Image: The specialized MSU is equipped with a 16-slice CT scanner (Photo courtesy of Northwestern Medicine).
A specialized ambulance equipped with a 16-slice computed tomography (CT) scanner can provide life-saving tissue plasminogen activator (tPA) 30 minutes faster than traditional ambulances.
The Northwestern Medicine (NM; Winfield, IL, USA) Mobile Stroke Unit (MSU) is a 14 ton ambulance fitted with a specialized CT scanner that takes detailed pictures of the brain, and a direct telemedicine connection to NM neurologists positioned in Central DuPage Hospital (Winfield, IL, USA). If the neurologist determines that the patient is experiencing an ischemic stroke, he can advise the MSU team to administer tPA while still en route to the hospital. The goal is to diagnose and treat stroke within the "Golden Hour", the first 60 minutes following onset of symptoms.
In addition to the neurologist, the dedicated MSU Stroke Care Team is comprised of a critical care nurse, a CT technician, an emergency medical technician (EMT) driver, and a critical care paramedic. The early intervention can lead to better outcomes, as stroke patients are typically not administered tPA until their arrival at the hospital. A recent data analysis of the MSU’s first year of operation found that on average, tPA was delivered to stroke patients 52 minutes after dispatch, compared to an average of 82 minutes for patients transported to hospital before receiving treatment.
“Treatment can be initiated within minutes of responding to a call. This is crucial because when it comes to stroke, time is a factor in treatment. By treating stroke patients faster, we are greatly improving the odds patients will suffer minimal to no long term deficits,” said Harish Shownkeen, MD, medical director of the Stroke and Neurointerventional Surgery Programs at NM Central DuPage Hospital. “For every minute you delay in getting treated for a stroke, you lose 1.9 million neurons; every minute the brain goes without oxygen, there is a 3.1 week acceleration of the natural aging process.”
Natural tPA is a serine protease found on endothelial cells. As an enzyme, it catalyzes the conversion of plasminogen to plasmin, the major enzyme responsible for clot breakdown. When manufactured using recombinant biotechnology techniques, it is referred to as recombinant tissue plasminogen activator (rtPA), which is used to treat embolic or thrombotic stroke. It is contraindicated in hemorrhagic stroke and head trauma.