Stroke, including both its ischemic and hemorrhagic presentations, continues to be a major cause of morbidity and mortality in the developed world. Time to treatment and accessibility of appropriate care are of the utmost importance in maximizing the opportunity for positive patient outcomes. Mobile Stroke Units (MSUs, mobile CT ambulances) are a novel platform designed to accelerate delivery of proven, time-dependent therapies for acute ischemic and hemorrhagic stokes in the field while directing patients to the medical center best suited to provide an appropriate level of care. Worldwide, the first of these specialized units debuted in Germany in 2011. Modeled on the German design, the UCLA Health Mobile Stroke Unit, live since September of 2017, responds to emergency medical services (EMS) dispatch calls for patients with stroke-like symptoms in order to facilitate effective, rapid diagnosis and acute treatment for stroke patients.
Assess the scope of diagnosis and in-field treatment for the UCLA Health Mobile Stroke Unit and perform sophisticated geospatial mapping of stroke incidence across LA County to more precisely determine the most clinically effective location for future units.
The current Mobile Stroke Unit locations were determined by collaborative agreements with EMS 911 providers, beginning with the Santa Monica Fire Department and expanding to include coverage for LA County Fire Department. Data recording dispatcher impression, time of dispatch, time of patient assessment, decision to admit to the mobile stroke unit, imaging, laboratory and clinical therapy time, amongst other factors, were included in the assessment of each case. Data for patients who received treatment for ischemic or hemorrhagic stroke was compared to national guidelines for stroke treatment and current national DTN times. Other clinical diagnoses aside from stroke in patients presenting with focal neurological changes were obtained by head CT and clinical exam criteria and assessment.
As of June 2018, the UCLA MSU has been in service for 119 days. In that time, it has been dispatched on 157 EMS calls, admitted 38 patients, administered tissue plasminogen activator (tPA) to six patients diagnosed with ischemic stroke and administered antihypertensive therapy to two patients diagnosed with hemorrhagic stroke. In the remaining patients admitted to the MSU, diagnoses included transient/minor stroke, seizure, brain tumor, aneurysmal subarachnoid hemorrhage, subdural hemorrhage, and toxic metabolic conditions. In standard stroke care, the recommended time from patient arrival at hospital to treatment administration (door-to-needle [DTN] time) is under 60 minutes, but 2014 American Heart Association data puts median DTN times at 77 minutes (range 60 to 98 minutes). However, for patients receiving tPA onboard the MSU, mean MSU onsite to treatment time was approximately 41 minutes (range 32-53 minutes). It is important to note that this MSU DTN metric also circumvents transport time, Emergency Department admission time, and hand-off time. It is only after all of this that hospital-based DTN treatment time metrics are evaluated. For MSU patients, the clot-busting medication, tPA, is administered in the field prior to door arrival time. Additionally, there is high value in prehospital precise/definitive clinical diagnosis and patient triage.
Mobile stroke units allow delivery of the hospital to the patient. These highly specialized ambulances allow for pre-hospital definitive diagnosis, treatment and tailored patient transport to higher levels of neurological care as needed. In the demonstration phase of operations of such specialty units, parallel work is being conducted to understand the most effective distribution of these units from a geospatial stroke distribution perspective within LA County Systems of Care.