Are fractures of the base of the skull influenced by the mass of the protective helmet? A retrospective study in fatally injured motorcyclists.

STUDY HYPOTHESIS: Information on the influence of the mass of the helmet on the pattern of head injuries suffered by motorcyclists involved in collisions is scarce. This study was undertaken to verify a possible connection between the weight of the helmet worn and the occurrence of a ring fracture of the base of the skull surrounding the foramen magnum. DESIGN: One hundred twenty-two fatally injured motorcyclists were studied retrospectively. In all cases, an autopsy had been performed. Data, including the autopsy report, were obtained from official police files. All helmets were studied in a technical laboratory. Statistical tests were performed using ANOVA, Fisher's exact test, Student's t test, and the chi 2 test. A p < 0.05 was considered significant. RESULTS: The overall incidence of this type of injury was 9.2%. There was a positive correlation between the incidence of complete or partial circular fractures of the base of the skull and the weight of the involved helmet. There was a significant increase (p = 0.012) in the incidence of this type of fracture when the helmet weighed more than 1,500 grams. An increase in the dynamic active mass caused by the combination of head and helmet leads to a supramaximal stress load during a collision, resulting in such injuries. CONCLUSIONS: In accidents with axial load shift, helmets weighing more than 1,500 grams increase the risk of a basal skull fracture. Therefore high-weight helmets should be avoided.

In vitro effects of different medium molecular hydroxyethyl starch solutions and lactated Ringer's solution on coagulation using SONOCLOT.

UNLABELLED: Hydroxyethyl starch (HES) solutions are widely used to replace intravascular volume. HES solutions differ from each other with regard to molecular weight and mode of hydroxyl substitution (degree of hydroxylation, C2:C6 hydroxyethyl ratio, concentration), factors which may have varying effects on coagulation. We studied, in vitro, three different HES preparations (molecular weight/degree of hydroxylation/concentration/C2:C6 ratio of substitution 70.000/0. 5/6%/3.2; Pharmacia & Upjohn Co., Erlangen, Germany; 130.000/0. 4/6%/11.2 and 200.000/0.5/6%/4.6; Fresenius Co., Bad Homburg, Germany) and, for comparison, lactated Ringer's solution (RL) at 33% and 66% dilution with whole blood. The influence of hemodilution was measured by using routine laboratory variables and SONOCLOT (Sonoclot II Coagulation and Platelet Function Analyzer, Sienco Co.) analysis, using a viscoelastic test, on the cellular as well as on the plasmatic hemostatic system. For statistical analysis of quantitative data, we used nonparametric analysis of variance and adequate post hoc tests. Qualitative data were analyzed by using the nonparametric Kruskal-Wallis test. A P value below 0.05 was considered significant. In contrast to the control group with RL, the liquid phase of coagulation (activated clotting time) was slightly affected by the 33% diluted HES solutions. HES 70.000, 130. 000, and 200.000 interfered significantly with the early stage of coagulation as expressed by the clot rate (gel/fibrin formation). Clot maturation and speed of maturation (time to peak) were strongly affected by HES 70.000 at all grades of dilution. HES 130.000 showed a faster clot formation process compared with the other HES solutions. HES 130.000 diluted 33% showed a better clot retraction as compared with the other HES solutions. In conclusion, in vitro hemodilution comparing different medium molecular weight HES solutions reveals that HES 130.000 seems preferable regarding some aspects of clot formation and retraction. RL affected clot formation only minimally, except for the early activation of clotting, which was measured by a shortened activated clotting time. IMPLICATIONS: We investigated the effect of different hydroxyethyl starch (HES) solutions (70.000, 130.000, 200.000) on coagulation. Regarding clot formation and retraction, HES 130.000 had some advantages over the other tested HES solutions. Lactated Ringer's solution affected coagulation only minimally, except for the early stage of clot formation.