Background: MSU’s are capable of ultra-early treatment of acute stroke patients in the field. We tested field use of a high-resolution CT and CT-angiography on our MSU.
Methods: We designed and implemented the first of its kind MSU equipped with a 16 slice CT scanner (24-row adaptive detector array, fixed 70 cm gantry, auto-injection system, Somatom Scope, Siemens), led by stroke fellowship trained MDs or ANVP-board certified nurse practitioners without telemedicine support. Head/neck CTA was performed on all suspected stroke patients immediately following noncontrast CT. The MSU is embedded within local Fire/EMS and is activated by 911, or by on-scene medics 14 days/month. Transport and drug re-stock agreements were developed with Comprehensive, Primary, and CSC-Capable (CSC-cap) competing stroke centers.
Results: Of 420 activations in the first year, our MSU transported a total 206 patients: 127 (62%) strokes and 79 (38%) stroke mimics. In all 127 acute stroke patients (68±16 years, 58% women, 65% African American, 34% White, 1% Hispanic), median CT/CTA completion time, from start of scan, to images ready for diagnostic viewing, was 3.5 minutes (IQR 3-4). Diagnosis was 15 (12%) hemorrhages, 12 (9%) suspected TIA, 100 (79%) acute ischemic stroke (AIS). AIS median NIHSS was 9, IQR 7-17. IV-tPA treatment rate was 38% with median scene arrival to bolus time of 13 min, IQR 11-16. Large vessel occlusion (LVO) was found in 30% of ischemic strokes. No patients required repeat imaging on arrival due to image quality, and 100% were accurately triaged to CSC, PSC, or CSC-cap hospitals without the need for subsequent transfer.
Conclusions: MSUs can effectively operate a high-resolution automated CT similar to in-hospital radiology settings. The addition of head/neck CTA in the field yields a high rate of LVO detection supporting definitive prehospital triage to Comprehensive Stroke Centers.