We’ve written about the quest for reliable and valid contact-free blood pressure measurement devices in the past. An impressive partnership among Cardiex, Blumio, and Infineon Technologies formed last July to develop radar-based blood pressure management. In 2018 we wrote about FibriCheck’s FDA approval for a photoplethysmography (PPG) and artificial intelligence app to detect heartbeats and detect atrial fibrillation.

The search for a clinical-grade blood pressure reading PPG-based app is still on. Toronto-based NuraLogix introduced such an app for general wellness awareness at CES 2021. Anura, the NuraLogix app, does not rely on traditional PPG with LED light sources against the skin, Instead, it uses Transdermal Optical Imaging (TOI) that is based on video images. A proprietary AI engine records blood pressure and a menu of additional wellness measurements based on facial blood flow. A conventional smartphone, laptop, or tablet video camera can provide 30 second a 30-second video of the subject’s face.

NuraLogix is careful to note in the app and on its website that Anura is not suitable for medical purposes to diagnose, treat, mitigate, or prevent any disease, disorder, physical state, or symptom. The app’s purpose is to improve the user’s awareness of their general wellness, according to the website disclaimer.

So, of course we tried it out to see how it compared with other devices. I installed the Anura Android version on a Samsung Note 8. I compared blood pressure and heart rate readings from Anura with readings from an Omron portable blood pressure monitor (model BP742N) and heart rate readings from a Fitbit Versa 2 smartwatch. I took multiple comparative readings at various times of the day using myself and my wife as subjects. To run the test, you hold the phone still for 30 seconds with your face fully in an onscreen circle. The app takes comparative measurements based on blood flow color at four locations on your face. Before taking the test you enter your age, height, weight, gender, and whether you have and are taking medication for hypertension.

For both my wife and me, the Anura app’s heart rate readings were spot on according to the results from the Omron and Versa 2. The app’s blood pressure readings were approximately the same as the Omron results for both systolic and diastolic blood pressure for my wife. The app was not so accurate in reading my blood pressure. The Anura app was very close to the Omron with my diastolic BP readings, differing in most test runs by 3 to 7 mmHg at most. Anura’s systolic BP readings on several occasions on two different days differed from the Omron from 4 to 20 mmHg, however. The greater differences in systolic readings were when my blood pressure was running at higher than my normal levels.

Even though the Anura app doesn’t claim to deliver medically precise blood pressure readings, my informal tests show that appears to perform well as a general-purpose wellness indicator. In addition to blood pressure, heart rate, heart rate variability, stress, and respiration rate, the app reports on cardiac workload, BMI, stress, waist-to-height ratio, body shape index, and facial skin age. Finally the app assigns derived cardiovascular risk, heart attack risk, and stroke risk percentages and an overall general wellness score. I can’t speak to the accuracy of any of those scores or assessments, but I also didn’t see any surprises.

As an impressive demonstration of the potential of image processing and AI, NuraLogix’s current app may be a sign of future developments that could be accurate enough for medical use.