OHS Canada Magazine

Smooth Descent

October 15, 2012

Health & Safety Ergonomics/Muscoloskeletal Injuries

Paramedics on Canada’s West Coast can now lay their burdens down — literally — when it comes to transporting patients up or down a flight of stairs.

Paramedics on Canada’s West Coast can now lay their burdens down — literally — when it comes to transporting patients up or down a flight of stairs.

In an effort to help curb musculoskeletal injuries (MSIs), the BC Ambulance Service (BCAS) equipped all of its ambulances with new tracked stair chairs this past April. Unlike the old stair chairs, which were metal frames with two wheels at the rear and a set of handles at the front and back, the new units are fitted with tracks that enable them to glide down the stairs, reducing the risk for strains and exertions.

“With the current design, that force is transferred down through the track system to the ground, alleviating some of the force requirements on the paramedics so they wouldn’t experience so much loading on the back or shoulders,” says Dr. Steven Fischer, assistant professor of biomechanics at Queen’s University’s School of Kinesiology and Health Studies in Kingston, Ontario.

In the past, two paramedics would have to lift up the cot-style stair chair on which the patient is seated, balancing their own weight and that of the chair while navigating through stairwells, which can be narrow, dirty or dimly-lit.

“The patient is elevated in the air so you get that unbalanced feeling, and if they reached out and grabbed something, it would throw the paramedic off,” says Corey Viala, provincial safety director for the Ambulance Paramedics of BC (Canadian Union of Public Employees Local 873) in Richmond, British Columbia. Viala also sits on the ambulance service’s oh&s procurement committee.



The chairs were first considered a few years ago, when BCAS — which oversees all emergency service operations in the province — acquired 20 units and put them on the busiest ambulances in the province to see if there was a quantifiable improvement in MSIs, reports Norm Matheson, superintendent with the BCAS.

“The time period was too short to see any measurable decrease in MSIs that may or may not have been as a result of the stair chairs,” Matheson says. Hence, an ergonomist was contracted to conduct a study comparing the stair chair with the stair cot that had been in use since the 1980s.

The ergonomist concluded the new-style tracked stair chair would be a “significant improvement for our staff to use and would significantly decrease the risk of MSIs while moving people down the stairs,” says Matheson, who also thinks the new additions are an improvement from the old units, which had awkwardly-placed handholds.

Based on the ergonomist’s recommendation, BCAS ordered 500 tracked stair chairs — enough for every ambulance in its fleet. All 3,500 paramedics in the province were also given a 45-minute training course on basic lifting, use on stairs and loading and unloading into the ambulance.

Recent claim numbers for paramedics serve as an indication of the physical toll associated with the job. Paramedics in British Columbia filed more than 2,000 claims related to back and other strains, dislocations and fractures, and tendonitis and other related injuries from 2007 to 2011. This translates to more than $19 million in claims and exceeded 100,000 days lost, notes information from WorkSafeBC.

With the new stair chairs, paramedics are essentially rolling or sliding their patients down the stairs. “Biomechanically, that is huge as far as loading the body” is concerned, says Dr. Steven Lavender, associate professor of integrated systems engineering at The Ohio State University in Columbus, Ohio. “If you’re not having to carry [a patient] down the stairs — and keep in mind, as you go through a landing there’s some manipulation there that also occurs — your back muscles and your biceps are working a lot less,” he adds.

In some cases, the stair chairs have enabled paramedics to improve their carrying posture, which “helps them keep a more neutral-oriented posture where possible,” suggests Dr. Lavender, also a certified professional ergonomist.


In a 2008 study conducted by Dr. Lavender, 11 two-person teams of firefighters and paramedics, who were hooked up to sensors attached to eight trunk muscles, transported a 75-kilogram (kg) dummy down a flight of steps. Four methods were used to transfer patients down, one of which was the tracked stair chair. Dr. Lavender says findings indicate that tracked stair chairs do create an increased load on the triceps from having to slow down during the descent, but chair types had no noticeable impact on the quadriceps.

While most stair chair testing was done with the 75-kg mannequin, his team did some pilot tests with occupant weights of up to 136 kg. “A heavier patient does increase the effort, but it is not as much as you’d think,” he says. With the tracked stair chairs, “what you find is that you are not carrying the weight; you’re just slowing the descent of that weight, and that’s a huge benefit.”

Viala says stair chairs are sturdier and more stable, as the tracks sit flat across three or four steps. The belting system also allows a patient’s weight to be supported on the stairs. However, he notes that they are five kilograms heavier than the old chair cots. “But that’s only with taking the units out of the cars as opposed to actually using them to remove a patient.”

As well, the tracked chairs lose the advantage over the old models when paramedics have to transfer a patient against gravity. As the chairs have a friction brake to prevent them from careening down the stairs if the paramedic loses his grip, they cannot be pulled up the stairs and must be carried just like the old units — with the extra weight of the tracks.

Fortunately, Dr. Lavender reports the first responders he had spoken with say basement evacuations are rare. “If somebody doesn’t feel well, where do they go? They go upstairs and lay on their bed. And then they decide they better call 911. That’s where the EMS guys find them,” he offers.

Although the study looked at first responders in suburban areas, urban areas with more high-rise apartment buildings would likely have similar results, he adds.

The limited space inside an emergency vehicle and the infrequency of ascending with a patient makes the stair chairs an easy choice, Lavender suggests. The units are also equipped with a handle at the top that extends away from the chairs. This gives the paramedic, who is likely walking backwards, more distance and reduces the chance of tripping.

With regards to the impact the stair chairs will have on reducing MSIs, Dr. Fischer says that information is still a few years down the road. “To know how those trends are progressing is difficult, because the data we are accessing is three or four years old. It takes time for the injury to develop and go through the process,” he adds.

Greg Burchell is assistant editor of canadian occupational health and safety news.

A Closer Look at Loads

A series of studies, published in 2002 by Western Michigan University in Kalamazoo, Michigan, looked at eight paramedics between 20 and 47 years old using six types of stair chairs, one of which had tracks. The six stair chair designs were evaluated with respect to three different carrying positions.

The studies found that stair chair type, position, task and the interaction between chair and paramedic “all had a significant effect upon spinal stress and variables compromising the relative risk of low back disorder,” but the tracked chair had significantly lower compression values and reduced the probability of lower back disorder.

The studies also noted that stair chair designs that require the leading param
edic descend the stairs facing forward reduced biomechanical loads on the body.

Similar findings were yielded in a follow-up to those studies presented in 2006, which looked at ten male emergency services workers aged between 20 and 39 years using two types of tracked stair chairs. The study compared different designs — varying by weight, track angle, handle height and adjustability — in relation to the biomechanical stresses placed on the bodies.

Like the 2002 studies, both tracked designs put the operator at the front of the chair walking down the stairs backwards at a higher risk of developing a lower back disorder than the operator at the rear of the chair walking forwards — an indication that further improvements can be made to reduce the impact stair chairs have on the body.



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