New portable device detects severe stroke with high accuracy in seconds
A portable volumetric impedance phase shift spectroscopy (VIPS) device worn like a visor is able to detect emergent large vessel occlusion (ELVO) indicative of severe stroke with 93 percent sensitivity and 92 percent specificity within seconds — placing its accuracy above current standard physical examination tools and unveiling its potential to improve the triage of patients with severe stroke requiring endovascular therapy (EVT).
“Transfer between hospitals takes a lot of time,” said study co-author Professor Raymond Turner of the Medical University of South Carolina in Mount Pleasant, South Carolina, US. “The benefit of EVT, however, is highly time dependent, with each additional hour resulting in up to a 20 percent decreased chance of achieving a good outcome … If we can give the information to emergency personnel out in the field that this is a large-vessel occlusion, that should change their thought process in triage as to which hospital they go to.”
The new VIPS device works by transmitting low energy radio waves through the brain. When there is a severe stroke, changes in the brain’s fluid lead to changes in the wave frequency reflected back, producing a bioimpedance asymmetry which is then detected by the device.
The study involved three cohorts of participants (mean age 62 years, 45 percent men): a healthy cohort (n=79), patients presenting with acute stroke at a comprehensive stroke centre (CSC; n=41), and patients presenting to CSCs with wide ranging brain pathology (n=128). [J Neurointerv Surg 2018;doi:10.1136/neurintsurg-2017-013690]
Compared with diagnoses by neurologists, the VIPS device could differentiate severe stroke from minor ones with 93 percent sensitivity and 92 specificity.
Similarly, the device showed a sensitivity of 93 percent and specificity of 87 percent in identifying severe stroke from all other subjects tested.
According to the researchers, the accuracy of the VIPS device is above that of existing diagnostic tools (sensitivity of 55–85 percent, specificity of 40–89 percent) based on physical examination, which are highly user dependent.
“The ideal diagnostic test to improve patient triage would be portable, fast, require minimal specialized training, pose no additional risks to the patient, perform in a reproducible and accurate manner, and be low cost such that it could be widely adopted in all ambulances to integrate into our current triage system,” said Turner and co-author, and the new device appears to satisfy most of the criteria.
Turner believed that the role of the VIPS device in severe stroke identification is akin to that of ECG in acute myocardial infarction.
“Future testing is necessary to validate this device as a diagnostic tool in specific patient populations and settings,” said Turner and co-authors. “With such a high diagnostic accuracy for severe stroke, other potential settings where triage is necessary might include locations with people at a higher than usual risk for stroke, such as nursing homes, in operations with increased stroke risk such as cardiothoracic surgery or carotid endarterectomy, and settings removed from standard medical care, such as cruise ships, flights, and third world settings where neuroimaging is not readily available.”