A Step Toward Safety

     The patient compartment of the average ambulance might be getting a safety-oriented facelift in future designs thanks to a study done by the National Institute for Occupational Safety and Health (NIOSH). The study, titled Creating a Safe Work Environment for Emergency Medical Service Workers, compared the standard GSA "Star of Life" ambulance, which meets KKK-1822 ambulance specification requirements, against the Winter Park (FL) Fire Rescue "Action Safe" Medtec ambulance designed by that department's personnel for improved safety and ergonomics (see Designing for Safety, June 2008). The results were presented last year at the American Society of Safety Engineers' Professional Development Conference.

     In the study, NIOSH recognizes the hazards unrestrained personnel face in a moving ambulance patient compartment. An unrestrained EMS worker can easily be thrown about and against hard, sharp objects found inside. NIOSH cites 2002 Bureau of Labor Statistics data indicating EMS personnel have an occupational fatality rate more than three times that of U.S. workers overall. The study showed the traditional Star of Life (SOL) design offers little opportunity for EMS personnel to remain restrained while treating the patient, as the layout usually won't allow a belted provider to reach the patient or critical equipment without releasing the bench seat lap belt. Conversely, Winter Park has a design in its ambulances that places the restrained EMS worker close enough to the patient and communication equipment to provide care.

     The NIOSH study set out to test the efficacy of the design. Using computer modeling and measuring tools, its authors crunched data to validate that even the smallest EMS worker can function within the Winter Park design. Authors used the accepted small female, average male and large male anthropometric measurements (the industry-accepted body sizes used for some crash-test manikins) to represent a reasonable cross-section of EMS workers. They programmed software to mimic the patient compartment of both the SOL and Winter Park designs, and established five "reach points" common with EMS patient care: the mouth and wrists of a computer-modeled average-size patient on a stretcher, and the radio, ECG and suction units.

     The study first found that in an SOL ambulance design with the EMS worker properly restrained on the bench seat and reaching toward these points, only the large male, with a larger "reach envelope," was able to hit the target locations on the patient. The small female and average-size male couldn't. In the Winter Park design, with all other factors the same, computer-generated male EMS workers could reach both target points on the patient, as well as the primary patient compartment radio. The female model could reach the patient's wrist and the radio while restrained, but not the patient's mouth.

     The Winter Park design incorporates a sliding seat with fixed five-point restraint system. This seat moves the worker closer to the patient while letting them remain restrained. Designers also changed the interior layout to make other commonly used items (e.g., the radio and ECG equipment) easier to reach. However, even with these changes, the overall size of the vehicle left both the ECG and suction units out of reach for all three worker sizes modeled.

     The study further showed that in order for an EMS worker to remain restrained and have the same patient access in an SOL ambulance, a tethering restraint system could be employed. Such a tether would let the worker slide forward on the bench seat to reach the patient while remaining restrained in case of a sudden deceleration event.

     The study concludes that "incremental improvements in worker safety can be achieved by modifying the environment through thoughtful positioning of equipment and worker in conjunction with improvements to personal protective equipment." It also suggests that overall design changes like those in the Winter Park model have the ability to improve worker safety more than tethered restraints alone, as they keep the worker closer to the seat—a safety device itself. Finally, the study concludes that more redesign work remains, as some equipment in both designs was still out of reach for all worker sizes.

     Though stopping short of advocating the use of mobile restraints, James Green, a NIOSH coauthor of the study, notes the issue of worker reach and mobility and the potential need for mobile restraints will continue to grow as ambulance service providers are given expanded duties and larger vehicles. However, of specific concern in both models and with all restraint types is the lack of test data on side-facing seats in front-end collisions or other sudden deceleration events. This ultimately may be solved by changes in worker seating positions and stretcher mounting locations for future designs.

     The take-home message from the study shows keeping EMS workers seated and restrained in moving ambulances will provide the safest environment in cases of crash, rollover or other event involving a sudden change in vehicle direction. Winter Park's innovative setup, which was actually in operation before the NIOSH study was completed, is not perfect, but according to Green is "a step in the right direction." Lt. Andrew Isaacs of Winter Park Fire Rescue, who had a significant role in the development of their design and authored the June 2008 EMS article, also participated in the NIOSH study as a subject matter expert. He believes the study validates his department's work.

     For a copy of the NIOSH study contact Green at jsg9@cdc.gov.

     Tom Batchelor is a fire lieutenant/paramedic with Longboat Key (FL) Fire Rescue. He has been involved in EMS for 28 years.