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Background: Mobile Stroke Units (MSUs) are capable of rapid initiation of intravenous thrombolysis and have the potential to improve acute stroke patient routing by providing conclusive imaging diagnosis of LVO (arterial sequences) and intracranial hemorrhage (parenchymal/extraparenchymal sequences). However, the incremental increase in diagnostic accuracy and effect on patient disposition have not been well delineated. Methods: Consecutive transports in a regionally-deployed MSU from September 2017-August 2019) were analyzed, comparing patient routing that would have occurred under standard ambulance protocols to routing and process outcomes after CT/CTA MSU imaging. Standard ambulance regional routing policy was direct to nearest PSC if Los Angeles Motor Scale (LAMS) 0-3 and direct to nearest CSC within 30m if LAMS 4-5. Results: Among 83 MSU transports, final diagnosis was acute cerebral ischemia in 68% and intracranial hemorrhage in 10%. Among 57 acute cerebral ischemia patients, Los Angeles Motor Scale (LAMS) score was 0-3 in 65% and 4-5 in 35%. All (100%) of patients with ICA/M1 occlusions had LAMS score 4-5. However, among patients with expanded range endovascular target occlusions (M2, basilar), LAMS scores were 0-3 in 56%, and MSU imaging permitted improved routing. Among 8 intracranial hemorrhage patients (2 IPH, 5 SDH, 1 SAH), MSU imaging permitted improved direct-to-CSC routing in the 62% of patients with LAMS scores 0-3. Among all MSU admissions, 15% (13) were rerouted based solely upon in-vehicle imaging, including 7% for radiographically proven endovascularly treatable occlusion, 7% for neurosurgical/NICU intracranial hemorrhage care, and 1% for neurosurgical tumor care. Transport times for re-routed patients was median 12 minutes, compared to closest stroke center median 6 minutes. Conclusion: More than 1 in 7 MSU evaluations result in improved routing of comprehensive stroke center-appropriate patients directly to a CSC facility, including AIS patients potentially eligible for thrombectomy, intracranial hemorrhage patients, and acutely-presenting brain tumor patients. In addition to speeding start of intravenous thrombolysis, MSUs can substantially improve timely access to CSC care.

Background: EMS 911 dispatchers must rapidly assess patient calls and allocate appropriate responding resources including, for stroke, advanced (rather than basic) life support standard ambulances and, in an increasing number of regions, specialty Mobile Stroke Units. While dispatcher accuracy in distinguishing stroke from other high risk conditions is not crucial for selecting ALS rather than BLS response, specialized MSU response necessitates a higher level of accuracy. Methods: We analyzed all transports between January 2018-August 2019 identified as stroke by dispatchers at sendout or by paramedics upon patient assessment in a large urban EMS system -LA County FD EMS, serving 4.1 million lives, 59 cities, 3,000 square miles, via 174 fire stations. Dispatchers are instructed to decide upon the appropriate diagnosis and responding resource within 60s of start of 911 call conversation. “Dispatcher Impression” (DI) and on scene paramedic “Provider Impression” (PI) were compared, and other care metrics analyzed. Results: In total, 12,528 runs were evaluated, of which 79.1% (9913) were dispatched as stroke and paramedics identified stroke in 47.6%. The sensitivity of dispatcher impression of stroke was 56.2% and the positive predictive value was 33.9%. The most common paramedic impressions in non-concordant patients dispatched as stroke were: generalized weakness in 24% (1587), altered mental status in 17% (1111), and syncope in 6% (403). In patients with a dispatcher impression of non-stroke but paramedic impression of stroke, the most common dispatcher impressions were: sick person in 29% (758), unconscious in 28.7% (750), and seizure in 4.6% (121). In dispatcher impressions of stroke, 100% were dispatched at ALS level; and in dispatcher impressions of non-stroke but eventual paramedic impression of stroke, 98.3% were dispatched at ALS level. Patient age over/under 40 & patient sex did not modify rates of dispatcher - paramedic impression concordance. Conclusions: Dispatchers identify more than half of paramedic-identified stroke patients and allocate appropriate ALS standard ambulances in almost all stroke patients. However, for efficient attaching of specialized MSU resources, improved dispatcher identification of stroke is desirable.

Background: Mobile stroke units (MSUs) permit advanced cerebrovascular diagnosis, triage, and treatment to be delivered in the field. While the range of acute cerebral ischemia and intraparenchymal hemorrhage patients encountered by MSUs has been described, the frequency, determinants, and outcomes of patients presenting with extraparenchymal intracranial hemorrhages (subdurals/subarachnoid/epidural) has not been well delineated. Methods: We analyzed consecutive transports among MSU programs in 3 cites, Los Angeles, Houston and Cleveland from program inception through August 2018 in the two former and through 2015 in the latter. Frequency and demographic, presenting, and treatment features of patients with subdural hematoma (SDH) and subarachnoid hemorrhage (SAH) were quantified. Results: Among 850 overall transports, extraparenchymal intracranial hemorrhages accounted for 18 (2.1%), and included 11 (1.3%) SDH and 7 (0.8%) SAH. Among the SDH patients, age was mean 70/median 77 (range 28 to 85). Special features of SDH cases included: acute on chronic blood on CT in 36%, seizures in 9%, and isolated head trauma in 9%. Among SAH patients, mean age was 57 (range 41-75). Special features of SDH/SAH cases included accompanying intraparenchymal hemorrhage in 17%. Of the 18 combined SDH/SAH patients (67% women), 4 (22%) required field intubation, 1 (5%) was actively treated in the field with KCentra to reverse anticoagulation, and 5 (28%) were treated in the field with antihypertensives. (See Figure for exemplar cases.) Conclusions: Extraparenchymal intracranial hemorrhages account for about 1 in 50 cases managed in Mobile Stroke Units. MSU response permits immediate definitive diagnosis by CT imaging, earlier start of indicated medical therapies, and direct routing to neurosurgically-capable stroke centers.