Going to the doctor’s office to take blood pressure readings provides an incomplete picture. People are usually nervous in the office, and the readings tilt high. But the bigger obstacle is that with infrequent measurements, doctors can take three to six months to figure out the proper medicine 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 home versions of blood pressure cuffs. Every day the participants took their blood pressure. When the study ended, he says, they found the doctors were able to nail down the appropriate treatment in 17 days, on average.
But getting consistent results from the home readings was difficult. Even top-of-the-line home devices sucked—their clunkiness made them hard to use, patients had to remember to keep them charged, and the Bluetooth could be flaky. “It was an absolute nightmare to use those things,” Sinha says. “Everything about the process was painful for these folks.”
A much better alternative would dispense with the unwieldy cuff. As he thought about how he might use a phone instead, Sinha started wondering whether a camera and flash might extract information from the fingertip. “Despite how far the fingertip is from your heart, it has a lot of arteries,” Sinha explains. “So when your heart beats, there’s a huge volume of blood coming through. It’s almost like a sound wave, toggling between expansive and compressive. That’s the blood pulse waveform.”
Sinha’s idea wasn’t original; people have been writing papers about the blood pulse waveform since the 1950s. But nobody had yet found a reliable way to measure blood pressure with a phone. “There are these holy grails in the research community—can you use an ordinary commodity device to capture things?” says Shwetak Patel, a University of Washington professor (and MacArthur Foundation “genius” grant winner) who is involved in developing such at-home testing, most recently for Google Health. Google recently released a Pixel phone app that uses the camera to measure pulse and respiratory rate. But blood pressure, Patel says, is one of those holy grails.
In 2014, one company thought it had an answer. An outfit called Aura released its Instant Blood Pressure app in Apple’s App store. “This app is a breakthrough for blood pressure monitoring” wrote “Archie1986” in the App store’s top review. But when the Federal Trade Commission looked into it, it found that the app didn’t work. And? The FTC also discovered that the gushing endorsement from Archie1986 was posted by Aura’s CEO.
Sinha felt he could do better. Extracting the waveform from a person’s fingertip was the easy part. The tricky part is analyzing it to get a useful blood pressure reading. Sinha says he’s come up with a way, though it still needs to be externally validated.
When Sinha told Olgin about his plans, the cardiologist was curious but cautious. “From a physics standpoint, it made perfect sense. But it wasn’t really until I started to see the data come in that I thought that this was really going to work the way it’s supposed to,” he says.
Around the time he was perfecting his tool, Sinha shared his vision with a venture capitalist named Greg Yap whose specialty was health care. When Yap became a partner at Menlo Ventures in 2019, he invested in Sinha’s company and invited him to move into Menlo’s San Francisco office as part of a new project called Menlo Labs.
Working from Menlo Labs, Sinha was still trying to figure out a business model for his idea. He also needed to attract an experienced entrepreneur to lead the company. Another partner at Menlo, Shawn Carolan, had just the person in mind, someone he had funded in multiple successful ventures.