Comparing the biomechanical and psychophysical demands imposed on paramedics when using manual and powered stretchers

The effect of power stretchers on occupational injury rates in an urban emergency medical services system

BACKGROUND

To examine occupational injury rates in a dual-response emergency medical services (EMS) system before and after implementation of a power-lift stretcher system.

METHODS

The seasonally-adjusted occupational injury rate was estimated relative to medical call volume (per 1000 calls) and workers (per 100 FTEs) from 2009 to 2019, and stratified by severity (lost-time, healthcare only), role (EMS, FIRE) and type (patient-handling). Power-lift stretchers were adopted between 2013 and 2015. Preinjury versus postinjury rates were compared using binomial tests. Interrupted time series (ITS) analysis was used to estimate the trend and change in injuries related to patient-handling, with occupational illnesses serving as control.

RESULTS

Binomial tests revealed varied results, with reductions in the injury rate per 1000 calls (-14.0%) and increases in the rate per 100 FTEs (+14.1%); rates also differed by EMS role and injury severity. ITS analysis demonstrated substantial reductions in patient-handling injuries following implementation of power-lift stretchers, both in the injury rate per 1000 calls (-50.4%) and per 100 FTEs (-46.6%), specifically among individuals deployed on the ambulance. Injury rates were slightly elevated during the winter months (+0.8 per 100 FTEs) and lower during spring (-0.5 per 100 FTEs).

CONCLUSIONS

These results support the implementation of power-lift stretchers for injury prevention in EMS systems and demonstrate advantages of ITS analysis when data span long preintervention and postintervention periods.

A participatory ergonomics intervention to re-design work and improve the musculoskeletal health of paramedics: protocol for a cluster randomised controlled trial

BACKGROUND

In this paper, we present the protocol for a cluster randomised controlled trial to evaluate the effectiveness and implementation of a participative risk management intervention to address work-related musculoskeletal disorders (WMSDs). The aims of the study include to evaluate the implementation process and the impact of the intervention on work related musculoskeletal pain and discomfort and exposure to physical and psychosocial hazards in paramedics over a 12-month period.

METHODS

The intervention in this study is to implement A Participative Hazard Identification and Risk Management (APHIRM) toolkit in an ambulance service. Eighteen work groups containing eligible participants (registered paramedics) will be randomised into the intervention or wait-list control arm in one of three rolling recruitment periods. The APHIRM toolkit survey will be offered at baseline and 12 months later, to all current eligible participants in each work group allocated to the trial. The intervention work groups will receive the remainder of the APHIRM toolkit procedures. Identifying data about individual participants will not be collected in the survey, to protect participant privacy and encourage participation. Changes in primary (musculoskeletal pain and discomfort) and secondary (exposure to physical and psychosocial hazards at work) outcomes measured in the survey will be analysed comparing the baseline and follow up response of the cluster. A process evaluation is included to analyse the implementation and associated barriers or facilitators.

DISCUSSION

This study is important in providing a comprehensive approach which focusses on both physical and psychosocial hazards using worker participation, to address WMSDs, a well-known and significant problem for ambulance services. The effectiveness of the intervention in work groups will be rigorously evaluated. If significant positive results are observed, the intervention may be adopted in ambulance services, both nationally and internationally.

TRIAL REGISTRATION

ISRCTN77150219. Registered 21 November 2021.

Designing criterion measures for physically demanding jobs

The Bureau of Labor Statistics reported that 39.1% of the civilian workforce in the United States performs physically demanding jobs that require lifting, carrying, pushing/pulling, kneeling, stooping, crawling, and climbing activities in varied environmental conditions. United States military occupations are similar to those in the civilian sector involving equipment installation, emergency rescues, and maintenance, along with combat arms occupations. This article provides an overview of the types of criterion measures used to assess the physical domain and approaches for designing and evaluating the criteria. It also includes a method for generating criterion measures that are applicable across multiple jobs.

Ambulance personnel's perceptions on their workplace well-being: A descriptive interpretative study

BACKGROUND

Ambulance personnel face numerous challenges during their working hours. Exposure to stressful situations and other factors in the outpatient emergency medical service can affect the health of ambulance personnel as well as their well-being.

OBJECTIVE

The main objective of this study was to explore the perceptions of ambulance personnel regarding their physical and mental well-being at the workplace.

METHODS

A qualitative descriptive-interpretative research design was used. Individual face-to-face and online interviews were conducted between February and April 2022. A total of 26 interviews were conducted to explore employees' perceptions regarding the impact of work on their health and well-being.

RESULTS

Ambulance personnel described in detail their perceptions of the impact of work on their physical and mental health and well-being. Three main themes emerged from our data: 1) the impact of work on the psychophysical condition of ambulance personnel; 2) the impact of work on the lifestyle of ambulance personnel; 3) the impact of work and the work environment on the lives of ambulance personnel.

CONCLUSION

Long-term work in emergency medical services affects the health and well-being of ambulance personnel. As demonstrated by this study, raising awareness on the importance of preventive and health promotion programmes, understanding employees' problems by considering their opinions, and providing relevant training are extremely important tools for preventing such problems among employees.

Use of the Airstretcher with dragging may reduce rescuers’ physical burden when transporting patients down stairs

Transporting patients down stairs by carrying is associated with a particularly high fall risk for patients and the occurrence of back pain among emergency medical technicians. The present study aimed to verify the effectiveness of the Airstretcher device, which was developed to reduce rescuers’ physical burden when transporting patients by dragging along the floor and down stairs. Forty-one paramedical students used three devices to transport a 65-kg manikin down stairs from the 3rd to the 1st floor. To verify the physical burden while carrying the stretchers, ratings of perceived exertion were measured using the Borg CR10 scale immediately after the task. Mean Borg CR10 scores (standard deviation) were 3.6 (1.7), 4.1 (1.8), 5.6 (2.4), and 4.2 (1.8) for the Airstretcher with dragging, Airstretcher with lifting, backboard with lifting, and tarpaulin with lifting conditions, respectively (p < 0.01). Multiple comparisons revealed that the Airstretcher with dragging condition was associated with significantly lower Borg CR10 scores compared with the backboard with lifting condition (p < 0.01). When the analysis was divided by handling position, estimated Borg CR10 values (standard error) for head position were 4.4 (1.3), 2.9 (0.9), 3.2 (0.8), and 4.0 (1.1) for the Airstretcher with dragging, Airstretcher with lifting, backboard with lifting, and tarpaulin with lifting conditions, respectively, after adjusting for participant and duration time (F = 1.4, p < 0.25). The estimated Borg CR10 value (standard error) for toe position in the Airstretcher with dragging condition was 2.0 (0.8), and the scores for the side position were 4.9 (0.4), 6.1 (0.3), and 4.7 (0.4) for the Airstretcher with lifting, backboard with lifting, and tarpaulin with lifting conditions, respectively, after adjusting for participant and duration time (F = 3.6, p = 0.02). Transferring a patient down stairs inside a house by dragging using the Airstretcher may reduce the physical burden for rescuers.

The influence of sex and strength capacity on normalized low-back exposure during lifting: Insights from a joint power analysis

OBJECTIVE

Investigate the influence of sex, strength capacity, and relative load mass on low-back exposure and lower extremity joint power generation in backboard lifting.

BACKGROUND

Sex and strength have been shown to influence lifting strategy, but without load mass being scaled to strength it is unknown which factor influences low-back exposures, and whether there are interactions with load mass.

METHODS

Motion capture and force plate data from 28 participants were collected during backboard lifting at load masses scaled to strength capacity. Differences in normalized peak low-back moment, peak knee-to-hip power magnitude ratio and timing were tested as a function of sex, strength, and load mass.

RESULTS

Stronger participants had lower normalized peak low-back moments (average 32% change from low-capacity across all load masses), with no significant sex effect (p = 0.582). As load mass increased, normalized peak low-back moment, peak knee-to-hip power magnitude and synchronicity decreased.

CONCLUSION

Training to both increase strength capacity and hip-joint power generation may be a strategy to reduce low-back exposure in backboard lifting.

Why cumulative loading calculated using non-weighted integration may not be suitable for assessing physical stress of the lower back: an empirical investigation of strain during lifting and lowering tasks

When work-related physical stress is assessed using non-weighted integration, it is assumed that different loading conditions have a sufficiently comparable effect on the human body as long as the area under the loading curve is the same. Growing evidence cast doubt on whether this simple calculation can adequately estimate physical work-related strain. This study investigates in vivo, focussing on the lower back, whether the non-weighted method adequately reflects work-related physical strain of the lower back. Strain data resulting from lifting/lowering tasks performed in a laboratory study with an identical area under the loading curve but different load intensities were compared. Results showed that the non-weighted method does not sufficiently reflect the resulting muscular, cardiovascular and perceived strain but underestimates the influence of higher load intensity even in the range of medium physical exposure. Further research is needed regarding the determination of weighting factors and limit values. Practitioner Summary Given the dynamic nature of most physical work activities, the assessment of time-varying loading of the lower back is of particular interest in practice. Results show that the widely used non-weighted calculation method does not accurately reflect the resulting physical strain but underestimates the influence of higher load intensity.Abbreviations: MSD: musculoskeletal disorders; WMSD: work-related musculoskeletal disorders; KIM-LHC: Key Indicator Method Lifting, Holding, Carrying; RES: right erector spinae longissimus; LES: left erector spinae longissimus; HR: heart rate; RPE: rating of perceived exertion; EMG: surface electromyography; ECG: electrocardiography; SENIAM: Surface ElectroMyoGraphy for the Non-Invasive Assessment of Muscles; MVC: maximum voluntary contraction; ANOVA: analysis of variance; Std. error: standard error HIGHLIGHTSResults of this empirical investigation suggest that the widely used non-weighted calculation method is not fully suitable for calculating cumulative loading of the lower back.Even in the range of medium physical exposure the non-weighted calculation method does not accurately reflect the resulting strain on the human body but tends to underestimate the influence of higher load intensity due to higher external weight.Despite the same cumulative loading value obtained when using the non-weighted method, the resulting physical strain values are generally about 20-25% higher.The results may be used to further develop ergonomic assessment methods in order to avoid a misclassification of loading conditions and to prevent the risk of overexertion.

Evaluation of a novel stair-climbing transportation aid for emergency medical services

Acute and planned transportations of patients are major tasks for emergency medical services (EMS) and often result in substantial physical strains with a major impact on the workers' health, because current transportation aids cannot provide sufficient support, especially on stairs. A new stair-climbing and self-balancing approach (SEBARES) has been developed and its usability is evaluated in the context of this paper. Twelve participants operated a prototype in a transportation scenario and user forces, user joint angles and the perceived usability were evaluated. Results show that user forces were within long-term acceptable ergonomic limits for over 90% of the transportation time and a mainly healthy upright posture of the back could be maintained. This resulted in a healthy working posture for 85% of the time, according to the OWAS method, and a good perceived usability. A comparison to the most ergonomic aid according to literature, a caterpillar stair chair, reveals that similar upright postures are assumed, while the operation of SEBARES required only 47% of the forces to operate the caterpillar stair chair. A comparison to a previous field study indicates a reduction of strenuous working postures by a factor of three, which further confirms the ergonomic advantages of this concept.

Exploring the need for and application of human factors and ergonomics in ambulance design: Overcoming the barriers with technical standards

Ergonomic risk factors, such as excessive physical effort, awkward postures or repetitive movements, were the leading causes of injuries amongst EMS workers in the United States, of which 90% were attributed to lifting, carrying, or transferring a patient and/or equipment. Although the essential tasks of patient handling, transport, and care cannot be eliminated, the design of ambulances and associated equipment is modifiable. Our aims were to identify the extent of Human Factors and Ergonomic (HFE) considerations in existing ambulance design standards/regulations, and describe how HFE and the standards/regulations were applied in the EMS system. Through an extensive environmental scan of jurisdictionally relevant standards/regulations and key informant interviews, our findings demonstrated that existing standards/regulations had limited considerations for HFE. As a result, HFE principles continue to be considered reactively through retrofit rather than proactively in upstream design. We recommend that performance-based HFE requirements be integrated directly into ambulance design standards.

Can the Use of Turn-Assist Surfaces Reduce the Physical Burden on Caregivers When Performing Patient Turning?

OBJECTIVE

To quantify differences in physical workload afforded by turn-assist surfaces relative to manual patient turns, and between nursing caregivers (turn-away vs. turn-toward) while performing partnered patient turning.

BACKGROUND

Nurse caregivers experience an increased risk of musculoskeletal injuries at the back or shoulders when performing patient-handling activities. Use of turn-assist surfaces can reduce the physical burden and risk on caregivers.

METHOD

Whole-body motion capture and hand force measures were collected from 25 caregivers (17 female) while performing partnered manual and technology-facilitated turns. Shoulder and low back angles and L4/L5 joint contact forces were calculated at the instant of peak hand force application for both caregivers.

RESULTS

Hand force requirements for the turn-away caregiver were 93% of the estimated maximum acceptable force when performing a manual turn. Use of a turn-assist surface eliminated hand forces required to initiate the patient turn for the turn-away caregiver, where their role was reduced to inserting appropriate wedging behind the patient once the facilitated turn was complete. This reduced shoulder moments by 21.3 Nm for the turn-away caregiver, a reduction in exposure from 70% of maximum shoulder strength capacity to 15%. Spine compression exposures were reduced by 302.1 N for the turn-toward caregiver when using a turn-assist surface.

CONCLUSION

Use of a turn-assist surface reduced peak hand force and shoulder-related exposures for turning away and reduced spine-related exposures for turning toward.

APPLICATION

Turn-assist devices should be recommended to decrease the risk of musculoskeletal disorder hazards for both caregivers when performing a partnered patient turn.

Paramedic equipment bags: How their position during out-of-hospital cardiopulmonary resuscitation (CPR) affect paramedic ergonomics and performance

This study investigates how the positions of paramedic equipment bags affect paramedic performance and biomechanical loads during out-of-hospital Cardiopulmonary Resuscitation (CPR). An experiment was conducted in which 12 paramedic teams (each including two paramedics) performed in-situ simulations of a cardiac-arrest scenario. CPR quality was evaluated using five standard resuscitation measures (i.e., pre- and post-shock pauses, and compression rate, depth and fraction). The spinal loads while lifting, pulling and pushing the equipment bags were assessed using digital human modeling software (Jack) and prediction equation from previous studies. The results highlight where paramedics are currently choosing to position their equipment. They also demonstrate that the positions of the equipment bags affect CPR quality as well as the paramedics' work efficiency, physiological effort and biomechanical loads. The spinal loads ranged from 1901 to 4030N; furthermore, every occasion on which an equipment bag was lifted resulted in spinal forces higher than 3400N, thus exceeding the maximum threshold stipulated by the National Institute for Occupational Safety and Health. 72% of paramedics' postures were categorized as high or very high risk for musculoskeletal disorders by the Rapid Entire Body Assessment. Guidelines related to bag positioning and equipment handling might improve CPR quality and patient outcomes, and reduce paramedics' risk of injury.

Physical capacity of New South Wales ambulance paramedics

BACKGROUND

Paramedics are among the most frequently injured health professionals in Australia. A lack of physical capacity may contribute to injury risk in this occupational population.

AIMS

This study sought to describe and compare the physical fitness of male and female paramedics across age groups to ascertain differences in physical capacity.

METHODS

A group of regional Australian paramedics (n = 140; 78 males; mean ± SD 37.4 ± 9.9 years; body mass index 28.1 ± 4.9 kg/m2) underwent a fitness assessment. Measures included upper, lower and core-body muscular strength and flexibility. Outcomes were compared between genders and across age groups using two-way between-groups analysis of variance.

RESULTS

Male paramedics had greater upper body strength (P < 0.05; push-ups) mean (95% CI): 22.6 (19.4-25.9) versus 18.7 (15.2-22.3); similar lower body strength (single-leg wall squat): 39.0 (32.6-45.3) s versus 36.7 (27.1-46.3) s; greater core strength (P < 0.05; prone plank hold): 87.9 (77.6-98.3) s versus 73.8 (63.7-83.8) s; similar upper body flexibility (back scratch): -4.0 (-6.7 to -1.3) cm versus -0.3 (-2.2 to 1.7) cm; and similar lower body flexibility (sit and reach): 20.4 (18.2-22.6) cm versus 26.1 (23.5-28.7) cm to female paramedics. Core, upper and lower body strength all decreased with age (P < 0.05).

CONCLUSIONS

Core, upper and lower body strength and upper body flexibility were poorer for older compared to younger regional paramedics in New South Wales, Australia. Future research should investigate whether these outcomes are associated with occupational injury risk. This information would assist in the design of injury prevention interventions for paramedics such as tailored workplace exercise programs.

To what extent do paramedics apply safe handling principles when transferring patients from stair chairs to stretchers?

The efficiency of training programmes in handling designed to prevent injuries has rarely been demonstrated by studies in the workplace. This study aimed to identify factors that may favour or inhibit the application of safe handling principles by paramedics performing full-body transfers of patients from a stair chair to a stretcher. In an observational field study, handling methods used in 45 patient transfers from a stair chair to stretcher were characterised. Principles concerning the physical environment seem to be applied frequently, but those applicable during the transfer are neglected. Principles taught during training may not be applied due to the physical constraints of the workplace and the underestimation of risk exposure. The results suggest that training should be enhanced, not by focussing on handling techniques but by focussing on compromise and the capacity to adapt work techniques based on the working context and the team-mate.

Manual patient transfers: factors that influence decisions and kinematic strategies employed by nursing aides

While extensive literature has characterised factors that influence the acceptable mass of 'boxes' during MMH tasks, less is known about these factors when moving 'people' in healthcare settings. This study examined factors that influence decisions/approaches employed during manual patient transfers. Sixteen nursing aides manually-transferred a standardised 'patient'; patient mass was adjusted (using a weight vest) to determine a maximum acceptable patient mass for this task (mass_max). Grip strength was the only worker characteristic significantly associated with mass_max (r = 0.48). Older worker age was associated with smaller peak trunk flexion (r =  -0.58) and shoulder abduction (r =  -0.59), and greater trunk axial twist (r = 0.52). Workers emphasised that patient characteristics (e.g. physical/cognitive status) influenced their decisions when performing transfers. These findings extend previous literature by suggesting that grip strength is a useful predictor of perceived work capacity, older workers adapt protective postural strategies during patient transfers and worker-patient dynamics are crucial during this high-risk occupational task. Practitioner Summary: This study examined manual patient transfers performed by nursing aides. Worker grip strength (but not age or size) was associated with perceptions of maximum acceptable patient mass. Kinematic changes suggested more conservative strategies used by older workers. Workers emphasised that patient characteristics substantially influenced their decisions when performing transfer tasks.