THE DRAMATIC episode of pulmonary embolism is shocking to the surgeon who suddenly loses his patient in the wake of an apparently uneventful recovery. It is not surprising, therefore, that this tragic event, although of no great frequency, became the topic of numerous investigations dealing with its causes, prevention and treatment.
Three distinct groups of factors can be distinguished in the causation of phlebothrombosis and the resulting embolism: (1) retardation of the venous flow, (2) structural changes in the wall of the affected blood vessels, especially in the endothelium, and (3) changes in the constituents of the blood and chemical changes responsible for coagulation of the blood.
The majority of authors agree that the first-mentioned factor, namely, the retardation of the venous flow, for which lack of muscular contractions is chiefly responsible, is of paramount importance in the genesis of thrombus with resulting embolism. It follows that stimulation of vascular