Clinical and Technological Approaches to the Prehospital Diagnosis of Large Vessel Occlusion
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- ambulance diversion
- brain ischemia
- emergency medical services
- emergency medical technicians
- sensitivity and specificity
Endovascular thrombectomy is highly effective for the treatment of acute ischemic stroke because of proximal large vessel occlusion,1 but the treatment effect falls rapidly with time.2 Almost all patients with severe stroke are transported by an emergency medical service (EMS), which is independently associated with reduced time to treatment.3 Nevertheless, delays are frequent in patients arriving for endovascular thrombectomy via secondary transport from another facility.1 To reduce time to treatment, some jurisdictions are exploring redirect policies, whereby patients bypass a closer primary stroke center and are instead transported directly to endovascular-capable facilities.4
Instituting a pathway for hospital bypass is a complex undertaking that involves the coordination of diverse stakeholders.4 Core components include patient selection criteria, interfacility agreements (eg, transfer and repatriation), paramedic training, and outcome evaluation. Approaches to patient selection have drawn recent interest, particularly in the use of simplified standardized clinical examinations for the diagnosis of proximal large vessel occlusion. In this review, we review current clinical and technological approaches to patient selection and discuss implementation in the context of jurisdictional features. The database search terms for this review article are provided in the online-only Data Supplement.
Diagnosis: Foundation for Triage
Proximal large vessel occlusion is the substrate for endovascular thrombectomy—field diagnosis of large vessel occlusion is the sine qua non for hospital bypass. In this section, we discuss important caveats in prehospital diagnosis and follow with a review of specific clinical and technological approaches.
Three caveats apply to the interpretation of studies of diagnostic tests for transport decision making: First, diagnosis is primarily a means to support transport decision making, not an end. If 2 diagnoses share the same transport destination, then it might not be so important to distinguish between them. For example, distinguishing between intracerebral hemorrhage (ICH) and large vessel occlusion may be …