The Science Behind STAT

How It Works

Shining A Light On Invisible Illness

STAT uses infrared light to measure blood flow changes in a shallow ear artery, which is an ideal window into the heart and brain. Unlike wrist-worn wearables that can only reach shallow capillaries which contain limited cardiac information, STAT aims directly at a shallow arterial branch of the External Carotid Artery, a parallel branch of the Internal Carotid Artery which is the primary blood supply to the brain. This enables unprecedented cardiac signal quality for a non-invasive wearable. Patents pending.

The Untapped Biometric Gold Mine of the Ear

This high quality signal is the secret sauce that enables STAT to infer new metrics from the detailed pulse waveform shape. STAT is no longer limited to basic metrics like other wearables, such as heart rate, but can now infer new metrics like STAT’s Flow Index and STAT’s Pressure Index.

STAT's Flow Index

See an example STAT pulse waveform below - note how a “normal flow” pulse looks “full” in comparison to how a “low flow” pulse looks “spurty.” The spurtiness occurs because the heart is not being filled with enough blood before it squeezes, most often caused by gravity pulling blood into the lower body so it can’t reach the heart. This causes the heart to “dry-heave” and pump out short spurts of blood (doctors call this “reduced preload”). This change in waveform shape is a key part of how the STAT Flow Index works. STAT's Flow Index does not output clinically relevant flow values such as mL/min or cm/s, but instead provides a 0-20 index to help you understand your body’s blood flow response to standing.

Note the “fullness” of the normal flow pulse on top, as compared to the “spurtiness” of the low flow pulse on bottom.

STAT's Pressure Index

STAT’s Pressure Index tracks relative changes in blood pressure by observing changes in the speed that pressure waves travel through your arteries. When your heart pumps, a primary pressure wave leaves your heart then bounces around your arterial tree. This shows up in STAT’s signal as multiple different peaks as you can see in the signal above. If blood pressure drops, pressure waves travel slower causing the relative locations of the reflected peaks to shift.

STAT’s Pressure Index does not output mmHg, but instead provides a 0-20 Trend score to help you understand your intraday blood pressure variations. STAT’s Pressure Index is not intended for diagnostic use and intentionally cannot be back-calculated/compared against diagnostic criteria such as the 130/80 mmHg hypertension threshold. Below is an example waveform of STAT’s Pressure Index vs a clinical monitor approved by the FDA to track continuous blood pressure in the ICU. This data was captured during tilt table testing at Duke where the patient experienced wild blood pressure variations leading to syncope.

Unlocking Data on Standing

Traditional wearables cannot accurately track standing because the motion and orientation of your wrist or finger do not tell you much about your body position. However, STAT is on the head, which is tightly coupled to the spine and experiences the largest vertical changes upon standing. By using an accelerometer, pressure sensor, and machine learning, STAT tracks exactly when you stand, how long you remain standing, and when you sit/lay back down. See below for how STAT analyzes your body’s response to each individual stand throughout the day:

Left: STAT CEO’s Intraday Heart Rate (peach curve) and Pressure Trend (blue curve) on April 7, 2023. Right: STAT CEO body’s response to a single stand from 2:17pm-2:22pm on April 7, 2023

Research

STAT is initially focused on creating a consumer digital health app that complies with the FDA’s “General Wellness” and “Device Software Functions and Mobile Medical Applications” guidances. This means STAT cannot be used for diagnostic purposes, and can only be used as a tool that may help patients live well with orthostatic conditions by enabling better self-management of symptoms. However, STAT is conducting ongoing validation research with top research institutions to generate the evidence for future potential usage as a remote patient diagnostic and/or a reimbursed medical device. The research displayed on this page may demonstrate future capabilities that will not be tied into the consumer “General Wellness” offering. The consumer device cannot have diagnostic utility, and the consumer’s user experience is being intentionally designed to avoid being misused in this way.

JACC:EP Johns Hopkins Report using STAT during Routine Tilt Table Testing (May 2023)

We tested the STAT device at Johns Hopkins during Tilt Table Testing, and STAT was able to pick up blood flow abnormalities much earlier than clinical ECG and a Blood Pressure Cuff were able to. It detected blood flow drops 2-12 minutes before they actually passed out.“ - Dr Hari Tandri, Cardiologist at Johns Hopkins

JACC publication reporting STAT usage in Johns Hopkins Tilt Table Testing

View Publication

Dysautonomia International Conference Research Update by STAT CEO, Daniel Lee, and Duke Cardiologist, Dr Marat Fudim (July 2023)

Science has already proven that the cause of most orthostatic symptoms is a decrease in blood flow to the brain. However, tracking this critical missing vital sign has been challenging, which is why many illnesses like POTS and ME/CFS remain “invisible.” That's why I'm thrilled about STAT, as it can track a correlate to cerebral blood flow much more easily and in an ambulatory fashion at that.” - Dr Marat Fudim, Cardiologist at Duke University