Case Study: Automated Patient Transfer Device

One of the growing problems facing the nursing career is a thinning staff, and with it the need to care for overweight patients with very little help. This effort has led to musculoskeletal disorders (MSDs) including back injuries, the most costly MSD injury. In fact, 12 percent of nurses leave the profession each year due to back injuries, and 52 percent suffer from chronic back pain. Those working in nursing homes have a higher rate of injuries. Until recently, moving a patient was performed manually or with minimal automation.

Allowing a single nurse to safely and comfortably transfer a patient without risk of injury required a fully automated device. Astir Technologies, of Concord, Mass., took this on as a goal, to use the latest technologies available to provide patient transfer in a manner that decreases hospital costs and reduces injuries to health care professionals, while minimizing the discomfort to the patient. With this in mind, the company designed and manufactured the PowerNurse.

All of the mechanisms are packaged in a low-profile (74-inch x 28-inch x 2.3-inch) assembly that rides over a standard hospital stretcher. With the PowerNurse, patients can be moved between hospital beds, stretchers, imaging equipment, operating room tables, and exam tables.

"Other less expensive friction reducing devices decrease but do not eliminate the risk of nurse injury while performing a lateral transfer," says Chris McNulty, Astir Technologies president and developer of the PowerNurse.

As with other advanced designs, the PowerNurse was made possible with the advances to technologies and the miniaturization that has taken place in recent years. A critical area evident in the device's design is that of the motors and gearboxes. High-power rare earth magnets and advances in motor winding have resulted in high torque motors in small packages.

McNulty's solution involves a series of conveyor belts, motors, and electronics that fit into a thin profile that allows the transfer of very heavy weights automatically. During development of his first prototype, more than 400lb was easily transferred using one-fifth of the capacity of the 250W Maxon EC45 motors designed into the device. This meant the 120W ECmax 40 motors could be used in the PowerNurse, while the larger EC45 motors could be used for a bariatric model in development.