ARTICLE IN BRIEF
A new dedicated stroke ambulance was introduced in Houston, based on similar models in use in Germany. A new study found that the mobile stroke unit in Germany resulted in faster door-to-needle time for thrombolytic therapy.
Houston is getting a “stroke ambulance” that is equipped with a CT scanner, laboratory, and neurologist ready to administer intravenous tissue plasminogen activator (tPA) on the way to the hospital to stroke patients who could benefit from the clot-busting drug.
The ambulance is modeled after units operating in Germany, where researchers reported encouraging results in reducing the amount of time that passes between when an ambulance is summoned and administration of tPA. The study, Prehospital Acute Neurological Treatment and Optimization of Medical care in Stroke Study (PHANTOM-S), compared use of specially outfitted ambulances designed to take full advantage of the so-called “golden hour,” the critical period right after stroke symptoms appear when it is most possible to limit brain damage, with conventional ambulance transports.
A team of researchers in Berlin reported in the April 23/30 edition of Journal of the American Medical Association (JAMA) that there was, on average, a 25-minute reduction in alarm-to-treatment time (95% CI, 20-29; p < .001); 51.8 minutes (95% CI, 49.0-54.6) with tPA when the stroke ambulance, or mobile stroke unit, responded to a call as compared with 76.3 minutes (95%CI, 73.2-79.3) when a regular ambulance service was in place. Also, the rate of tPA usage was 33 percent with the mobile stroke unit, significantly higher than the 21-percent rate during weeks of conventional emergency response.
“Our experience is that our pre-hospital stroke thrombolysis service is frequently used and safe,” Heinrich Audebert, MD, a professor of neurology at Charité University Hospital in Berlin and coauthor of the JAMA study, told Neurology Today. “It increases the thrombolysis rate and shortens the time to treatment.”
The Houston project is the brainchild of James Grotta, MD, FAAN, formerly the chair of neurology at University of Texas Health Science Center and the director of its stroke program. He is now based at Memorial Hermann-Texas Medical Center, where he is coordinating the launch of the stroke-response ambulance to service the Houston area. He became intrigued with the idea after learning of the initiatives in Germany.
“To me, the most effective way we can improve on what we are already doing with stroke care is to get patients to treatment earlier,” Dr. Grotta told Neurology Today, for which he serves as an editorial advisory board member. “No matter what we do, we've got to do it faster.”
Despite a number of public health campaigns to increase the awareness of stroke and its symptoms, many people are slow to call for help and do not show up at the emergency department until after the treatment window for tPA has closed, Dr. Grotta noted. The recommended treatment window for administering tPA is within three hours of symptom onset, though some doctors will administer the drug for up to 4.5 hours to certain patients. It is estimated that only about 5 percent of stroke patients get tPA, Dr. Grotta said, far short of the number of patients who could benefit. Research has shown that early treatment with tPA results in better outcomes.
The JAMA study reported on an emergency response vehicle named STEMO — the stroke emergency mobile — that is equipped with a CT scanner, point-of-care laboratory, telemedicine connection, a stroke identification algorithm at the dispatcher level, and a prehospital stroke team that includes a neurologist, paramedic, and radiology technician. The point-of-care laboratory offers tests for blood count, electrolytes, creatinine, glucose, and international normalized ratio.
Researchers conducted a 21-month randomized controlled trial that compared emergency response and treatment times during weeks when STEMO was operating with weeks when normal ambulance service was in effect. The catchment area included about 1.3 million residents. If the CT scan done on board the stroke ambulance indicated an ischemic stroke rather than a hemorrhagic one and the patient met other criteria for treatment, tPA was administered on route to the hospital.
“Compared with usual care the use of ambulance-based thrombolysis resulted in decreased time to treatment without an increase in adverse events,” the researchers reported. “Further studies are needed to assess the effects on clinical outcomes.”
IS IT COST-EFFECTIVE?
Another outstanding question is whether such an approach is cost effective. The German researchers reported that the stroke ambulance cost the US equivalent of $1.4 million.
A similar ambulance has been operating in Homburg, in southwest Germany, since 2008. Klaus Fassbender, MD, a chairman and professor of neurology at the University of Saarland, told Neurology Today that a randomized trial involving 100 patients found that the time between alarm to therapy decision — for or against thrombolysis — was reduced from 76 to 35 minutes. Symptom onset to therapy time was 71.5 minutes with the mobile stroke unit compared with 152 minutes with conventional service.
“In the right setting, this concept can significantly improve stroke treatment,” Dr. Fassbender said in an e-mail. “Further research is necessary.”
Dr. Grotta said the Houston stroke ambulance was funded mainly by $1.5 million from private donations, including the gift of an ambulance by a local ambulance company. The project is a joint effort of the University of Texas Medical School, Memorial Hermann Hospital, Houston Fire Department-Emergency Medical Services, and partnering hospitals in the Texas Medical Center.
“I think there is an opportunity to really make a difference in how we do things,” said Dr. Grotta, who will be on board the ambulance along with neurology fellows this summer. Dr. Grotta plans to conduct a study of the stroke ambulance's effectiveness, including the question of whether it is cost-effective. He said that eventually replacing the doctor with telemedicine conferencing might be necessary to make the service more affordable.
Dawn Kleindorfer, MD, a professor of neurology at the University of Cincinnati, said it is important to study the potential benefits of a dedicated stroke ambulance, but she said it was difficult to imagine how the service could be paid for under the US form of health care, where each point of care — ambulance, doctor consult, hospital — is typically billed separately. She agreed that using telemedicine instead of a physician on board might be a good alternative from a cost perspective.
She noted that an analysis of data from hospitals in the Cincinnati area found that the average time from symptom onset to ED presentation was 2.5 hours, almost too late for tPA, Dr. Kleindorfer said.
“We know that every minute counts,” Dr. Kleindorfer said. “Every minute that goes by, brain cells are dying.”
Lawrence Wechsler, MD, FAAN, a chair and professor of neurology at the University of Pittsburgh, said that the stroke ambulance may work in some communities and not in others, depending on the configuration of hospitals and emergency response services. He said the idea had been discussed in Pittsburgh, which uses telemedicine to connect Pittsburgh stroke specialists with other hospitals. He noted the city's emergency response network operates with the goal of getting stroke patients to a hospital within 20 minutes.
“We know that the faster we treat patients the better they do,” Dr. Wechsler said. “So the target is reduced time to treatment — whatever that takes.”
He said a stroke ambulance could help shave wasted time, but “the question is, ‘Is this the right way to do it?’” The question of whether long-term outcomes will be improved along with better response time needs to be studied, he added.
Efforts to educate the public on the crucial time element involved in stroke treatment also must continue, Dr. Wechsler said. Unlike a heart attack, which tends to hurt, stroke symptoms may be vague and not immediately frightening to a person.
“It's easy to say to yourself, ‘I'll lie down for a little bit and it will go away.’”
EXPERTS COMMENT ON THE STROKE AMBULANCE