Mobile stroke units improve response times and outcomes for patients


Mobile Stroke Treatment Units—specialised emergency rooms on wheels—are saving critical minutes in the diagnosis and treatment of stroke patients, according to two new studies presented at the American Stroke Association’s International Stroke Conference 2015 (Nashville, USA, 11–13 February, 2015).

“Due to how critical time is in the treatment of stroke, using Mobile Stroke Treatment Units (MSTU) to provide pre-hospital evaluation and treatment of stroke should revolutionise the care of these patients,” said Muhammad Shazam Hussain, lead researcher and head of the Cleveland Clinic Stroke Program.

MSTUs are specialised ambulances staffed with a nurse, paramedic, emergency personnel and a CT technologist. The unit also contains lab testing equipment and a CT scanner, which is required to diagnose the type of stroke. A stroke physician at the main hospital evaluated each patient via telemedicine and a neuroradiologist remotely assessed CT images. Two-way video conferencing allowed communication with the patient, family and stroke experts.

The CT image is an important diagnostic test distinguishing a haemorrhagic stroke from an ischemic stroke. The treatment for these types of strokes is different, and cannot be started until the CT scan is complete.

In this analysis, researchers report the evaluation and treatment in the first three weeks of implementation of the MSTU in Cleveland as compared to a control group of patients brought to the emergency department via traditional ambulance in the preceding three months. They measured the time from call dispatch from emergency medical service to the time a CT was completed and clot-busting treatment with tPA was started.

Twenty-three patients were treated in the MSTU and 34 in the emergency room. There were no significant differences in age or gender between the groups. Researchers found:

  • The median time for alarm to MSTU arrival at scene was 13 minutes.
  • There was a significant reduction of median alarm to CT scan completion times (41 minutes in MSTU vs. 62 minutes in emergency room patients).
  • There was a significant reduction in time to treatment (median alarm-to-thrombolysis times – 64 minutes in MSTU vs. 104 minutes in emergency room patients).
  • Six patients received clot-busting medication in the MSTU group and five in the emergency room group.
  • There were no early complications of clot-busting in the MSTU group.

“Estimates are that stroke victims lose two million neurons (brain cells) per minute, so this reduction in time with the MSTU could potentially result in much better outcomes,” Hussain said.

In addition, researchers noted that the rate of clot-buster treatment was much higher in the MSTU than in the hospitals (26% vs. 14%). This also was much higher than the national average of 3–8%.

“The main reason for patients not getting treated is that they do not arrive in time for this treatment—4.5 hours from symptom onset,” Hussain said.

Hussain noted that another advantage of the mobile unit is being able to triage patients to the most appropriate hospital for their condition. An ischaemic stroke patient with a large clot sitting in a major brain artery usually requires intravenous catheter-based treatment—available in larger facilities—in addition to an intravenous clot buster.

“We eliminate the need to transfer them from a small hospital to a larger hospital by getting them there directly, saving critical time and making the difference between patients being able to receive advanced, lifesaving treatments,” Hussain said.

In another study researchers at The University of Texas Health Science Center at Houston (UTHealth) reported how they created the first mobile stroke unit to operate in the USA.

An ambulance company donated an ambulance and the Mobile Stroke Unit (MSU) build-out, begun with the purchase of a computed tomography (CT) scanner. A consortium was formed to set procedures and policies and obtain city and state licensing, undertake inspections and develop an accountability system. Staffed by a neurologist and a registered nurse with stroke expertise, CT technology and paramedic and telemedicine connectivity, the MSU responds to acute stroke dispatches within a five-mile radius from 8am–6pm daily.

“Intravenous tPA remains the only level 1A treatment for ischaemic stroke. Pooled analyses confirm the relationship of treatment success with time from symptom onset to initiation of treatment. However, despite two decades of efforts to streamline systems of care, most patients are treated beyond the two hours when tPA is most effective,” said Stephanie A Parker, lead author and project manager of the UTHealth Mobile Stroke Unit at the UTHealth Medical School in Houston, USA.

The UTHealth MSU treated its first patient in May 2014, and is carrying out acute stroke treatment within 10–18 minutes of arrival on location. During a nine-week run-in phase, approximately two patients per week were treated with tPA on the MSU, 40% of whom were treated within the first hour from symptom onset, Parker said.

“Our ultimate goal is to show that patients treated on the mobile stroke unit will have better outcomes because of earlier treatment and, therefore, will have fewer long-term acute care needs and/or rehabilitation needs,” Parker said.