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.     

The effects of caregiver experience on low back loads during floor and overhead lift maneuvering activities

This study investigated the effects of caregiver experience on peak external forces and moments generated at the L5/S1 joint of the low back when maneuvering loaded floor-based and overhead-mounted patient lifting devices. Twenty caregivers were divided into more-experienced and less-experienced groups based on the product of two factors: their years of lifting experience and the frequency of lifting the caregivers had done in the past. Ground reaction forces and moments as well as motion capture data were recorded while caregivers performed five different maneuvering tasks with both lifts in each of three conditions (caregiver subjects worked alone, as the primary caregiver in a pair, and as the secondary caregiver in a pair). Six outcome measures (net external forces and moments at the L5/S1 joint) were recorded. Multivariate analyses of variance of all net external forces and moments were done separately for the floor and overhead lifts. A significant effect of experience level was found for the floor lift (p = 0.006) but not for the overhead lift (p = 0.163). A follow-up univariate analysis of floor lift activities found significant differences between more-experienced and less-experienced caregivers for Turn, Push and Legs Up activities.

Relevance to industry

Previous work has shown that overhead lifts reduce the loads on caregivers compared to floor lifts. The findings of this study further underscore the need to purchase overhead lifts to protect less-experienced caregivers (including informal family caregivers) who are at increased risk of back injury when maneuvering floor lifts.     

Effects of work experience and exertion height on static lifting strengths and lift strategies of experienced and novice female participants

In this study, 46 female experienced workers and inexperienced novices (23 each) were recruited to determine their maximum lifting strength at 15 exertion heights between 10 and 150 cm from the floor. The results revealed that the experienced workers' strengths at all 15 heights exhibited relatively little fluctuation, and were approximately 50–70 N lower than those of novices when heights were ≤50 cm. No differences in strengths were observed at 60–150 cm between the groups. The experienced workers tended to adopt a consistently deep squat at lower heights (≤50 cm) and a more erect posture with stiffened arms at higher heights (≥70 cm), resulting in lower L4/L5 disc compression forces and shoulder moments than in novices, respectively. In contrast to the lifting techniques adopted by experienced workers to effectively avoid overloading, the findings suggest that novice female workers who lack experience should be cautious and trained for performing lifting tasks.     

Evaluation of lifting and lowering velocities while using a patient lift for transfer during nursing care

Using a patient lift to assist in transfer can alleviate physical burden and reduce the risk of lower back disorders. However, it requires more time than applying manual transfer techniques, often resulting in caregivers opting out of its use. This study used two experiments to examine the lifting and lowering velocities experienced by caregivers and residents when using a patient lift during nursing care. In experiment 1, the usability, subjective assessment of velocity, heart rate (HR), electromyography (EMG), working time, and so on were measured at eight lift velocities (ranging from 0.01 to 0.15 m/s in 0.02 m/s intervals) during the transfer task of 10 female students in a laboratory. In experiment 2, the same measured parameters as in experiment 1 except for HR and EMG were measured at four lift velocities (ranging from 0.03 to 0.09 m/s in 0.02 m/s intervals) during the transfer task of six elderly residents by 12 caregivers at an elderly care facility. The residents and caregivers rated 0.05–0.09 m/s as appropriate velocities in both experiments. Specifically, the best velocities for lowering the lift without the resident, lifting with the resident, and lowering were 0.07–0.09 m/s, 0.05–0.07 m/s, and 0.05 m/s, respectively. We conclude that the studied velocities are appropriate when the lift is used by caregivers at an elderly care facility. Since the appropriate velocity is different for each transfer subtask, we suggest that manufacturers should program suitable velocities into lifts according to the subtasks deemed important by the caregivers.     

The influence of lift frequency,lift duration and work experience on discomfort reporting

Discomfort surveys are commonly used to assess risk in the workplace and prioritize jobs for interventions before an injury or illness occurs. However, discomfort is a subjective measure and the relationship of discomfort to work-related factors is poorly understood. The objective of this study was to understand how reports of discomfort relate to work-related risk factors for the low back. A total of 12 novice and 12 experienced manual materials handlers performed repetitive, asymmetric lifts at different load levels and at six different lift frequencies throughout an 8-h exposure period. Discomfort was recorded hourly throughout the day. Analyses were performed to determine which experimental factors influenced reporting of discomfort and if discomfort trends matched spine loading trends. Novice lifters reported significantly higher discomfort levels than experienced subjects. They also reported increases in discomfort as moment exposure increased and as the exposure time increased. Novices lifting at 8 Nm load moment level reported increased discomfort from 0.07 to 0.63 by the end of the day, at 36 Nm they reported an increase from 0.04 to 0.40 and at 85 Nm they reported an increase from 0.37 to 3.06. Experienced subjects, on the other hand, reported low levels of discomfort regardless of moment exposure, lift frequency or exposure duration. The reported discomforts were generally unrelated to the biomechanical loading on the spine. Discomfort reporting appears to be more a reflection of experience than of work risk factor exposure. Experienced subjects may have more efficient motor patterns, which reduce spinal load and thus discomfort. Novice subjects seemed to have a lower threshold of discomfort. Caution is needed when using discomfort reporting as a means to identify jobs in need of interventions, in that biomechanical loading may not be accurately represented. Discomfort should only be used as a supplement to objective measures, such as spinal loading, to assess the risk of low back disorders.     

The influence of lift frequency, lift duration and work experience on discomfort reporting

Discomfort surveys are commonly used to assess risk in the workplace and prioritize jobs for interventions before an injury or illness occurs. However, discomfort is a subjective measure and the relationship of discomfort to work-related factors is poorly understood. The objective of this study was to understand how reports of discomfort relate to work-related risk factors for the low back. A total of 12 novice and 12 experienced manual materials handlers performed repetitive, asymmetric lifts at different load levels and at six different lift frequencies throughout an 8-h exposure period. Discomfort was recorded hourly throughout the day. Analyses were performed to determine which experimental factors influenced reporting of discomfort and if discomfort trends matched spine loading trends. Novice lifters reported significantly higher discomfort levels than experienced subjects. They also reported increases in discomfort as moment exposure increased and as the exposure time increased. Novices lifting at 8 Nm load moment level reported increased discomfort from 0.07 to 0.63 by the end of the day, at 36 Nm they reported an increase from 0.04 to 0.40 and at 85 Nm they reported an increase from 0.37 to 3.06. Experienced subjects, on the other hand, reported low levels of discomfort regardless of moment exposure, lift frequency or exposure duration. The reported discomforts were generally unrelated to the biomechanical loading on the spine. Discomfort reporting appears to be more a reflection of experience than of work risk factor exposure. Experienced subjects may have more efficient motor patterns, which reduce spinal load and thus discomfort. Novice subjects seemed to have a lower threshold of discomfort. Caution is needed when using discomfort reporting as a means to identify jobs in need of interventions, in that biomechanical loading may not be accurately represented. Discomfort should only be used as a supplement to objective measures, such as spinal loading, to assess the risk of low back disorders.     

A biomechanical assessment of floor and overhead lifts using one or two caregivers for patient transfers

This study investigated the differences in peak external hand forces and external moments generated at the L5/S1 joint of the low back due to maneuvering loaded floor-based and overhead-mounted patient lifting devices using one and two caregivers. Hand forces and external moments at the L5/S1 joint were estimated from ground reaction forces and motion capture data. Caregivers gave ratings of perceived exertion as well as their opinions regarding overhead vs. floor lifts. Use of overhead lifts resulted in significantly lower back loads than floor lifts. Two caregivers working together with a floor lift did not reduce loads on the primary caregiver compared to the single-caregiver case. In contrast, two-caregiver operation of an overhead lift did result in reduced loads compared to the single-caregiver case. Therefore, overhead lifts should be used whenever possible to reduce the risk of back injury to caregivers. The use of two caregivers does not compensate for the poorer performance of floor lifts.     

The effects of a back belt on posture, strength, and spinal compressive force during static lift exertions

The experiment reported in this paper evaluated changes in lifting posture, static lifting strength and the estimated L3/L4 spinal compressive force resulting from the use of an abdominal support or ‘back' belt. Torso posture and maximum static lift strength were measured for eight male and eight female subjects using symmetric and asymmetric hand positions at calf height and elbow height. Body posture, and hand forces were also used as input to a three-dimensional static biomechanical model of the torso used to estimate L3/L4 spinal compressive force. The results showed axial twist of the torso to be significantly lower for calf height asymmetric exertions when the abdominal support belt was worn. The measured reduction in axial twist was approximately four degrees. No other significant effects on posture due to the support belt were found. Static lift strength was not significantly increased or reduced when the support belt was used. Predicted spinal compressive force was significantly lower when a support belt was worn (2840 N compared to 3125 N when the belt was not worn). Overall, the results of the experiment demonstrate a very limited benefit to the user of abdominal support belts, primarily due to reduced or restricted motion during asymmetric and lower-level lifts.Relevance to industryBack belts are commonly used in industry to mitigate manual materials handling hazards. One assumption often made by those recommending the use of back belts is that they substantially reduce the bending and twisting of the torso. The experiment reported in this paper tests this assumption and provides information on the utility of back belts.     

Proteomic approaches to the study of malignant lymphoma: Analyses on patient samples

We describe the application of proteomic techniques for protein profiling and biomarker discovery in malignant lymphoma. Hematologic malignancies are primarily characterized by their clinical, morphological, immunophenotypical, and molecular-genetic features. However, when based on these parameters, apparently identical lymphomas may show distinct clinical courses, suggesting underlying biological heterogeneity. Recent proteomic analyses have identified differences in protein expression both with regard to subclassification of the malignant lymphoma entities, as well as in correlation with clinical outcome. In this review, studies on quantification of differential protein expression in and between malignant lymphoma entities are included. Studies are included that are based on patient samples, that is, serum/plasma or cytological specimens, as well as intact tumor tissues, together with studies that focus on tumor cells alone, or in conjunction with the tumor microenvironment. For biomarker discovery in malignant lymphoma, these approaches are used to uncover the underlying biological mechanisms and identify proteins with potential diagnostic and prognostic utility, either as predictive biomarkers or as novel future treatment targets.     

Postural and trunk muscle response to sudden release during stoop lifting tasks before and after fatigue of the trunk erector muscles

The effect of fatigue on the muscular and postural response to sudden release of different stoop lifting loads was studied. Ten male volunteers performed a series of stoop lifting trials before and after fatigue of the erector spinae. Trials were performed using loads of 20, 40, 60, and 80N, and sudden release of load was triggered randomly on one of the repetitions using an electromagnetic release. The onset of release was registered by an accelerometer, centre of pressure (COP) motion was recorded via a forceplate, and EMG activities of the latissimus dorsi (LD), erector spinae (ES), rectus abdominus (RA), external oblique (EO) and internal oblique (IO) muscles were recorded. A slightly reduced lifting speed was seen after fatigue, particularly at the higher loads, but this had little effect on the perturbing force at release, which was dominated by the release load. A significant effect of fatigue was seen on the antero-posterior COP motion, with the postural disturbance being decreased after fatigue. Fatigue resulted in a significant increase in ES (p = 0.029) and LD (p = 0.015) relaxation times and, while the response patterns (relaxation, contraction or no response) of the anterior trunk muscles (RA, EO, IO) were not always consistent, the proportion of response by relaxation was greater after fatigue. This resulted in a lower incidence but longer duration of co-contraction of the ES-RA, ES-EO and ES-EO muscle groups following fatigue, such that the mean co-contraction duration of these groups showed no significant differences before and after fatigue. The response to sudden release is a balance between maintaining postural stability and at the same time preventing the trunk musculature from overloading the spine and risking tissue injury. While fatigue of the trunk extensors does not appear to increase either the risk of fall or stumble or the incidence of co-contraction following sudden release of stoop lifting tasks, the duration of co-contraction appears to increase following fatigue. Further study is required to quantify the loading on the spine during sudden release of different lifting tasks before and after more realistic fatigue conditions.     

Efficacy of three interventions at mitigating the adverse effects of muscle fatigue on postural control

This study evaluated the efficacy of three interventions at reducing the adverse effects of muscle fatigue on postural control. The first provided rest breaks according to perceived decrements in postural stability, while the other two involved auditory stimulations (static pure tone and moving conversation). Sixteen participants performed repetitive box handling (lifting + lowering) over 1.5 h to induce muscle fatigue mainly in the lumbar extensors. Trials of quiet upright stance were completed at 10-min intervals, during which the interventions (or a control condition) were applied. Postural control was assessed using perceived stability (PS) and several measures derived from centre-of-pressure (COP) time series. Allowance of rest breaks did not significantly affect any of the objective measures, though a trend indicated an offset to fatigue-induced decreases in PS. Both the static pure tone and moving conversation led to significant changes in the dependent measures indicating a mitigation of fatigue-induced postural instability. PRACTITIONER SUMMARY: We examined the effects of three control strategies on postural control in the presence of muscle fatigue induced by a simulated occupational task. The findings can facilitate the development of future strategies or practical interventions to reduce falling risk and prevent falls.     

Reliability and validity of self-reported assessment of exposure and outcome variables for manual lifting tasks: a preliminary investigation

The reliability and validity of self-reported assessment of exposure and outcome variables were examined for manual lifting activities among ten physiotherapists. In this study, the participants evaluated the effects of five lifting variables on perceived effort, twice separated by a one-week period. One hundred and sixty-two lifting conditions were evaluated by each subject. The exposure and outcome lifting variables were described in linguistic terms. Intra-class correlation coefficient (ICC(1,1)) analysis revealed a mean value of 0.62 for all lifting activities. The self-reported assessment was cross-validated with the NIOSH lifting index by mapping the linguistic variables into numerical ranges. Moderate correlations (r = 0.54 and 0.53, p<0.01) were obtained between perceived physical exertion/perceived risk and lifting index. The findings of this study provide preliminary indications that human-based methodologies may be further explored on experienced workers.     

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.     

Load on knee joint and knee muscular activity during machine milking

Abstract

Ten professional milkers simulated 20 different standardized machine-milking work postures. Various differences in level between milkers and cow, and various postures at each level, were studied. Knee muscular activity was recorded electromyographically. In the milking procedure when attaching the teat cups to the udder the body position was photographed and the loading moment of force about the bilateral knee axis was calculated by means of a biomechanical model. Working with straight knees resulted in comparatively high moments tending to extend the knee (with the highest mean of 56 N m). This moment was for some subjects close to their maximum strength capacity. A 65° knee angle in the standing postures with small level-difference between cow and milker gave the least knee loading moment (i.e. around zero) independently of body weight. The horizontal distance between operator and cow showed high importance for the amplitude of the knee load. The model for determining knee load can generally be applied to other similar activities when standing bent forwards.     

The effect of handle design on upper extremity posture and muscle activity during a pouring task

In this study, the effect of container handle parameters on shoulder and upper limb muscle activity and joint posture during a pouring task is investigated. Results indicated that a low handle position and a vertical handle slope minimised the loading of the shoulder muscles. A high and sloped handle minimised the muscle activity and wrist deviation of the lower arm. The effects of diameter were not significant for most dependent variables during the lifting phase of the task; however, beneficial effects were seen with the smallest handle diameter during the pouring phase. A trade-off existed between the shoulder and the hand/wrist posture with the different handles. The findings of significance with relatively small effect size suggest a high sensitivity of the system to any changes. In the real world, speed, space and work conditions are important factors that influence how a task is performed. This emphasises the importance of proper handle design.

Practitioner Summary: In this study, the effect of container handle design on the muscle activity and postures of the upper extremity during a pouring task were analyzed using the experimental data collected from electromyography and motion tracking systems. The low handle height and vertical handle slope design yielded the lowest shoulder muscle activity.     

Balancing documentation and direct patient care activities: A study of a mature electronic health record system

US hospitals now fully embrace electronic documentation systems as a way to reduce medical errors and improve patient safety outcomes. Whether spending time on electronic documentation detracts from the time available for direct patient care, however, is still unresolved. There is no knowledge on the permanent effects of documenting electronically and whether it takes away significant time from patient care when the healthcare information system is mature. To understand the time spent on documentation, direct patient care tasks, and other clinical tasks in a mature information system, we conducted an observational and interview study in a midwestern academic hospital. The hospital implemented an electronic medical record system 11 years ago. We observed 22 health care workers across intensive care units, inpatient floors, and an outpatient clinic in the hospital. Results show that healthcare workers spend more time on documentation activities compared to patient care activities. Clinical roles have no influence on the time spent on documentation. This paper describes results on the time spent between documentation and patient care tasks, and discusses implications for future practice.Relevance to industryThe study applies to healthcare industry that faces immense challenges in balancing documentation activities and patient care activities.     

The influence of handrim design on the contact forces on hands' surface: A preliminary study

This study is aimed at investigating how contact forces are distributed over the hand's surface during manual wheelchair propulsion with two different designs of handrim. Twenty able-bodied subjects performed a wheelchair propulsion protocol comprising five consecutive pushes: start-up, straight motion and braking. The protocol was repeated twice, each time with a handrim type: the standard round metallic tube handrims, and a prototype of an ergonomic handrim. During all the tests, contact forces over the users' hand surfaces were measured through a pair of gloves instrumented with ten force sensors each. The average values of each sensor were used to compare both handrims, and statistical tests were used to verify significant differences. The results indicate that the handrim design influences the magnitude of contact forces on hands' surface. There was a reduction in the magnitude of the contact forces in both regions – metacarpals and distal phalanges – during the three propulsion phases with the use of the ergonomic handrim. Among all ten sensors, the distal phalange of the third finger registered the greater forces during start-up, forward motion and braking. The reduction on the contact forces with the use of the ergonomic handrim is possible due to the increased surface and the anatomical shape. Improving handrim design can contribute the ergonomics of manual propulsion, thus benefiting users' comfort and safety in wheelchair mobility.Relevance to industryThis study contributes to the knowledge of the ergonomics of manual wheelchair propulsion, with the main focus on the hand-handrim interface. Thus, it can benefit designers and manufacturers in developing handrims with ergonomics features, as well as improve the users' comfort and safety during manual wheelchair usage.     

Co-activation and maximal EMG activity of forearm muscles during key tapping

Many workers with repetitive motion tasks develop work related musculoskeletal diseases. In this study, the impact of required forces in dynamic key touch pressure and key displacements on forearm extensor and flexor muscles was investigated. The aims were to evaluate the co-activation of forearm extensor and flexor muscles during a 2 min tapping task at 4 Hz and to assess possible changes in maximal surface electromyography (sEMG) activation during tapping using different keys with variable force–displacement characteristics. 13 subjects took part in the experiment and performed ten tapping sequences, using a different key make (with different force-displacement characteristics) each time. Two channels of sEMG were used to monitor forearm muscle activation. Results showed (a) that the co-activation of forearm extensor and flexor muscles increases with rising key makes force, and (b) that coordination between extensor and flexor muscles improves over time.The findings indicate that keyboards with make-force levels over 0.59 N are ergonomically inadequate. Differences in key displacement were less important.

Relevance to industry

Chronic pain in the forearm due to repetitive tasks is common among employees working with computers. This paper presents and discusses results showing higher muscle activity and bad intramuscular coordination when using high make-force keys.     

Simulation of surface EMG for the analysis of muscle activity during whole body vibratory stimulation

This study aims to reproduce the effect of motor-unit synchronization on surface EMG recordings during vibratory stimulation to highlight vibration evoked muscle activity. The authors intended to evaluate, through numerical simulations, the changes in surface EMG spectrum in muscles undergoing whole body vibration stimulation. In some specific bands, in fact, vibration induced motion artifacts are also typically present.     

Muscle activity and range of motion during active trunk rotation in a sitting posture

Twisted trunk postures during tractor driving are associated with low-back pain. The purposes of this study were to quantify the muscle activity as a function of twisting angle, to quantify the range of motion (ROM) during active trunk rotation and to determine whether there were any differences between tractor drivers and office workers and between twisting direction for these variables. The subjects performed exertions in a seated position, twisting from the neutral position to the end of the ROM. The results showed that external oblique and erector spinae had significantly different activation patterns depending on twisting direction. For the contralateral external oblique and the ipsilateral erector spinae, the muscle effort required to twist the trunk was low up to about 20° twisting angle, then the muscle effort needed to twist the trunk increased progressively. No significant differences due to occupation or twisting direction were found. The result implies that work in twisted trunk postures might be a risk factor for low-back pain.