The syndrome of fat embolism and its origin

Abstract

The solution of the now century-old riddle of fat embolism has been much delayed by a misunderstanding which is reflected even in terminology. In patients who die shortly after injury microscopic droplets of fat are found obstructing small vessels, particularly in the lungs but also sometimes in other organs. Lung embolism is found in nearly all patients when injury includes a fracture of a long bone. On the other hand, a well defined clinical syndrome is observed only in certain patients with bone fractures. The syndrome is characterized by severe pulmonary, circulatory, and neurological signs and symptoms which lead to death in a high percentage of cases. A distinction must be made between the pathological entity of fat emboli in small vessels of those who die after bone injury and the clinical syndrome. The relationship between the two phenomena is far from clear. As a consequence many surgeons believe that fat embolism is infrequent, whilst most pathologists find necropsy evidence of fat embolism to be very common. This confusion is mirrored in the statistics on fat embolism where, depending on the criteria of diagnosis, its frequency is said to range between 5% and nearly 100% (Evarts, 1965). A study of the incidence and severity of fat embolism at necropsy among injured and uninjured cases was therefore undertaken.