Analysis of pulmonary fat embolism in blunt force fatalities

Objective: To investigate the incidence, severity, and origin of pulmonary fat embolism (PFE) in persons dying from blunt force trauma within 24 hours of injury. Methods: The study population consisted of blunt force fatalities. Controls were subjects dying from natural causes or nonblunt force injury. Tissue w as removed from lung lobes and prepared for histologic examination using os mium tetroxide to stain for fat, Lung sections were graded for PFE on a sca le of 0 (no emboli) to 4 (five or more emboli in a majority of fields). Results: The blunt force group consisted of 56 decedents. Mortality was 93% within 4 hours. Fractures were present in 54 (96%) of decedents, and soft tissue injury was universal. Thirty eight (68%) of decedents were positive for PFE vs, 3 of 20 (15%) in controls. Mean score for PFE was 2.94 +/- 1.15 and 1.01 +/- 0.94, respectively (p < 0.005). Bone marrow emboli were not o bserved in any of the sections, Severity of PFE was positively associated w ith survival time. Analysis of PFE against sex, age, height, weight, number of injuries, and number of fractures showed no significant correlations. Conclusions: A significant degree of PFE develops rapidly in a majority of persons dying of blunt force trauma, Although the source of fat for emboliz ation has been suggested to be bone marrow, no evidence of myeloid tissue w as found in any of the lung sections, Nor was there a correlation of PFE an d number of fractures. Soft tissue injury is considered the primary cause o f PFE.