Hospitals have a problem, and it’s not a new one. In fact, this problem has existed for as long as there have been hospitals, as long as people have gotten hurt or sick and needed extended periods or rest.
See, when people lie down for long periods of time — such as in a hospital bed — the inactivity resulting from this creates a unique issue: blood gets stuck in the veins running through their legs. Classified officially as “deep vein thrombosis,” these blood clots form behind valves within veins and can be serious. Sometimes these clots break free and travel to the lungs, where they cause a pulmonary embolism, which could be deadly. In fact, the Centers for Disease Control and Prevention (CDC) estimates that one in 10 in-hospital deaths in the United States are tied to deep vein thrombosis.
Although doctors and scientists have known that inactivity is tied to this issue since the middle of the 1800s, preventing it remains tricky. The best case involves getting patients to move around somewhat regularly, “stretching their legs,” to borrow an apt phrase. But some patients can’t do that for a variety of reasons, whether their recovery requires bedrest or they simply can’t get up. As a result, natural blood flow slows down and stagnates in the legs. In those cases, the standard tool used across health systems has been a mechanical cuff slid onto a patient’s legs that periodically inflates and stimulates blood flow.
However, this method was not actually founded in science, just general concepts about how blood flows. As a result, while it does help some patients, deep vein thrombosis remains an issue for immobilized patients. Even if clinicians mix in (costly) anti-coagulant drugs, there is a risk that the drugs could cause uncontrollable bleeding, which makes them unusable for the highest-risk patients, such as those who have had a stroke or a traumatic surgery.
It is here, where Mark Kahn, MD, the director of the Center for Vascular Biology, and his former post-doctoral researcher John Welsh, PhD, step in.
Kahn, Welsh, and a group of researchers decided to look at flow within the lymphatic vascular system, which then informed how they thought about venous valves and how they related to disease.
“We began to look at venous valves and their gene expression compared to lymphatic valves,” Kahn said “We got to understand something that wasn’t well understood: Venous valves were the point of origin for a lot of pathologies.”
Normally, the body’s defense against a condition like deep vein thrombosis is simple movement. The researchers showed that movements such as those caused by walking — flexing the foot which tightens the calf muscle — triggers a reflex that activates a program genetically hard-wired into your body to move blood rapidly through the body. In this, blood blasts through your valves and makes it difficult for any blood to get stuck behind the valve and clot.
But they found that when someone stops these movements that trigger the reflex — such as when they lie in hospital beds for long periods of time — that genetic system can go offline. As a result, blood flow slows and clots behind the valves. The standard cuffs being used to methodically promote blood flow weren’t doing enough to reactivate the program.
“They all functioned in a way that moved blood forward but didn’t have an effect on the valves that we thought was critical,” Welsh said.
Uncovering this system gave the clearest picture yet of why deep vein thrombosis happens. As such, Kahn, Welsh, and others determined that they could create a new tool to address it.
Initially, they called the tool “Osciflex” when they became a part of the Penn Health-Tech pilot award program in 2019. Through the program they developed a sleeve-like product that fit more comfortably than the cuffs. Initially, this product flexed the foot, which led to a reflexive movement of the calf muscle that triggered the body’s blood flow mechanism. But that, by nature, was uncomfortable. They tried tinkering, but, over time, it actually stopped producing the desired effect.
“We finally got one that was really comfortable, and I really remember this because it was on my leg when we figured it out,” Kahn said. “But it didn’t work anymore. It wasn’t triggering the reflex.”
This was where the team created the device they’re using now, which they think can create a huge difference clinically: the “Oscipulse.”
The concept was similar to the cuffs, but it focused on more rapid compression.
“It’s more like a quick tap, a fluid wave similar to the way things would behave during something like walking,” Kahn said.
This, theoretically, keeps the genetic blood flow program active and effectively moves blood along that might otherwise get stuck behind the valves. To test the Oscipulse, the pilot program enrolled 10 healthy people to test the hypothesis. They did this, Kahn said, by taking ultrasounds of the healthy people contracting their calves in the same way they would during walking. Then, they again imaged people using the device, as well.
“We really benefited from developing the ultrasound protocol and creating a biomarker to look for,” Welsh explained. “We were able to try out more compression, less, and then use ultrasound to assess changes in the design.”
The same pulse was seen in the calf muscle for people simply flexing and those wearing the device, indicating that the Oscipulse was mimicking healthy behavior.
Since then, the team spun a company out of Penn Health-Tech and named it after the initial device, Osciflex. On top of that, Oscipulse is now moving along in its progress toward FDA approval via a Phase II trial with roughly 20 in-hospital patients. The team received $1.7 million in funding from the National Institutes of Health’s Small Business Innovation Research program to set up the trial, which is underway. “Dream Team” funding from the Penn Cardiovascular Institute has also been a huge boon into testing the comfortability of the device for patients. Each is a step closer toward clinical use, which Kahn believes could just be a couple of years away.
“Our ultimate goal is to replace the compression devices that don’t work particularly well but are used on a majority of patients across the country,” Kahn said. “This is something that’s relatively simple, ready for manufacturing, and guided by research. We think it can help a lot of people.”
Editor’s Note: Kahn is the co-founder and chief medical officer of Osciflex. He stands to financially benefit from future commercialization of Osciflex’s products.