Massive pulmonary embolism--medical management.

useful if practicable because this is invariably raised in acute myocardial infarction but is normal in pulmonary embolism. A "paradoxical" arterial pulse, which falls at the onset of inspiration and rises on expiration by more than 15 mm. Hgso that the change is detectable by the finger palpating the femoral pulse-is almost invariably present in acute cardiac tamponade from pericardial effusion. Unfortunately, it is also present sometimes in acute cardiac dilatation from any cause and is not infrequent in acute pulmonary embolism. Electrical alternans on the E.C.G. is a frequent sign of cardiac tamponade and is virtually a diagnostic finding. Sudden internal haemorrhage as from a ruptured ectopic pregnancy may cause collapse with air hunger and restlessness, tachycardia, and gallop rhythm. The arterial blood gases are usually normal but there may be hypocapnia and the site of bleeding usually very rapidly becomes obvious. To sum up, the mainstays of diagnosis of acute pulmonary embolism are alertness to the possibility, the observation of tachypnoea and hyperpnoea in an acutely ill patient, measurement of the arterial blood gases, and pulmonary angiography. The clinical findings, aided only by electrocardiography and chest radiography allow the diagnosis to be made with confidence in most patients, but angiography should still be carried out for confirmation and for establishment of severity.