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Carts: Energy and Environment

June 25, 2010
by John Degaspari
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A dependable power supply and seamless blending with EHR form the foundation of successful cart-based deployments
Chuck podesta
Chuck Podesta

Cart-based computing has proven to be a dependable resource in clinical settings, providing an excellent opportunity for point-of-care documentation. Where they have been successfully deployed, carts - or Workstations on Wheels (WOWs), in common parlance - have freed nurses, physicians and other clinicians from the need to jot down notes on paper or trundle back and forth between the patient's bed and a unit's stationary computers. For that to happen, of course, carts must operate seamlessly in the hospital unit's wireless and physical environments, as well as provide plenty of power for laptops and other electronic devices within easy reach of the health professionals who use them.

Case in point: the Burlington, Vt.-based Fletcher Allen Healthcare, which introduced carts as part of the rollout of its electronic health record (EHR) system that went live last June. “When we went live on the inpatient records on EHR, carts were part of the implementation,” says Chuck Podesta, Fletcher Allen senior vice president and CIO. Prior to its EHR launch, the hospital had almost no carts; it now has over 250 carts in service, and will soon be adding more, he says.

Yet the mobility that Fletcher Allen's WOWs have provided has come with a host of technical issues that needed to be carefully sorted through well in advance of the deployment of the carts or the EHR launch, Podesta says. One was the presence of a dependable wireless network, allowing the untethered laptops to exchange data with a server. The other was a robust battery that will last through an entire shift.

As a power source, Podesta says the hospital settled on nickel-metal hydride batteries, after initially trying sealed lead-acid batteries. The decision was based on battery life and charging time, he explains. Sealed lead-acid batteries provide power for six to eight hours, while nickel-metal hydride batteries supply power for up to 14 hours, depending on the type of use. Nickel-metal hydride batteries fully recharge in three hours, half the charge time of their lead-acid counterparts. The carts are equipped with a low-battery signal to alert the clinician about a drained battery. “Most clinicians will plug in the cart [battery] and move to another cart to continue working,” Podesta says. The battery manufacturer also offers a recycling program, allowing convenient disposal for batteries.

Equally important to power consumption are the devices themselves. At Fletcher Allen, the carts power laptop computers linked to a separate flat-screen monitor and keyboard. Podesta says the hospital also makes use of energy-efficient thin client computers that sign on to the server through the wireless network.

Texas Health Resources, a 14-hospital system based in Arlington, has a five-year track record with carts, which now number about 1,000 in the system's facilities. “Carts are used in every nursing department on the clinical side in all of our hospitals,” says chief technology officer Mark Eimer. He reports that the experience has been positive overall.

At Texas Health, sealed lead-acid 12-volt batteries power laptop computers for about eight hours. On average, the batteries provide between 300 and 400 charges before having to be replaced, he says. Each unit has its own allocation of carts, which, when out of use, are plugged into a nearby wall outlet for charging. To make sure that carts stay in good working order, a field service team checks that carts are charged and serviceable during regular rounds.

Eimer says that cart-based computing will continue to have a place at Texas Health hospitals. In the future, he expects the carts to house and power a wider array of equipment, such as large flat-screen monitors and barcode readers. “Eventually,” he says, “as we start to do medical device integration, we will have vitals monitoring on the carts as well.”

Healthcare Informatics 2010 July;27(7):32