Going to the doctor to take blood pressure readings gives an incomplete picture. People are generally nervous in the office and the readings are very high. But the biggest hurdle is that with infrequent measurements, doctors can take three to six months to determine the right medication and dosage to control hypertension.
Early on, Olgin and Sinha decided to see how much they could improve outcomes by getting patients to measure blood pressure at home. They undertook a study with homemade versions of blood pressure cuffs. Each day, the participants took their blood pressure. At the end of the study, he says, they found that doctors were able to develop the right treatment in 17 days, on average.
But getting consistent results from the home readings was difficult. Even high-end home devices suck: their clumsiness made them difficult to use, patients had to remember to keep them charged, and Bluetooth could be spotty. “It was an absolute nightmare to use these things,” says Sinha. “Everything in the process was painful for these people.”
A much better alternative would do without the unwieldy cuff. As he pondered how he could use a phone instead, Sinha began to wonder if a camera and flash could extract information with the tip of a finger. “Despite how far the fingertip is from your heart, it has a lot of arteries,” says Sinha. “So when your heart is beating, there is a huge volume of blood flowing through. It’s almost like a sound wave, switching between expansive and compressive. It is the waveform of the blood pulse.
Sinha’s idea was not original; people have been writing blood pulse waveform articles since the 1950s. But no one had yet found a reliable way to measure blood pressure with a phone. “There is this holy grail in the research community – can you use an ordinary base camera to capture things? says Shwetak Patel, a professor at the University of Washington (and recipient of a MacArthur Foundation “engineering” scholarship) who is involved in the development of these home tests, most recently for Google Health. Google recently released a pixel phone application that uses the camera to measure pulse and respiratory rate. But blood pressure, Patel says, is one of those holy grails.
In 2014, a company thought it had an answer. A company called Aura has released their Instant Blood Pressure app in the Apple App Store. “This app is a breakthrough for blood pressure monitoring,” “Archie1986” wrote in the App Store’s Top Review. But when the Federal Trade Commission looked into the matter, it found that the the application did not work. And? The FTC also discovered that the gushing approval of Archie1986 was issued by Aura’s CEO.
Sinha felt he could do better. Extracting the waveform from a person’s fingertip was the easiest part. The tricky part is analyzing it to get a useful blood pressure reading. Sinha says he has found a way, although it has yet to be validated from the outside.
When Sinha informed Olgin about his plans, the cardiologist was curious but cautious. “From a physical point of view, it made perfect sense. But it wasn’t until I started seeing the data coming in that I thought it was really going to work as expected, ”he says.
While he was perfecting his tool, Sinha shared his vision with a venture capitalist named Greg Yap who specialized in healthcare. When Yap became a partner at Menlo Ventures in 2019, he invested in Sinha’s business and invited her to move into Menlo’s office in San Francisco as part of a new project called Menlo Labs.
Working at Menlo Labs, Sinha was still trying to find a business model for her idea. He also needed to attract an experienced entrepreneur to run the business. Another Menlo partner, Shawn Carolan, had just the person in mind, someone he had funded in several successful ventures.