What If Stroke Diagnosis Started in the Ambulance? The Role of Portable Technology in Accelerating LVO Detection and Treatment

Each year, approximately 795,000 Americans suffer a stroke,¹ making it a leading cause of disability and death nationwide. Of these, more than 100,000 experience a large vessel occlusion (LVO),² a severe form of ischemic stroke requiring rapid diagnosis and intervention. This article explores how portable technology, particularly optical blood flow monitors, can revolutionize prehospital stroke diagnosis and improve outcomes by enabling faster and more accurate triage in the ambulance.

Speed is critical for reducing the devastating effects of LVO stroke. Endovascular therapy (EVT) can remove the clot from the brain to restore blood flow and improve stroke outcomes. Because 2 million neurons die each minute,³ treatment should begin as early as possible for the best possible outcome, but EVT is only available at specialized stroke centers. Therefore, ensuring patients are directed to the correct hospital is paramount.

Emergency medical services (EMS) often lack reliable tools to determine whether a patient experiencing a stroke is also experiencing an LVO in the field. As a result, EMS providers transport most patients with LVO to the nearest hospital rather than directly to a facility equipped for EVT. Once the LVO is diagnosed in the emergency department, the patient will then be transported to an EVT-capable hospital, but this delay in treatment diminishes the overall benefit.

Portable devices known as optical blood flow monitors use noninvasive light-based technology to measure cerebral blood flow in real time. By detecting disruptions in blood flow patterns, these monitors can quickly identify LVO strokes and empower EMS providers to make more informed transport decisions.

A recent study⁴demonstrated that this technology outperforms examination-based techniques in detecting LVO stroke in patients who present to the emergency department with suspected acute stroke. A follow-up paper⁵explored how the detection threshold can be adjusted to prioritize either sensitivity or specificity, which could support a more tailored triage strategy across different care environments.

Studies of Optical Blood Flow Monitors’ Effectiveness

The initial study, conducted in 2024 by researchers at the University of Pennsylvania and Brown University, aimed to improve early detection of LVO. It evaluated 135 patients with suspected stroke within 24 hours of symptom onset. All patients underwent a 70-second bedside scan with the optical blood flow monitor,⁶ as well as standard acute stroke imaging, including CT angiography, to confirm or rule out LVO.

Among the cohort, 39% had LVO. The device demonstrated a sensitivity of 79% for detecting LVO,⁷ meaning it correctly identified nearly 4 of 5 patients who truly had LVO. It also achieved a specificity of 84%, indicating it accurately ruled out LVO in more than 4 of 5 patients who did not have the condition.

In current practice, some EMS providers use examination-based stroke scales to identify patients who are likely to have LVO. The optical blood flow monitor demonstrated significantly greater accuracy in identifying LVO, as determined by receiver operating characteristic (ROC) analysis. Researchers concluded that optical blood flow monitoring may offer a more reliable method for identifying LVOs in prehospital settings.

Advancing Stroke Detection in the Field

Building on the initial findings, a 2025 follow-up commentary⁵ from researchers at the University of Pennsylvania, Brown University, and Temple University emphasized that “one size does not fit all” when it comes to LVO treatment. EMS systems face different constraints depending on their location, such as distance to the nearest stroke center or limited ambulance availability. Still, most current screening tools use a fixed standard to determine whether a patient likely has LVO without considering EMS factors and local hospital dynamics. For example, the cost of a false positive or a false negative may be different in urban vs rural systems of care.

The authors explored how tools like optical blood flow monitors could support a more nuanced decision-making process by adjusting the diagnostic threshold based on local needs. For example, the cost of missing an LVO is high. As a result, many regions may prefer to prioritize sensitivity, acknowledging that this increases the number of false positives. In urban centers, where the distance between hospitals is relatively short, this may be viable. However, in more rural settings, systems may need to prioritize specificity to minimize false positives if resources cannot support longer transport times to an EVT-capable hospital.

Together, the study and follow-up commentary point to new ways technology can more accurately diagnose patients with LVO. When EMS teams have better tools to identify an LVO early, they can make faster and more informed decisions about where to take a patient.

Adapting Optical Blood Flow Imaging for Individualized Care

Today, EMS teams rely mostly on examination-based stroke scales, such as the Rapid Arterial Occlusion Evaluation or the Los Angeles Motor Scales, to assess stroke severity in the field. Although these tools are quick and easy to use, they have limitations when it comes to accurately identifying LVO.⁸ Thus, there remains a clear need for a reliable and highly accurate LVO detector in the prehospital space.

Expanding access to reliable LVO detection tools in ambulances can significantly increase the number of patients who receive timely and effective treatment. Portable cerebral blood flow monitors can help EMS teams decide whether a patient should bypass the nearest hospital and head straight to a specialized stroke center.

This technology can help reduce false negatives, meaning fewer patients with LVO are mistakenly sent to hospitals that can’t treat them. It also cuts down on false positives, preventing unnecessary transfers to advanced stroke centers. As a result, emergency departments are less likely to be overwhelmed, and stroke teams can stay focused on the patients who truly need their care.

The Future of Stroke Diagnosis and Treatment

Research has long shown that the sooner an LVO is identified and a patient receives EVT, the better their chances of recovery. A recent study⁹ of patients with acute LVO stroke reinforced that point. The study showed that patients who received EVT were more than twice as likely to regain functional independence and had lower mortality rates a year after their stroke.

As optical blood flow imaging technology continues to advance, so does its potential to transform how we diagnose and treat stroke. With improved accuracy, portability, and adaptability, noninvasive technologies could make stroke diagnosis faster, more individualized, and better aligned with real-world care.

Emerging technologies such as portable optical blood flow monitors have the potential to transform stroke diagnosis and treatment. By enabling faster and more accurate detection of LVO strokes in the field, these tools can help ensure patients receive the right care at the right time.

As research and collaboration among clinicians, technologists, and EMS providers continue, integrating portable optical blood flow monitors into standard emergency protocols could mark a turning point in stroke care. This advancement would help ensure that more patients receive timely, targeted treatment, ultimately improving survival and recovery rates nationwide.

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