FlowSense Monitors Hydrocephalus Shunts: Exlusive with Anna Lisa Somera, CEO of Rhaeos


Hydrocephalus patients have an excess of cerebrospinal fluid in the brain, which needs to be drained away through a ventricular shunt. However, these shunts regularly fail, with potentially life-threatening results. At present, there isn’t an easy way to check that a shunt is still working, and clinicians typically use brain MRI/CT scans to see if a shunt is still draining correctly.

Not only are these imaging procedures inconvenient and expensive, but in the case of CT they may expose a hydrocephalus patient to significant amounts of radiation if regular assessments are required. To address this, Rhaeos, a company based in Illinois, is trying to bring to market its FlowSense device, a wearable non-invasive patch that looks like a bandage and which can provide data on flow through a shunt.  

Rhaeos was recently announced as the MedTech Innovator 2020 Grand Prize Winner, and will receive $350K in prize money. Medgadget had the opportunity to talk with Anna Lisa Somera, CEO of Rhaeos, about the FlowSense.

See a video about the FlowSense system below.

Conn Hastings, Medgadget: Please give us an overview of hydrocephalus and how it is currently treated.

Anna Lisa Somera: Hydrocephalus is an incurable neurological condition that over 1 million Americans live with for their entire lives. These patients, who have an overabundance of cerebrospinal fluid in their brains, are either born with hydrocephalus, acquire it through trauma, or get it through the natural aging process.

Hydrocephalus patients are typically treated with a ventricular shunt that drains excess fluid from the ventricles of brain to a distal site such as the abdomen. In the US alone, about 40,000 shunt placement procedures are performed and about $2 billion is spent on hydrocephalus treatment every year. Shunt technology, which consists of a valve and catheter, was first developed in the 1940s and remains largely unchanged today.

When working properly, ventricular shunts allow patients to live a full and active life as we’ve seen in one of our favorite teenage patients who swims competitively.

Medgadget: What are the potential consequences if a ventricular shunt stops working? How long do these shunts typically remain viable?

Anna Lisa Somera: It is a sad reality that these life-saving devices fail often. Studies have shown that about half of all shunts fail within two years and nearly all fail within about 10 years. In fact, many hydrocephalus patients suffer from frequent and repeated shunt failures that can land them in the emergency room or operating room multiple times every year. We have even met young patients who have had over a dozen brain surgeries before they even reach their teenage years.

When a shunt stops working, patients can experience many different symptoms, ranging from a simple headache to vomiting, disorientation, or dizziness. Left untreated, a shunt failure can be fatal. Many parents of children with hydrocephalus frequently bring their kids to the emergency room because symptoms that would be benign for most children – for example, picking up a stomach bug at preschool and vomiting in the middle of the night – can be evidence of a life-threatening condition for their child.

Medgadget: How do clinicians currently check to see if a ventricular shunt is working?

Anna Lisa Somera: Shunt failures are very hard to diagnose and impossible to predict, leading physicians to routinely order tests such as brain MRI or CT scans that are expensive and can expose patients to high doses of radiation. Diagnostic decision making is even more complicated when young children or patients who have difficulty communicating are involved and, because hydrocephalus patients often have comorbidities, this is frequently the case.

Unfortunately, the radiologic tests available to surgeons do not directly assess flow – the most direct indicator of shunt function – but instead give information only on secondary factors such as ventricle size and shunt mechanical defects. Because of this limitation, the diagnostic performance of these tests is poor. Nonetheless, these methods are widely used because there’s currently simply no accepted method to directly assess shunt flow non-invasively.

Also, repeated CT scans of the brain, especially in kids, is a significant cause for concern, as the lifetime radiation exposure can be quite high. This exposure is a widely-cited reason, among researchers as well as patients and parents, as a substantial motivator to find an alternative shunt assessment method.

Medgadget: Please give us an overview of FlowSense, and how it works.

Anna Lisa Somera: FlowSense is a wireless non-invasive flow sensor that is placed on the skin over the shunt tubing. It was invented by the John Rogers lab at Northwestern University – one of the biggest academic labs in the world and a leader in wearable technologies.

The device uses a small heater to gently increase the temperature of the skin directly above the shunt tubing and then precisely measures that temperature at upstream and downstream locations. When there’s no flow, we’ve seen that the temperature of the skin increases isotropically – equally in all directions around the heater. But when there is flow, the heat moves anisotropically – unequally around the heater – with a small but measurable relative temperature increase downstream from the heater. We use high-precision temperature sensors and Bluetooth technology to send this temperature data to an iPad, which analyzes the flow and gives feedback to the physician. This is all performed with a small flexible device with a form factor that makes it look a lot like a bumpy adhesive bandage.

Medgadget: When do you anticipate that the product will be available clinically? Are you currently pursuing clinical trials?

Anna Lisa Somera: Our first version of FlowSense, which we expect to bring to market in 2021, is a single-use disposable device intended for use in the hospital. It takes only about five minutes to complete the flow assessment. In our next-generation device, which we’ve recently begun to develop with a strategic partner, patients will be able to use the device at home – much like many of us use wearable fitness trackers – to not only assess flow at a given time, but also to predict a shunt failure before it sends them to the emergency room.

To date, we’ve been thrilled to work with world-renowned academic partners who have performed the first clinical evaluations of this technology at Northwestern Memorial Hospital and Lurie Children’s Hospital in Chicago, with the work published in Science Translational Medicine and NPJ Digital Medicine.

We’ve also had the privilege of working closely with the FDA to define our regulatory path and clinical data needs after having received a breakthrough device designation for FlowSense. We anticipate kicking off additional clinical studies early next year to gather data for regulatory approval and to show the economic value of FlowSense.

We anticipate that a great deal of the product development and clinical work will be funded through pending NSF and NIH grants in combination with investors in our current seed round. We plan to follow that with a Series A round to bring FlowSense to market next year.

Medgadget: Congratulations on winning the MedTech Innovator Grand Prize 2020. How does Rhaeos plan to use the winnings?

Anna Lisa Somera: Winning has been an enormous honor and is the culmination of a great deal of hard work from the Rhaeos team in collaboration with a fantastic slate of advisors. Our biggest goal when participating in the MedTech Innovator program was to really listen to the advisors and incorporate as much of their knowledge and wisdom as possible into our strategic plans. But to win the Grand Prize was beyond our wildest imagination.

We plan to use the proceeds to finalize the device development process and begin enrollment in our clinical studies. Perhaps more importantly, we hope to use the spotlight that comes with winning to highlight the challenges that hydrocephalus presents to patients and caregivers and the ways that we can use technology to improve their lives.

Link: Rhaeos company homepage…

Flashback: Non-Invasive Monitor for Hydrocephalus Shunt Malfunctions

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