Researchers at Worcester Polytechnic Institute have developed a smartphone app that uses a camera to measure key vital signs. The type of technology used by the Worcester researchers is far and above more useful than a simple heart rate monitor, such as the Instant Heart Rate app.
Recently, the Instant Heart app makers received millions in funding — I hope it wasn’t based solely on the heart rate monitor app they have developed. Having a patient’s heart rate alone isn’t that useful for a clinician, and it’s extremely easy to measure your heart rate on your own, just put your fingers to your wrist or neck.
But the work by Worcester researchers is completely different, exciting and unlike the Instant Heart Rate app, could have real impact. The researchers have developed an application that uses the smartphone’s built-in video camera to not only measure heart rate, but heart rhythm, respiratory rate and blood oxygen level (pulse ox) — all without needing a peripheral device. Amazing.
Other than blood pressure and temperature, these are four key vital signs we clinicians are always monitoring in our patients. Knowing a heart rate alone doesn’t help me too much, but knowing a patient’s respiratory rate is elevated along with a decreasing pulse ox tells me they are headed in the wrong direction.
The implications for this are enormous.
For example, imagine if asthmatics have this application. They could monitor their own vital signs, and be easily able to communicate if their blood oxygen concentration is getting low while they are having an acute asthma exacerbation.
Another great application, if a patient is short of breath and having pleuritic chest pain, he or she can use this app. If it shows an elevated heart rate and decreased oxygen concentration, one of my immediate differential diagnoses is a pulmonary embolism (blood clot in the lungs).
So how accurate is this app? Per researchers, in their paper, they say just as accurate as traditional peripheral devices.
This is how the smartphone app works:
The application, developed by Chon and WPI colleagues Yitzhak Mendelson, associate professor of biomedical engineering, Domhnull Granquist-Fraser, assistant professor of biomedical engineering, and doctoral student Christopher Scully, analyzes video clips recorded while the patient’s fingertip is pressed against the lens of the phone’s camera. As the camera’s light penetrates the skin, it reflects off of pulsing blood in the finger; the application is able to correlate subtle shifts in the color of the reflected light with changes in the patient’s vital signs. Chon, who is an expert on signal processing, has previously developed algorithms that monitor a range of vital signs using traditional clinical devices like a Holter heart monitor. In the new study, Chon and his team created and adapted algorithms to process the data gathered by the phone’s video camera.
Researchers used a Droid smartphone for their tests, but state the technology could easily be transitioned to other smartphones with video capability.