Most ischemic stroke patients have to wait until they arrive at a hospital and undergo testing before receiving antithrombotic therapy. A new study in the New England Journal of Medicine shows that it is feasible for paramedics to administer a neuroprotective agent while still in the field to optimize patient outcome.
Brain ischemia kills 2 million nerve cells every minute, according to the American Heart Association (AHA), leading neurologists to develop the mantra "time equals brain." A stroke patient can lose a significant number of nerve cells during long ambulance response and transport times. Tack on a 90-minute door-to-needle time, and brain ischemia has had enough time to cause significant damage before emergency department physicians can even think about administering tissue plasminogen activator (tPA).
In this new study, Dr. Jeffrey Saver, director of the University of California, Los Angeles (UCLA) Comprehensive Stroke Center, and his colleagues wondered if recovery rates would improve if paramedics could administer therapeutic drugs to possible stroke patients.
The researchers started by showing paramedics how to use the Los Angeles Prehospital Stroke Screen to rapidly assess whether a patient had suffered a stroke. After assessing the patient, the paramedic would use a cellphone to contact a neurologist to determine if the patient should be included in the study. With neurologist approval, the paramedic would ask the patient if he wanted to be included in the trial then administer the drug.
Researchers randomly assigned 1,700 enrolled patients suspected stroke patients to two groups, with 857 subjects in the experiment group receiving intravenous magnesium sulfate and 843 participants in the control group receiving placebo. Both groups received injections within two hours of symptom onset. Paramedics administered a loading dose before arrival at the hospital, where a 24-hour infusion was begun upon arrival.
The final diagnosis was cerebral ischemia in 73.3 percent of participants, intracranial hemorrhage in 22.8 percent and a stroke-like condition in 3.9 percent. The median interval between the time the patient was asymptomatic to the start of drug infusion was 45 minutes, and 74 percent of subjects received the infusion within the first hour.
Research into whether magnesium sulfate is particularly helpful in cases of acute ischemic stroke has provided mixed results. At least one study suggests magnesium sulfate is a safe and useful neuroprotective agent for patients experiencing acute ischemic stroke and lacunar stroke.
That 2013 study looked at 107 patients with ischemic stroke signs and symptoms lasting less than 12 hours, with 55 participants in the experimental group receiving 4 g of MgSO(4) over 15 minutes and then 16 g over the next 24 hours and the control group receiving placebo. Based on subject scores on the National Institute of Health Stroke Scale (NIHSS), subjects receiving intravenous magnesium sulfate showed significant recovery in comparison with the control group.
Researchers used the Rankin Scale to determine the subjects' degree of disability at 90 days after the stroke event. While the researchers found no significant differences in Rankin Scale scores between the experiment and control groups, the scientists did determine that paramedics could be giving life-saving treatment to ischemic stroke patients before transporting them to the hospital.
The National Institutes of Health (NIH) National Institute of Neurological Disorders and Stroke (NINDS) funded the study.
