Dr Smock's Research Paper
Protecting yourself from Air Bag Injuries
An introduction to the research report by William Smock, MD
Over the last ten years, Dr. William Smock, a specialist in emergency medicine at the Department of Emergency Medicine at the University of Louisville, has been studying the effects of airbag injuries. Dr. Smock's research, which has been funded by a grant from the University, shows that there is significant danger of injury to the arms, hands and upper body from airbag module covers. In many cases, severe injuries could be prevented if only the drivers understood the danger and how to deal with it.
Most research conducted by the government and car manufacturers has been about airbag fatality cases, rather than these severe injuries, which are far more prevalent.
Data published by NHTSA (the National Highway Traffic Safety Administration) only covers those fatalities investigated by NHTSA, yet emergency room physicians across the country have considerable experience with airbag injuries. Drivers and passengers in the risk groups identified by NHTSA are not the only ones in danger. Dr. Smock's research points out that Air Bag covers are causing severe multiple fractures, amputations of hands fingers and arms, and disabling injuries to all people - both drivers and passengers.
Dr Smock's recommendations include not using the horn just before an accident since your hand will be in front of the detonating bag. This is true also for passengers - don't reach out for the dashboard in an accident. The force of an airbag (they detonate with about 1200 lbs of force at speeds up to 210 mph) can break or amputate your arms and hands. These forces, which Dr. Smock indicates can reach more than six times the established human tolerance level, can permanently disable or kill even people Unfortunately, although these recommendations will help, they do not solve the problem for those in the high risk groups, such as shorter drivers, child passengers or the elderly. For them, an airbag on/off switch which makes it possible to sometimes turn off the airbag, may be the only solution. Until the new, safe airbags which NHTSA is mandating are developed and installed in all cars, you need to keep informed and look out for your own safety. Dr. Smock has designed stickers to place on the steering wheel cover and over the passenger's airbag on the dash that warn about the danger of Air Bag injuries.
The following summary of Dr. Smock's research report, presents the results of his work investigating these severe and disabling injuries from airbag module covers. The original article was published in the Journal of Trauma, Injury, Infection and Critical Care, Vol.38, No. 4
Note: you can click on any photo or drawing in the following report to see the full picture
The Journal of Trauma: Injury, Infection, and Critical Care Vol. 38, No. 4
Copyright © 1995 by Williams & Wilkins Printed in the U.S.A.
Airbag Module Cover Injuries
William Spafford Smock, MD, MS,
and George R. Nichols, II, MD
Serious and fatal injuries can be sustained when anatomic structures are in close proximity to an airbag module cover at the moment of airbag deployment Three cases of injuries in vehicle operators associated with airbag module covers are reviewed and discussed. Injuries ranged from the traumatic avulsion of a thumb to the development of a subdural hematoma with associated cerebral edema and respiratory arrest. Motor vehicle operators should be aware that although airbags can significantly reduce the severity of injuries sustained in frontal collisions the module cover has the potential to inflict serious, even fatal injuries.
(From the Department of Emergency Medicine, University of Louisville School of Medicine, and the Office of the Chief Medical Examiner, Kentucky Medical Examiner's Office, Louisville, Kentucky.
Address for reprints: William S. Smock, MD, Department of Emergency Medicine, University of Louisville School of Medicine, Louisville, KY 40292)
Key Words: Airbag module, Airbag-associated injuries, Automotive safety.
The airbag-induced injury, once thought to be rare, is now being reported in increasing numbers.1-12 The automotive and insurance industries have promoted airbags as life-saving and injury-reducing devices. Automotive industry research data and the current literature support the premise that, given similar collision configurations, individuals in vehicles equipped with airbags sustain fewer and less serious injuries than individuals in vehicles without them.3,5 However, there are hazards and risks associated with airbag development.1-18 When airbags for passenger vehicles were still in the research and development phase, the automotive industry conducted tests that clearly demonstrated the potential for fatal injuries associated with airbag deployment.13-17 The industry itself came to the conclusion that the life-saving airbag could also be life-threatening.
The driver's-side airbag module is located within the center of the vehicle's steering wheel and may be covered by a variety of materials. These materials include thermoplastic, rigid urethane foam covered with polyvinyl or rigid metal plates covered with foam and vinyl. At the moment of deployment the cover splits along seams intentionally weakened in manufacture and rapidly opens outward to allow the airbag to inflate. The velocity of deployment has been measured by the National Highway Traffic Safety Administration (NHTSA) and averages 144 mph with maximum velocities of 211 mph reported.18
The three cases presented all involve restrained female operators, none of whose height exceeded 5 feet 3 inches. In each case anatomic structures came into direct contact with the airbag module cover during deployment.
MATERIALS AND METHODS
The Department of Emergency Medicine at the University of Louisville and the Kentucky Medical Examiner's Office are conducting an on-going prospective study to identify and describe injuries and injury patterns associated with airbag deployment. Ten cases of airbag-induced injuries involving ten adult vehicle operators have been included in the study to date. Subjects are enrolled if they arrive at the emergency department of a level-I trauma center with injuries that the attending physician feels may possibly be related to airbag deployment or when a patient is referred to the Kentucky Medical Examiner's Office for a postmortem, a living forensic evaluation, or consultation. Only three of the ten cases involved contact with the airbag module cover. The remainder were non-life-threatening injuries associated with contact with the airbag and the by products of the combustion process.
Case 1. A 25 year-old woman, 5 feet 3 inches and 115 pounds, was the driver of a 1991 Ford Taurus (Fig. 1) when the vehicle left the roadway and traveled down the highway median until it struck the leading edge of a concrete barrier. The vehicle contacted the barrier in a head-on configuration. The woman was wearing the lap-shoulder belt. At the time of impact the airbag deployed as designed. The patient stated she gripped the steering wheel in a bracing maneuver which resulted in the placement of her thumb over the right edge of the airbag module cover (Fig. 2).
The patient sustained a 4 cm, 75% circumferential laceration to the palmar surface with avulsion of the right thumb at the MCP joint as well as superficial abrasions and contusions on the chest and upper extremities. Underlying the avulsion-laceration was severe muscle and neurovascular injury which included lacerations of all thenar musculature except the flexor pollicis longus and an open fracture-dislocation of the first metacarpal. The dorsal aspect of the thumb remained attached by 1.5 cm of intact epithelium.
Examination of the vehicle revealed the presence of blood on the airbag. The vehicle interior was devoid of occupant induced damage (Fig. 3). The exterior sustained moderate front-end damage (Fig. 1).
Case 2. A 52-year-old woman, 5 feet I inch and 125 pounds, was the operator of a 1990 Ford Taurus (Fig. 4) that was attempting to make a left turn when the vehicle's front end was struck by an on-coming vehicle. She was wearing the lap-shoulder belt. The patient stated that her right forearm was across the module cover as she was turning the steering wheel (Fig. 5) when the airbag deployed. The patient's vehicle sustained only minor damage and the 73-year-old operator of the on-coming vehicle, a 1987 Honda Accord, was uninjured.
Fig 4. A 1990 Ford Taurus which was involved in a minor frontal collision. The driver sustained severely comminuted fractures of the elbow and the ulna, a mid shaft humerus fracture, and a radial head dislocation secondary to impact from the airbag module cover.
The patient sustained multiple fractures of the right upper extremity which included a severely comminuted fracture of the ulnar olecranon and ulnar shaft, a radial head dislocation, a comminuted fracture of the medial epicondyle with elbow dislocation and fracture of the humeral shaft (Figs. 6, 7).
Examination of the vehicle's interior failed to reveal any evidence of occupant-induced damage. Exterior damage was limited to minor damage to the front bumper (Fig. 5). The patient reported a speed of less than 5 mph at the time of the collision.
Case 3. A 35-year-old woman, 5 feet 2 inches and 110 pounds, was the driver of a 1991 Ford Taurus (Figs. 8, 9) when the vehicle's front bumper grazed a guard rail for approximately 24 feet. She was wearing the lap-shoulder belt. The incident occurred on a rural interstate highway in the early morning hours. The vehicle was occupied by five other occupants who were asleep at the time of contact with the guard rail. When the vehicle came to rest, the driver's husband, who was restrained in the right rear seat, exited the vehicle and came around to the driver's side. He found his wife unconscious in her lap-shoulder restraint with blood coming from her nose and left ear. The airbag had deployed and was deflated when the patient's husband removed her from the vehicle. The unconscious patient was being transported to a local hospital by a passing motorist when she suffered respiratory arrest. On arrival at the local hospital the patient was noted to have significant mid-face trauma with bilateral epistaxis, corneal abrasions, contusions of the chest and fixed and dilated pupils. The patient was transferred to a regional medical center where a head CT scan revealed the presence of a left-sided subdural hematoma overlying the frontal and parietal regions on the left, subarachnoid hemorrhage, and severe cerebral edema. The patient was pronounced brain dead and subsequently became hypotensive and sustained a cardiac arrest.
FIG 5. An illustration of contact between the driver's forearm and a deploying airbag module cover.
A postmortem examination confirmed the left-sided subdural and subarachnoid hemorrhages as well an extensive area of contusion and abrasion over the left side of the face from the cheek to the left temporal area. Of the five other occupants, 3 sustained no injury and the remaining two: a nose bleed by one and a superficial laceration by the other.
Examination of the vehicle's interior revealed a tear on the left lower portion of the module cover (Fig. 10) from contact with the left side of the victim's face (Fig. 11). The presence of blood on the airbag and the shoulder harness was also noted. The vehicle exterior sustained minimal damage to the front bumper from the sliding contact with the guard rail (Figs. 8, 9).
The induction of benign, serious, and fatal injuries secondary to airbag deployment in the laboratory is well documented in the airbag research and development literature.13-17 More recently the clinical medical literature has documented the presence of these kinds of injuries as a consequence of airbag deployment.1-12
Horsch et al. reported the inducement of massive thoracic and abdominal injuries when 51.0 -- 3.8 kg pigs were placed against a deploying airbag module. Reported injuries included cardiac perforations with pericardial tamponade, multiple rib fractures with flail segments, lacerations of the brachiocephalic artery, spleen, and liver, gall bladder rupture, lacerations of the inferior vena cava, and cardiac contusions. Research from Lau et al. at the General Motors Research Laboratories indicates that an extremely high rate of loading develops when a body region is in direct contact with the airbag module at the moment of deployment. The amount of concentrated force measured at the sternal area of the swine was as high as 20 kN which is more than six times the established human tolerance level of 3.3 kN. 17 Similar testing with the Hybrid III dummy also indicated that the force generated "was above expected human tolerance and was consistent with the level of injury observed in swine".17
The production of serious and fatal injuries in humans in real-world "accident" circumstances secondary to airbag deployment, although relatively small in overall numbers, is increasing. Reported injuries include cardiac rupture, cardiac perforations, traumatic avulsions of digits, subdural hematomas, ocular trauma, and fractures involving the upper extremities.2,6,8-12
FIG 6. A roentgenogram of the driver's elbow which shows comminuted fractures of the ulna and dislocation of the elbow and radial head secondary to contact with the deploying airbag module cover.
The injuries reported in this subset of cases all resulted from contact with or impact from the deploying airbag module cover. All of the subjects were restrained drivers with a height of 5 feet 3 inches or less. Their height necessitated advancing the driver's seat to the full-forward position, placing them at a disadvantage in regard to their proximity to the airbag module. The National Highway Traffic Safety Administration, in September of 1992, acknowledged in its final report on airbag deployment characteristics that "a large portion of the reported injuries are to smaller occupants who tend to be seated closer to the steering wheel than most other occupants."18 It was also determined that the average velocity of airbag deployment in a similar vehicle, a 1991 Ford Tempo, was 167 mph.18
Huelke et al reported nine cases in which upper extremity injuries, including severely comminuted fractures and lacerations, were induced from contact with the deploying module cover. Of note from Huelke's report is the fact that eight of the nine vehicles had a module cover of a similar design to that of the vehicles in the three cases presented. The module cover of the Taurus has a large polyvinyl flap which measures approximately -5 1/4 X 8 1/2 inches and flips outward at greater than 160 mph upon deployment.
FIG 8. A side view of a 1991 Ford Taurus in which the driver sustained fatal head injuries as a result of impact from the deploying airbag module cover.
If injuries associated with the module cover are to be prevented then anatomic structures must not be in proximity to the cover at the time of deployment. This may not always be possible if the driver is sufficiently short to necessitate a full-forward position of the seat, even when they are properly restrained. An operator may find himself or herself "out-of-position" and too close to the module when they fail to properly utilize their safety restraint system. An operator may find his or her hands in close proximity to the cover while performing normal driving functions such as honking the horn or setting the cruise control. Forearms may be in front of the module cover while turning the steering wheel, as was seen in case 2. Injuries may appear unavoidable in light of current designs but might be averted if design changes were implemented and the operator warned of the potential dangers associated with contact with the module cover and airbag deployment.
FIG 9. A frontal view of a 1991 Ford Taurus which depicts the damage to the front bumper from a sliding contact with a guard rail.
The airbag deployment forces that demonstrably caused serious and fatal injuries in the laboratory are now being seen in real-world collisions. The three cases discussed vividly demonstrate that the deploying airbag has the potential to induce serious and fatal injuries if the vehicle occupants are in close proximity to the module cover at the moment of deployment. There also appears to be an increased potential for injuries when occupants of short stature, even when properly re-strained, operate airbag-equipped vehicles.
FIG 10. The airbag module cover. Note the damage to the lower left corner from contact with the driver's face.
FIG 11. An illustration of the airbag module cover impacting a driver's face during deployment
1. Braude LS: Protective eyewear needed with driver's-side air bag? Arch Ophthalmol 110:1201, 1992
2. Huelke DF, Moore JL, Compton TW, et al: Upper extremity injuries related to air bag deployments. SAE Publication No. 940716. Detroit, Society of Automotive Engineers
3. Huelke DF, Moore JL, Ostrom M: Air bag injuries and occupant protection. J Trauma 33:894, 1992
4. Ingraham HJ, Perry HO, Donnefeld ED: Air-bag keratitis. N Engl J Med 324:1599, 1991
5. Insurance Institute for Highway Safety: Close study of injuries yields concern, not alarm. Status Report 28(11):1, 1993
6. Lancaster GI, DeFrance JH, Borruso JJ: Air-bag-associated rupture of the right atrium. N Engl J Med 328:358, 1993
7. Larkin GL: Airbag-mediated corneal injury. Am J Emerg Med 9:444, 1991
8. Mishier KE: Hyphema caused by air bag. Arch Ophthalmol 109:1635, 1991
9. Rimmer S, Schuler JD: Severe ocular trauma from driver's side air bag. Arch Ophthalmol 109:774, 1991
10. Rosenblatt M, Freilich B, Kirsch D: Air bags: Trade offs. N Engl J Med 325:1518, 1991
11. Smock WS: Traumatic avulsion of the first digit secondary to air bag deployment. Scientific Poster. In Proceedings of the 36th Association for the Advancement of Automotive Medicine. Des Plaines, 111, AAAM, 1992, p 444
12. Smock WS, Nichols GR, Fuller PM: Air bag induced fatal injuries: A case report. Presented at the American Academy of Forensic Sciences, Boston, February, 1993
13.Campbell D: Air cushion restraint systems development and vehicle application. In The 2nd International Conference on Passive Restraints. SAE Paper No. 720407. Detroit, Society of Automotive Engineers, 1972
14. Prasad P, Daniel RP: A biomechanical analysis of head, neck and torso injuries to child surrogates due to sudden torso acceleration. SAE Paper No. 841656. Detroit, Society of Automotive Engineers, 1984
15. Mertz HJ, Marquart JF: Small car air cushion performance serious and fatal injuries if the vehicle occupants are in close considerations. SAE Paper No. 851199. Detroit, Society of Automotive Engineers, 1985
16. Horsch J, Lau 1, Andrzejak D, et al: Assessment of air bag deployment loads SAE Paper No. 902324. Detroit, Society of Automotive Engineers, 1990
17. Lau IV, Horsch JD, Viano DC, et al: Mechanism of injury from air bag deployment loads. Accid Anal Prevent 25:29, 1993
18. National Highway Traffic Safety Administration: Air bag deployment characteristics. Springfield, Va, National Technical Information Service, September 1992
Acknowledgments: We thank Mr. George Batik for his assistance with the illustrations and Mr. Keith Klippstein of the Lake Oswego Review for his photograph of the vehicle in case 2.