Hello, there. Hello!

My fascination with pneumatic tubes began a few summers ago during a family reunion in Maine. One of my sisters is a doctor, and one night while we lazed on a couch, she recounted how when she was in residency, she and her colleagues played a game where they would race against a canister going through the hospital’s tube system to see if they could beat its journey to the lab.

The story made me sit up, and not just because the canister always won. Tubes?! In this economy?

Like many, I thought pneumatic tubes — systems that use a blower to push or pull a cylindrical canister through a series of pipes — were an antiquated technology whose vestiges I saw in bank drive-thrus as a kid. But here was my sister telling me that tube systems were thriving in healthcare: we can’t digitize blood vials and lab samples (yet) and a canister moved by compressed air moves faster than a resident’s feet.

I was hooked and began setting up interviews.

“A pneumatic tube system today for a new hospital… is like putting a washing machine or a central AC system in a new home. It just makes too much sense to not do it,” said Cory Kwarta, CEO of Swisslog Healthcare, a corporation that — under its TransLogic company — has built pneumatic tube systems in hospitals for over 50 years.

Healthcare’s use of tubes, however, goes farther back than 50 years.

In the early 20th century, healthcare became a scientific endeavor, with different spaces within a hospital marked for new technologies — like x-rays — or procedures, like surgical units. “Instead of having patients in one place, with the doctors and the nurses and everything coming to them, and it's all happening in the ward, [hospitals] became a bunch of different parts that each had a role,” Jeanne Kisacky, an architectural historian who wrote about the rise of the modern hospital told me.

Hospitals got bigger because of this, which meant nurses and doctors spent much of their days moving from one department to another. That was an inefficient! And tiring on the feet!

Pneumatic tube technology stepped in to save the day. By the 1920s, more and more hospitals started installing tube systems. At first, the canisters moved medical records, prescription orders, and items like money and receipts — similar cargo to what banks and retail stores used tubes for at the time. As early as 1927, however, the systems were also marketed to hospitals as a way to transfer specimens to a central lab.

By the 1960s, tubes were becoming standard in healthcare. As a hospital administrator explained in the January 1960 issue of Modern Hospital, “We are now getting eight hours’ worth of service per day from each nurse, where previously we had been getting about six hours of nursing plus two hours of errand running.”

Efficiency for the win!

When computers and credit cards became a thing in the 1980s, canisters shifted to carrying lab specimens, pharmaceuticals, and blood products rather than pieces of paper.

Today, roughly 60% of what hospital tube systems carry are lab specimens, 30% are pharmaceuticals, and 5% are blood products for phlebotomy, with the remainder being miscellaneous items. (What kind of miscellaneous items, you ask? Consider this foreshadowing for next week’s post.)

The canisters, sometimes also called carriers or capsules, hold up to five pounds and move through piping six-inches in diameter — just big enough to hold a 2,000 milliliter IV bag — at speeds of 18 to 24 feet per second, or roughly 12 to 16 miles per hour.

The canisters could go faster, but its cargo might not fare well. If blood samples, for example, are jostled around too much, they can degrade, skewing lab results.

The technology has also gotten more sophisticated in recent years. Historically, carriers moved from one point to another via static tube lines. But in the 2010s, manufacturers developed networked systems. “It’s like a train system, and you're on one track and now you have to go to another track,” explained Steve Dahl, an executive vice president at Pevco, a company that has been building tubes for hospitals since 1978.

In a networked system, a canister moves from one tube line to another via a diverter or transfer unit, a device that can shift between tube lines depending on the final destination of a canister. Now, any new hospitals or retrofits happening will likely have networked capabilities.

Take Penn Medicine’s state-of-the-art Pavilion in Philadelphia. It opened in 2021 and has three pneumatic systems: the main one for items directly related to healthcare like lab specimens (which you can see in this cool video), and two separate ones for linen and trash. (Linen and trash, you say?! That’s right! Another post for another week!)

The Pavilion’s main system runs over 12 miles of pipe and completes over 6,000 transactions on an average day. Sending a canister from the two farthest points of the system — a distance that’s multiple city blocks — takes just under five minutes. To walk that distance would take around 20 minutes, not including getting to the proper floor where that item needs to go.

Michigan Medicine in Ann Arbor also has a massive network; it has over 6,000 daily transactions and 13.6 miles of tubes (this number is especially impressive considering that NYC’s pneumatic mail service had only 27 miles of tubes at its peak). Steven Fox, the pneumatic tube electrical engineer lead there, compared the scale his system moves to an African elephant, which weighs about six tons or 12,000 pounds. “We try to keep [a canister’s] load to five pounds apiece,” he said. “So we could probably transport about 30,000 pounds per day. That's two-and-a-half African elephants that we transport from one side of the hospital to the other every day!”

There are different tubes for different specimens as well: Michigan has a separate tube line dedicated for transporting nuclear medicine, which is radioactive. Getting the medicine to where it needs to be is a five to eight-minute walk — too long given its short shelf life. Instead, the medicine gets there — via a lead-lined capsule — in a less than a minute.

The equipment to maintain these labyrinthian highways is vast. Michigan and Penn have between 150 to 200 stations where doctors, nurses, and technicians can pick up or send off a canister. To keep those systems moving requires around 30 blowers and over 150 transfer units to shift a capsule to another tube line as needed. At Michigan Medicine, for example, moving a canister from one end of the system to another would see it go through 20 to 25 pieces of equipment to get there.

With systems this large and complex, there’s a lot that goes into managing and troubleshooting them. There are also tales about items that went through the tubes that just… shouldn’t have.

But that’s for next week’s post.

A portion of this post comes from an article I wrote for MIT Technology Review’s June 2024 issue.

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