Journal Watch: Equipment Placement, Ergonomics, and Performance

Reviewed This Month

Paramedic Equipment Bags: How Their Position During Out-of-Hospital Cardiopulmonary Resuscitation (CPR) Affect[s] Paramedic Ergonomics and Performance

Authors: Harari Y, Riemer R, Jaffe E, Wacht O, Bitan Y  

Published in: Appl Ergon, 2020; 82: 102977

While most of you are likely aware of the injury risks associated with working in EMS, you may not know that risk is about three times higher than for all other private industry occupations. Many of these EMS injuries are due to lifting and moving, resulting in muscle strains, sprains, and back pain. Nonoptimal positioning of heavy objects that must be lifted or moved has been identified as a contributing factor to these injuries. However, the effects of handling equipment bags have not been widely studied. 

The objectives of this study included investigating where paramedics choose to position their equipment around the patient during out-of-hospital cardiac arrest; investigating CPR quality and paramedic work efficiency, effort, and biomechanical loads during CPR; and investigating whether and to what extent the positioning of equipment bags around the patient affects CPR quality as well as paramedic work efficiency, physiological effort, and biomechanical loads. 

Study Design

This study was an experiment conducted with the Israeli national emergency medical services system, Magen David Adom. It included 24 participants. There were equal numbers of men and women and a mixture of experienced paramedics and paramedic students with some field experience. 

Teams were grouped randomly, and each included a senior and junior paramedic. Each of the 12 teams completed two 10-minute (to enable five CPR cycles, including electric shocks and medication administrations) cardiac arrest simulations using Laerdal’s SimMan ALS SkillMaster 4000. During the simulation the paramedics used the same equipment bags they’d use in the field. The bags included an airway bag, a medication bag, a monitor/defibrillator, and a small oxygen tank. 

First the authors measured the mass of the bags and the force required to push or pull them along the floor. The maximum force applied during the pushing or pulling was recorded and the average maximum force calculated for each bag. 

The simulations took place in a lab. A wooden frame was constructed in the center of the lab and made to simulate the available area in a small bedroom. There was a grid on the floor used to mark the original position of each bag. All simulations were video-recorded. The authors used these videos to manually identify each paramedic’s interaction with the equipment around the patient. An interaction was defined as “an event which a bag was either moved (e.g., lifting, pushing, or pulling) or used without being moved (e.g., extracting equipment from a bag).” 

To evaluate CPR quality the authors were guided by the American Heart Association 2015 guidelines. They assessed the percentage of compressions within a depth range of 5–6 cm, the percentage of compressions with a rate of 100–120 compressions per minute, the preshock pause, the postshock pause, and the length of time compressions were performed as a percentage of the total resuscitation (in other words, the compression fraction). 

To evaluate the paramedics’ work efficiency, the authors assessed the total number of times the paramedics changed their position during the simulation. The percentage of time spent changing positions and total number of steps walked by the paramedics during the simulation were also evaluated. 

Physiologic effort was assessed objectively and subjectively. The objective measures were the paramedic’s peak and average heart rate. The authors used the Borg test for the subjective assessment. This test measures the paramedics’ perceived level of exertion on a scale of 6 (very light effort) to 20 (maximal effort) after each simulation. 

Finally, biomechanical loads were evaluated with both direct measures and ergonomic assessments. The direct measures included the number of times the bags were handled and the cumulative force required to move them. The ergonomic assessments used the video recordings to evaluate the risk of injury based on the paramedics’ postures and loads. They calculated the peak compression forces acting on the paramedic when interacting with the bags. 

Statistical analysis (MANOVA) was performed to evaluate the effects of the equipment bag positions on CPR quality and ergonomics. The test was appropriate based on the type of data being assessed and question being addressed. 

Results

The authors found the average percentage of compressions within the recommended rate was 68% and the average percentage of compressions within the recommended depth was 27%. The average preshock and postshock pauses were both 2.8 seconds, and the average compression fraction was 91%. The average number of times the paramedics changed positions was 12.6, and an average of 7% of the simulation was spent changing positions. An average of 28 steps were walked by the paramedics during the simulation. The average paramedic peak heart rate was 156 bpm (average 123 bpm), and the average Borg score was 11.6. The bags were handled an average of 6.8 times, and the total force required to move them was 89 N. 

Importantly, the statistical analysis found CPR quality and biomechanical loads were influenced by the positions of all four equipment bags. The work efficiency was influenced by the positions of the medication bag and oxygen tank. The paramedics’ effort was influenced by the positions of the medication bag and monitor-defibrillator. 

Conclusion

While this study did not identify the optimal positions for equipment bags, it did find the position of the bags impacts CPR quality and the risk of injury for EMS professionals. This is an important finding and should direct leaders to identify optimal placement and offer guidelines/recommendations to improve CPR quality and EMS professional safety. 

Read this manuscript in full—the authors did a fantastic job explaining their experiment and go into a lot of detail to explain their tests and why they were chosen. There are also some great figures that complement the results.    

Antonio R. Fernandez, PhD, NRP, FAHA, is a research scientist at ESO and an assistant professor in the department of emergency medicine at the University of North Carolina–Chapel Hill. He is on the board of advisors of the Prehospital Care Research Forum at UCLA.