This will be the first in a series of posts about ergonomics in the veterinary clinic–and everywhere else. It’s been a long pandemic, but in the past half-year I’ve had a couple of opportunities to talk about veterinary tasks aside from surgery. Today’s slushy snowstorm seems like a good time to share some of the illustrations and ideas from these presentations.
Lifting and Carrying: the fundamentals
Let’s start with some ergonomics fundamentals: lifting and carrying. This post shares some basic concepts that we’ll be able to apply later to specific veterinary activities like lifting and carrying dogs.
First, what are the characteristics of a lifting task that can make it more or less hazardous?
- Weight of load
- Distance of your hands from your lower back
- Height of lift (From floor or from above knee height? How high do you need to lift?)
- Twisting and side bending
- Working in a restricted space
- Good grip, or irregular, bulky, floppy, unpredictable load
- Flooring condition (dry, clean, good condition, or wet or uneven)
- Communication and coordination when lifting as a team
For our lifting and carrying example, we’ll use the ubiquitous brown cardboard box. In the first illustration, the lifter is carrying a box near her body and near waist height. This puts the object close to her center of mass and puts the least amount of strain on her body. It makes intuitive sense to us that she would carry the box this way instead of carrying it with her arms extended, far away from her body and her center of mass.
In this next set of illustrations, it looks a bit strange to carry the box with extended arms. But when the worker is carrying a larger box of the same weight, she is essentially doing just that– carrying the weight further from her center of mass and putting more strain on her back. A bulky object’s center of mass is further from the worker’s center of mass, meaning that even if this object is the same weight as the first box, it puts more strain on the worker’s back. The increased strain is due to the leverage created by the weight’s greater distance from the worker’s core.
(Want to learn more about how lifting strain increases depending on the size, shape, and weight of the object and the height of the lift? Check out the NIOSH Lifting Equation.)
Another circumstance where the worker might be holding an object far from her center of mass is when obstructions in the environment require her to do so. Removing objects that obstruct work areas (such as boxes obstructing a countertop) may seem obvious but it can also be the “low hanging fruit” when making ergonomic improvements.
Yet another reason for carrying a weight far from one’s body because it the load is smelly, damp, messy, or covered in some bodily fluid– but the same principles apply. If it’s a soiled but lightweight cat carrier, it makes sense to hold it at arm’s length on the way to the wash area. But if it’s a whole load of smelly laundry or a patient covered in pee, using a protective barrier (plastic bag or clean towel) and holding the weight close to the body is a better choice because it allows for a more secure hold and less strain on the lower back.
Lifting or placing objects below the knees or above the shoulders also adds additional strain on the worker’s body. Low placement may put strain on knees and lower back, while high placement can strain shoulders and arms (and introduce the risk of the object falling). Heavy items that need to be lifted and carried (cases of wet food; trays of instrument packs) should be near waist level to reduce the strain of lifting them. Lightweight objects can be placed on high shelves, with the bottom shelves reserved for heavier objects that will be transported with mechanical help like a wheeled cart or items that are used less often.
Mechanical help can be an excellent way to reduce strain when transporting objects. Gurneys, hand trucks, carts, and other devices bear the weight of the load, freeing the worker from the heavy lift.
Next time we’ll talk about the ergonomics of lifting and carrying dogs– stay tuned!