The hidden dangers of patient lifts
Pushing and pulling lead to injury
Are your patient lifts injuring your employees?
Lift equipment is designed to prevent back injuries, but when you select floor-based lifts, you also should consider the impact of shear force as health care workers push or pull the lifts to transport patients, advises William Marras, PhD, CPE, professor and director of the Biodynamics Laboratory at Ohio State University in Columbus.
Marras and his colleagues tested floor-based lifts with large and small wheels, on carpeting and hard surfaces. They found significant risk of injury from shear forces in pushing and pulling, especially when making a sharp turn in a confined space.1
“As soon as you turn, you saw huge differences, especially if you’re making turns into a confined space, such as a bathroom,” he says. “The nature of the risk is very different from [patient] lifting.”
The risk of injury is at a higher level on the spine — at lumbar disc 3 and above — while the risk of patient lifting typically is found in the low back at L5 and below. These gradual injuries may not be apparent until there is significant damage and pain, says Marras.
“It’s not until you start affecting the outer layers of the disc that you even know you have a problem, and then it’s too late,” he says.
It actually takes about a third as much shear force to cause damage as that caused by lifting, he says. “The tolerance of the human body is much, much reduced,” he says.
Marras advises employee health professionals to look at their patient needs, equipment, and other risk factors when evaluating lift equipment. Ceiling lifts are most effective at preventing patient handling injuries. Even when used with heavy patients, they were not associated with shear forces sufficient to cause disc damage, Marras found.
A study by the National Institute for Occupational Safety and Health found that the rotational movement of floor-based lifts required 10 times as much force as ceiling lifts, increasing the risk of injury.2
Floor lifts vary in the risk associated with moving patients. Self-propelled lifts remove most of the effort required in pushing or pulling. Floor lifts are also safer if they have larger wheels, if the turning radius is wider, and if they are used on a hard surface, he says.
Yet patient weight also plays a role. Marras found that even with larger wheels on a hard surface, the shear forces were high enough to damage spinal tissue when moving the heaviest patients (360 pounds) in a confined space using a floor lift.
Floor-based lifts are clearly safer than manual lifting, notes Marras. But hospitals should consider the risks associated with turning and moving the lifts. “[W]hile patient handling systems do have the potential to minimize risk of low back pain, using the floor-based systems under certain conditions can still represent a significant risk to the caregiver,” Marras and his colleagues concluded.
References
1. Marras WS, Knapik G, Ferguson S. Lumbar spine forces during maneuvering of ceiling-based and floor-based patient transfer devices Ergonomics 2009; 52:384-397.
2. Rice MS, Woolley SM, Waters TR. Comparison of required operating forces between floor-based and overhead-mounted patient lifting devices. Ergonomics 2009; 52:112-120.
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