Researchers at the University of Cincinnati (UC) College of Medicine have found that the current guidelines of 15-20 minutes for emergency medical services (EMS) to get stroke patients to a medical center with advanced stroke care may be too short. The new study finds that some patients could benefit from a bypass time that is double or even triple these recommendations, instead going directly to a hospital with comprehensive stroke care.

The findings are published online in Prehospital Emergency Care, the official journal of the National Association of EMS Physicians.

"If a loved one is having a stroke, what hospital should EMS take them to?” says Justin Benoit, MD, assistant professor in the Department of Emergency Medicine, and the lead author of the manuscript. "To get the best outcome, current guidelines may be too conservative. It matters where the ambulance takes your loved one.”

Current guidelines from the American Stroke Association (ASA) for prehospital acute ischemic stroke recommend against bypassing an IV tissue plasminogen activator tPA-ready hospital if additional transportation time to an endovascular-ready hospital exceeds 15-20 minutes.

Benoit says what prompted him and his co-authors to examine this was the development of endovascular treatment for stroke, a clot-removal procedure which he compares to cardiac catheterization for a heart attack. In 2014, a landmark study (known as MR CLEAN) that looked at endovascular treatment began to change stroke care dramatically, according to Benoit. Four subsequent trials further proved the benefit of endovascular stroke treatments, which are minimally invasive procedures performed inside the blood vessels, also known as a thrombectomy.

"When cardiac catheterization for the heart was new, that really changed what EMS had to do with heart attack patients,” says Benoit. "Systems of care had to change to catch up with this new technology. So now, decades later, the same thing is happening with the brain, where we have a new stroke treatment, but it’s only available at select places.”

Benoit says currently only about 100 or so comprehensive stroke centers in the United States are equipped to perform endovascular therapy on stroke patients, including UC Medical Center.

"This is a big deal now for EMS, because when it comes to EMS, it’s all about getting the right patient to the right place in the right time,” says Benoit. "We know from many different disease processes—trauma, heart attack, etc—if you go to the wrong hospital it hurts patients. It’s very important that the patient gets to the correct hospital on the first attempt. We don’t want secondary transfer.”

Just as Benoit and his colleagues in the UC College of Medicine began to examine the implications of trials showing the benefits of endovascular stroke treatment, the ASA issued guidelines recommending against bypassing a tPA-ready hospital if additional transportation time to an endovascular-ready hospital exceeds 15-20 minutes.

In an effort to use data to inform the decision-making process of bypassing a tPA-ready hospital in favor of an endovascular-ready hospital, Benoit began working with Mark Eckman, MD, Posey Professor and director of the Division of General Internal Medicine at the UC College of Medicine, to create a decision analysis model. Decision analysis is a technique that pulls in data and studies from a variety of sources and puts them into a model designed to answer a particular question.

Benoit says one of the major challenges in the prehospital treatment of stroke is that EMS has no way of knowing the severity and type of stroke suffered by the patient. The amount of time that has passed since the stroke began is one of three key variables the manuscript authors took into account when analyzing the 15-20 minute recommendation for bypassing a tPA-ready hospital for an endovascular-ready hospital. The other two variables are how long it will take to get the patient to the tPA-ready hospital and how long it will take to get the patient to the endovascular-ready hospital.

Benoit says they wanted to use the decision analysis model to determine the outcome of a stroke patient based on what type of hospital EMS took them to for initial treatment. After taking the three variables into account, along with other factors, their model determined that the 15-20 minute window recommended by the ASA is probably too conservative.

"Our model suggests you could, in certain scenarios, go two to three times longer than that bypass time, meaning 30-45 minutes or possibly even an hour,” says Benoit, who adds he’s not sure if these findings will impact the ASA guidelines. He says more clinical research is needed, with the goal of using that data to help determine the best choice for prehospital care of stroke patients.