Prehospital neuroprotective therapy for acute stroke: results of the Field Administration of Stroke Therapy-Magnesium (FAST-MAG) pilot trial

Abstract

Background and purpose: To demonstrate that paramedic initiation of intravenous magnesium sulfate (Mg) in the field in focal stroke patients is feasible, safe, and yields significant time-savings compared with in-hospital initiation of neuroprotective therapy.

Methods: We performed an open-label clinical trial. Inclusion criteria were: (1) likely stroke as identified by the Los Angeles Prehospital Stroke Screen; (2) age 45 to 95; and (3) treatment initiation within 12 hours of symptom onset. Paramedics initiated 4 g Mg loading dose in the field, followed by 16 g over 24 hours in hospital.

Results: Twenty patients were enrolled, with mean age 74 (range 44 to 92), and 50% were male. Final diagnosis was acute cerebrovascular disease in all (ischemic 80%, hemorrhagic 20%). Study agent infusion began a median of 100 minutes after symptom onset (range 24 to 703), and 70% received study agent within 2 hours of onset. The interval from paramedic arrival on scene to study agent start was: field-initiated, 26 minutes (range 15 to 64) versus in-hospital initiated (historic controls), 139 minutes (range 66 to 300; P<0.0001). Paramedics rated patient status on hospital arrival as improved 20%, worsened 5%, and unchanged 75%. Median NIHSS on hospital arrival was 11 in all patients and 16 in patients unchanged since field treatment start. Good functional outcome at 3 months (Rankin < or = 2) occurred in 60%. No serious adverse events were associated with field therapy initiation.

Conclusions: Field initiation of Mg sulfate in acute stroke patients is feasible and safe. Prehospital trial conduct substantially reduces on-scene to needle time and permits hyperacute delivery of neuroprotective therapy.