NEW YORK, Aug 20 (Reuters) -- Air bags can help save lives, but it's becoming more and more clear that they can also cause death and injury.
Letters in this week's issue of The New England Journal of Medicine report different types of injuries in drivers following air-bag deployment in low-speed accidents. The injuries include short-term hearing loss, long-term nerve injury to a hand, and severe damage to the aorta -- the main artery carrying blood from the heart. In the latter case, the injury led to the death of an elderly man more than two months after a minor, low-speed accident triggered the release of the air bag in his car.
"An 84-year-old man who was not wearing a seat belt meant to back his car out of the garage, but mistakenly went forward striking the garage wall head on at less than 16 kilometers per hour (10 miles per hour)," wrote Dr. Brian deGuzman and colleagues at Saint Francis Hospital and Medical Center in Hartford, Connecticut. The man had an injured face and severe bruising and tenderness of the chest after being hit by the air bag, although he was awake and alert. Computed tomography (CT) scans indicated he had a serious injury to the aorta -- the major artery that carries blood away from the heart. After surgery to repair the torn vessel, the man developed kidney and lung failure, and died of complications 10 weeks after the accident.
"Physicians must maintain a high index of suspicion for injury when evaluating drivers who were not wearing seat belts when air bags deployed, regardless of the speed of collision," deGuzman wrote.
In another letter, Vermont physicians report the case of a 30-year-old man who was hit in the side of the head by an air bag, which was triggered as his car slid off of a snowy road at about 25 miles per hour. Shortly afterward, he noticed a loss of hearing and ringing in his ear, according to Dr. Mitchell Kramer and colleagues at Mid-Vermont Ear, Nose and Throat in Rutland, Vermont.
Tests showed that hearing loss in his left ear ranged from mild at low frequencies to profound at high frequencies. His hearing improved somewhat with treatment, but hearing loss at high frequencies persisted for at least two months.
And in a third case, a 44-year-old woman dislocated both wrists as they were pushed away from the steering wheel by an inflating air bag. After four weeks in casts, the right hand returned to normal, but she continued to have pain, swelling, and stiffness in the left hand for three months. The woman was diagnosed with reflex sympathetic dystrophy syndrome, a condition requiring steroid treatment and intensive physical therapy.
About 5% of patients with trauma develop the syndrome, in which nerves become hyperexcitable or sensitized, resulting in continuous pain, noted Dr. Nimisha Shah and Dr. Arthur Weinstein, of Westchester County Medical Center in Valhalla, New York.
In July, the Harvard Center for Risk Analysis reported that "the risk of moderate to serious head injury appears to be reduced significantly by the presence of an air bag on the driver's side." However, the Center also found reports of injuries to the chest, eyes, face, hands, wrists, and arms due to air bags.
"Overall, it appears that about 40% of air-bag deployments result in at least one occupant injury (although most of these injuries are minor). Some of these injuries are occurring in low-speed crashes where the air bag protection was probably not necessary," write the Harvard authors in Risk in Perspective. "More study is needed to determine the overall impact of air bags on the frequency and severity of injuries to drivers and passengers."
An air bag inflates at a speed between 98 to 211 miles per hour in roughly a tenth of a second.
SOURCE: The New England Journal of Medicine (1997;337:573-575); Risk in Perspective (July 1997;7)
