#7 Visor for Prehospital Stroke Diagnosis 


When a patient has suffered a stroke, his or her outward symptoms often suggest the condition; weakness in the body, slurred speech, and confusion. From outward appearance, however, it is difficult say with confidence the cause and type of stroke a patient is experiencing. Confirmation of stroke and identification of stroke type are the most crucial steps to intervention. And as timing of intervention is of the utmost importance, rapid diagnosis is essential. Once a patient has arrived at the hospital, medical staff is able to properly diagnose a stroke, and visualize the blocked artery (ischemic stroke), or the ruptured blood vessel (hemorrhagic stroke) causing trauma. However, a speedy trip to the hospital is not always ensured. To make use of the downtime that is the ride to the hospital, engineers have designed a visor for prehospital stroke diagnosis.

A noninvasive bioimpedance spectroscopy device that detects changes and distribution of cerebral fluids, the visor is able to detect brain pathologies like stroke, trauma, swelling, and others. When placed on a patient’s head, the visor emits low-energy frequency waves through the hemispheres of the brain. As the waves pass through the brain’s fluid, their frequencies change. The visor then assesses the changes in frequency between the two hemispheres. If the frequencies are markedly different, they indicate the occurrence of a stroke – the greater the difference, the greater the stroke’s severity.

Intended for use by emergency medical technicians, the visor is expected to be instrumental in providing hospital staff a more clear patient profile and speeding up time to treatment. Much like the portable ECGs used to triage patients in emergency situations, the visor is an efficient diagnostic tool. Diagnosis of a stroke with the visor in the field allows for immediate patient transport to comprehensive stroke centers with the ability to treat stroke – centers that are not always the first stop. In addition to ambulances, the visor also has applications in locations with high stroke probability (e.g. nursing homes) and settings where neuroimaging is not readily available (e.g. developing nations).

In studies, the visor has shown a 92% accuracy rate in identifying patients that have suffered a major stroke, while the accuracy rate of stroke diagnoses for emergency medical personnel using standard physical examination tools has been known to range anywhere from 40-89%. The device received FDA 510(k) clearance in January 2018 and is expected to be commercially distributed and used in the year 2019. The clearance includes a broad indication for use as an aid in the assessment of fluid volume differences between the cerebral hemispheres in patients undergoing neurologic assessment. The company is continuing clinical studies to further validate the device for identifying specific brain pathologies, including hemorrhage. With stoke they say “time is brain,” and implementation of the visor is poised to save both.

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