Correlation of occupant injuries in traffic accidents and dummy responses in mathematical simulations

An enhanced method for evaluating the effectiveness of protective devices for road safety application

This paper presents an enhanced probabilistic approach to estimate the real-world safety performance of new device concepts for road safety applications from the perspective of Powered Two-Wheeler (PTW) riders who suffer multiple injuries in different body regions. The proposed method estimates the overall effectiveness of safety devices for PTW riders by correlating computer simulations with various levels of actual injuries collected worldwide from accident databases. The study further develops the methodology initially presented by Johnny Korner in 1989 by introducing a new indicator, Global Potential Damage (GPD), that overcomes the limitations of the original method, encompassing six biomechanical injury indices estimated in five body regions. A Weibull regression model was fit to the field data using the Maximum Likelihood Method with boundaries at the 90% confidence level for the construction of novel injury risk curves for PTW riders. The modified methodology was applied for the holistic evaluation of the effectiveness of a new safety system, the Belted Safety Jacket (BSJ), in head-on collisions across multiple injury indices, body regions, vehicle types, and speed pairs without sub-optimizing it at specific crash severities. A virtual multi-body environment was employed to reproduce a selected set of crashes. The BSJ is a device concept comprising a vest with safety belts to restrict the rider's movements relative to the PTW during crashes. The BSJ exhibited 59% effectiveness, with an undoubted benefit to the head, neck, chest, and lower extremities. The results show that the proposed methodology enables an overall assessment of the injuries, thus improving the protection of PTW users. The novel indicator supports a robust evaluation of safety systems, specifically relevant in the context of PTW accidents.

Electron paramagnetic resonance analysis of transferrin-bound iron in animal models of blunt trauma

BACKGROUND

Blood iron sequestration is known to be implicated in the systemic acute-phase response to trauma injury. The objective of the present research was to assess the effect of iron sequestration in animal models of blunt trauma by means of electron paramagnetic resonance spectroscopy of iron in complex with transferrin, a main iron-transporting protein in blood, and to correlate this effect with the extent of induced injury.

METHODS

Two animal models of blunt trauma were explored in the present study. Blunt trauma in the rat model was produced by exposure of 14 animals to blast overpressure (BOP) (at peak BOP of either 86 +/- 5 kPa or 112 +/- 2 kPa) generated in a shock tube. Blunt trauma in the porcine model was produced by impact of high-speed projectiles made from a rubber-tipped, plastic composite weighing 28.64 +/- 0.12 g (mean +/- SEM, n = 8) with a length of approximately 6 cm and a diameter of approximately 4 cm. The projectiles were propelled by compressed helium onto eight animals at a velocity of 101.8 +/- 3.8 m/s (mean +/- SEM, n = 8) at the point of impact. Each experiment was accompanied by a pathology assessment using an injury scoring system developed for blunt trauma injuries to derive a severity score for whole-body involvement. Amounts of transferrin-bound iron (TRF-[Fe3+]) in whole blood and blood plasma samples were measured using quantitative electron paramagnetic resonance spectroscopy. The observed alterations in the amounts of blood TRF-[Fe3+] were correlated with estimated injury score ratios in each animal.

RESULTS

Blunt trauma produced by either BOP exposure of rats or projectile impacts in pigs was accompanied by TRF-[Fe3+] sequestration observed in both blood and blood plasma. The amount of TRF-[Fe3+] in blood was shown to have inverse correlation with the extent of injury (Pearson r = -0.90 in the rat model and r = -0.93 in the porcine model) estimated by injury score ratios and was not dependent on location of the injury (lung, liver, spleen, or jejunum).

CONCLUSION

The presented data suggest that assessment of TRF-[Fe3+] in blunt trauma can provide a good deal of information on severity of injury. The response of TRF-[Fe3+] can be considered as a potential surrogate marker of the systemic alterations in blunt trauma and, therefore, warrants further investigation in a human pilot study.