J Korean Soc Emerg Med.  2019 Dec;30(6):501-511. 10.0000/jksem.2019.30.6.501.

Biomechanical demands comparison in 119 emergency medical services activities when using manual and powered stretcher carts: a scenario-based randomized cross-over simulation study

• Song SW
• Kang MS
• Kang HJ
• Park JH
• Choi MJ
• Hong KJ
• Shin SD

• KMID: 2470540
• DOI: http://doi.org/10.0000/jksem.2019.30.6.501

Abstract

OBJECTIVE
The purpose of this study was to compare the biomedical demands between a manual stretcher cart (Manual Cot) and a novel powered stretcher cart (Power Cot) during simulated routine stretcher handling activities.
METHODS
A randomized cross-over design mannequin simulation study was planned. Fourteen participants sequentially performed routine stretcher handling tasks, including unloading, lowering, raising, and loading tasks with the Manual Cot and Power Cot. The biomechanical workload of each participant was assessed by measuring the muscle activity of four muscles (bilateral L4/5 erector spinae and rectus femoris) through an 8-channel electromyogram (EMG) measurement system by attaching the surface EMG. The time required to perform each task was measured, and after the end of the simulation, the participants were given a subjective questionnaire consisting of seven items (five-point Likert scale) on the usefulness and usability of the two stretcher carts.
RESULTS
Fourteen participants, six males and eight females, performed four routine stretcher handling scenarios. The median total task times for the Manual Cot and Power Cot were similar (95 seconds; range, 49-105 vs. 94 seconds; range, 84-140; P=0.063). For the lowering, raising, and loading tasks, the effects of Power Cot were significantly lower than the normalized muscle voluntary contraction (%) cumulative sum of the back or thigh (P<0.05). Compared to Manual Cot, the use of Power Cot resulted in a decrease in total muscle activity of 18.0-63.5% in the back muscles and 6.7-83.9% in the thigh muscles during the task simulation. The participants preferred the Power Cot in terms of usefulness in subjective perceptions.
CONCLUSION
This simulation study identified that the Power Cot reduced the physical stress of emergency medical services workers without any significant performance time delay when performing stretcher-handling activities.

Keyword

Stretchers; Emergency medical services; Occupational injuries; Ergonomics; Electromyography

MeSH Terms

Back Muscles
Cross-Over Studies
Electromyography
Emergencies*
Emergency Medical Services*
Female
Human Engineering
Humans
Male
Manikins
Muscles
Occupational Injuries
Stretchers
Thigh