[Correlation between the survival duration and trauma severity in persons who died from posttraumatic fat embolism].

INTRODUCTION: Posttraumatic fat embolism follows the injury. The fat emboli in circulation could cause death in three ways: isolated lung fat embolism, systemic fat embolism and fat embolism syndrome (FES). In forensic pathology, only two trauma scores, based on disintegration of anatomic structures, could be used for objectivization, comparison and establishment of severity of injuries. One of them is Injury Severity Score--ISS, based on Abbreviated Injury Scale--AIS. The second one is Hannover Polytrauma Score--HPTS, based on the total sum of all injuries and age of the injured person.

OBJECTIVE: The objectives of this paper were to establish the correlation between outliving period and trauma severity (based on ISS and HPTS values), in persons died from posttraumatic fat embolism and/or its complications, and to establish which of these score systems could be better for prediction of development of the posttraumatic fat embolism.

METHOD: The retrospective autopsy study was performed and it included the material of the Institute of Forensic Medicine in Belgrade for period 1988-2001. The autopsy reports and clinical medical data were analyzed, for persons died from posttraumatic fat embolism and/or its complications. In all cases, the fat embolism was the single cause of death, verified by autopsy. In each case, ISS and HPTS values were obtained. The sample was statistically prepared (chi2 test, correlation coefficient, regression line).

RESULTS AND DISCUSSION: The sample included 50 persons: 41 males and 9 females. The proportion of men was statistically significant (chi2 = 20.480; p < 0.001). Average age of male was 55.26 years (SD = 21.39) and of female was 55.78 (SD = 17.45). There was no statistically significant disproportion among the age distribution of the sample (chi2 = 6.4; p > 0.05). The outliving period varied from 1-14 days: the average was 5.92 (SD = 3.39; Med. 5.50; Mod. 2). The average value of 1SS was 19 (SD = 7.70; Med. 19; Mod. 14), and for HPTS average value was 28.16 (SD = 12.87; Med. 26.50; Mod. 12). In literature, there have been data about critical ISS value: 12-20. HPTS value of 20 to 35 was lethal in 25%. Each injured of our sample had, at least, one long bone or pelvic fracture. There was negligible negative correlation between outliving period and 1SS and HPTS values in our sample: coefficient of linear correlation r = -0.117, t = 0.83 and r = -0.088, t = 0.59. Our sample was representative (t = 8.37). These data pointed out that the outliving period of the observed patients, died from post-traumatic fat embolism, was not in relation to general severity of injuries but to fat embolism per se and its consequences. There was low positive correlation between ISS and HPTS values: r = 0.296, t = 2.147, coefficient of determination r2 = 0.0876 and linear regression HPTS = 18.7588+0.4948 ISS. These data indicated that direct correlation between scores was only about 9% and the rest of correlation i.e. 91% depended on other factors.

CONCLUSION: There was negative negligible correlation between outliving period and severity of injury based on ISS and HPTS, in patients died from posttraumatic fat embolism. So, these score systems are useless for prediction of duration of the outliving period in the injured died from fat embolism as well as for prediction of posttraumatic fat embolism as cause of death.