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Advantages of medevac transport challenged

Some experts find helicopter no better than ground travel

By Robert Little

October 5, 2008

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Even as emergency medical officials in Maryland consider stricter criteria for flying patients, in the wake of last weekend's fatal medevac helicopter crash in Prince George's County, some trauma specialists think they should be exploring a more fundamental question:

Should accident victims be transported by helicopter at all, especially in urban areas?

The idea borders on heresy in Baltimore, a city whose pioneering trauma center became a global model and where Dr. R Adams Cowley coined the phrase "golden hour," defining how quickly a patient should get to a hospital to have the best chance of survival. "Whenever someone says they want to ratchet it back," says Dr. Thomas M. Scalea, physician in chief at Shock Trauma, "I tell them 'OK, how many people can die next year to make that worthwhile?'"

Yet with more than 500,000 medical transport flights now being operated in the United States each year, and eight fatal accidents in the past year, some trauma specialists question how often they are used.

Skeptics, including a few of the nation's top trauma surgeons, cite studies that cast doubt on some of medevac's basic assumptions - that helicopters get patients to a hospital faster than ambulances, or that they increase a trauma patient's chance of survival.

One study, for example, found that helicopter transport made no difference for patients with severe injuries. Another found that while helicopter patients got initial treatment more quickly, they arrived at a hospital later than patients transported by ground ambulance.

If hospitals and emergency medical systems assessed the research objectively, the skeptics argue, many systems would limit helicopter use to rural emergencies or extreme situations such as high-rise evacuation and offshore rescue.

"In Maryland there's a culture that you ought to use a helicopter and you have to go to Shock Trauma," said Dr. Kenneth L. Mattox, chief of surgery at Ben Taub General Hospital in Houston. "But why? The little data we have says ground ambulances are superior."

Added Dr. Norman E. McSwain Jr., director of trauma at Tulane University and chief of surgery at the trauma center in New Orleans, "There is just too much flying of helicopters for non-medical reasons or for reasons that really have nothing to do with patient care. It's the kind of thing that we have got to get under control."

Questions about medevac safety are inevitably raised after every accident but are often tamped down by emotional anecdotes of high-speed rescues and lives saved.

Numerous medical studies validate one of the main tenets of Baltimore's vaunted trauma system - that critically injured patients fare better when they are treated in a dedicated, well-equipped and well-staffed trauma center like Shock Trauma.

The best way to get the patients there, however, is far from clear.

A detailed study in Phoenix in the 1980s found that helicopter transport didn't make a difference for patients with severe injuries. A similar study in London a decade later indicated helicopter transport might be harmful to patients with minor injuries.

A 2002 study of 16,699 cases in Boston came to a more complex conclusion: Trauma patients transported by helicopter were three times more likely to die than those transported by ambulance, though statistically they fared better when the increased severity of their injuries was taken into account.

Maryland officials are unswayed by the research, which they say is evolving and unclear.

"If it's my family or my patients, and there's no definitive research, then I want to have a paramedic and a helicopter available," said Dr. Robert R. Bass, director of the Maryland Institute for Emergency Medical Services Systems.

Scalea, of Shock Trauma, said he has no doubt that use of helicopters saves lives. There were about 4,500 medevac flights in Maryland last year.

"The accident victim who's staggering and slurring his words: Is he drunk or does he have a brain injury? If the pre-hospital guys had X-ray vision, then they could diagnose every injury at the scene. But as a medical community, and as a country, we've made the decision that over-triage is preferable to the alternative," he said.

"We know injury is a time-related disease."

Dr. Bryan E. Bledsoe, a University of Nevada emergency medicine specialist, published a study in 2006 on more than 37,000 trauma patients flown from the scene of injury to a trauma center and concluded that more than 60 percent did not have life-threatening injuries. A quarter were discharged in less than a day - evidence, he said, that they didn't need to fly.

The statistics might be a mere curiosity, he said, if not for the risk that helicopter transport poses. Ground ambulances crash too, but rarely with such deadly consequences.

By Bledsoe's analysis, a medevac pilot or crew member with a 20-year career has a one-in-three chance of being involved in a fatal crash.

"It clearly needs to be re-evaluated," Bledsoe said "Somewhere along the line, there's been a paralysis of intellect where helicopters are concerned."

Maryland officials are re-evaluating, but they say the unpredictable and potentially deadly nature of trauma care makes easy answers elusive.

Maryland guidelines call for flights to be operated in cases in which a trauma center is longer than a 30-minute drive away. That would seem to preclude almost every accident inside the Beltway, but medics also consider traffic congestion, which sometimes means flying just a few miles.

"You can err on the side of patients, and perhaps fly too many to a trauma center, or you can err on the side of under-triage and potentially lose some patients," Bass said. "There is no perfect way."

The two patients involved in last week's crash in Maryland, one of whom survived, were both alert and talking when they boarded the helicopter, but had been selected to fly the 30-mile trip to the nearest trauma center based on the nature of the car accident that caused their injuries.

The "mechanism" of injury - in their case a 12- to 18-inch dent into their vehicle's passenger compartment - is used throughout the country to predict medical problems that are not otherwise apparent, though recent scientific studies suggest that the technique is inaccurate as much as 80 percent of the time.

Maryland's emergency medical officials say they are re-evaluating their reliance on mechanism of injury to determine the method of transport. McSwain and others said they should also consider having paramedics or emergency technicians quickly transport such patients to a nearby community hospital, where doctors could use X-rays or ultrasound to determine whether they need to go to a trauma center.

Last week's car accident in Waldorf occurred about 10 miles from a community hospital in LaPlata where doctors could conceivably have assessed whether the victims needed to fly.

Advocates of helicopter transport see that as an unnecessary delay in treatment and say it ignores one of a helicopter's greatest assets - its on-board paramedic. While ground ambulances are often staffed by technicians trained in basic life support techniques, helicopters typically carry paramedics trained in advance treatments such as resuscitation and airway intubation. And they are often among the system's most experienced responders, because of the volume of complex cases they see.

"You have to look at it as bringing Shock Trauma to the patient," said Dr. Kevin Hutton, an emergency medicine physician and chairman of the Foundation for Air-Medical Research and Education in Virginia. "When you call a helicopter, you're asking for the highest level of care available at the scene."

In that context, even short flights make sense, Hutton said. He recalled a patient he once treated who had to be delicately removed from a piece of machinery after an industrial accident. Paramedics intubated and stabilized him while a helicopter waited outside. The trauma center was close enough for an ambulance - less than two miles away - but with a helicopter the patient got there within minutes and had already received advanced care.

"Is it better to front-load all of that at the risk of determining later that it wasn't necessary? Or is it better to miss a few and have them die?" he asked. "I think that's a very effective and appropriate use of helicopters."

Yet critics question whether the supposed advantage of advanced on-scene treatment is any more valid than for air transport over ground transport.

A 1996 study in Los Angeles of almost 6,000 patients found that victims of severe trauma fared better when they got a ride to the hospital in a friend's car than if they waited for an ambulance or helicopter. A study in Canada found that the more advanced the on-scene care was, the less likely a patient was to survive - even when physicians responded to accidents.

Mattox said such studies reveal that the biggest need for trauma patients is to be treated at a hospital, not at the scene. And while helicopters travel faster than ground vehicles, the time spent warming up engines and preparing patients for transport can minimize or eliminate the speed advantage. The London study found helicopter patients were treated by paramedics 25 minutes faster, on average, but typically arrived at a hospital 10 to 20 minutes later than patients in ambulances.

"When you see these helicopters on television loading a patient, what do you almost always see in the background? A ground ambulance," said Mattox, who is among the nation's leading researchers into the practice of using intravenous fluid to treat trauma patients. "In many cases, if they had just loaded the patient and gotten to the closest appropriate hospital, instead of waiting for the helicopter, the patient would be better off."

"If we could show a survival difference, or even a morbidity difference, I would be the first to say, 'Let's do it,'" Mattox added. "But we can't."

Bledsoe said he often holds up Maryland's medevac system - state-financed and -maintained, well integrated into the region's emergency response system - as one of the best. In other states, where helicopters are typically privately owned, commercial interests can encourage operators to take unnecessary risks and transport patients to inappropriate facilities. Still, he considers Maryland's helicopter fleet - including 6 commercial aircraft and 12 operated by the state police - to be excessive.

"Whenever people ask me which system is the model, I always say Maryland's. I think conceptually it's very good," Bledsoe said.

"You probably only need two or three helicopters, though. They're easy to justify out in Western Maryland or in other rural areas, but why are they flying people around Baltimore and Washington?"

Bass disagrees.

Helicopter transports have dropped off slightly in the past year, perhaps because emergency medical crews are adhering closely to the state's triage guidelines on when to call for air transport.

But any acceptable system will fly patients who, in hindsight, did not need to fly helicopters, he said. Medics err on the side of caring for a patient. And that won't change.

"I also believe it's not just about cost, and not just about safety," Bass said, "but also the thinking that when you really need that helicopter, you want it to be available."

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