A Mobile Stroke Treatment Unit for Field Triage of Patients for Intraarterial Revascularization Therapy Russell Cerejo, Seby John, Andrew B. Buletko, Ather Taqui, Ahmed Itrat, Natalie Organek, Sung-Min Cho, Lila Sheikhi, Ken Uchino, Farren Briggs, Andrew P. Reimer, Stacey Winners, Gabor Toth, Peter Rasmussen, Muhammad S. Hussain From the Cerebrovascular Center, Cleveland Clinic, Cleveland, OH (RC, SJ, AT, AI, KU, SW, GT, PR, MSH); Department of Neurology, Cleveland Clinic, Cleveland, OH (ABB, NO, SMC, LS); Department of Epidemiology and Biostatistics, School of Medicine, Case Western Reserve University, Cleveland, OH (FB); Critical Care Transport Team, Cleveland Clinic, Cleveland, OH (APR); and Frances Payne Bolton School of Nursing, Case Western Reserve University, Cleveland, OH (APR).

ABSTRACT INTRODUCTION: Favorable outcomes in intraarterial therapy (IAT) for acute ischemic stroke (AIS) are related to early vessel recanalization. The mobile stroke treatment unit (MSTU) is an on-site, prehospital, treatment team, laboratory, and CT scanner that reduces time to treatment for intravenous thrombolysis and may also shorten time to IAT. METHODS: Using our MSTU database, we identified patients that underwent IAT for AIS. We compared the key time metrics to historical controls, which included patients that underwent IAT at our institution six months prior to implementation of the MSTU. We further divided the controls into two groups: (1) transferred to our institution for IAT and (2) directly presented to our emergency room and underwent IAT. RESULTS: After 164 days of service, the MSTU transported 155 patients of which 5 underwent IAT. We identified 5 historical controls that were transferred to our center for IAT. Substantial reduction in times including median door to initial CT (12 minute vs. 32 minute), CT to IAT (82 minute vs. 165 minute), and door to MSTU/primary stroke center departure (37 minute vs. 106 minute) were noted among the two groups. Compared to the 6 patients who presented to our institution directly, the MSTU process times were also shorter. CONCLUSION: Our initial experience shows that MSTU may help in early triage and shorten the time to IAT for AIS.

Keywords: Mobile Stroke Treatment Unit (MSTU), prehospital emergency care, stroke, thrombectomy. Acceptance: Received March 31, 2015, and in revised form May 27, 2015. Accepted for publication May 28, 2015. Correspondence: Address correspondence to Muhammad Shazam Hussain, Cerebrovascular Section, Cleveland Clinic, 9500 Euclid Ave, S80, Cleveland, OH 44106. E-mail: [email protected]. Contributorship Statement: Russell Cerejo and Seby John contributed equally and should be considered cofirst authors of this manuscript. All authors contributed toward the study design, data interpretation and writing of this manuscript. J Neuroimaging 2015;25:940-945. DOI: 10.1111/jon.12276

Introduction Recent published trials have proven the efficacy of intraarterial therapy (IAT) for treatment of acute ischemic stroke (AIS) due to emergent large vessel occlusion (ELVO).1–5 While multiple factors influence the outcome of patients after IAT, fast and effective reperfusion is of paramount importance. As noted with intravenous (IV) thrombolysis, “time is brain” is similarly applicable to endovascular reperfusion irrespective of the method, and the likelihood of a favorable outcome is closely and directly linked to the time to reperfusion.6 Despite many multicenter registries available regarding IAT for AIS, much of the focus has been on the intraprocedural aspects of treatment, with sparse emphasis on prehospital processes. Sun et al recently reported that more than three-quarter of the delays to reperfusion occurred before the start of IAT, which correlated with poorer outcomes after the procedure.7 The “hub-and-spoke” model of interfacility transfers is becoming routine as more comprehensive stroke centers (CSCs) become certified. A large proportion of patients eligible for and treated with IAT will eventually be transferred from primary stroke centers (PSCs) to CSCs. Significant delays exist within current hospital transfer practices at various stages of

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the process, with the transfer itself introducing delays. With the known strong correlation of time and stroke outcome, such delays are expected to produce lower than anticipated outcomes with endovascular therapy. Therefore, the transfer process requires substantial improvement. One strategy that reduces the time to treatment is the provision for diagnosis and treatment directly at the emergency site. The Mobile Stroke Treatment Unit (MSTU) is a new model of ambulance-based prehospital stroke treatment that has been implemented in two German cities and recently in Houston, USA and has been shown to be feasible for prehospital IV thrombolysis.8–10 Our institution launched an MSTU in July 2014. We report our initial experience of patients with AIS, triaged and transferred by the MSTU who underwent IAT and report the impact of the MSTU on the prehospital stroke care processes for patients with AIS eligible for endovascular treatment.

Methods The Cleveland Clinic MSTU pilot project is a collaborative effort between the Cleveland Clinic and the City of Cleveland,

◦ 2015 by the American Society of Neuroimaging C

Fig 1. Pictures of mobile stroke treatment unit (MSTU) and area served by MSTU. (A) Map showing city limits of Cleveland covered by MSTU. (B) The MSTU Ambulance. (C) Inside the MSTU – showing point of care laboratory testing and telemedicine equipment. (D) Inside the MSTU – showing CT scanner, patient gurney, MSTU personnel seats. OH. The MSTU covers Cleveland city limits spanning 77.70 square miles, serving an estimated population of 390,113.11 The MSTU is equipped with a certified critical care transport nurse, paramedic, emergency medical technician, and computed tomographic (CT) technologist. A vascular neurologist evaluates the patient via telemedicine (InTouch Health RP-XPRESS) and, both the neuroradiologist and the vascular neurologist can remotely assess images obtained by Ceretom (Neurologica, Danvers, MA) mobile CT, which are sent via 4G Verizon network with a dedicated bandwidth. The MSTU is also equipped with a portable point of care (POC) laboratory that can measure hemoglobin, platelet count, white blood cell count, prothrombin time/INR, blood glucose and serum electrolytes (Fig 1). The MSTU runs from 8 am to 8 pm, seven days a week and is based at the Cleveland Clinic main hospital campus. When the emergency medical service (EMS) of the city of Cleveland receives a “911” call, the Medical Priority Dispatch System – Stroke Diagnostic Tool is used to alert for possible stroke, which if positive results in the simultaneous dispatch of a regular EMS ambulance and the MSTU.12 Initial clinical assessment by the EMS is performed using the Cincinnati Prehospital Stroke Scale.13 If EMS determines that symptoms are nonstroke, the MSTU is called off. If suspicious for a stroke, the MSTU team assumes care and obtains a brief history, identifies and registers the patient in our electronic health records, obtains vital signs, and stabilizes the patient if necessary. The patient is then

transferred into the MSTU where a noncontrast enhanced CT scan of the head is performed and the data are transmitted to the neuroradiologist. A peripheral IV catheter is inserted and blood is drawn for necessary POC laboratory testing. The stroke physician assesses the patient via telemedicine and completes a National Institute of Health Stroke Scale (NIHSS) score. Through the electronic health record, prior encounters with the patient (if applicable) and neuro-imaging can be reviewed by the treating neurologist. Depending on the clinical scenario, appropriate therapy is administered in the MSTU. If determined to be an ischemic stroke, IV thrombolysis is administered in the MSTU, if patients meets appropriate criteria. The patient is then transported to the nearest stroke center with resources to meet the stroke type and severity. If patients have NIHSS ࣙ 8, they are triaged immediately to an interventional capable center. Institutional review board approval was obtained for this study. The following time points were collected: last known well time, time EMS/MSTU was dispatched, door time (time patient entered the MSTU, or time patient arrived in the emergency room (ER) for historical controls), time of first CT, time of MSTU departure from the scene or time of departure from PSC and groin puncture time. Using the MSTU database, we identified those patients who were triaged by the MSTU who underwent IAT for AIS. We compared these patients to historical controls that were transported to our enterprise hospitals via

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Table 1. Clinical Characteristics and Key Metrics of: (1) Patients Evaluated in MSTU versus Patients Transferred from PSC to CSC (2) Patients Evaluated in the MSTU versus Patients Initially Evaluated at CSC Characteristics

Gender [males (%)] Age in years [median (IQR)] NIHSS [median (IQR)] tPA [n (%)] Anterior Circulation AIS [n (%)] Advanced Imaging CT Angiogram [n (%)] MRI [n (%)] Times in minutes [median (IQR)] Dispatch to MSTU/PSC Door Door to CT Door to MSTU/PSC Departure Transport between MSTU/PSC to CSC CSC Door to IAT CT to IAT MSTU/PSC Door to IAT

MSTU (n = 5)

PSC→CSC (n = 5)

3 (60) 75 (51.5 – 81) 19 (18.5 – 21.5) 5 (100) 5 (100)

2 (40) 82 (64.5 – 89.5) 11 (9 – 21) 2 (40) 5 (100)

4 (80) 3 (60) 19 (16 – 24) 12 (9 – 13.5) 37 (22.5 – 40) 14 (6.5 – 15) 52 (39.5 – 63) 82 (65.6 – 103) 93 (75 – 116.5)

5 (100) 3 (60) 31(26 – 40) 32 (22 – 36.5) 106 (103.5 – 119.5) 26 (15 – 29.5) 75 (49 – 88) 165 (150-201) 200 (185-223)

CSC (n = 6)

5 (83) 71 (51.25 – 79.25) 9.5 (7 – 20) 3 (50) 5 (83.33) 6 (100) 4 (67) – 14 (12 – 17) – – – 127 (53.75 – 152.75) 140.5 (70 – 163.75)*

MSTU = Mobile stroke treatment unit; tPA = Tissue plasminogen activator; Dispatch = Time EMS / MSTU was dispatched; PSC = Primary stroke center; CSC = Comprehensive stroke center; IAT = Intraarterial therapy; AIS = Acute ischemic stroke; IQR = Interquartile range. * CSC door to IAT.

Cleveland EMS six months prior to implementation of MSTU and underwent IAT for AIS. Inclusion criteria for these patients were: (1) initial evaluations at stroke centers/ER that are also served by MSTU and (2) presentation between 8am to 8pm. Patients that clinically deteriorated after initial assessment and were then taken to IAT were excluded. In this comparison, door time was taken as PSC or MSTU door time. We also compared data on patients who presented to our institution (CSC) directly via EMS or self-transport with AIS, and subsequently, underwent IAT in the six months prior to implementation of the MSTU. We only included patients that presented between 8 am to 8 pm. All historical controls were triaged by a neurologist either personally or over the phone.

vs. 106 min). The transfer time to the CSC once departed and the time from CSC arrival to groin puncture were also similar between groups. We also compared the MSTU data to patients presenting directly to our CSC ER either via EMS or private transport. Out of 238 patients that presented to our ER during the stipulated time period, 8 patients underwent IAT out of which 6 patients met inclusion criteria. Clinical characteristics and time key metrics between the MSTU and this cohort are elaborated in Table 1. The door to IAT times and CT to IAT times were 93 minutes versus 140.5 minutes and 82 minutes versus 127 minutes, respectively.

Discussion Results As of December 31, 2014, after 164 days in service (3-days off for routine maintenance), the MSTU had been dispatched 539 times and had transported 155 patients. Among these, 5 patients were determined at have an AIS from ELVO at the scene and triaged directly to an interventional capable center. They underwent CT Angiogram in the hospital that confirmed ELVO and were subsequently taken for IAT. Between January 2014 and mid-July 2014, 425 patients were transferred to our facility for stroke of which 31 underwent IAT. Five of these were patients met inclusion criteria for the historical control group. They were initially evaluated at a PSC and were subsequently transferred to IAT capable centers. Baseline characteristics of the MSTU and control group are outlined in Table 1. Two patients in the control group were transported by air from the PSC to CSC, the remaining patients were transported by the ground. Median key times for the two groups are outlined in Table 1. The time from dispatch to door was similar in both groups (dispatch times were available for only 3 patients in the control group). Patients evaluated in the MSTU had shorter door to IAT times (93 min vs. 200 min) and CT to IAT times (82 min vs. 165 min) compared to controls. On further evaluating the transfer times we found that time spent in the MSTU was substantially less compared to a PSC (37 min 942

Our early experience with the use of MSTU demonstrates its effectiveness in rapid triage of patients with AIS from ELVO to a facility with interventional capabilities, thereby, saving precious time spent in interhospital transfers. Our data reveals that although time from EMS dispatch to arrival to a PSC was similar to the MSTU, longer length of time was spent in the PSC before the patient was eventually transferred to a CSC. This time was almost threefold longer in the control group. Consequently, the time from door to groin puncture, and the first picture to groin puncture was shorter by almost one-half in the MSTU group. All 5 patients triaged by the MSTU went on to have successful recanalization, with significantly improved postprocedure examination (Table 2). Our data further suggest that initiating prehospital acute stroke care in the field did not delay the time to IAT when compared to patients that presented directly to CSC (Fig 2). Approximately 35–40% of all patients experiencing AIS suffer an ELVO within the internal carotid artery, middle cerebral artery, and vertebro-basilar vasculature.14,15 The number of options for endovascular treatment of AIS has increased substantially over the past decade and with the advent of stent-retrievers, recanalization rates have improved significantly (TICI 2b/3 rates of 80-90%).16 Initial trials studying

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Table 2. Clinical Details of Patients Evaluated in the MSTU and Control Groups that Underwent IAT Patient

Initial NIHSS

IV tPA

Patients Evaluated in the MSTU 1 19 Yes 2 19 Yes 3 20 Yes 4 23 Yes 5 18 Yes Patients Evaluated Directly at CSC 1 9 No 2 29 Yes 3 10 No 4 7 Yes 5 7 Yes 6 17 No Patients Transferred from PSC → CSC 1 16 No 2 26 No 3 11 Yes 4 8 Yes 5 10 No

Advance Imaging (MRI)

Thrombus Location

Initial TICI

Final TICI

Discharge NIHSS

Yes No No Yes Yes

RICA/M1 Sup. R M2 Right M1 Left ICA Left M1

0 0 0 0 0

2B 2B 2B 3 2B

8 3 1 0 3

No Yes Yes No Yes Yes

Basilar/ L PCA RM1/LICA Left M1 RICA RICA/RM1 LICA

0 0 0 0 0 0

3 0 3 3 2B 3

0 N/A 3 4 6 N/A

No Yes No No Yes

Right M1 LCCA/LM1 Right M1 Left M1 Right M1

1 0 0 0 0

1 2B 0 2B 2B

11 N/A N/A 2 6

MSTU = Mobile stroke treatment unit; PSC = Primary stroke center; CSC = Comprehensive stroke center; ICA = Internal carotid artery; M1 = First segment of middle cerebral artery; M2 = Second segment of middle cerebral artery; CCA = Common carotid artery; PCA = Posterior cerebellar artery; TICI Score = Thrombolysis in cerebral infarction score; NIHSS = National Institute of Health Stroke Scale; IV tPA = Intravenous tissue plasminogen activator.

Fig 2. “Door to IAT”: Comparison amongst groups and potential areas of delay (MSTU = Mobile Stroke Treatment Unit; PSC = Primary Stroke Center; CSC = Comprehensive Stroke Center; IAT = Intra-arterial therapy; *median).

clinical outcomes, such as IMS III, were not able to show the efficacy of endovascular therapy, due to use of older devices and also due to prolonged times to groin puncture and recanalization. More recently, five clinical trials (MR CLEAN, ESCAPE, EXTEND-IA, SWIFT PRIME, and REVASCAT) have established the clinical effectiveness of IAT for ELVO.1–5 These trials utilized stent-retriever technology and also focused on early, rapid treatment, which contributed to the benefit seen. As with IV thrombolysis, time is of utmost importance for all forms of endovascular reperfusion. Evidence from intraarterial cohorts has also shown evidence of improved recovery and lower mortality in patients who achieved short onset to reperfusion times.6 However, delay in transferring patients to centers that provide endovascular therapy is a major limitation.17,18 A single-center retrospective study suggested that for every minute of delay in transfer, there is a 2.5% lower probability that a patient receives endovascular therapy.17 In the Interventional Management of Stroke (IMS) III study, patients who received tissue plasminogen activator (tPA) at another facility

before transfer had longer times to groin puncture, compared to patients who did not receive tPA or those in whom tPA was given in the same hospital where endovascular treatment was performed.19 Also, one of the few trends for benefit was in the subgroup of patients who received IV tPA within 2 hours of symptom onset and those who has groin stick for IAT within 90 minutes of IV tPA administration.20 With the known strong correlation of time and stroke outcome, such delays are expected to produce lower than anticipated outcomes with endovascular therapy. As more CSCs become certified, the “hub-and-spoke” model of interfacility transfers from PSCs to CSCs will ultimately constitute a large proportion of patients treated with IAT.21 Substantial delays exist within this transferring process. Current practices at many facilities have inefficiencies between EMS arrival and hospital departure. These include time spent in activating the helicopter, transporting of the transport team to the patient’s room, repeating clinical assessments, printing copies of hospital records, returning back to the helipad, and reactivating the helicopter engine while loading the patient. Many of the same delays apply for ground transport transfers also. The significance of faster transfer can be enormous. In a recent analysis of patients in the Rapid Reperfusion Registry, median time from onset of symptoms to groin puncture was 234 minutes. The authors calculated that if the IAT curve could be shifted by 60 minutes closer to the 3-hour mark as observed in the second quintile of their dataset, the overall rate of good outcome approached 48.5%. This rate of good outcome would establish an absolute difference of 10% when compared to the IV tPA group in IMS III, which was the estimated difference in powering the original study.7 Therefore, transfer time is a crucial area that needs substantial improvement. One novel strategy that reduces the time to treatment is the provision of diagnosis and treatment directly at the emergency site (the MSTU concept). This strategy was first proposed in Germany in 2003,22 and shown to be feasible in 2010,23 In 2012, Walter et al reported findings from a

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single-center prospective randomized trial involving 100 patients in Saarland, Germany.8 They demonstrated a 50% reduction in the delay to a therapy decision regarding IV tPA administration. The median alarm to-therapy decision time of 35 minutes and the symptom-onset-to-needle time of 72 min were shorter than all other reported time limits for stroke management. In 2014, Ebinger et al reported on a similar model implemented in Berlin, Germany.9 The study included 6182 patients who were randomized to weeks with and without availability of the mobile stroke ambulance. Compared to control weeks, there was a reduction by 25 minutes from mean-alarm to treatment time. In addition, the rate of tPA administration was 33% during MSTU weeks, compared to 21% during control weeks. Apart from prehospital thrombolysis, the MSTU concept enables prehospital triage of cerebrovascular patients to be transferred appropriately.24 Our study is the first report of the demonstration of MSTU effectiveness in triaging AIS patient for IAT. Our data suggest that the time spent in the PSC where initial evaluation and treatment was performed contributed the most to the delay to IAT. The MSTU obviates the need for an additional hospital stop before being transferred to an interventional capable center, and as such drastically shortens time to reperfusion with IAT. The importance of time delay encountered in transfers has been recognized in cardiology, in the care of patients with acute coronary syndrome. The American Heart Association defined the door-in/door-out time metric to collect the time interval from admission to the first hospital to ambulance departure to the treatment hospital. Faster treatment time and lower mortality was achieved when the door-in/door-out time metric was 30 minutes or less.25 Despite the improvement in recanalization rates and procedure times,26–29 a look at the time interval from last known well to treatment from 1999 to 2013 has not decreased substantially and remains close to the 4–5 hour time window described in PROACT II.30 Similar to cardiology, treatment of stroke also has to focus on the prehospital assessment and triage of patient.31 Multiple time metrics have been proposed for IAT for stroke, with no consensus on a single time metrics. Some of the measures include door-to-puncture,7 picture-to-puncture,32 and puncture-to-reperfusion. The first two metrics measure in part, delays associated with patient transfer. Result from our initial experience shows a drastic decrease in both these measures using the MSTU. Irrespective of the metric use, the MSTU reconfigures these times by bringing the ER to a patient with stroke, and may help improve outcomes with IAT.

Conclusion Prehospital assessment and triage of patients with severe AIS from ELVO directly to CSCs is an important mechanism to significantly decrease time to treatment. Our initial experience demonstrates the effectiveness of the MSTU in this process and holds significant promise for improving outcomes in AIS patients eligible for IAT by decreasing time to IV thrombolysis, and time to mechanical thrombectomy.

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