Incidence of pulmonary fat embolism at autopsy: An undiagnosed epidemic

Background: To determine the incidence, time course, and severity of pulmonary fat embolism (PFE) and cerebral fat embolism (CFE) in trauma and nontrauma patients at the time of autopsy. Methods: Prospectively, consecutive patients presenting for autopsy were evaluated for evidence pulmonary and brain fat embolism. The lung sections were obtained from the upper and lower lobe of the patients' lungs on the right and left and brain tissue. This tissue was prepared with osmium tetroxide for histologic evaluation. The number of fat droplets per high power field was counted for all sections. The autopsy reports and medical records were used to determine cause of death, time to death, injuries, if cardiopulmonary resuscitation (CPR) was attempted, sex, height, weight, and age. Results: Fifty decedents were evaluated for PFE and CFE. The average age was 45.8 years ± 17.4 years, average body mass index was 30.1 kg/cm ± 7.0 kg/cm, and 68% of the patients were men. The cause of death was determined to be trauma in 68% (34/50) of decedents, with 88% (30/34) blunt and 12% (4/34) penetrating. CPR was performed on 30% (15/50), and PFE was present in 76% (38/50) of all patients. Subjects with PFE had no difference with respect to sex, trauma, mechanism of injury, CPR, external contusions, fractures, head, spine, chest, abdominal, pelvic, and extremity injuries. However, subjects without PFE had significantly increased weight (109 ± 29 kg vs. 86 ± 18 kg; p = 0.023) but no difference in height or body mass index. PFE was present in 82% (28/34) of trauma patents and 63% (10/16) nontrauma patients. Eighty-eight percent of nontrauma patients and 86% of trauma patients who received CPR had PFE. Trauma patients with PFE showed no significant difference in any group. Eighty-eight percent of trauma patients died within 1 hour of injury, and 80% (24/30) of them had PFE at the time of autopsy. CFE was present only in one patient with a severe head and cervical spine injury. Conclusion: PFE is common in trauma patients. CPR is associated with a high incidence of PFE regardless of cause of death. PFE occurs acutely within the "golden hour" and should be considered in traumatically injured patients. Further studies are needed to evaluate the pathogenesis of PFE.