Prehospital identification of acute ischaemic stroke with large vessel occlusion: a retrospective study from western Norway

Abstract

Background: In 2019, the emergency medical services (EMS) covering the western Norway Regional Health Authority area implemented its version of the prehospital clinical criteria G-FAST (Gaze deviation, Facial palsy, Arm weakness, Visual loss, Speech disturbance) to detect acute ischaemic stroke (AIS) with large vessel occlusion (LVO). For patients with gaze deviation and at least one other G-FAST symptom, a primary stroke centre (PSC) may be bypassed and the patient taken directly to a comprehensive stroke centre (CSC) for rapid endovascular treatment (EVT) evaluation. The study aim was to investigate the efficacy of the G-FAST criteria for LVO patient selection and direct transfer to a CSC.

Methods: This retrospective study included patients with code-red emergency medical communication centre (EMCC) stroke suspicion ambulance dispatch between August to December 2020. Stroke suspicion was defined as having at least one G-FAST symptom at EMS arrival. We obtained patient data from dispatches from EMCCs, EMS records and local EVT registries. Clinical features, CT images, and reperfusion treatment were recorded. The test characteristics for gaze deviation plus one other G-FAST symptom in detecting LVO were determined.

Results: Among 643 patients, 59 were diagnosed with LVO at hospital arrival. In this group, seven fulfilled the G-FAST criteria for direct transport to a CSC at EMS arrival on scene, resulting in a sensitivity of 12% (95% CI 5% to 23%). The specificity was 99.66% (95% CI 98.77% to 99.96%), the positive predictive value 78%, and the negative predictive value 92%. EVT was performed in 64% (38/59) of LVO cases. Median time from PSC arrival to start of EVT at a CSC was 163 min.

Conclusion: The use of local G-FAST prehospital criteria by EMS personnel to identify patients with AIS with LVO is not suitable for selection of patients with LVO for direct transfer to a CSC.

Keywords: emergency ambulance systems; pre-hospital care; stroke.

Figure 1

Flow chart presenting study population by diagnosis after ED assessment including imaging. For the AIS group, proportion of patients with LVO is presented, including the proportion of patients fulfilling G-FAST prehospital criteria for LVO stroke suspicion. Fulfilled G-FAST criteria demanded presence of gaze deviation, and at least one of the following symptoms present: facial palsy, arm weakness, visual loss and speech difficulties. EMS, emergency medical service; G-FAST, Gaze deviation, Facial palsy, Arm weakness, Visual loss, Speech disturbance.