Mayo Clinic's 1949 'Iron Monster' pneumatic tubes still makes thousands of deliveries a day

Apr. 12—ROCHESTER — In the 2024 world of cutting-edge AI technology,

Mayo Clinic's 1949 "Iron Monster" 4-by-7 inch pneumatic tube system

still moves thousands of plastic cylinders full of medical samples every day under Rochester's streets and through buildings.

The 75-year-old apparatus

and a "new" 6-inch system installed in 2000 move a combined total of about 10,000 packages daily through 52,908 feet of pneumatic tubes. That includes a 1.1-mile stretch of brass tubing under Second Street Southwest from Mayo Clinic's downtown campus to St. Marys Hospital.

Things that are too large for a carrier in the pneumatic system are transported in Electric Track Vehicle "cars," sort of an electric train that travels on tracks next to the downtown subway halls.

"The pneumatic tubes and our ETV system are still very critical for our existing facilities," said Mayo Clinic's Department of Facilities and Support Services Chair Doug Holtan. "Our volumes are still very strong and they are used every single day."

While pneumatic tube systems are used at most modern hospitals with more than 200 beds, Mayo Clinic was a pioneer in using the early 1800s technology.

Pneumatic tubes were famously introduced to Mayo Clinic by the inventive Dr. Henry Plummer. The heart of the tube system was built into the historic Plummer Building, which opened in 1928.

"Mayo has grown up around having very fast transport systems that can get important things, priceless things from one place to another very quickly," said Dean Black, who is in charge of Mayo Clinic's downtown conveyance systems. "The original equipment is not what we use today, but we use systems that are very, very, very similar. We just use computers to control them."

For decades, the system used air to push "tons of paper" in the form of patient records and X-rays around Rochester to aid patient care.

Most of those types of documents now travel digitally. However, air still whooshes thousands of carriers through Mayo Clinic's tubes today with patient blood samples and drugs making up most of today's cargo.

Doctors examining patients at the Mayo Clinic Emergency Department at St. Marys Hospital at 1216 Second Street SW can take a blood sample and load it into a tube carrier.

That sample will travel 1.1 miles through one of the two brass tubes running under Second Street to the fourth-floor labs in the Hilton Building at 210 Second St SW. Moving at 28 feet per second, it takes five minutes and 20 seconds to make the trip. Hilton technicians will quickly test the sample and message the results to the doctor, ideally within 20 minutes.

Given the kind of deliveries being made, it is easy to understand why medical staffers get nervous if the tube system isn't working. A slow delivery could impact a diagnosis and ultimately a patient's life.

"It has to work. It's possible that people could die if it doesn't," said Black. "It can be awfully frustrating. It has to run. When it's not working right, there's substantial pressure on us to fix it."

Black and his team are on-call after hours and on holidays. Sensors in the system track the progress of each carrier. While there are many calls about minor tube issues, major failures are very rare.

One major incident was in 1984. A damaged cylinder jammed up a tube during transit under Second Street between downtown and St. Marys Hospital.

Within a few hours, a special coupler was created to hook the clogged pipe up to a fire hydrant. Blasting 1,000 pounds of water into the tube solved the situation and popped the defective carrier out of Mayo Clinic's circulation system.

Another issue was when de-icing salt corroded the bolts used to fix a tube running under the Mayo Building sidewalk. All of the underground hardware is brass or galvanized, so using the ordinary bolts on a minor fix was the mistake that resulted in a major repair project.

Mayo Clinic's love for pneumatic tubes extends beyond downtown Rochester. Even Mayo Clinic's Northwest and Southeast facilities use pneumatic tubes, though they are not connected to the downtown or St. Marys systems.

They use tubes similar to what drive-up bank tellers use to deliver prescriptions to patients without needing to walk inside the doors. A messaging system connects to pharmacists and doctors to answer any questions that a patient might have about a drug.

The main Mayo Clinic system also transports drugs to nurses and doctors on the downtown campus and to St. Marys Hospital. The difference is that the drugs are delivered to secure stations, where a medical professional needs to use a code combination to access the drug delivery.

While air-driven tubes are the heart of Mayo Clinic's conveyance system, things that are too large for a carrier in the pneumatic system are transported via the ETV circuit.

Looking like a slightly-overgrown mailbox clinging to an old Lionel toy train track, the ETV system was installed in 1988 to deliver things too large for a pneumatic canister. Almost 400 ETV "cars" travel on 12,700 feet of track next to the subway halls. It is one of the largest such systems in use.

The ETVs and pneumatic system converge on Mayo Clinic's Tube Central hub in downtown Rochester where tracks line the ceiling and a string of side-by-side tube stations deliver carriers. While Tube Central is pretty quiet in 2024, black-and-white photos show it was packed with many people in the 1950s/1960s who would handle transferring packages to the correct tube or track to get them where they were supposed to go.

One thing that hasn't changed too much is the carrier cylinders. The hard plastic tubes have felted coverings on the ends. There are about 4,000 carriers in use at Mayo Clinic today.

The conveyance department checks all of the carriers every few weeks to see if any need repairs or should be retired. While that sounds like simple task, Mayo staffers grow very attached to their favorite carriers and want to protect them from being taken out of circulation.

"People love their carriers. They say 'That's my carrier. You can't have that.' They hide them everywhere. Some keep them up in the ceiling," said Black. "So carriers are easy to miss when you're out there maintaining stuff. You might not know that Nurse Suzy has her little stash of carriers that she hides that nobody else gets to use."

While pneumatic tubes are very efficient and useful, they are undeniably an old-fashioned device that calls to mind steam locomotives and other outdated technologies. However, these old systems still have capabilities that new tech can't match.

Black said Mayo Clinic made plans to retire the 1949 tube system back in 2010 or 2011. It was soon sidetracked when they realized the limitations of modern pneumatic tube systems.

"The four-by-seven was on the way out. The software we were running was written in-house. We don't do that anymore. It was difficult to find replacement parts and things. The plan was to take out the old reliable four-by-seven and completely replace it with a 6-inch system," recalled Black. "But a 6-inch system won't go the 1.1 miles between downtown and St. Marys, so we were kind of stuck. And the more we thought about it, there's no reason that this old reliable Iron Monster hardware."

A company came in and replaced the ancient electronics and put a new front-end operating system in place to run the 1949 iron and brass pneumatic tube system.

The question is how the "Iron Monster" will fit into Mayo Clinic's future projects, like the

$5 billion "Bold. Forward. Unbound" project

with new clinical buildings sporting cutting-edge artificial intelligence systems and robotics.

Black believes that pneumatic tubes will be pretty hard to replace.

"Until they come up with a Star Trek transporter that can fly a sample from one place to another, you gotta move it somehow," he said.

Nothing has been finalized yet when it comes to the plans for the next generation of Mayo Clinic buildings. However, new technologies are developing that might be able to handle the work done by the reliable Iron Monster.

"The electronic track vehicles and the pneumatic tubes have been a backbone for our existing facilities... They've served us very well. We do plan to incorporate the latest in robotics and automation technologies that have the ability to be even more efficient, faster into our facilities," said Holtan. "These new technologies, I think, are going to be the pneumatic tubes of the future for us, if you will."

While those plans for incorporating new ways to move a medical sample or a drug from one place to another are being worked out, Black and team will continue to work in Mayo Clinic's basements and mechanical rooms to keep the pneumatic tubes of today still moving thousands of carriers a day.