You just can't e-mail blood samples

Pneumatic tubes converge in the diverter room, where packages from various hospital areas are routed to their proper destinations. Photo by Rex Bavousett.

But what if the message isn’t words but a blood sample? Or a medical document requiring an original signature? Or a bottle of pills? And with a sick patient to care for, every second counts? Try calling the blood bank and asking them to e-mail you a unit of O-negative, pronto.

At University of Iowa Hospitals and Clinics, the fastest way to get a small physical object from one place to another is the pneumatic tube transport system.

Pneumatic tube systems are sometimes depicted in the movies as a quaint old technology for getting notes back and forth within large buildings. Simply place your message in a sealed canister, pop it in a tube, and off it goes to its destination, whisked away on a puff of air.

Most people only encounter these systems at the drive-through lane at the bank. But for almost every large hospital in America, the pneumatic tube system is still a vital tool. Far from antiquated, these systems are complex, computer-driven, and constantly updated. While many transactions can be done by phone or e-mail, the tube system relieves the need for staff members to make trips around the hospital on foot.

"It’s one-third of a mile from one end of the hospital to the other," said Dick Bald, hospital engineer in Facility Capital Development. "It would take about seven to ten minutes to walk fast from end to end. And that’s if there are no elevator trips."

"A prescription drug can make the same trip in about two minutes via pneumatic tube, regardless of what floor levels the sender and recipient are on," said Karl Kamber, administrative pharmacist. "Many pneumatic tube transactions within the same region of the hospital complex are completed within 30 seconds."

At top speed, a canister whizzes through the tubes at 25 feet per second. If the canister contains a specimen in a fragile container, the speed is reduced to 15 feet per second.

Gloria Rolfson, nurse in the Medical Intensive Care Unit, loads a canister into one of 88 pneumatic tube stations. By entering information into the station’s keypad, she can send the canister to a station across the hospital in two minutes or less. Photo by Rex Bavousett.

The hospital actually has several tube systems lurking behind the walls and under the floorboards. The main system links 88 stations, positioned in labs, clinics, and nursing areas throughout the hospital, via a network of more than 22,000 feet of tube. This system connects the labs and the pharmacy to locations all over the hospital. There’s also a smaller system of just 10 stations that transports specimens from the different critical care areas to the Critical Care Lab. In addition, there are three specialized point-to-point systems, two for transporting samples between specialty clinic lab areas and the Specimen Control Lab area, and the third for transporting blood from the blood bank to the blood bank satellite and operating room suite.

These systems don’t just get occasional use. On a typical day, the UIHC tube system delivers about 3,000 canisters. During peak hours, between 7 a.m. and 7 p.m., the traffic moves at about 200 transactions per hour. If each transaction saved a person just five minutes of walking time, that means the whole system saves 250 hours of staff time every day.

Deep in the lower level of General Hospital is the heart of the system, a thunderously loud room called the diverter room. Madhav Kamath, facility operations engineer, explained the function of this room.

"It’s like the main switching yard of a railroad. In a small town, there are still going to be switching tracks, just as at the hospital there are small diverters elsewhere within each zone. But this is the main one where they interrelate."

What that means is that most canisters making their way through the main tube system must pass through the diverter room. Here, giant fans suck the packages in and blow them back out again. In between, they pass through a tangle of steel tubes and flexible switches that routes each package toward its proper destination. To prevent the packages from getting stuck, the tubes must make very wide turns, with a radius of four feet. The tubes in the diverter room are like a sculpture, with their gently curving lines.

Most of the time, though, there’s nobody inside the diverter room to enjoy the spectacle. In fact, except for repairs and regular maintenance, the system is designed to work 24 hours a day, 365 days a year, with no human intervention. Installed in 1978, it originally was controlled by a computer the size of a refrigerator. The most recent technological advance was the changeover to personal computers. Now the system is run by networked PCs, and the entire system is serviced by emergency power to assure that it is available for use. The hospital also maintains a supply of spare parts for immediate repairs as the occasion arises. From a monitor in the control room, engineers can follow individual packages as they wend their way across a schematic diagram of the whole system. On those rare occasions when a package doesn’t arrive, a call to the control room can track it down.

All of which raises one question. What happens to the empties when they’re not in use? Is there a central storage place for canisters that are, so to speak, on break?

As it turns out, no. The system is designed so that the empties are stored not in the middle, but at all the various end points.

"The analogy is that of a taxi stand," Kamath said. "Every sending or receiving station has a site where there are three taxis parked, waiting to pick up the next customers."

Odds are they won’t be waiting long.

Article by Sam Samuels