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009 The ambulance clinical triage-for acute stroke treatment (ACT-FAST) algorithmic pre-hospital triage tool for endovascular thrombectomy: ongoing paramedic validation
  1. Henry Zhao1,2,
  2. Lauren Pesavento1,2,
  3. Edrich Rodrigues1,
  4. Patrick Salvaris1,
  5. Karen Smith3,
  6. Stephen Bernard3,
  7. Michael Stephenson3,
  8. Mark Parsons1,2,
  9. Nawaf Yassi1,2,
  10. Stephen M Davis1,2,
  11. Bruce CV Campbell1,2
  1. 1The Melbourne Brain Centre and Department of Neurology, Royal Melbourne Hospital, Melbourne, VIC, Australia
  2. 2Department of Medicine, Faculty of Medicine, Dentistry and Health Sciences, The University of Melbourne, Melbourne, VIC, Australia
  3. 3Ambulance Victoria, Melbourne

Abstract

Introduction The ambulance clinical triage-for acute stroke treatment (ACT-FAST) algorithm is a severity based 3-step paramedic triage tool for pre-hospital recognition of large vessel occlusion (LVO), designed to improve specificity and paramedic assessment reliability compared to existing triage scales. ACT-FAST sequentially assesses 1. Unilateral arm fall to stretcher <10 s; 2a. Severe language disturbance (right arm weak), or 2b. Severe gaze deviation/hemi-neglect assessed by shoulder tap (left arm weak); 3. Clinical eligibility questions. We present the results of the ongoing Ambulance Victoria paramedic validation study.

Methods Ambulance Victoria paramedics assessed ACT-FAST in all suspected stroke patients pre-hospital in metropolitan Melbourne, Australia, and in the Royal Melbourne Hospital Emergency Department since July 2017. Algorithm results were validated against a comparator of ICA/M1 occlusion on CT-angiography with NIHSS ≥6 (Class 1 indications for endovascular thrombectomy).

Results Data were available from n=119 assessments (ED n=68, pre-hospital n=51). Patient diagnoses were LVO n=20 (15.6%), non-LVO infarcts n=45 (38.5%), ICH n=10 (8.3%) and no stroke on imaging n=44 (37.6%). ACT-FAST showed 85% sensitivity, 88.9% specificity, 60.7% (72% excluding ICH) positive predictive value and 96.7% negative predictive value for LVO. Of 10 false-positives, 4 received thrombectomy for non-Class 1 indications (basilar/M2 occlusions/cervical dissection), 3 were ICH, and 1 was tumour. Three false-negatives were LVO with milder syndromes.

Discussion The ongoing ACT-FAST algorithm validation study shows high accuracy for clinical recognition of LVO. The streamlined algorithmic approach with just two examination items provides a more practical option for implementation in large emergency service networks. Accurate pre-hospital recognition of LVO will allow bypass to endovascular centres and early activation of neuro-intervention services to expedite endovascular thrombectomy.

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