THE DEMONSTRATED effectiveness of pulmonary embolectomy with the aid of extracorporeal circulation1-4,9,10 increases the need for a diagnostic method of differentiating pulmonary embolism from other causes of shock, particularly acute myocardial infarction. It is suggested that measurement of the pulmonary arterial pressure and left atrial pressure provides such a differentiation. This suggestion has been tested in the experimental laboratory; in addition, the diagnostic value of pressure measurements in the left atrium and pulmonary artery by suprasternal puncture has been shown in a small group of patients suspected of pulmonary embolism.
—In 15 mongrel dogs under light pentobarbital sodium anesthesia, pressures were measured in the aorta, left atrium, and pulmonary artery using a cannulation-strain gauge technique. Pulmonary flow was also measured by a gated sine wave electromagnetic flow meter with a noncannulating, extravascular probe.In five animals, branches of the left anterior descending coronary artery were serially