A biomechanical and ergonomic evaluation of patient transferring tasks: wheelchair to shower chair and shower chair to wheelchair.

A laboratory study was conducted to evaluate five different manual techniques (two-person manual lifting; rocking and pulling the patient using a gait belt with two persons; walking belt with one and two persons) and three different mechanical hoists (Hoyer lift, Trans-Aid and Ambulift) for transferring patients from wheelchair to shower chair and shower chair to wheelchair. Six female nursing students with prior patient transfer experience served both as nurses and as passive patients. Static biomechanical evaluation showed that the mean trunk flexion moments, erector spinae muscle forces and compressive and shear forces at the L5S1 disc for the four pulling methods ranged from 92 to 125 Nm, 1845 to 2507 N, 1973 to 2641 N and 442 to 580 N, respectively, as compared to about 213 Nm, 4260 N, 5050 N and 926 N for two-person manual lifting. Perceived stress ratings for the shoulder, upper back, lower back and whole body were significantly lower for pulling methods than those for lifting the patient (p less than or equal to 0.01). Patients found pulling techniques, except the gait belt, to be more comfortable and secure than the lifting method (p less than or equal to 0.01). However, most of the nurses believed that Medesign and the one-person walking belt would not work on those patients who cannot bear weight and those who are heavy, contracted or combative. A two-person walking belt was the most preferred method. Two out of three hoists (Hoyer lift and Trans-Aid) were perceived by the nurses to be more stressful than one- and two-person walking belts. The patients found these two hoists to be more uncomfortable and less secure than with three of the five manual methods (one- and two-person walking belts and Medesign). Pulling techniques and hoists took significantly longer amounts of time to make the transfer than manually lifting the patient (p less than or equal to 0.01). The two-person walking belt, using a gentle rocking motion to utilize momentum and a pulling technique, and Ambulift are recommended for transferring patients from wheelchair to shower chair and shower chair to wheelchair.     

Prevention of back injuries in healthcare workers

A laboratory study was conducted to evaluate five different manual techniques (two-person lifting; rocking and pulling the patient using a gait belt with two persons; walking belt with handles with one and two persons; and a patient handling sling with cutouts with one person) for transferring patients from wheelchair to toilet and toilet to wheelchair. In addition, three different mechanical hoists (H, T and A) were studied for transferring patients from toilet to wheelchair. Six female nursing students with prior patient transfer experience served both as nurses and passive patients.

The mean trunk flexion moments, erector spinae muscle forces and compressive forces for the four manual pulling methods ranged from 93 to 133 Nm, 1861 to 2653 N and 1974 to 2745 N, respectively, as compared to about 200 Nm, 4100 N and 4800 N for two-person manual lifting. Manual lifting was perceived to be the most stressful by the nurses and the least comfortable and secure by the patients. Hoist A was perceived to be the least stressful and the most comfortable and secure. Hoists H and T were perceived to be more stressful, less comfortable and less secure than the walking belt.

An intervention study was conducted in two units of a nursing home (140 beds and 57 NAs) to determine the effectiveness of ergonomic changes. Nursing assistants (NAs) in the two units of the nursing home were trained in the use of selected devices and shower rooms and toilets were modified. The mean acceptability rates for walking belt and hoist A were 81% and 87%, respectively. The reported incidence and severity rates for back injuries over 13 months decreased from 83 to 43 and from 634 to 0, respectively, after the intervention. Nursing assistants perceived their job as “very light” after the intervention as compared to between “somewhat hard” and “hard” before intervention.     

Muscle activity during patient transfers: a preliminary study on the influence of lift assists and experience

The purpose of this study was to examine muscle activity patterns during patient handling during manual transfers, and transfers using floor and ceiling lifts. EMG patterns during transfers from bed to wheelchair and wheelchair to bed as well as patient repositioning in novices and experienced participants were examined. Surface EMG was recorded from the upper and lower erector spinae, latissimus dorsi and trapezius muscles bilaterally. Overall, normalized mean and peak muscle activity were lowest using the ceiling lift, increasing with the floor lift, which were lower than manual transfers (novices: all p < 0.01). Experienced patient handlers demonstrated approximately two times greater trapezius and latissimus dorsi activity than novices, combined with lower mean erector spinae activity (p < 0.05, for most tasks). Integrated EMG for all muscles was directly proportional to the transfer time and was lowest during the manual transfer followed by the ceiling lift, with the floor lift being highest. The difference between the muscle activity patterns between the experienced and novice patient handlers may suggest a learned behaviour to protect the spine by distributing load to the shoulder. Further examination of the muscle activation patterns differences between experience levels could improve training techniques to develop better patient handling strategies.     

Muscle activity during patient transfers: a preliminary study on the influence of lift assists and experience

The purpose of this study was to examine muscle activity patterns during patient handling during manual transfers, and transfers using floor and ceiling lifts. EMG patterns during transfers from bed to wheelchair and wheelchair to bed as well as patient repositioning in novices and experienced participants were examined. Surface EMG was recorded from the upper and lower erector spinae, latissimus dorsi and trapezius muscles bilaterally. Overall, normalized mean and peak muscle activity were lowest using the ceiling lift, increasing with the floor lift, which were lower than manual transfers (novices: all p?<?0.01). Experienced patient handlers demonstrated approximately two times greater trapezius and latissimus dorsi activity than novices, combined with lower mean erector spinae activity (p?<?0.05, for most tasks). Integrated EMG for all muscles was directly proportional to the transfer time and was lowest during the manual transfer followed by the ceiling lift, with the floor lift being highest. The difference between the muscle activity patterns between the experienced and novice patient handlers may suggest a learned behaviour to protect the spine by distributing load to the shoulder. Further examination of the muscle activation patterns differences between experience levels could improve training techniques to develop better patient handling strategies.     

A comprehensive analysis of low-back disorder risk and spinal loading during the transferring and repositioning of patients using different techniques.

Although patient handlers suffer from low-back injuries at an alarming rate worldwide, there has been limited research quantifying the risk for the specific tasks performed by the patient handlers. The current study used both a comprehensive evaluation system (low-back disorder risk model) and theoretical model (biomechanical spinal loading model) to evaluate risk of LBD of 17 participants (12 experienced and five inexperienced) performing several patient handling tasks. Eight of the participants were female and nine were male. Several patient transfers were evaluated as well as repositioning of the patient in bed; these were performed with one and two people. The patient transfers were between bed and wheelchair (fixed and removable arms) and between commode chair and hospital chair. A 'standard' patient (a 50 kg co-operative female; non-weight bearing but had use of upper body) was used in all patient handling tasks. Overall, patient handling was found to be an extremely hazardous job that had substantial risk of causing a low-back injury whether with one or two patient handlers. The greatest risk was associated with the one-person transferring techniques with the actual task being performed having a limited effect. The repositioning techniques were found to have significant risk of LBD associated with them with the single hook method having the highest LBD risk and spinal loads that exceeded the tolerance limits (worst patient handling job). The two-person draw sheet repositioning technique had the lowest LBD risk and spinal loads but still had relatively high spinal loads and LBD risk. Thus, even the safest of tasks (of the tasks evaluated in this study) had significant risk. Additionally, the current study represented a 'best' case scenario since the patient was relatively light and co-operative. Thus, patient handling in real situations such as in a nursing home, would be expected to be worse. Therefore, to have an impact on LBD, it is necessary to provide mechanical lift assist devices.     

Ergonomic evaluation of slide boards used by home care aides to assist client transfers

Home care aides risk musculoskeletal injury because they lift and move clients; the body weight of most adults exceeds the NIOSH recommended limit for lifting. Methods to reduce manual patient lifting in institutional settings are often technically or economically infeasible in home care. Our goal was to identify suitable, safe, low-technology transfer devices for home care use. Sixteen experienced home care aides performed client transfers from wheelchair to bed (upward) and bed to wheelchair (downward) in a simulated home care environment (laboratory), using four different slide boards and by hand without a device. Aides’ hand forces were measured during client transfers; aides also evaluated usability of each board. Hand forces exerted while using slide boards were mostly lower than in manual transfer, and forces were lower in downward versus upward transfers. Aides judged a board with a sliding mechanism easier to use than boards without a sliding mechanism.

Practitioner Summary: This paper provides quantitative biomechanical measurements showing that slide boards reduced the hand forces needed by home care aides to transfer clients from bed to wheel chair and vice versa, compared to manual lifting. Using a semi-quantitative usability survey, aides identified boards with a sliding mechanism easiest to use.     

Spine loading and trunk kinematics during team lifting

Two-person or team lifting is a popular method for handling materials under awkward or heavy lifting conditions. While many guidelines and standards address safe lifting limits for individual lifting, there are no such limits for team lifting, and these lifts are poorly understood. The literature associated with team lifting offers some interesting paradoxes. Many studies have indicated that people lift less per individual under team conditions compared with one-person lifting. Yet, at least one study has reported an increase in team-lifting capacity when subjects were height-matched. The current study explored the spine loading characteristics of one- and two-person lifting teams when subjects lifted under several sagittally symmetric and asymmetric conditions. Spine compression was lower for two person lifts for a given weight, while lifting in sagittally symmetric conditions whereas lateral shear became much greater for two-person lifts under asymmetric lifting conditions. This study has linked these changes to differences in trunk kinematic patterns adopted during one- versus two-person lifting.     

Spine loading and trunk kinematics during team lifting

Two-person or team lifting is a popular method for handling materials under awkward or heavy lifting conditions. While many guidelines and standards address safe lifting limits for individual lifting, there are no such limits for team lifting, and these lifts are poorly understood. The literature associated with team lifting offers some interesting paradoxes. Many studies have indicated that people lift less per individual under team conditions compared with one-person lifting. Yet, at least one study has reported an increase in team-lifting capacity when subjects were height-matched. The current study explored the spine loading characteristics of one- and two-person lifting teams when subjects lifted under several sagittally symmetric and asymmetric conditions. Spine compression was lower for two person lifts for a given weight, while lifting in sagittally symmetric conditions whereas lateral shear became much greater for two-person lifts under asymmetric lifting conditions. This study has linked these changes to differences in trunk kinematic patterns adopted during one- versus two-person lifting.     

Moving loads manually

Many aspects that must be considered in the manual handling of loads are mentioned. These include legal aspects, recommended loads, techniques of lifting and carrying, dress, pulling and pushing, and pace of work. A new film on lifting and handling is noted and a plea is made for industry to consider training one or two workers as instructors in good techniques of physical moving of loads.     

Lumbo-sacral loads and selected muscle activity while turning patients in bed

Handling patients in bed using a piqué (a waterproof padded sheet placed under the patient) is associated with a high incidence of risks for the spine with, in particular, the activity of pulling and turning the patient with the pique representing the highest risk. Fifteen female nursing aides were evaluated for compression and shear forces at the L5/S1 joint and for selected muscular activities in the trunk and shoulders. Films, force platforms and EMG recordings supplied the data; dynamic segmental analyses were performed to calculate reaction forces at L5/S1, and a planar single-muscle equivalent was used to estimate internal loads. Different execution parameters were examined including execution velocity, height of bed, direction of effort, leg position and knee support. A ‘free’ task, and a manual task not involving the pique, were also investigated. Recommendations are made for reducing spinal loading. The results also suggest that a change of direction in the trunk motion may present some risks when associated with handling of heavy loads. Furthermore transfer of problems from a particular joint to other joints is likely to occur.     

Patient handling with and without slings: an analysis of the risk of injury to the lumbar spine

Health professionals handling patients are known to be at risk of sustaining work related low back injuries. It is not known whether the use of lifting slings reduces the risk of injury to the lumbar spine for patient handlers. This study used kinematic variables and subjective ratings of body part stress and lifter preference as measures of relative risk for three two-person techniques for carrying a patient from one chair to another chair. The techniques used no slings, one and two slings respectively. Twenty-two nurses performed five trials each of the three techniques. Kinematic measures of angular displacement, velocity and acceleration were obtained using the lumbar motion monitor and visual analogue scales were used to obtain measures of body part stress for seven body parts. Angular displacement, velocity and acceleration were significantly greater (p < 0.05) in the frontal, sagittal and transverse planes for the no sling technique compared to techniques using slings. Comparatively small yet significant differences between techniques using slings were recorded for sagittal flexion and rotation. There was no significant difference between one and two sling techniques for other dependent variables. Mean total body stress rating was higher for the no sling technique and all subjects indicated that their first preference was for slings. Although all three measures of risk rated the no sling technique as carrying a higher level of risk than the techniques using slings. No single measure adequately captured all aspects of relative risk. The elimination of manual patient handling is thought to be the best option for the reduction of work related back injuries in patient handlers. Where resources or technology are not yet adequate to provide practical alternatives and where the use of manual technique for a seat to seat task is unavoidable, the use of patient handling slings will reduce the risk.     

Review paper A comparative study of methods for establishing load handling capabilities

There has been much effort in recent years to quantify manual handling capabilities. Four main techniques have been used to this end; biomechanical modelling; the measurement of intra-abdominal pressure; psychophysics; and metabolic/physiological criteria. The aim of this study was to compare quantitatively the data produced from the first three techniques. The comparisons were limited to bimanual, sagittal plane lifting, which of all manual handling activities has been studied the most comprehensively, except that pushing and pulling data were compared from the psychophysics and intra-abdominal pressure (‘force limits’) databases. It was found that the data from ‘force limits’ proposed weights for bimanual lifting in the sagittal plane are lower than those reported to be psychophysically acceptable except for lifting close to and around the shoulder. The closest agreement between the databases was for lifting from an origin above knuckle height. The ‘force limits’ data were found to propose weights of lift which are at a minimum when lifting with a freestyle posture from the floor whereas the psychophysical technique proposes weights which are at a maximum when lifting from the floor. The psychophysical data were found to generate compressive forces at L5/S1 according to a static sagittal plane biomechanical model about 10% in excess of the NIOSH action limit (NIOSH 1981) when lifting from the floor, although over other lifting ranges the compressive forces were less than the NIOSH action limit. Lifting the (force limits) weights generated compressive forces which were on average 55% less than the AL (range 45 to 60%) when lifting in an erect posture. The data for pushing according to the psychophysical and ‘force limits’ database showed good agreement, but for pulling the ‘force limits’ weights were considerably greater than those selected psych ophysically. The implications of these findings are discussed.     

A comparative study of methods for establishing load handling capabilities

There has been much effort in recent years to quantify manual handling capabilities. Four main techniques have been used to this end; biomechanical modelling; the measurement of intra-abdominal pressure; psychophysics; and metabolic/physiological criteria. The aim of this study was to compare quantitatively the data produced from the first three techniques. The comparisons were limited to bimanual, sagittal plane lifting, which of all manual handling activities has been studied the most comprehensively, except that pushing and pulling data were compared from the psychophysics and intra-abdominal pressure ('force limits') databases. It was found that the data from 'force limits' proposed weights for bimanual lifting in the sagittal plane which [corrected] are lower than those reported to be psychophysically acceptable except for lifting close to and around the shoulder. The closest agreement between the databases was for lifting from an origin above knuckle height. The 'force limits' data were found to propose weights of lift which are at a minimum when lifting with a freestyle posture from the floor whereas the psychophysical technique proposes weights which are at a maximum when lifting from the floor. The psychophysical data were found to generate compressive forces at L5/S1 according to a static sagittal plane biomechanical model about 10% in excess of the NIOSH action limit (NIOSH 1981) when lifting from the floor, although over other lifting ranges the compressive forces were less than the NIOSH action limit. Lifting the 'force limits' weights generated compressive forces which were on average 55% less than AL (range 45 to 60%) when lifting in an erect posture. The data for pushing according to the psychophysical and 'force limits' database showed good agreement, but for pulling the 'force limits' weights were considerably greater than those selected psychophysically. The implications of these findings are discussed.     

An ergonomic evaluation of nursing assistants' job in a nursing home

Thirty-eight nursing assistants (NAs) in a nursing home ranked and rated 16 different patient handling tasks for perceived stresses to the low back. The nursing assistants were observed for 79 4?h shifts and were videotaped for 14 4?h shifts to describe a typical workday and to determine the number of patient-handling tasks performed per shift, the use of assistive devices, and biomechanical stresses to the low back. In addition, data were collected on nursing assistants' and patients' characteristics.

The top eight ranked tasks included transferring patient from toilet to wheelchair (WC), WC to toilet, WC to bed, bed to WC, bathtub to WC, chairlift to WC, weighing patients and lifting patients up in bed. The mean ratings of perceived exertion for these tasks were between ‘somewhat hard’ and ‘hard’. The estimated compressive force on L5/S1 disc for the 50th percentile patient weight ranged from 3·7 to 4·9 KN. Nursing assistants worked in teams of two and performed 24 patient transfers per 8?h shift by manually lifting and carrying patients. Assistive devices (a hydraulic lift and gait belt) were used less than 2% of the time. Patient safety and comfort, lack of accessibility, physical stresses associated with the devices, lack of skill, increased transfer time, and lack of staffing were some of the reasons for not using these assistive devices. Environmental barriers (such as confined workspaces, an uneven floor surface, lack of adjustability of beds, stationary railings around the toilet, etc.) made the job more difficult. Nursing assistants had a high prevalence of low-back pain and 51 % of nursing assistants visited a health care provider in the last three years for work related low-back pain.     

An ergonomic evaluation of nursing assistants' job in a nursing home.

Thirty-eight nursing assistants (NAs) in a nursing home ranked and rated 16 different patient handling tasks for perceived stresses to the low back. The nursing assistants were observed for 79 4 h shifts and were videotaped for 14 4 h shifts to describe a typical workday and to determine the number of patient-handling tasks performed per shift, the use of assistive devices, and biomechanical stresses to the low back. In addition, data were collected on nursing assistants' and patients' characteristics. The top eight ranked tasks included transferring patient from toilet to wheelchair (WC), WC to toilet, WC to bed, bed to WC, bathtub to WC, chairlift to WC, weighing patients and lifting patients up in bed. The mean ratings of perceived exertion for these tasks were between 'somewhat hard' and 'hard'. The estimated compressive force on L5/S1 disc for the 50th percentile patient weight ranged from 3.7 to 4.9 KN. Nursing assistants worked in teams of two and performed 24 patient transfers per 8 h shift by manually lifting and carrying patients. Assistive devices (a hydraulic lift and gait belt) were used less than 2% of the time. Patient safety and comfort, lack of accessibility, physical stresses associated with the devices, lack of skill, increased transfer time, and lack of staffing were some of the reasons for not using these assistive devices. Environmental barriers (such as confined workplaces, an uneven floor surface, lack of adjustability of beds, stationary railings around the toilet, etc.) made the job more difficult. Nursing assistants had a high prevalence of low-back pain and 51% of nursing assistants visited a health care provider in the last three years for work related low-back pain.     

An evaluation of patient lifting techniques

Abstract

In the present laboratory study five two-person manual lifting techniques were evaluated as to the amount of physical exertion required of the nurses. Ten female volunteers served as nurses; two healthy volunteers (weight: 55 kg and 75 kg) served as passive patients. The working postures and motions were recorded on videotape. The data thus obtained were used in a anatomical-biomechanical analysis. The perceived exertion by the nurses was measured as well. In almost all situations the compressive forces on the nurse's spine exceeded their acceptable limit of 3425 N. Differences between the lifting techniques were most obvious when the 55 kg patient was lifted. Ratings of the perceived exertion (RPE scores) were higher in symmetrical handling than in asymmetrical handling. The three techniques using asymmetrical hand positions produced less subjective stress. RPE scores and rotation of the back were negatively correlated. Rotating the back when moving a patient from one side to the other seems to ease the task. On the whole, the results of the biomechanical evaluation are in line with the subjective perception of the nurses. In both instances the barrow lift appeared to be the most strenuous one; the Australian lift resulted in low compressive forces and a moderate level of perceived exertion     

The handling of patients on geriatric wards. A challenge for on-the-job training

Patient lifting habits were studied on seven geriatric wards in five hospitals. The methods used were workplace analysis, questionnaire and video analysis of lifts. Mechanical hoists were regularly used only on the ward that had well organised on-the-job-training. The reasons given for not using the hoist (lack of space or time, etc) were similar on this and the other wards where hoists were used irregularly. Lifting with hoists is slower than without aids, but the total extra time needed for their use is only 3-6% of the 8-hour work shift. Stooped and twisted trunk positions occurred less often when lifting aids were used than without an aid. However, some nurses worked in bad spine-loading positions, even when using lifting aids. To eliminate these postures from nursing work, more attention should be paid to working postures during the organised training of patient handling.     

Designing ergonomic interventions for emergency medical services workers--part III: Bed to stairchair transfers

The objective of the current work was to test interventions aimed at reducing the low-back musculoskeletal loads experienced by firefighters/paramedics (FFPs) providing emergency medical services (EMS) that involve transferring a patient between a bed and a stairchair. The interventions, developed or selected using focus groups, were a prototype Drew People Movertrade mark, and a Transfer Sling. These interventions changed the coupling between the EMS worker and the patient. They were compared with an under-axilla lift. Eleven FFP teams transferred a 75kg dummy between a bed and a stairchair. Both interventions were tested using two-person transfers. In addition, the Transfer Sling was tested using a one-person transfer. Surface electromyographic (EMG) data were collected from 8 trunk muscles from each participant along with spine kinematic data. Additionally, ground reaction force data obtained from two forceplates were acquired for one member of each FFP team that was used to estimate directional spine moments using a 3D linked-segment model. In the two-person transfers, there was 19 degrees less trunk flexion (p=0.002) for the FFP on the patient's left side and a trend towards less motion for the FFP on the patient's right side (p=0.079) when using the interventions. Both FFPs showed reductions in the ipsilateral Erector Spinae activity using the Drew People Mover and the Transfer Sling that averaged approximately 9% MVC, which corresponds to a 21% decrease in the muscle activation levels. While the overall EMG was greater when performing a single-FFP transfer, the Transfer Sling reduced the bilateral Erector Spinae activity by approximately 20%. During the two-person transfers, the FFP on the forceplate to the right side of the patient showed a reduction in the forward bending moment using the Drew People Mover relative to the Sling and under-axilla conditions. During the single-person transfers, only the twisting moment was significantly reduced through use of the Transfer Sling. These objective measures, when combined with the subjective ratings of perceived exertion and the verbal feedback lead us to recommend the use of these interventions for bed to stairchair transfers.     

Designing ergonomic interventions for EMS workers - part II: lateral transfers

The objective of the current work was to test ergonomic interventions aimed at reducing the low back musculoskeletal loads experienced by firefighters/paramedics (FFPs) providing emergency medical services (EMS) when performing lateral transfers between a bed and a stretcher or between a stretcher and a hospital gurney. The interventions, developed using focus groups, were a bridgeboard to reduce the frictional force resisting the lateral sliding of the patient, the use of rods along each side of the patient to facilitate the grasping and handling of the bedsheet on which the patient is typically transferred, and a single rod that, when rolled in the bedsheet, resulted in the task being changed from a lifting task to a pulling task. Eleven two-person teams laterally transferred a 75 kg dummy with each intervention between a bed and simulated stretcher. Two roles were defined. For the two-sided transfers, the FFP roles were termed "stretcher-side" and "bed-side." Surface electromyographic (EMG) data were collected from 8 trunk muscles from each participant along with spine kinematic data. Additionally, kinetic data were obtained for the FFP in the stretcher-side role. Trunk flexion moments and Erector Spinae activity were reduced for the FFP in the stretcher-side role when using the bridgeboard and the single rod both individually and in combination. The single rod reduced the Erector Spinae activity in the FFP who typically would have been on the bed. For FFPs in both roles the single rod increased Latissimus Dorsi activation relative to the standard bedsheet transfer condition, although, this effect was moderated when the single rod was used in combination with the bridgeboard. Ratings of perceived exertion also supported the use of the single rod relative to the corresponding control condition.     

Effects of carrying methods and box handles on two-person team carrying capacity for females

This study used a psychophysical approach to examine the effects of carrying methods and the presence or absence of box handles on the maximum acceptable weight carried and resulting responses (heart rate and rating of perceived exertion) in a two-person carrying task. After training, 16 female subjects performed a two-person carrying task at knuckle height for an 8-h work period. Each subject performed 4 different carrying combinations two times. The independent variables were carrying methods (parallel and tandem walking) and box handles (with and without handles). For comparison with two-person carrying, the subjects also performed one-person carrying. The results showed that the maximum acceptable weight carried (MAWC), heart rate (HR), and rating of perceived exertion (RPE) were significantly affected by the presence of box handles. However, the subjects' MAWC, HR, and RPE values were not significantly influenced by the carrying methods. The test-retest reliability of the psychophysical approach was 0.945. The carrying efficiency of two-person carrying was 96.2% of the one-person carrying method. In general, the use of box with handles allows the subjects to carry a higher MAWC (with lower HR and RPE) compared to carrying boxes without handles.