to rule out other causes of dyspnea or chest pain. Electrocardiographic changes such as T-wave inversion in leads U1-U4, pN-pattern in lead U1, 81P3T3-pattern, as well as incomplete or complete blockade of the right branch of the His bundle indicate a load on the right ventricle and are usually found in more severe cases of pulmonary embolism; in milder cases, sinus tachycardia, present in 40% of patients, may be the only abnormality. Finally, atrial arrhythmias, most commonly atrial fibrillation, may be associated with acute pulmonary embolism.
Lasix for hearth
The combined assessment of symptoms, clinical data, and RF of venous thromboembolism makes it possible to classify patients with suspected pulmonary embolism into separate categories of clinical or, so-called pre-test likelihood of pulmonary embolism. Belonging to one group or another corresponds to the actual prevalence of confirmed pulmonary embolism. This preliminary assessment can be done either by clinical assessment or using prognostic scales. The key point of all diagnostic algorithms is that for the final determination of the likelihood of having pulmonary embolism in a patient, the results of imaging methods (post-test assessment) are evaluated in combination with the initial pre-test probability. Since the probability of pulmonary embolism after the test (i.e., after the imaging test) depends not only on the characteristics of the diagnostic test itself, but also on the probability of pulmonary embolism before it is performed, this is a key step in all pulmonary embolism diagnostic algorithms. The value of evaluating clinical data has been confirmed in a number of studies.
The clinical evaluation usually includes routine tests such as a chest x-ray and an electrocardiogram. However, taking into account their low standardization, several clear scales of clinical prediction have been developed. The most commonly used scales are the Revised Geneva Scale and the Wells Scale. In order to increase their use in real clinical practice, both scales were simplified; simplified versions have also been validated. Using a three-level classification, the proportion of patients with confirmed pulmonary embolism can be expected to be ~ 10% in the low probability category, 30% in the medium probability category, and 65% in the high probability category. When a two-tiered approach is used, the proportion of patients with confirmed pulmonary embolism is ~ 12% in the unlikely pulmonary embolism category and 30% in the probable pulmonary embolism category. A prospective direct comparative study of these scales has confirmed their similar diagnostic ability.
Searching for pulmonary embolism in every patient with shortness of breath or chest pain can lead to unreasonably high diagnostic costs and unnecessary complications when performing unnecessary tests. For patients in the emergency department, specific exclusion criteria for pulmonary embolism have been developed to select patients in whom the likelihood of pulmonary embolism is so low that a diagnostic evaluation should not even be initiated. They include eight clinical indicators associated with the absence of pulmonary embolism: age <50 years pulse <100 beats / min > 94% lack of unilateral leg edema; lack of hemoptysis; no recent injury or surgery; no history of VTE and no hormonal therapy. The results of a prospective study to validate these criteria and a randomized clinical trial (RCT) using them demonstrated the possibility of safely excluding pulmonary embolism in the presence of all eight criteria in a patient with a low clinical probability of pulmonary embolism. However, the low overall prevalence of pulmonary embolism in the surveyed groups does not allow generalizing their results.