Does the frontal airbag avoid thoracic injury

Arch Orthop Trauma Surg (2006) 126:541–544 DOI 10.1007/s00402-006-0181-y123TRAUMA SURGERYDoes the frontal airbag avoid thoracic injury?G. Matthes · U. Schmucker · E. Lignitz · M. Huth · A. Ekkernkamp · J. SeifertReceived: 7 October 2005 / Published online: 19 July 2006© Springer-Verlag 2006AbstractIntroduction The airbag is an established car safety device. However, recent studies pointed out that even the airbag might cause injuries. Nevertheless, most physicians do consider a lower risk in accident victims sustaining severe injury of the chest, when a deployed frontal airbag has been reported. We set out to verify the frequency and pattern of thoracic injury in car drivers protected by a frontal airbag during tra Y c accidents.Methods This investigation was conducted as part of a prospective surveillance analyzing tra Y c accidents.Enrolled were car drivers included in a databank between January 2001 and December 2004 consecu-tively. The chance for sustaining chest injury with or without a frontal airbag was described using the rela-tive risk.Results A total of 188 car drivers were included in the analysis. In 54 (28.7%) cases a deployed airbag and in 134 (71.3%) the absence of an airbag has beendocumented. Out of those cases 16 (29.6%) drivers with airbag and 30 (22.4%) without airbag sustained a chest injury. The mean abbreviated injury scale (AIS)of chest injuries in drivers with deployed airbag was 2.3(1–5; SD §1.45; mean injury severity scale [ISS] 21.1[SD §17.18]), in drivers without airbag 1.6 (1–4;SD §1.12; mean ISS 15.8 [SD §20.6]). For belted drivers with an airbag the relative risk to sustain chest injury was 1.96 compared to those without an airbag.Conclusions The airbag does not avoid chest injury de W nitively. Much more, it has been demonstrated that the relative risk to sustain relevant thoracic injury seems to be almost higher in restrained drivers with a frontal airbag.Keywords Vehicle accidents · Frontal airbag · Chest injury · Relative riskIntroductionTrauma is the most frequent cause of death in young individuals [1].Fortunately, due to considerable improvements in preclinical as well as clinical health care the rate of fatally injured accident victims in Germany has been reduced by roughly 20% within the last 30years [2].However, besides those e V orts to improve medical care it is of major importance to focus on prevention.For this reason technical car safety research plays a crucial role.The airbag is supposed to be a milestone in the development of car safety devices. Although Hetrick and Lindner announced the actual patent in the 1950s it took another 30years to reach production stage. InG. Matthes (&) · U. Schmucker · M. Huth · A. Ekkernkamp · J. SeifertDepartment of Orthopedic and Trauma Surgery, Ernst-Moritz-Arndt-University Greifswald, Sauerbruchstr., 17 487 Greifswald, Germany e-mail: gerrit.matthes@uni-greifswald.de G. Matthes · A. Ekkernkamp · J. SeifertDepartment of Orthopedic and Trauma Surgery, Unfallkrankenhaus Berlin, Berlin, Germany E. LignitzDepartment of Forensic Medicine,Ernst-Moritz-Arndt-University Greifswald, Greifswald, Germanythe following years several improvements in the airbag have been achieved. Today, besides the conventional full size frontal airbag several other airbag systems like front seat passenger-, side- or head airbags are part of the safety package of almost every modern vehicle.Despite the incomparable triumph of that safety device, recent studies pointed out that the airbag itself might cause injuries, especially of the eye and ear. Nev-ertheless, out of their own experience, most physicians do consider a lower risk in accident victims sustaining severe injury, especially of the chest, when a deployed frontal airbag in the vehicle has been reported.We set out to verify the frequency and pattern of thoracic injury in car drivers protected by a frontal air-bag during tra Y c accidents.MethodsGeneralThis investigation was conducted as part of an ongoing prospective, non-interventional surveillance analyzing road tra Y c accidents in north-eastern Germany where an area of 2,090km2 within the County of Mecklen-burg-Vorpommern was selected.The general data include, besides environmental con-ditions, speci W cs regarding the mechanism of accident, car safety devices and, of course, the pattern and sever-ity of injuries according to the injury severity scale (ISS).With that, approximately 500–3,000 items per acci-dent are collected and entered into a designated data-base.ObjectiveThe database of our accident research project was searched retrospectively for data pertaining to car driv-ers. Speci W c search criteria were: documented presence or absence of a frontal airbag and clearly described pattern of thoracic injury.The following hypothesis was postulated:The presence of a frontal airbag does not prevent tho-racic injury in vehicle drivers de W nitively.IndividualsEnrolled in the analysis were all car drivers included in the databank consecutively between January 2001 and December 2004 who ful W lled the criteria of a vehicle driver entangled in an accident with a complete docu-mentation concerning the presence or absence of a frontal airbag and the pattern of thoracic injury.Injuries were veri W ed either by clinical diagnostics or in deceased patients by forensic autopsy. Individuals with incomplete documentation or missing data were not included.StatisticsAll data were collected using an Excel-Worksheet (Microsoft, Vermont).Enrolled individuals were divided into a group of drivers with airbag and a group without airbag.The severity of thoracic injuries was weighted using the abbreviated injury scale (AIS); the general injury severity was scored using the ISS. The pattern of tho-racic injury was addressed descriptively.The chance for sustaining chest injury with or with-out a frontal airbag was described using the relative risk whereby chest contusions were not included pre-supposing minor therapeutical relevance. Also individ-123uals who did not use the seat belt were not included in the W nal risk analysis.ResultsBetween January 2001 and December 2003, 277 acci-dents with 336 car drivers were included in the data-base. A total of 188 individuals revealed clear information concerning the presence or absence of an airbag. In 54 (28.7%) cases a deployed airbag and in 134 (71.3%) the absence of an airbag has been docu-mented (Fig.1). Out of those cases 16 (29.6%) drivers with airbag and 30 (22.4%) without airbag sustained a chest injury; 35 (76.1%) of the chest-injured patients were male, 11(23.9%) were female. The mean age was 37.7 (18–73; SD §15.9) years. The mean AIS of the chest injuries in drivers with deployed airbag was 2.3(1–5; SD§1.45; mean ISS 21.1 [SD§17.18]), in driv-ers without airbag 1.6 (1–4; SD§1.12; mean ISS 15.8 [SD§20.6]). However, 7 out of those 46 individuals died (15.2%) due to their pattern of injury.The majority of accidents were classi W ed as head-on collision (Fig.2).There was a clear correlation between the severity of the chest injury and the overall injury severity (Spearman’s rho: P=0.696; Fig.3).Regarding the type of thoracic injury, in both groups the chest contusion was most frequent (airbag: 7 [43.8%]; no airbag: 20 [66.7%]).Interestingly, only one individual of the group of drivers with deployed airbag sustained a rupture of the thoracic aorta. However, according to the documenta-tion, this patient was not restrained.The complete listing of all chest injuries in both groups is described in Fig.4.In the next step individuals with chest contusion as a minor injury without substantial therapeutical conse-quence were dropped from the analysis. Furthermore, only drivers with documented use of seat belt were included (Fig.5). With that 146 drivers were enrolled (45 [30.8%] with airbag; 101 [69.2%] without airbag); 7 (15.5%) drivers with a deployed frontal airbag and 8 (7.92%) drivers without an airbag sustained thoracic injury. The mean AIS of the chest injuries in restrained drivers with deployed airbag was 3.14 (SD§1.03), in restrained drivers without airbag 2.75 (SD§0.85). Thus, for belted drivers with an airbag the relative risk123to sustain chest injury was 1.96 compared to those without an airbag.DiscussionThere is still a high frequency of individuals sustaining severe or even fatal injuries in tra Y c accidents world-wide. Following the data of the World Health Organi-zation (WHO), within next years increasing numbers of trauma victims are to be expected [3].For that, improvements in health care as well as the development of better vehicle safety devices are of major importance.Besides the seat belt the airbag is considered as the most important invention regarding car safety.During the long evolution of that safety device mostly technical experiments were conducted to verify the airbag’s e Y ciency. Only in the last years the W rst studies dealing with real accidents were published, ver-ifying the ability of the airbag to reduce injury severity [4–8]. Interestingly, the results of those studies are not uniform. While several studies demonstrated a reduced overall mortality after tra Y c accidents with cars having a frontal airbag, McGwin et al., for example, did not W nd a signi W cant reduction in injury severity using an airbag device. Moreover, they demonstrated that unre-strained passengers protected by an airbag sustained more severe injuries of the lower extremities [9]. On the other hand, a Canadian study showed that in spite of the fact that the total frequency of head injury was not reduced by airbags, the severity of head injuries was lowered signi W cantly [8]. Younger publications revealed a higher incidence of eye injuries and tempo-rary hearing loss caused by airbags [10–12].In general, it is critical to transfer results of Anglo-American investigations to European conditions, as there are major di V erences concerning vehicle types and tra Y c environment. Due to that we set on an investigation using our database, whereby we focused on thoracic injury.After vehicle accidents—out of our experience—most physicians intend to underestimate the chance of an underlying chest injury, in case of a deployed airbag. This might be caused by the idea that chest traumata by the steering wheel would be avoided by an airbag.Regarding our results, it has been demonstrated that the relative risk to sustain relevant thoracic injury seems to be almost higher in restrained drivers with a frontal airbag (RR 1.96).Surely, due to the relatively small number of individ-uals included in this study, further investigations with much larger numbers of cases are recommended.Hence, it has been demonstrated that the physician needs to be aware of chest trauma in vehicle drivers, even if a deployed airbag has been reported. References1.Peden M, Scur W eld R, Sleet D, Mohan D, Hyder AA, Jara-wan E, Mathers C (2004) World report on road tra Y c injury prevention. World Health Organisation2.Regel G, Lobenho V er P, Lehmann U, Pape HC, PohlemannT, Tscherne H (1993) [Results of treatment of polytrauma-tized patients. A comparative analysis of 3,406 cases between 1972 and 1991]. 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