Usually in Tech In Plain Sight, we talk about technology you probably see every day, even if you don’t notice it. But we hope you don’t get to see one of the latest crop of medical robots, such as the LUCAS chest compression system. If you watch the popular TV series “The Pitt”, though, you may have caught a glimpse of one of these medical marvels. They aren’t fiction. They are very real devices.

Calling them robots might be stretching the definition a little. They don’t roam the halls looking for patients. But once attached to someone in cardiac arrest, they can take over one of the most important — and physically demanding — parts of CPR: chest compressions.

Keep The Blood Moving

When someone’s heart stops pumping blood, time is critical. CPR doesn’t normally restart the heart on its own. Instead, chest compressions produce enough blood flow to keep oxygen reaching the brain and heart while rescuers work on the underlying problem and, when appropriate, use a defibrillator.

Doing that well is harder than it looks on television. Current American Heart Association guidelines call for adult chest compressions 100 to 120 times per minute, at least 5 cm deep but generally no deeper than 6 cm, while allowing the chest to recoil fully between compressions. Interruptions should be kept to a minimum.

That’s hard physical work. In fact, studies show compression depth begins to fall after only about 90 to 120 seconds, which is one reason CPR teams normally swap compressors every two minutes. But a robot doesn’t get tired.

Meet LUCAS

LUCAS stands for Lund University Cardiopulmonary Assist System, reflecting the device’s origins in Lund, Sweden. Early versions entered clinical use around 2002-2003 and were pneumatically powered. Later versions replaced the compressed-gas system with an electric motor and battery.

The current LUCAS 3 looks something like a small drill press straddling the patient as you can see in the video below. A backplate goes beneath the torso, and a frame locks onto it. An electrically driven piston presses a suction-cup-like pad against the sternum. Internally, the motor drives a belt and ball screw that moves the piston up and down.

Factory settings are around 102 compressions per minute and roughly 53 mm compression depth for a typical adult, although parameters can be configured.

Beyond tirelessness, another obvious advantage is that LUCAS doesn’t need hands. Medics can deal with ventilation, drugs, defibrillation, IV access, and the dozens of other things occurring during a cardiac arrest. More importantly, the device can keep compressing while a patient is being carried, wheeled through corridors, or transported in an ambulance — situations where doing good manual CPR is awkward and sometimes dangerous to the practitioner.

So Does It Save More People?

You might reasonably expect perfectly regular machine CPR to beat a tired human. Large randomized trials haven’t demonstrated that, however. The 4,471-patient PARAMEDIC trial found 30-day survival of 6.3% with LUCAS versus 6.8% with manual CPR, not a statistically significant difference. The 2,589-patient LINC trial similarly found essentially identical four-hour survival — 23.6% versus 23.7% — and no significant improvement in longer-term neurological outcomes.

That doesn’t make the machines useless. It says something slightly different: high-quality mechanical CPR hasn’t proven superior to high-quality manual CPR as a routine replacement. The International Liaison Committee on Resuscitation currently recommends against routine mechanical CPR, while specifically noting that it can be a reasonable alternative when sustained manual compressions are impractical or would endanger the practitioner.

One issue is setup. Installing the machine adds a time penalty: compressions must stop briefly while the backplate and mechanism are positioned. Good training is essential to keep that interruption short. Another problem is that some studies show potential links to higher rates of internal chest injuries, such as bleeding around the lungs. There have also been rare device malfunctions or power failures that can compromise care.

Not The Only Game In Town

LUCAS isn’t alone. ZOLL’s AutoPulse takes a very different mechanical approach. Instead of a piston pushing on one spot, a motor tightens a broad load-distributing band around the patient’s chest.

There’s also the German corpuls cpr, which returns to the piston idea but uses a cantilevered single-arm mechanism. That leaves much of the chest unobstructed and makes the system useful during procedures such as cardiac catheterization.

So perhaps these aren’t quite the autonomous robot doctors science fiction promised us. But when your heart has stopped, and a machine is tirelessly pumping your chest a hundred times a minute while the medical team works around it, you probably won’t complain. We hope you don’t have to find out.

We’ve seen DIY devices, though certifying medical devices for actual use isn’t for the faint of heart. Robots can also help train humans to do better CPR.

Featured image is a still from the instructional video “Physio-Control LUCAS 3 Chest Compression System – Hospital Use” by MFI Medical.

Humanoid robots, even scaled-down ones, tend to be expensive. The Berkeley Humanoid Lite offers a more accessible and economical option by centering the design around 3D printed actuators that make up the bulk of the robot’s frame.

The actuators are made by combining motors with printed cycloidal gearboxes and an embedded magnetic encoder. They’re modular, so even if one has no desire to recreate the whole robot it might be worth checking out the actuator design details to see if they might be useful in some other way.

The Berkeley Humanoid Lite isn’t a finished product so much as an open-source, easily customized reference design. The GitHub repository contains everything one might need, and you can watch some basic demonstrations, including VR-driven teleoperation, in the video embedded below.

At a total hardware cost of under $5,000 USD it’s still expensive, but much more economical than other humanoid robots, open-source or not. As mentioned, even if one doesn’t plan to build one, the modular actuator design is worth keeping in mind for other purposes.

Many of us have noted a tremendous price increase in many computer components for some mysterious reason. Whatever this cause is will be debated among the various modern philosophers and Diogeneses, but regardless of cause we all still have to live in this world and make do. That turns us towards getting maximum value from the things we already have rather than trying to go out and buy more computer components right now, like [svofski] using his vast swath of existing microSD cards to build an SD card library.

The library is based around a tiny robotic arm that can physically grip the cards and move them in and out of a reader. The first iteration of the arm involved rotating the two pincers, but this turned out to be overly complicated and [svofski] eventually settled on a design resembling a rack and pinion that slides the two pincers together instead. With the gripper sorted out, it’s placed in system called T-bot arrangement, similar to coreXY kinematics, that lets it pick and place among 12 microSD card slots.

Many of the parts in this build were directly from or inspired by 3D printers, making it relatively simple with so many parts available. [svofski] didn’t build it for a specific use case, though; mostly it was constructed out of fascination for robotic tape changers which perform a similar function. But for anyone who actually needs to duplicate a large number of SD cards, or other types of removable media, this could prove to be a fairly handy robot.