Fourteen years ago, a plunge from a tree left him with a broken back and a determination to keep others from suffering the way he did.

As an emergency-room physician, Wood knew that most accidents like his involve hunters falling from tree stands. He set about designing a harness able to prevent such falls. But the more he researched the subject, the more he discovered that harnesses sometimes do more harm than good.

"I wanted to create a full-body harness, because full-body harnesses give the best chance at survival," said Wood, who lives in Fort Ashby. "While doing my research, I learned about suspension trauma. What I found was that if you hang in a harness long enough, you will die."

Wood found that the U.S. Occupational Safety and Health Administration recommends immediate rescue of workers who fall and are suspended in full-body harnesses.

"According to OSHA, death can occur in 30 minutes or less," Wood said.

In a recent presentation to state Division of Natural Resources and West Virginia Hunter Education Association officials, Wood outlined why people sometimes die from hanging legs-down in a harness.

"With a full-body harness, the leg straps are the problem," he explained. "When a person is hanging in a harness, the leg straps constrict the thighs and put pressure on the big arteries that feed blood to the legs.

"The heart is a pump, and it has the power to push the blood past that constriction, but there is no pump in the legs to push the blood back to the heart. The blood pools in the legs, where it loses oxygen and becomes toxic."

Wood said that in only a few minutes, five to six pints of blood - 70 percent of the body's volume - can accumulate in a person's legs.

"When that happens, the heart can't get enough blood to feed the rest of the body. Blood pressure gets lower and lower. When it gets low enough, you pass out. After you pass out, you're dead within 5 to 10 minutes."

Tree stand manufacturers since 2009 have been required to include a suspension relief strap, a dangling strap with a loop the suspended hunter can stand in to relieve pressure in the groin area. Wood said the straps can definitely help, but often aren't enough to save victims' lives.

"Workers have survived up to two hours using a suspension relief strap, but it's not a cure-all," he explained. "Sometimes a hunter will hang in his harness for hours, or even overnight, before someone finds him."

While designing his harness, Wood came to the conclusion it needed a feature that would allow victims to quickly lower themselves to the ground. He developed a prototype and has had the Rescue One CDS (Controlled Descent System) harness and its variations on the market since fall 2009.

He insists, however, that his goal in preaching the perils of suspension trauma is not to market his harness.

"There are other harnesses on the market that allow hunters to lower themselves, and those get the job done too," he said. "As a physician, I want to get the word out to hunters that they can't just hang there in their harnesses and expect to survive. If they aren't in harnesses that allow them to descend, they need to do everything they possibly can to get back into their tree stand as quickly as possible.

"If they can't get back up, they need to bring their legs up to heart level or above to keep the blood from pooling. One way to do that is to turn around and prop one's legs against the tree.

"Another thing - people who feel like they're going to pass out need to fight the feeling for all they're worth. If you pass out, you're dead."

Wood said the scariest part about suspension-related trauma is that even victims who are rescued relatively quickly can die soon afterward of cardiac arrest, or can die a few days later of kidney failure.

"What's really scary is that emergency medical technicians and even a lot of physicians don't understand how to treat a suspended person. Most EMTs or rescue squads would immediately lay the victim down and carry him out on a stretcher. That's the wrong thing to do.

"If a suspension victim is allowed to lie down soon after being rescued, all that toxic blood goes quickly rushing back to the heart. The heart gets its oxygen from the blood it circulates. A big slug of oxygen-starved blood can trigger a massive myocardial infarction - a heart attack," Wood said.

"And even if no heart attack occurs, the kidneys can be damaged by all the toxic substances that accumulate in the pooled blood. An Austrian study of rescued mountain climbers showed that several seemingly healthy victims died several days later of kidney failure."

To help prevent such tragedies from happening, Wood has developed a series of recommendations for rescuers and for hunters who have to be rescued:

"If the victim is conscious, he should stay seated at least 30 minutes before being laid down. If unconscious, he should be kept horizontal and should not have his legs elevated. If possible, he should be given oxygen. He should also be given fluids, intravenously if that option is available. And he should be transported immediately to a hospital with a kidney dialysis unit."

Wood's warnings and misgivings might lead hunters to believe they're better off not wearing harnesses. Wood said nothing could be farther from the truth.

"Hunters are much better off wearing harnesses than going without," he said.

"Six thousand hunters a year are injured or killed in falls from tree stands. Eighty percent of those injured end up needing surgery. Thirty percent end up with partial or total paralysis. The statistics for suspension trauma are not nearly that grim, so I would definitely advise hunters to use harnesses."

But only certain types of harnesses.

"I would avoid the belt-type and chest-harness types," he added. "Both of those can restrict breathing and can end up suffocating the user. I would go with a full-body harness of some kind, and preferably one that allows the victim to lower himself to the ground."

For the past several months, Wood has been taking his warnings about suspension trauma to hunter-safety educators, to wildlife officials and to gatherings of doctors and emergency-care workers.

"Right now, both the hunting and medical communities know far too little about suspension trauma," he said. "That needs to change."

Reach John McCoy at johnmc...@wvgazette.com or 304-348-1231.