Vehicle-related injuries : with emphasis on fatality prevention

Sammanfattning: According to WHO, Sweden should aim to reduce unintentional fatalities, particularly vehicle-related injuries, by 25% by the year 2000. The aim of this thesis was to analyze vehicle-related injuries and injury events, especially the contributory effects of alcohol and disease and the injury reducing capacity of helmets and airbags in order to point out some preventive measures.Alcohol: Alcohol is the main contributing factor in fatal traffic crashes. In a study on 121 traffic fatalities in Washtenaw County, Michigan, USA, different sources of data for alcohol involvement were compared. In police reports alcohol involvement was found in 51% of the fatalities, in autopsy reports in 63%, and in hospital emergency records in 91%. To avoid bias in the estimation of the fraction of alcohol-related fatalities, it is important to routinely investigate all severe and fatally injured cases in traffic crashes, ideally as soon as possible after the crash.In a study on traumatic car fatalities (n=597) in northern Sweden, 58% of the single vehicle (SV) drivers were inebriated (multi-vehicle, MV 10%), the mean blood alcohol concentration (BAC) was 1.9 g /l (MV 1.6 g/1), and liver steatosis was found in 37% of the cases (MV 2%). Increased BAC was associated with fatty liver, indicating chronic alcohol abuse. To reduce injuries among these types of victims, passive protection is of great importance.Disease: Autopsied drivers (n=126) in northern Sweden who had died from natural causes in traffic were studied. This fraction was 25% of all driver fatalities. Cardiovascular causes of death were found in 96% of the deceased. Neither the victims nor other occupants suffered severe traumatic injuries. A minority of the victims had experienced previous symtoms of disease. Further restriction of individuals with, for example, cardiovascular diseases would probably have no significant impact on traffic safety since at present the identification of high-risk individuals is difficult.Helmets: Head injuries in 948 injured bicyclists, including 105 fatalities, were analysed. Head/face injuries were found in 64% of the fatal and 38% of the nonfatal cases with a median age of 55 years and 18 years, respectively. Head trauma was mostly blunt with only a few severe face injuries. Of the nonfatal cases with head injuries, 48% might have had an injury reduction effect if a bicycle helmet had been used, compared with 67% of the fatalities with head injuries.A helmet with a hard shell, chin cover, accurate retention system, that reduces rotation and translation impact is recommended. To increase helmet use among bicyclists, a law is probably the most effective measure as has been shown for motorcyclists. However, head injuries were less frequent among snowmobile riders than among bicyclist and motorcyclist riders, and in most cases the snowmobile riders with head injuries but without helmet had broken other traffic laws, indicating that in this crash category there was a low compliance to compulsary laws.Airbags: In a field study of car crashes where an airbag deployed, the effectiveness of the bag, as well as injuries to the skin and eye from the deployment of the bag, is reported. In laboratory tests with airbag deployment on human volunteers, tethering was found to eliminate skin abrasion within a distance of 250-300 mm. At a distance of 225 mm, the folding technique had the optimal influence on abrasions followed by a marginal effect of tethering. However, injuries due to airbag deployment must be considered as negligible compared with the airbag's role in reduction of severe and fatal injuries.