Treating car crash injuries an evolving science

Paramedics usually arrive on an accident scene first and are trained to work quickly to stabilize an injured motorist

(CNN) -- Someone is hurt in a motor vehicle accident in the United States every six seconds, according to federal safety officials. Crashes kill at least 40,000 people each year and leave more than 5 million others injured.

For many, symptoms of accident injuries might not show up for hours or even days after the mishap.

During a vehicle accident, "the head suddenly stops, but inside the skull the brain for a split second can keep moving. It shifts inside the skull," said Dr. David Thurman at the Centers for Disease Control and Prevention in Atlanta.

According to Thurman, tissue can be bruised and blood vessels in the brain can tear, even if the crash occurred at only 20 or 30 miles an hour.

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"When those veins tear, this can result in slow bleeding and that in turn can put pressure on the brain. It can start to squeeze the brain and this can be very serious. If it's not treated, it can be fatal," explained Thurman.

The resulting injury, called a subdural hematoma, occasionally occurs after the patient has been checked out at a hospital and found to be OK. For that reason, paramedics are trained with a checklist of trauma warning signs, including increased headaches, confusion and difficulty awakening from sleep.

One of the most common injuries resulting from a vehicle accident is whiplash. Dr. Barry Myers of Duke University says it's difficult to understand exactly what causes the condition because so many parts of the body are involved, including the head, neck, chest and spine.

"The chest comes up, then the neck squishes a little bit and then it goes back. Which one's causing the injury? We have to know that if we're going to make better cars," said Myers.

Auto accidents also may leave hidden injuries.

"Trauma that doesn't necessarily incapacitate you at the time may have long-term effects that you don't see for 10 or 20 or 30 years," explained Myers.

Nine trauma centers nationwide have begun to share the data gleaned from thousands of injury accidents. As part of the Crash Injury Research and Engineering Network (CIREN), details of the accident are first entered into a computer database that all of the centers may share.

"(If) another CIREN center gets the same type of crash, as the patient's being transported to the hospital, the medical personnel can review the case and know what's wrong with him before he arrives," explained Detective James Bean, with the Fairfax County Police Department in Virginia.

The information can be very helpful in cases where accident victims walk away with undetected internal injuries. Dr. Samir Kakhry, a trauma surgeon at Inova Fairfax Hospital, cites a recent accident involving the driver of a car that was struck by an 18-wheeler.

"The patient arrived short of breath. With the knowledge of what happened at the scene, what we've learned over the years from projects like CIREN, we quickly moved to diagnose what's called a tension pneumothorax, which is a ruptured lung, leaking air and compression of the lung and heart," said Kakhry.

The CIREN system provides real-world data that can't be obtained from crash test dummies, according to federal safety officials who designed the program. Accident trends also are brought to the attention of automakers.

"You are seeing doctors thinking differently about car crashes and engineers thinking differently about what they do in the laboratory. We think that's good," explained Ricardo Martinez, formerly the head of the National Highway Traffic Safety Administration.

The federal government and private donors, including U.S. automakers, have been funding the CIREN system. Organizers hope that more trauma centers will begin to participate.

A report from the National Traffic Safety Administration calculated the total damage from U.S. motor vehicle accidents in 1994 at more than $150 billion. Taxpayers covered 9 percent of the cost, or about $13.8 billion, according to safety investigators. That's about $144 in added taxes for each household in the United States.

An estimated 15 million U.S. children are riding completely unbuckled, according to the National Safety Council. Among those involved in fatal accidents, 60 percent were not using seat belts or a child safety seat.

Experts say infants should be in rear-facing car seats, but may be moved to a forward-facing seat after their first birthday. Those from four to eight should ride in booster seats, according to safety officials, and all youngsters under the age of 12 should be in the back seat, away from air bags.

A recent Pennsylvania study found that children who weigh less than 80 pounds and use conventional seat belts are nearly four times more likely to be seriously hurt in a crash than youngsters sitting in safety or booster seats.

Children who don't fit the seat belt properly can hit their heads on their knees, jerk forward and damage their spines, or slide out of the belt altogether.

Researchers discovered that more than four-fifths of 4- to 8-year-olds had moved up to adult seat belts too soon, according to study author Flaura Winston of the Children's Hospital of Philadelphia and the University of Pennsylvania School of Medicine.

"What happens with children who are put into seat belts too young," said Winston, "is that their leg is too short, their thigh is too short and they scoot forward on the seat. The shoulder belt fits over their face; the lap portion comes up over their belly. It's not comfortable… it's not safe."

Winston's investigators looked at 2,077 children ages 2 through 5 involved in vehicle crashes from late 1998 through late 1999. Reporting in the journal Pediatrics, they found that 98 percent of the youngsters were restrained, but 40 percent of those were protected with a seat belt.

Safety experts recommend that children up to age 4 be restrained in child safety seats and those older be placed in booster seats until they are large enough to fit properly in a seat belt, usually by age 9.

A booster seat allows a child to sit higher and fit better in the shoulder belt. Only Washington state requires the use of booster seats.

CNN Correspondents Elizabeth Cohen and Pat Etheridge and Correspondent Kathleen Koch contributed to this report, written by CNN.com Editor Mike Cunningham.