High-tech toilet seat monitors your heart as you sit on the can

If developing heart disease scares the poo out of you, this new monitor may be just the thing.

Engineers at Rochester Institute of Technology have designed a high-tech toilet seat that effortlessly flushes out data on the state of your cardiovascular system. The tricked-out porcelain throne measures your blood pressure, blood oxygen level, and the volume of blood your heart pumps per beat (stroke volume)—taking readings every time you sit down to catch up on some reading of your own.

The engineers, led by David Borkholder, recently published a prototype of the seat in the open-access journal .

According to the inventors, the seat’s daily data dump could make patients and their doctors privy to early warning signs of heart failure, potentially helping to prevent further deterioration and avoid costly hospital stays. Moreover, the seat could ease in-home monitoring for heart patients, who often strain to consistently track their tickers with other, non-toilet-based monitors.

“The toilet seat–based cardiovascular monitoring system has the potential [to] fill a gap in patient monitoring by capturing trend data that has been previously unattainable,” they write. “This system has the potential to address many of the challenges with in-home monitoring in a form factor that integrates into the daily routine of patients, bypassing barriers to adherence and providing a comprehensive and accurate set of clinically relevant measurements.”

For their design, Borkholder and colleagues aimed for a wireless, battery-powered, easily-cleanable seat with embedded sensors that transmit measurements to a cloud database. The design includes sets of sensors that read three types of information: sensors on the top of the seat measure the heart’s electrical activity, reporting an electrocardiogram (ECG); a single sensor also on the top takes an optical measure of blood volume, creating a photoplethysmogram (PPG); and four load sensors on the bottom of the seat (which is attached to a toilet with a floating hinge) measure the ballistic force of the cardiac cycle, recording a ballistocardiogram (BCG).

Using combinations of this data, the seat estimates stroke volume, blood pressure, and the peripheral blood oxygenation.

The PPG sensors are used to assess peripheral blood oxygenation, taking optical measurements on the back of the thigh at two wavelengths (red and infrared), as in standard pulse oximetry.  This is based on the principle that oxygenated hemoglobin and deoxygenated hemoglobin absorb the light differently (oxygenated absorbs more infrared, while deoxygenated absorbs more red light). By comparing the two waveforms and calibrating the seat to each individual patient, the readings can estimate oxygenation.

The engineers noted that the BCG readings have previously been found to correlate with the amount of blood forced out of the left ventricle of the heart at every beat. Together, with cardiac cycle information from the ECG, the seat uses BCG data to estimate stroke volume, which is an important indicator of how well the heart is pumping.

Last, the seat estimates blood pressure with a set of calculations from BCG and PPG data.  Earlier research found that blood pressure can be estimated using the pulse wave velocity of blood, which is the speed with which a pressure wave shoots down arteries. That wave velocity can be extrapolated using an estimate of a patient’s aorta length and the time it takes for the wave to go down it. The toilet-monitor squeezes out an estimate for transit time by comparing the timing of the ballistic measurements of a heart beat and the wave features in the peripheral arteries, which are measured by the optical PPG sensors.

To see how their toilet seat estimates stacked up to standard, hospital-grade equipment, the engineers recorded blood pressure and blood oxygenation readings from 18 volunteers over 8 weeks, taking readings up to five times a week. They also compared the seat’s stroke volume estimates to those of nearly 150 patients undergoing standard ECGs in a hospital. In all cases, the seat generally hit within the accuracy ranges of standard equipment, in some cases exceeding accepted accuracy standards.

The engineers say that the seat needs more testing and they’d like to compare it to other measurement methods, such as a cardiac MRI. However, they’re hopeful that it could one day “facilitate the transition from a reactive to proactive-based approach to health care,” catching cardiovascular problems long before they become dire.

The toilet-based monitor does have one, rather significant draw back though: the seat doesn’t actually work while a user is, well, using the toilet. Relieving oneself messes up the measurements.

“In future in-home studies, algorithms will be developed to identify and reject periods of urination and defecation through classification of motion artifacts and the physiologic shifts associated with this change in state,” the engineers write.

, 2018. DOI: 10.2196/12419  (About DOIs).

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