By Margot Sanger-Katz
The Concord Monitor
CONCORD, N.H. — In 2002, emergency medicine specialists at the Denver Health Medical Center wanted to find out how much response times affected the survival of the major trauma patients they treated — often the victims of car crashes, gunshots and stabbings. They treated the kind of patients for whom every minute — they thought — would matter.
But after studying two years’ worth of their hospital’s major trauma cases, the researchers found no effect. Patients who arrived at the hospital quickly fared no better than those who took longer to reach the emergency room. Confused by this result, the specialists widened their analysis to look at all the patients who came to the city’s emergency rooms by ambulance. Again, the data showed, response time didn’t matter. They looked at patients with heart attacks, respiratory problems and other life-threatening health emergencies. None found a correlation between response time and survival
“It’s a patient satisfaction and public relations issue, but in terms of patient outcome,” said Dr. Vincent Markovchick, who worked on the studies, “a very rapid response time makes no difference.”
As municipalities in New Hampshire and nationwide have made efforts to improve the quality of their ambulance services, they have often looked to their response times as the best measure of performance. The federal government has set an eight-minute response time target that fire departments and rescue squads endeavor to meet, often at great expense. Response time is an easily measured, intuitive proxy for the quality of EMS care. But though research in EMS is limited, no major published studies refute the Colorado results. According to Markovchick, there’s simply no science that supports the national standard.
“The eight-minute standard is a very arbitrary number that was established 20 or 30 years ago,” Markovchick said. “It was a guess.”
EMS is less than 40 years old, and it has developed without a lot of scientific guidance about best practices. For years, states failed to gather comprehensive information about system performance.
The latest research makes it difficult to know what investments will have the best payoff for communities hoping to improve their pre-hospital care. Studies show not just that expensive response time improvements may have limited benefit but also that investing in paramedic-level care may not be cost-effective.
The federal eight-minute response time target was built around one particularly life-threatening emergency: sudden cardiac arrest. For patients who suffer from cardiac arrest, every minute that passes until their hearts are shocked back into rhythm dramatically decreases their chances of survival. In the 1970s and ‘80s, studies suggested that if personnel could reach cardiac patients within eight minutes, they could save many of them.
The latest thinking is that for patients to have a decent chance of meaningful survival, they really should be shocked within four minutes of when their hearts stop beating. And that’s not four minutes from when the ambulance is called; it’s four minutes from the beginning of the event. Those cases represent less than 1 percent of all 911 calls. And overall, survival from this type of heart attack is less than 5 percent.
Most rural ambulance services have already dispensed with a four- or eight-minute standard. In a densely populated city, it’s possible to keep drive times short by spreading ambulances around. When it takes 10 minutes to drive from the fire station to the edges of town, a one-ambulance community will necessarily take longer to reach some patients.
“I know people would like to see it quicker, but from a safety perspective, I don’t know how much faster you’d like to see them driving,” said Epsom fire Chief Stewart Yeaton.
But how long is acceptable? Should a volunteer department with a 15-minute response time invest in full-time staff to cut that number down to 12 minutes? The answers are hard to come by.
Most ambulance calls are for minor medical conditions where experts say a taxi ride would serve just as well. Patients with sprained ankles, broken wrists or kidney stones may prefer medical care right away, but a few minutes won’t change their prognosis.
But there are certain medical conditions where EMS and emergency room doctors say they know minutes matter. In trauma cases, doctors talk about the “golden hour” in which a patient should reach an operating room at an appropriate hospital. (Despite the wide use of the term in the emergency medical community, studies have also failed to show any proof that an hour is a critical time — most trauma patients who die do so either more quickly or more slowly.)
Other time-sensitive emergencies, experts say, include strokes, respiratory distress and severe allergic reactions. But medical research has yet to establish firm standards for how long those patients can wait before it’s too late to save them.
Several researchers said they doubt a few minutes of improvement on a rural response time would make much of a difference.
Locally, nearly every large municipal EMS department boasts paramedics on every ambulance. But research done by Dr. Ian Stiell and others involved in the large scale Ontario Prehospital Advanced Life Support studies suggests that it takes careful training and use of medics to show a benefit to patients.
Stiell’s research, which is ongoing, initially showed no benefit to medic care when it looked across the range of health emergencies. But as he drilled down to particular kinds of care, the findings were different.
In cases of respiratory distress, patients had higher survival rates when they had access to advanced life support.
In trauma cases, their rates were lower.
“That was kind of disturbing,” Stiell said.
Cardiac patients did about the same no matter who treated them. What mattered, Stiell said, was whether they were treated with CPR and a defibrillator quickly.
Paramedics are trained to perform myriad treatments that basic EMTs can’t do: They can administer drugs, insert breathing tubes and start IVs. Those skills can benefit a patient who needs the right kind of speedy care, but only if the medic also has the judgment to know what treatment to offer and the skills to do it right.
“They can put the tube in, but that’s only a tiny part of it. The sort of cognitive skill of when to put it in, that’s far more important,” Stiell said. “Just because you know how to put it in doesn’t mean that’s what you’re supposed to do.”
An error, either in judgment or technique, while performing advanced life support skills, can have catastrophic consequences. “At the basic level, it’s pretty difficult to kill someone. At the medic level, it’s pretty easy,” said Weare EMS Capt. Bob DeStefano, who recently completed paramedic training.
Just as surgeons drive down their error rates the more frequently they perform a particular operation, paramedics have been found to be better at assessing critically ill patients and administering paramedic-level treatments the more often they do it. In rural settings, that level of experience can be difficult to maintain.
Rich Serino, the deputy administrator of FEMA, who until recently ran Boston EMS, said Boston’s department thought carefully about the best way to use paramedics. Instead of putting a medic on every ambulance, he said, they opted to put one in every fourth ambulance. Basic EMTs respond to every emergency, and the paramedics back them up when they are needed.
Serino said the system, which has become a model, saves the city the expense of staffing as many medics, who command higher salaries because of their training. He said it also ensures the medics on staff see enough tough cases to keep their skills sharp.
Researchers and municipal EMS directors talk about the design of an overall EMS system — not reliance on any one measure — as the key to providing the best care to patients in trouble.
They all agree that staffing ambulances with skilled EMTs who could provide a reliable, predictable response was important. But they also agree those systems worked better on larger scales, where it was possible to measure outcomes and maximize EMTs’ exposure to a variety of calls.
They pointed to a parallel body of research suggesting an ideal system can go beyond ambulances, particularly when it comes to cardiac patients. In recent years, manufacturers have developed automatic external defibrillator machines, or AEDs, that can be used by the lay public and work just as well as an EMT’s paddles.
Markovchick said expanding the use of these machines could make a real difference in cardiac arrest survival. Put them in police squad cars, school gymnasiums, nursing homes and malls, he said, and teach people to use them.
One large study supports this approach. In Las Vegas, casinos collaborated to train all their security guards in how to use AEDs. By 2000, the survival of people stricken with cardiac arrest in the casinos improved to 53 percent of all cases — better than the survival rate for patients in hospitals — according to a study in the New England Journal of Medicine.
The city of Seattle encouraged community members to learn how to use AEDs and ensured that every high school student took a CPR course before graduation. A recent study showed that Seattle may be the best city in North America in which to suffer cardiac arrest — the city outperformed nine others in a study published in the Journal of the American Medical Association.
In rural areas, expanding access to CPR and defibrillators makes particular sense, experts said. “Anybody can do CPR,” said Sue Prentiss, New Hampshire’s EMS chief. “It doesn’t take an EMT to do it. Anybody can use a defibrillator.”
Copyright 2009 Concord Monitor