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Effects of training and experience on patient transfer biomechanics
International Journal of Industrial Ergonomics 40 (2010) 282–288
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Effects of training and experience on patient transfer biomechanics J.N. Hodder a, *, S.N. MacKinnon b, A. Ralhan c, P.J. Keir a a
Department of Kinesiology, McMaster University, 1280 Main St West, Hamilton, Ontario, Canada School of Human Kinetics and Recreation, Memorial University of Newfoundland, St. John’s, Newfoundland, Canada c Eastern Health Authority, 300 Prince Philip Drive, St. John’s, Newfoundland, Canada b
a r t i c l e i n f o
a b s t r a c t
Article history: Received 7 October 2008 Received in revised form 7 December 2009 Accepted 14 January 2010 Available online 21 February 2010
Nursing is one of the professions at highest risk for the development of low back disorders, with patient handling identified as a leading contributor. The purpose of this study was to assess a component of the Back Injury Prevention Program (BIPP) that provided direct instruction on patient handling technique. Trunk kinematics and muscle activities were collected as indicators of low back loading. Novice participants (before and after instruction) and experienced nurses (previously trained) were monitored while they performed three selected patient transfers. Following BIPP instruction, muscle activity in novice participants was reduced by up to 18.1% MVE. Trained novices and nurses had generally smaller thoracolumbar spine angles by approximately 12 with lower variability in spine angle. Nurses had a smaller range of spine motion than novices combined with higher trapezius and deltoid activities, which may be a load reduction strategy for the back. The BIPP patient transfer instruction provided improved thoracolumbar biomechanics for new trainees and experienced nurses. Relevance to industry: Mechanical lifts are not viable in all hospital or home care settings, thus manual patient handling training is still a necessary and important facet of initial and continuing nursing education. Back education and patient handling instruction provides a cost effective prevention strategy in nursing. Ó 2010 Elsevier B.V. All rights reserved.
Keywords: Nursing Low back disorder Patient handling Transfer techniques
1. Introduction Nursing has been identified amongst the top professions at risk for development of occupationally-related low back disorders (LBDs) (Hignett et al., 2007; Karwowski et al., 2005; Yip, 2004; Retsas and Pinikahana, 2000; Marras et al., 1999). The American Nurses Association reported that of approximately 5000 nurses polled in 2001, 85% experienced back pain at work (Houle, 2001). In Canada, from 1996 to 2000, the incidence of back injuries in the healthcare sector was higher than all other industries combined (Engst et al., 2004). The etiology of LBD is complex, consisting of physical, psychosocial, individual, sociocultural and work organizational factors (Karwowski et al., 2005). Although many of these factors are present in nursing, the physical factors involved in patient handling have been frequently implicated as the origin of LBD (Cartledge, 2001; Yip, 2001; Retsas and Pinikahana, 2000; Marras et al., 1999). Patient handling activities identified as having a high risk of injury include: repositioning or adjusting a patient in bed,
* Corresponding author. Tel.: þ1 905 525 9140x20175; fax: þ1 905 523 6011. E-mail address: [email protected] (J.N. Hodder). 0169-8141/$ – see front matter Ó 2010 Elsevier B.V. All rights reserved. doi:10.1016/j.ergon.2010.01.007
transferring a patient to/from the bed/chair/commode, assisting a patient while walking and assisting a patient rise from a sitting position (Skotte et al., 2002; Yip, 2001; Engvist et al., 1998; Owen and Garg, 1991). The use of retrofit ceiling lifts and portable mechanical lifts has been successful in reducing back compressive forces of these transfers by 60% (Santaguida et al., 2005; Owen and Garg, 1991). However, these are not always economically feasible and not all spaces can accommodate a lift, such as in homes and older institutions. Training patient transfer personnel in safe transfer techniques has been used in the past as a cost effective intervention (Hignett et al., 2007; Johnsson et al., 2002; Garg et al., 1991). Developing alternative ergonomic interventions for patient handling has proven difficult. Patients are asymmetrical, non-rigid bodies that impose awkward hand coupling with an element of unpredictability. Non-compliant patients or unanticipated actions from patients can lead to unexpected loading and increase the risk of injury. In addition, unlike many workplaces, workload is dependent on fulfilling the needs of the patients and, administratively, is unlikely to be reduced due to limited nursing resources. The need to educate nurses and patient handlers is intuitive, yet ‘‘back education’’ programs have not been successful in reducing injury incidence by themselves (Finch Guthrie et al., 2004; Hignett, 1996; Venning, 1988). Recently, Skotte and Fallentin (2008) found
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that transfer technique and non-mechanical assistive devices, such as a draw-sheet, had a greater impact on low back loading than the weight or disability level of the patient. Practical training in transfer technique combined with theoretical training has been shown to improve posture and other risk factors that may lead to injury (McCannon et al., 2004). Using a combined approach of practical and theoretical training, the Back Injury Prevention Program (BIPP) developed by the Occupational Health and Rehabilitation Services Department of the Health Science Center in St. John’s (presently named Eastern Health), Newfoundland and Labrador provides instruction on patient handling technique while identifying injury mechanisms and emphasizing back safety (Bouchier, 1996). Additionally, the program conditions nurses to perform a risk analysis prior to attempting a patient transfer to select the most appropriate approach. The BIPP has been incorporated as part of the practicum for Bachelor of Nursing program at Memorial University and the Centre for Nursing Studies. As well, nurses that enter the Health Care Corporation are trained and/or retrained to refresh the principles of BIPP. Although the BIPP program has been in place for over a decade, a thorough biomechanical analysis of the program elements has yet to be performed. The purpose of this study was to analyze trunk kinematics and muscle activity during three patient handling tasks selected from the BIPP program in novices, before and after training, as well as trained experienced nurses. 2. Methods 2.1. Participants Twelve untrained individuals and 10 experienced nurses participated. The 12 females without previous patient handling training (novices) had a mean height of 166.1 6.6 cm, mean weight of 65 12.2 kg and were 23.7 1.4 years of age. The 10 experienced female nurses had been previously trained in BIPP transfers (in the past 2 years) and were recruited from the Health Care Corporation of Newfoundland (159.9 6.0 cm; 73.0 19.5 kg; 41.6 10.2 years of age; 11.3 9.5 years of employment). Three selected transfers were performed by novice participants and experienced nurses while muscle activity and three-dimensional thoracolumbar kinematics were collected for analysis. The study
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protocol was approved by the Human Investigations Committee of Memorial University. All participants provided informed, written consent prior to participation. Novice participants attended three sessions on two consecutive days. During the first session, the experiment was explained and they viewed a 3-min video of the three patient handling tasks they would perform. No further instruction was given and the participants completed three consecutive repetitions of the three tasks in random order. On day two, novice participants received two hours of standardized instruction of the BIPP biomechanical principles and practice of the transfer tasks, which were critiqued and corrected by a qualified BIPP instructor. The final session occurred approximately two hours after the training session and repeated the protocol of the first day (without reviewing the video). Experienced nurses attended one experimental session. The experienced nurses were informed of the three transfer tasks to be performed and no further instruction was provided. Task order was assigned randomly to each participant and each task was repeated three consecutive times. 2.2. Tasks 2.2.1. Task 1: patient reposition (from side of bed) A two person reposition of the patient to the head of the bed using a draw-sheet was performed with the participant and a standard assistant (Fig. 1). The BIPP protocol for this transfer required the participant to raise the bed to waist height. With the draw-sheet already under the patient, the participant began the transfer with the left foot aligned directly below the hip of the patient and the right foot pointing towards the head of the bed. Holding the draw-sheet tight at the patient’s hip and shoulder level and elbows braced at their sides, the participant would shift her weight from the left leg to the right leg, moving the patient within 6 cm of the head of the bed for a successful trial. The standardized patient handler mirrored these actions simultaneously. 2.2.2. Task 2: patient reposition (from head of bed) A two person reposition of the patient to the head of the bed using a draw-sheet was performed with the participant and a standard assistant positioned at the head of the bed (Fig. 2). The BIPP protocol for this task required the bed height to be adjusted such that
Fig. 1. Task 1: Movement sequence for repositioning patient towards the head of the bed with experienced nurse at the side of the bed in foreground and standardized patient handler in background.
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Fig. 2. Task 2: Movement sequence for repositioning patient towards the head of the bed with experienced nurse at the head of the bed in foreground and standardized patient handler in background.
the patient handlers can ‘‘stand tall’’ on their right knee which was placed on the corner of the bed, while the left leg was extended and toe remained in contact with the ground. Facing the opposite corner of the bed, the participant cradled the patient’s shoulder with the draw-sheet and, in unison with the other handler, sat back onto their heel, moving the patient within 6 cm the head of the bed. 2.2.3. Task 3: patient transfer from bed to wheelchair A single person patient transfer from sitting at the edge of the bed to a wheelchair (left to right) was performed using a transfer belt (Fig. 3). The BIPP instructions are to lower the bed such that both of the patient’s feet are flat on the ground. The wheelchair was placed with the brakes engaged at a 45 angle to the bed, and the armrest closest to the patient removed. The patient handler placed their left foot outside of the leg of the patient and the right foot in the direction of the wheelchair, keeping the patient within their base of support. Three rocking motions from left foot to right foot were used to gain momentum so that the patient cleared the bed, at which point the patient was pivoted to the right and lowered to the wheelchair. Successful completion of task 3 required that the patient be relocated to the chair without further adjustment.
2.2.4. Surrogate patient and secondary patient handler A healthy surrogate patient (175 cm, 81 kg) participated in all tasks. The surrogate patient followed the actions according to BIPP guidelines for transfer selection. During tasks 1 and 2, the patient was completely passive. According to BIPP, a single person transfer (task 3) is appropriate to use when the patient is able to follow verbal instructions, able to bear partial weight, yet need assistance to move from one seated position to another. A qualified BIPP instructor trained the patient until his actions were consistent and repeatable for each transfer. The second patient handler which assisted participants in tasks 1 and 2 was trained in a similar manner. 2.3. Data collection For each task, four muscles were monitored bilaterally. The left and right trapezius (LTR, RTR), left and right external oblique (LEO, REO) and left and right erector spinae (LES, RES) muscles were collected for all tasks. The fourth muscle collected was dependent on the task, the left and right posterior deltoid (LPD, RPD) were investigated in tasks 1 and 2, and the left and right rectus femoris (LRF, RRF) for task 3. Maximum voluntary excitations (MVE) were collected for each muscle investigated at the beginning of each
Fig. 3. Task 3: movement sequence for the patient transfer from bed to chair using the one person pivot technique.
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protocol. Prior to electrode placement, the skin was shaved, abraded and cleaned with rubbing alcohol to reduce impedance. Pairs of disposable surface electrodes (KendallÒ Medi-trace 100 series, Wabasha, MN) were placed along the fibre direction at the midbelly of each muscle. Electromyography signals were sampled at 1000 Hz, band-pass filtered from 20 to 500 Hz, rectified and averaged by software using a 10 ms moving window (ME3000P/MegaWin; Mega Electronics Ltd. Kuopio, Finland) before being analogue to digitally converted and stored on a computer for later analysis. A lumbar motion monitor (LMM; Chattecx Corp., Chattanooga, TN) measured angular displacements of the thoracolumbar spine in three dimensions. The LMM was calibrated and sized according to manufacturer instructions and then affixed to the participant’s back using the provided harness. The LMM data were collected at 60 Hz and stored on a computer. The EMG and LMM were launched simultaneously to synchronize the data in relative time. 2.4. Data analysis For each muscle, peak EMG was normalized to MVE’s and averaged over three trials for each participant. Maximum angular displacement and range of motion (ROM; in degrees) in each direction (sagittal, lateral and twist) were averaged over the three trials. Note that peak values are presented but means were also analyzed. Kinematics and EMG of each group were compared to each other (Fig. 4). Repeated measures analyses of variance (ANOVA) were used to compare pre- and post-training EMG and spine angles (peak and range of motion for all 3 directions) for the novice group (a ¼ 0.05). Univariate ANOVA (a ¼ 0.05) were used to compare EMG and trunk kinematics of untrained novices versus experienced nurses and trained novices vs. experienced nurses. 3. Results 3.1. Task 1: patient reposition (side of bed) 3.1.1. Effects of training on novice participants Training had a significant effect on LTR muscle activity, decreasing from 21.7 10.4% to 12.3 5.8% (F1 ¼ 6.2, p ¼ 0.023) after training (Table 1). The RPD had the largest reduction (by 11.3% MVE) but its large variability did not allow for statistical significance. Training lowered activity in all muscles but only modestly and did not attain statistical significance. Overall, novice spine posture prior to training was relatively neutral with a maximum angular displacement of 6.0 5.6 in left axial twist direction (Table 2). After training, participants were
significantly more extended. Peak back flexion changed significantly from 4.4 11.4 (flexion) to 5.3 7.6 (extension), and peak extension which increased by 8.3 (F1 ¼ 8.1, p ¼ 0.019). Training significantly reduced the ROM in the sagittal plane from 10.3 6.6 to 6.5 7.9 (F1 ¼16.0, p ¼ 0.003). Lateral bend and axial twist were not significantly affected with training (Table 2). 3.1.2. Novice participants versus experienced nurses Both before and after training, novices had lower peak activity than experienced nurses in all muscles except REO and LPD which were always higher in novices (Table 1). Trained novices had lower LTR (significantly) and RTR activity than experienced nurses by 26.5% (F1 ¼ 20.2, p ¼ 0.000) and 19.5% MVE, respectively (Table 1). Overall, experienced nurses maintained a relatively neutral posture throughout the reposition task with a maximum angular displacement of 5.0 8.4 extension and maximal range of motion of 6.7 4.9 axial twist (Table 2). When compared to untrained novices, experienced nurses had significantly smaller lateral right bend displacement with 4.5 4.7 versus 0.2 4.7 (F1 ¼ 4.8, p ¼ 0.044). Experienced nurses also had less sagittal ROM (10.3 6.6 ) than untrained novices (3.4 2.8 ; F1 ¼ 8.4, p ¼ 0.01) and axial twist ROM (12.7 4.9 versus 6.7 4.9 ; F1 ¼ 7.3, p ¼ 0.015). 3.2. Task 2: patient reposition (head of bed) 3.2.1. Effects of training on novice participants For task 2, significant reductions in peak muscle activity for the RTR (9.1% MVE; F1 ¼ 5.2, p ¼ 0.049), RPD (16% MVE; F1 ¼ 6.3, p ¼ 0.037), LES (10.5% MVE; F1 ¼ 5.7, p ¼ 0.041) and LEO (19.7% MVE; F1 ¼ 7.9, p ¼ 0.02) were seen after training (Table 1). Decreases were also found in all other muscles after training (with the exception of the LPD), yet did not attain statistical significance (Table 1). Trunk angle decreased with training for flexion, extension and lateral bend. After training, novices had significantly smaller peak right bend by 6.7 (F1 ¼ 6.0, p ¼ 0.037) and smaller lateral range by 6.0 (F1 ¼ 5.8, p ¼ 0.039). While both peak extension and flexion decreased by 5.8 and 7.4 , respectively (Table 2). However, peak left twist increased significantly by over 4 (1.3 6.4 to 3.1 3.8 ; F1 ¼ 5.1, p ¼ 0.05). 3.2.2. Novice participants versus experienced nurses There were no significant differences in muscle activity between nurses and untrained novices. Nurses did have lower peak RPD activity than untrained novices (37.9 25.3% MVE versus 50.9 33.4% MVE), however the difference was not significant.
Dependent Measures
Comparisons 1. Repeated Measures ANOVA -
Untrained novice vs. Trained novices
2. Univariate ANOVA -
Trained novices vs. Experienced nurses
-
Untrained novices vs. Experienced nurses
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Independent Measures
1a. EMG measures -
1. Patient reposition from side of bed
Bilateral: trapezius, erector spinae, external obliques and posterior deltoid
2. Kinematic measures 2. Patient reposition from head of bed 3. Patient transfer from bed to wheelchair
-
Mean peak sagittal, lateral and axial twist displacement and range of motion
1b. EMG measures -
Bilateral: trapezius, erector spinae, external obliques and rectus femoris
Fig. 4. A schematic indicating the statistical comparisons used in the study. Indicated are the comparisons, independent (task) and dependent (EMG, posture) variables used. Repeated measures ANOVA were used to test novices before and after training.
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Table 1 Mean peak EMG with standard deviation (%MVE) of untrained novices (Novice-U), trained novices (Novice-T) and experienced nurses (Experienced). Trapezius (%MVE)
Posterior Deltoid (%MVE)
Erector Spinae (%MVE)
External Oblique (%MVE)
Left
Right
Left
Right
Left
Right
9.6 11.8 5.6 5.6 9.1 6.0
37.8 7.5 26.5 15.3b 44.9 18.5
28.9 12.3 25.3 11.6 30.3 13.1
40.9 19.5 37.4 17.2 53.8 44.2
36.4 10.4 34.3 15.9 42.9 27.1
43.6 23.4 38.0 24.3 38.5 20.7
32.2 21.0a 23.1 17.6 36.5 21.7
17.8 25.6 22.3 13.6 30.7 18.6
50.9 33.4a 34.9 32.8 37.9 25.3
30.2 14.3a 19.7 8.6 29.7 14.8
28.4 17a 21.5 8.8 22.6 8.4
40.7 22.1a 21.0 11.0b 32.7 12.6
36.5 22.0 22.1 10.9b 38.3 18.1
50.6 25.2 37.7 20.9 58.9 26.3
Rectus Femorisd 25.5 13.6 33.0 24.1 42.7 25.2
32.5 21.5a 45.3 23.5 54.1 25.2
76.2 15.3 63.7 23.1 60.4 21.6
87.9 7.1a 74.0 21.6 61.6 18.9c
61.2 16.2 50.8 18.5 49.6 20.5
52.7 20.4 59.6 23.5 55.0 18.4
Left
Right
Task 1 Novice-U Novice-T Experienced
21.7 10.4a 12.3 5.8b 38.8 17.1c
35.0 7.5 32.4 20.9 51.9 21.2c
Task 2 Novice-U Novice-T Experienced
17.9 12.3 13.6 5.8b 39.7 31.2
Task 3 Novice-U Novice-T Experienced
45.2 23.1a 27.1 18.2 41.2 25.6
a b c d
Significant difference between untrained and trained novices (p < 0.05). Significant difference between trained novices and nurses (p < 0.05). Significant difference between untrained novices and nurses (p < 0.05). Rectus femoris collected for Task 3.
Trained novices had significantly lower muscle activity than nurses for the LTR (26.1% MVE; F1 ¼ 6.8, p ¼ 0.019), LEO (11.7% MVE; F1 ¼ 4.8, p ¼ 0.043) and REO (16.2% MVE; F1 ¼ 5.7, p ¼ 0.029; Table 1). Experienced nurses had significantly lower sagittal ROM than both untrained and trained novices by 7.0 (F1 ¼ 5.7, p ¼ 0.028) and 3.8 (F1 ¼ 4.3, p ¼ 0.05), respectively (Table 2). Nurses also showed significantly less twist ROM than both trained (F1 ¼14.3, p ¼ 0.001) and untrained (F1 ¼10.6, p ¼ 0.005; Table 2). Interestingly, nurses had significant greater left twist than both untrained (F1 ¼14.4, p ¼ 0.001) and trained (F1 ¼ 7.9, p ¼ 0.012) novices, indicating that they were biased in the left direction (Table 2).
3.3.2. Novice participants versus experienced nurses Nurses had lower RES activity (61.6 18.9% MVE) than untrained (87.9 7.1% MVE) and trained (74.0 21.6% MVE) novices, however the difference was only significant between nurses and untrained novices (F1 ¼16.9, p ¼ 0.001; Table 1). LEO activity was about 12% MVE lower in nurses than untrained novices (49.6 versus 61.2% MVE) while both LRF and RRF were 17.2–21.6% MVE larger than untrained and 8.8 - 9.7% MVE larger than trained novices; however, none of these were significant due to high variability (Table 1). Maximum twist ROM was significantly less for experienced nurses (11.1 5.4 ) than untrained (16.9 5.2 ; F1 ¼ 5.6, p ¼ 0.03) and trained (20.8 8.8 ; F1 ¼ 8.1, p ¼ 0.011) novices (Table 2).
3.3. Task 3: patient transfer from bed to wheelchair 4. Discussion 3.3.1. Effects of training on novice participants Training significantly reduced peak LTR from 45.2 23.1% MVE prior to training to 27.1 18.2% MVE after training (F1 ¼ 7.2, p ¼ 0.025). Although not significant, LES activity was lower after training (76.2 15.3% MVE to 63.7 23.1% MVE; Table 1). A significant increase was found for the RRF, with novices having a mean peak of 10.5 7.4% MVE prior to training and 13.8 7.4% after training (F1 ¼ 6.12, p ¼ 0.035; Table 1). There were no significant differences in trunk posture due to training in novices (Table 2).
Low back disorders have plagued the nursing profession for decades (Owen and Garg, 1991). While ‘‘no lift’’ policies have significantly reduced injuries (Li et al., 2004; Zhuang et al., 1999), mechanical lift assists have not always been deemed feasible for many reasons such as patient condition that limit sling use, and constraints on economic resources and physical space. Safe transfer training has been used as a cost effective intervention (Hignett et al., 2007; Johnsson et al., 2002; Garg et al., 1991) and the BIPP, used in the current study, follows many of the aspects that are key
Table 2 Mean LMM angular displacements with standard deviation (deg) averaged for untrained novices (Novice-U), trained novices (Novice-T) and experienced participants (Experienced). Negative values indicate displacement was opposite direction of column heading. Lateral Bend (deg) Left
Right
Task 1 Novice-U Novice-T Experienced
1.6 2.9 3.7 2.2 4.8 4.2
4.5 4.7 1.0 4.8 0.2 4.7c
Task 2 Novice-U Novice-T Experienced
3.3 4.0 1.6 2.6 2.3 4.1
Task 3 Novice-U Novice-T Experienced
4.8 3.4 5.9 3.1 3.1 5.0
a b c
Sagittal Bend (deg) ROM
Axial Twist (deg)
Ext
Flex
ROM
9.7 7.2 5.7 4.3 5.9 3.0
2.3 8.6a 10.6 8.3 5.0 8.4
4.4 11.4a 5.3 7.6 2.7 9.7
10.3 6.6 6.5 7.9 3.4 2.8c
6.0 5.6 7.4 2.9b 2.1 6.9
2.4 6.7 0.4 6.1 1.5 6.6
12.7 4.9 11.2 6.6 6.7 4.9c
10.9 7.6a 4.2 4.6b 0.3 3.8c
16.1 9.5a 10.1 3.5b 4.6 2.5c
3.1 6.5 2.7 10.5 4.1 9.9
13.6 11.7 6.2 10.2 10.2 10.5
15.5 8.2 12.2 4.5b 8.5 3.2c
1.3 6.4a 3.1 3.8b 8.1 4.0c
10.0 5.1 8.3 3.3 11.3 3.4
13.2 7.6 11.3 4.8b 4.6 2.5c
2.0 3.0 8.6 9.0 3.3 5.2
2.0 2.9 8.6 9.0b 3.3 5.2
11.0 2.9 12.2 8.1 6.1 5.2
14.9 9.8 13.2 9.0 10.1 10.6
17.6 4.8 19.9 7.0 13.8 3.7
3.4 5.7 5.0 5.9 3.1 4.1
11.0 2.9 12.2 8.2 6.1 5.2
16.9 5.2 20.8 8.8b 11.1 5.4c
Significant difference between untrained and trained novices (p < 0.05). Significant difference between trained novices and nurses (p < 0.05). Significant difference between untrained novices and nurses (p < 0.05).
Left
Right
ROM
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to a successful training program (Hignett et al., 2007; Bouchier, 1996). These features include assessment tools, incorporating patient handling skill instruction into curriculum and clinical practice, as well as providing simple equipment such as the drawsheets used in this study. The aim of this study was to quantify the postural changes that occur with BIPP. Previous investigations have examined the effectiveness of various patient transfer training using quantitative techniques such as video analysis, ground reaction forces, LMM and EMG (Skotte and Fallentin, 2008; Garg et al., 1991; Gagnon et al., 1987), as well as qualitative techniques (Kee and Seo, 2007; Johnsson et al., 2002). In the current study, spine kinematics and muscle activity was used to quantify the postural changes that occurred as a result of being taught the transfer techniques in BIPP. While training improved muscle activity and back posture during the repositioning task from the side of the bed (task 1), the results were modest. The initial postures adopted by the novices prior to training approximated neutral, thus there was little room for improvement (Table 2). The increase in spine extension after training was not expected and may be a strategy of the novices to maintain an upright posture while attempting to master the side-toside weight shift (Table 2). The thoracolumbar spine positions and displacements for the trained novices and experienced nurses are below those considered to be correlated with low risk, with the exception of left bend (Marras et al., 1995). Reductions in peak muscle activity after training, ranged from 2.1% to 11.3% MVE depending on the muscle, indicating a modest reduction in maximal spinal loading due to the training provided. Nurses used a more neutral spine posture and a smaller range of motion than novice participants yet they had greater muscle activity for all muscles except the right EO, than the novices (Table 1). Similar results were reported by Keir and MacDonell (2004), who found that, regardless of the side of the bed or the transfer technique used, experienced handlers consistently had higher TR activity levels. They theorized that the increase was due to experienced patient handlers preferentially loading their shoulders as a protective strategy for their backs. However, adjusting postures to minimize low back pain has been previously acknowledged to transfer loads to other joints, such as the shoulders, thus increasing the risk of injury to tissues other than those of the back (Gagnon et al., 1987; MacKinnon and Vaughan, 2005). Recently, Kee and Seo (2007) found that the shoulder was the most prevalent site of injury symptoms in their study of musculoskeletal disorders in 162 Korean nursing personnel. Thus, future improvements to BIPP should consider the effects on the shoulder joint during patient transfer training. For the second task, repositioning the patient while at the head of the bed, training decreased novice participants maximum muscle activity in all muscles except right TR (Table 1). Training also reduced peak lateral and sagittal spine angles in novices by a small but significant amount (Table 2). BIPP training appeared to have a greater impact on novice participants for this task compared to the reposition from the side of the bed, likely due to the increased mechanical advantage learned for this technique, resulting less muscular effort after training. Repositioning while at the head of the bed found nurses to have higher muscle activity than untrained and trained novices, with the exception of the left TR (Table 1). Although experienced nurses were slightly more flexed and twisted than novices, they tended to use less range of motion perhaps suggesting some form of abdominal and back bracing (likely learned through experience). The LMM angular displacements and ranges for the trained novices and nurses were found to be lower than the low risk values of Marras et al. (1995), with the marginal exception of left bend. When transferring the patient from the bed to the wheelchair, training the novice participants resulted in reduced all peak muscle activity except for the RF (Table 1). The BIPP technique for this
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transfer promotes involvement of the legs by shifting weight between the legs, thus increased in RF activity would indicate compliance. This task was considered the most complex performed and had the highest variance in all participants, regardless of training. However, novices had lower TR and ES activity after training (Table 1), which combined with a reduction in lateral displacement (Table 2), and suggests that training resulted in a more neutral spine posture and better (closer) load location. Experienced nurses exhibited higher muscle activity in their right trapezius than novices regardless of training. Higher trapezius (TR) activity may again be indicative of a protective strategy to redistribute load away from the lumbar spine (Keir and MacDonell, 2004). This is further supported by the nurses’ significantly lower erector spinae (ES) activity and higher rectus femoris (RF) activity. Although modest in magnitude, both nurses and trained novices had less twist and flexion/extension than those who had not received previous training in the weight shifting technique. Previously, during a bed to chair transfer working nurses were found to have peak trunk flexion angles around 40 greater than the trained participants in the current study (Garg et al., 1991). After training, both nurses and novices had peak spine angular displacements that would be termed ‘‘low risk’’ in all axes, providing support for the techniques taught by BIPP (Marras et al., 1995). There are a few limitations to the current study. First, while we chose to report peak, rather than mean, posture and EMG data, the interpretation of the mean data was consistent with the data presented in this paper. In addition, previous literature has shown that trunk flexion angle is a major contributor to back loading and a good predictor of injury risk (Nelson and Hughes, 2009; Hoozemans et al., 2008), thus peak posture should reflect the greatest risk. The BIPP training, whether recent (novices) or within the past two years (experienced nurses), reduced peak muscle activity and spine angles for the tasks analyzed. Second, due to being observed, the nurses may have been more mindful of their posture than during a typical work shift, thus their lumbar motion and muscle activity may not be representative of actual work. Third, normalizing muscle activity to their maximal effort may have increased variability as the novices were likely more familiar with performing maximal efforts than the nurses. It is not clear whether the high peak activities seen in the nurses was due to lower maximal efforts or were due to altered motor strategies. It should be noted that both the trained novices and nurses had large variance in muscle activation levels and trunk kinematics. Thus individual differences in anthropometrics, strength and subtle differences in technique play a major role in the current assessment. Although not the focus of the current study, consideration should be given to the frequency of re-training in order to optimize learning retention. Finally, separate ANOVA’s were used to compare groups despite some borderline normality due to the nature of some variables. 5. Conclusion Overall, training reduced spine deviation and peak muscle activity, thus reducing the load on the back and injury risk. In all three tasks, the BIPP training provided to novices resulted in more favourable muscle activities and lumbar motions. Nurses appeared to retain the training as their kinematics were similar to the trained novices but their EMG may suggest some learned or protective behaviours. There is a continuing need to ensure that nurses are trained in the proper biomechanical theories and practical motions to protect themselves and their patients when mechanical lifts are not available such as in repositioning a patient in bed. Issues such as evaluating other susceptible joints such as the shoulder, onsite evaluation, and training retention by nurses and nursing aides should be further evaluated.
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Acknowledgements The authors would like to thank Michael Holmes and Stephen Mills at Memorial University for their assistance during data collection. As well as the BIPP trainers from Eastern Health, formerly the Health Care Corporation of St. John’s, for their dedication to this study.
References Bouchier, P.A., 1996. Back Injury Prevention Program for Nursing Occupations. Occupational Health and Safety Branch of the Department of Environment and Labour, St. John’s, Newfoundland. Cartledge, S., 2001. Factors influencing the turnover of the intensive care nurses. Intensive and Critical Care Nursing 17, 348–355. Engst, C., Chhokar, R., Miller, A., Yassi, A., 2004. Preventing back injuries to healthcare workers in British Columbia, Canada and the ceiling lift experience. In: Charney, W., Hudson, A. (Eds.), Back Injury Among Healthcare Workers: Causes, Solutions, and Impacts. Lewis Publishers, Boca Raton, pp. 253–263. Engvist, I., Hagberg, M., Hjelm, E.W., Menckel, E., Ekenvall, L., 1998. The accident process preceding overexertion back injuries in nursing personnel. Scandinavian Journal of Work Environmental Health 24 (5), 367–375. Finch Guthrie, P., Westphal, L., Dahlman, B., Behnam, K., Ferrell, D., 2004. A patient lifting intervention for preventing the work-related injuries of nurses. Work 22, 79–88. Gagnon, M., Chehade, A., Kemp, F., Lortie, M., 1987. Lumbo-sacral loads and selected muscle activity while turning patients in bed. Ergonomics 30, 1013–1032. Garg, A., Owen, B., Beller, D., Banaag, J., 1991. A biomechanical and ergonomic evaluation of patient transferring tasks: bed to wheelchair and wheelchair to bed. Ergonomics 34 (3), 290–312. Hignett, S., Fray, M., Rossi, M.A., Tamminen-Peter, L., Hermann, S., Lomi, C., Dockrell, S., Cotrim, T., Cantineau, J.B., Johnsson, C., 2007. Implementation of the manual handling directive in the healthcare industry in the European Union for patient handling tasks. International Journal of Industrial Ergonomics. 37, 415–423. Hignett, S., 1996. Postural analysis of nursing work. Applied Ergonomics 27 (3), 171–176. Hoozemans, J.M., Kingma, I., de Vries, W., van Dieen, J., 2008. Effect of lifting height and load mass on low back loading. Ergonomics 51 (7), 1053–1063. Houle, J., 2001. NursingWorld.org Health and Safety Survey, September 2001. American Nurses Association, Washington (DC). Johnsson, C., Carlsson, R., Lagerstrom, M., 2002. Evaluation of training in patient handling and moving skills among hospital and home care personnel. Ergonomics 45 (12), 850–865. Karwowski, W., Jang, R., Rodrick, D., Quesada, P.M., Cronin, S.N., 2005. Self-evaluation of biomechanical task demands, work environment and percieved risk of injury by nurses: a field study. Occupational Ergonomics 5 (1), 13–27.
Keir, P.J., MacDonell, C.W., 2004. Muscle activity during patient transfers: a preliminary study on the influence of lift assists and experience. Ergonomics 47 (3), 296–306. Kee, D., Seo, S.R., 2007. Musculoskeletal disorders among nursing personnel in Korea. International Journal of Industrial Erogonomics.37, 207–212. Li, J., Wolf, L., Evanoff, B., 2004. Use of mechanical patient lifts decreased musculoskeletal symptoms and injuries among health care workers. Injury Prevention 10, 212–216. Marras, W.S., Lavender, S.A., Leurgans, S.E., Fathallah, F.A., Ferguson, S.A., Allread, W.G., Rajulu, S.L., 1995. Biomechanical risk factors for occupationally related low back disorders. Ergonomics 38 (2), 377–410. Marras, W.S., Davis, K.G., Kirking, B.C., Bertche, P.K., 1999. A comprehensive analysis of low-back disorder risk and spinal loading during the transferring and repositioning of patients using different techniques. Ergonomics 42 (7), 904–926. MacKinnon, S., Vaughan, C.L., 2005. Effect of the reach distance on the execution of one-handed submaximal pull forces. Occupational Ergonomics 5 (3), 161–172. McCannon, R., Miller, M.K., Elfessi, A., 2004. The effectiveness of job specific training on the occupational performance of student nurses. Work 23 (2), 105–110. Nelson, N.A., Hughes, R.E., 2009. Quantifying relationships between selected workrelated factors and back pain: a systematic review of objective biomechanical measures and cost-related health outcomes. International Journal of Industrial Ergonomics 39 (1), 202–210. Owen, B.D., Garg, A., 1991. Reducing risk for back pain in nursing personnel. American Association of Occupational Health Nurse Journal 39 (1), 24–32. Retsas, A., Pinikahana, J., 2000. Manual handling activities and injuries among nurses: an Australian hospital study. Journal of Advanced Nursing 31 (4), 875–883. Santaguida, P.L., Pierrynowski, M., Goldsmith, C., Fernie, G., 2005. Comparison of cumulative low back loads of caregivers when transferring patients using overhead and floor mechanical lifting devices. Clinical Biomechanics 20 (9), 906–916. Skotte, J.H., Essendrop, M., Hansen, A.F., Schibye, B., 2002. A dynamic 3D biomechanical evaluation of the load on the low back during different patienthandling tasks. Journal of Biomechanics 35, 1357–1366. Skotte, J., Fallentin, N., 2008. Low back injury risk during repositioning of patients in bed: the influence of handling technique, patient weight and disability. Ergonomics 53 (7), 1042–1052. Venning, P.J., 1988. Back injury prevention among nursing personnel: the role of education. American Association of Occupational Health Nurse Journal 36 (8), 327–332. Yip, Y.B., 2001. A study of work stress, patient handling activities and the risk of low back pain among nurses in Hong Kong. Journal of Advanced Nursing 36 (6), 794–804. Yip, Y.B., 2004. New low back pain in nurses: work activities, work stress and sedentary lifestyle. Journal of Advanced Nursing 46 (4), 430–440. Zhuang, Z., Stobbe, T.J., Hsiao, H., Collins, J.W., Hobbs, G.R., 1999. Biomechanical evaluation of assistive devices for transferring residents. Applied Ergonomics 30, 285–294.
Contents lists available at ScienceDirect
International Journal of Industrial Ergonomics journal homepage: www.elsevier.com/locate/ergon
Effects of training and experience on patient transfer biomechanics J.N. Hodder a, *, S.N. MacKinnon b, A. Ralhan c, P.J. Keir a a
Department of Kinesiology, McMaster University, 1280 Main St West, Hamilton, Ontario, Canada School of Human Kinetics and Recreation, Memorial University of Newfoundland, St. John’s, Newfoundland, Canada c Eastern Health Authority, 300 Prince Philip Drive, St. John’s, Newfoundland, Canada b
a r t i c l e i n f o
a b s t r a c t
Article history: Received 7 October 2008 Received in revised form 7 December 2009 Accepted 14 January 2010 Available online 21 February 2010
Nursing is one of the professions at highest risk for the development of low back disorders, with patient handling identified as a leading contributor. The purpose of this study was to assess a component of the Back Injury Prevention Program (BIPP) that provided direct instruction on patient handling technique. Trunk kinematics and muscle activities were collected as indicators of low back loading. Novice participants (before and after instruction) and experienced nurses (previously trained) were monitored while they performed three selected patient transfers. Following BIPP instruction, muscle activity in novice participants was reduced by up to 18.1% MVE. Trained novices and nurses had generally smaller thoracolumbar spine angles by approximately 12 with lower variability in spine angle. Nurses had a smaller range of spine motion than novices combined with higher trapezius and deltoid activities, which may be a load reduction strategy for the back. The BIPP patient transfer instruction provided improved thoracolumbar biomechanics for new trainees and experienced nurses. Relevance to industry: Mechanical lifts are not viable in all hospital or home care settings, thus manual patient handling training is still a necessary and important facet of initial and continuing nursing education. Back education and patient handling instruction provides a cost effective prevention strategy in nursing. Ó 2010 Elsevier B.V. All rights reserved.
Keywords: Nursing Low back disorder Patient handling Transfer techniques
1. Introduction Nursing has been identified amongst the top professions at risk for development of occupationally-related low back disorders (LBDs) (Hignett et al., 2007; Karwowski et al., 2005; Yip, 2004; Retsas and Pinikahana, 2000; Marras et al., 1999). The American Nurses Association reported that of approximately 5000 nurses polled in 2001, 85% experienced back pain at work (Houle, 2001). In Canada, from 1996 to 2000, the incidence of back injuries in the healthcare sector was higher than all other industries combined (Engst et al., 2004). The etiology of LBD is complex, consisting of physical, psychosocial, individual, sociocultural and work organizational factors (Karwowski et al., 2005). Although many of these factors are present in nursing, the physical factors involved in patient handling have been frequently implicated as the origin of LBD (Cartledge, 2001; Yip, 2001; Retsas and Pinikahana, 2000; Marras et al., 1999). Patient handling activities identified as having a high risk of injury include: repositioning or adjusting a patient in bed,
* Corresponding author. Tel.: þ1 905 525 9140x20175; fax: þ1 905 523 6011. E-mail address: [email protected] (J.N. Hodder). 0169-8141/$ – see front matter Ó 2010 Elsevier B.V. All rights reserved. doi:10.1016/j.ergon.2010.01.007
transferring a patient to/from the bed/chair/commode, assisting a patient while walking and assisting a patient rise from a sitting position (Skotte et al., 2002; Yip, 2001; Engvist et al., 1998; Owen and Garg, 1991). The use of retrofit ceiling lifts and portable mechanical lifts has been successful in reducing back compressive forces of these transfers by 60% (Santaguida et al., 2005; Owen and Garg, 1991). However, these are not always economically feasible and not all spaces can accommodate a lift, such as in homes and older institutions. Training patient transfer personnel in safe transfer techniques has been used in the past as a cost effective intervention (Hignett et al., 2007; Johnsson et al., 2002; Garg et al., 1991). Developing alternative ergonomic interventions for patient handling has proven difficult. Patients are asymmetrical, non-rigid bodies that impose awkward hand coupling with an element of unpredictability. Non-compliant patients or unanticipated actions from patients can lead to unexpected loading and increase the risk of injury. In addition, unlike many workplaces, workload is dependent on fulfilling the needs of the patients and, administratively, is unlikely to be reduced due to limited nursing resources. The need to educate nurses and patient handlers is intuitive, yet ‘‘back education’’ programs have not been successful in reducing injury incidence by themselves (Finch Guthrie et al., 2004; Hignett, 1996; Venning, 1988). Recently, Skotte and Fallentin (2008) found
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that transfer technique and non-mechanical assistive devices, such as a draw-sheet, had a greater impact on low back loading than the weight or disability level of the patient. Practical training in transfer technique combined with theoretical training has been shown to improve posture and other risk factors that may lead to injury (McCannon et al., 2004). Using a combined approach of practical and theoretical training, the Back Injury Prevention Program (BIPP) developed by the Occupational Health and Rehabilitation Services Department of the Health Science Center in St. John’s (presently named Eastern Health), Newfoundland and Labrador provides instruction on patient handling technique while identifying injury mechanisms and emphasizing back safety (Bouchier, 1996). Additionally, the program conditions nurses to perform a risk analysis prior to attempting a patient transfer to select the most appropriate approach. The BIPP has been incorporated as part of the practicum for Bachelor of Nursing program at Memorial University and the Centre for Nursing Studies. As well, nurses that enter the Health Care Corporation are trained and/or retrained to refresh the principles of BIPP. Although the BIPP program has been in place for over a decade, a thorough biomechanical analysis of the program elements has yet to be performed. The purpose of this study was to analyze trunk kinematics and muscle activity during three patient handling tasks selected from the BIPP program in novices, before and after training, as well as trained experienced nurses. 2. Methods 2.1. Participants Twelve untrained individuals and 10 experienced nurses participated. The 12 females without previous patient handling training (novices) had a mean height of 166.1 6.6 cm, mean weight of 65 12.2 kg and were 23.7 1.4 years of age. The 10 experienced female nurses had been previously trained in BIPP transfers (in the past 2 years) and were recruited from the Health Care Corporation of Newfoundland (159.9 6.0 cm; 73.0 19.5 kg; 41.6 10.2 years of age; 11.3 9.5 years of employment). Three selected transfers were performed by novice participants and experienced nurses while muscle activity and three-dimensional thoracolumbar kinematics were collected for analysis. The study
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protocol was approved by the Human Investigations Committee of Memorial University. All participants provided informed, written consent prior to participation. Novice participants attended three sessions on two consecutive days. During the first session, the experiment was explained and they viewed a 3-min video of the three patient handling tasks they would perform. No further instruction was given and the participants completed three consecutive repetitions of the three tasks in random order. On day two, novice participants received two hours of standardized instruction of the BIPP biomechanical principles and practice of the transfer tasks, which were critiqued and corrected by a qualified BIPP instructor. The final session occurred approximately two hours after the training session and repeated the protocol of the first day (without reviewing the video). Experienced nurses attended one experimental session. The experienced nurses were informed of the three transfer tasks to be performed and no further instruction was provided. Task order was assigned randomly to each participant and each task was repeated three consecutive times. 2.2. Tasks 2.2.1. Task 1: patient reposition (from side of bed) A two person reposition of the patient to the head of the bed using a draw-sheet was performed with the participant and a standard assistant (Fig. 1). The BIPP protocol for this transfer required the participant to raise the bed to waist height. With the draw-sheet already under the patient, the participant began the transfer with the left foot aligned directly below the hip of the patient and the right foot pointing towards the head of the bed. Holding the draw-sheet tight at the patient’s hip and shoulder level and elbows braced at their sides, the participant would shift her weight from the left leg to the right leg, moving the patient within 6 cm of the head of the bed for a successful trial. The standardized patient handler mirrored these actions simultaneously. 2.2.2. Task 2: patient reposition (from head of bed) A two person reposition of the patient to the head of the bed using a draw-sheet was performed with the participant and a standard assistant positioned at the head of the bed (Fig. 2). The BIPP protocol for this task required the bed height to be adjusted such that
Fig. 1. Task 1: Movement sequence for repositioning patient towards the head of the bed with experienced nurse at the side of the bed in foreground and standardized patient handler in background.
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Fig. 2. Task 2: Movement sequence for repositioning patient towards the head of the bed with experienced nurse at the head of the bed in foreground and standardized patient handler in background.
the patient handlers can ‘‘stand tall’’ on their right knee which was placed on the corner of the bed, while the left leg was extended and toe remained in contact with the ground. Facing the opposite corner of the bed, the participant cradled the patient’s shoulder with the draw-sheet and, in unison with the other handler, sat back onto their heel, moving the patient within 6 cm the head of the bed. 2.2.3. Task 3: patient transfer from bed to wheelchair A single person patient transfer from sitting at the edge of the bed to a wheelchair (left to right) was performed using a transfer belt (Fig. 3). The BIPP instructions are to lower the bed such that both of the patient’s feet are flat on the ground. The wheelchair was placed with the brakes engaged at a 45 angle to the bed, and the armrest closest to the patient removed. The patient handler placed their left foot outside of the leg of the patient and the right foot in the direction of the wheelchair, keeping the patient within their base of support. Three rocking motions from left foot to right foot were used to gain momentum so that the patient cleared the bed, at which point the patient was pivoted to the right and lowered to the wheelchair. Successful completion of task 3 required that the patient be relocated to the chair without further adjustment.
2.2.4. Surrogate patient and secondary patient handler A healthy surrogate patient (175 cm, 81 kg) participated in all tasks. The surrogate patient followed the actions according to BIPP guidelines for transfer selection. During tasks 1 and 2, the patient was completely passive. According to BIPP, a single person transfer (task 3) is appropriate to use when the patient is able to follow verbal instructions, able to bear partial weight, yet need assistance to move from one seated position to another. A qualified BIPP instructor trained the patient until his actions were consistent and repeatable for each transfer. The second patient handler which assisted participants in tasks 1 and 2 was trained in a similar manner. 2.3. Data collection For each task, four muscles were monitored bilaterally. The left and right trapezius (LTR, RTR), left and right external oblique (LEO, REO) and left and right erector spinae (LES, RES) muscles were collected for all tasks. The fourth muscle collected was dependent on the task, the left and right posterior deltoid (LPD, RPD) were investigated in tasks 1 and 2, and the left and right rectus femoris (LRF, RRF) for task 3. Maximum voluntary excitations (MVE) were collected for each muscle investigated at the beginning of each
Fig. 3. Task 3: movement sequence for the patient transfer from bed to chair using the one person pivot technique.
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protocol. Prior to electrode placement, the skin was shaved, abraded and cleaned with rubbing alcohol to reduce impedance. Pairs of disposable surface electrodes (KendallÒ Medi-trace 100 series, Wabasha, MN) were placed along the fibre direction at the midbelly of each muscle. Electromyography signals were sampled at 1000 Hz, band-pass filtered from 20 to 500 Hz, rectified and averaged by software using a 10 ms moving window (ME3000P/MegaWin; Mega Electronics Ltd. Kuopio, Finland) before being analogue to digitally converted and stored on a computer for later analysis. A lumbar motion monitor (LMM; Chattecx Corp., Chattanooga, TN) measured angular displacements of the thoracolumbar spine in three dimensions. The LMM was calibrated and sized according to manufacturer instructions and then affixed to the participant’s back using the provided harness. The LMM data were collected at 60 Hz and stored on a computer. The EMG and LMM were launched simultaneously to synchronize the data in relative time. 2.4. Data analysis For each muscle, peak EMG was normalized to MVE’s and averaged over three trials for each participant. Maximum angular displacement and range of motion (ROM; in degrees) in each direction (sagittal, lateral and twist) were averaged over the three trials. Note that peak values are presented but means were also analyzed. Kinematics and EMG of each group were compared to each other (Fig. 4). Repeated measures analyses of variance (ANOVA) were used to compare pre- and post-training EMG and spine angles (peak and range of motion for all 3 directions) for the novice group (a ¼ 0.05). Univariate ANOVA (a ¼ 0.05) were used to compare EMG and trunk kinematics of untrained novices versus experienced nurses and trained novices vs. experienced nurses. 3. Results 3.1. Task 1: patient reposition (side of bed) 3.1.1. Effects of training on novice participants Training had a significant effect on LTR muscle activity, decreasing from 21.7 10.4% to 12.3 5.8% (F1 ¼ 6.2, p ¼ 0.023) after training (Table 1). The RPD had the largest reduction (by 11.3% MVE) but its large variability did not allow for statistical significance. Training lowered activity in all muscles but only modestly and did not attain statistical significance. Overall, novice spine posture prior to training was relatively neutral with a maximum angular displacement of 6.0 5.6 in left axial twist direction (Table 2). After training, participants were
significantly more extended. Peak back flexion changed significantly from 4.4 11.4 (flexion) to 5.3 7.6 (extension), and peak extension which increased by 8.3 (F1 ¼ 8.1, p ¼ 0.019). Training significantly reduced the ROM in the sagittal plane from 10.3 6.6 to 6.5 7.9 (F1 ¼16.0, p ¼ 0.003). Lateral bend and axial twist were not significantly affected with training (Table 2). 3.1.2. Novice participants versus experienced nurses Both before and after training, novices had lower peak activity than experienced nurses in all muscles except REO and LPD which were always higher in novices (Table 1). Trained novices had lower LTR (significantly) and RTR activity than experienced nurses by 26.5% (F1 ¼ 20.2, p ¼ 0.000) and 19.5% MVE, respectively (Table 1). Overall, experienced nurses maintained a relatively neutral posture throughout the reposition task with a maximum angular displacement of 5.0 8.4 extension and maximal range of motion of 6.7 4.9 axial twist (Table 2). When compared to untrained novices, experienced nurses had significantly smaller lateral right bend displacement with 4.5 4.7 versus 0.2 4.7 (F1 ¼ 4.8, p ¼ 0.044). Experienced nurses also had less sagittal ROM (10.3 6.6 ) than untrained novices (3.4 2.8 ; F1 ¼ 8.4, p ¼ 0.01) and axial twist ROM (12.7 4.9 versus 6.7 4.9 ; F1 ¼ 7.3, p ¼ 0.015). 3.2. Task 2: patient reposition (head of bed) 3.2.1. Effects of training on novice participants For task 2, significant reductions in peak muscle activity for the RTR (9.1% MVE; F1 ¼ 5.2, p ¼ 0.049), RPD (16% MVE; F1 ¼ 6.3, p ¼ 0.037), LES (10.5% MVE; F1 ¼ 5.7, p ¼ 0.041) and LEO (19.7% MVE; F1 ¼ 7.9, p ¼ 0.02) were seen after training (Table 1). Decreases were also found in all other muscles after training (with the exception of the LPD), yet did not attain statistical significance (Table 1). Trunk angle decreased with training for flexion, extension and lateral bend. After training, novices had significantly smaller peak right bend by 6.7 (F1 ¼ 6.0, p ¼ 0.037) and smaller lateral range by 6.0 (F1 ¼ 5.8, p ¼ 0.039). While both peak extension and flexion decreased by 5.8 and 7.4 , respectively (Table 2). However, peak left twist increased significantly by over 4 (1.3 6.4 to 3.1 3.8 ; F1 ¼ 5.1, p ¼ 0.05). 3.2.2. Novice participants versus experienced nurses There were no significant differences in muscle activity between nurses and untrained novices. Nurses did have lower peak RPD activity than untrained novices (37.9 25.3% MVE versus 50.9 33.4% MVE), however the difference was not significant.
Dependent Measures
Comparisons 1. Repeated Measures ANOVA -
Untrained novice vs. Trained novices
2. Univariate ANOVA -
Trained novices vs. Experienced nurses
-
Untrained novices vs. Experienced nurses
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Independent Measures
1a. EMG measures -
1. Patient reposition from side of bed
Bilateral: trapezius, erector spinae, external obliques and posterior deltoid
2. Kinematic measures 2. Patient reposition from head of bed 3. Patient transfer from bed to wheelchair
-
Mean peak sagittal, lateral and axial twist displacement and range of motion
1b. EMG measures -
Bilateral: trapezius, erector spinae, external obliques and rectus femoris
Fig. 4. A schematic indicating the statistical comparisons used in the study. Indicated are the comparisons, independent (task) and dependent (EMG, posture) variables used. Repeated measures ANOVA were used to test novices before and after training.
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Table 1 Mean peak EMG with standard deviation (%MVE) of untrained novices (Novice-U), trained novices (Novice-T) and experienced nurses (Experienced). Trapezius (%MVE)
Posterior Deltoid (%MVE)
Erector Spinae (%MVE)
External Oblique (%MVE)
Left
Right
Left
Right
Left
Right
9.6 11.8 5.6 5.6 9.1 6.0
37.8 7.5 26.5 15.3b 44.9 18.5
28.9 12.3 25.3 11.6 30.3 13.1
40.9 19.5 37.4 17.2 53.8 44.2
36.4 10.4 34.3 15.9 42.9 27.1
43.6 23.4 38.0 24.3 38.5 20.7
32.2 21.0a 23.1 17.6 36.5 21.7
17.8 25.6 22.3 13.6 30.7 18.6
50.9 33.4a 34.9 32.8 37.9 25.3
30.2 14.3a 19.7 8.6 29.7 14.8
28.4 17a 21.5 8.8 22.6 8.4
40.7 22.1a 21.0 11.0b 32.7 12.6
36.5 22.0 22.1 10.9b 38.3 18.1
50.6 25.2 37.7 20.9 58.9 26.3
Rectus Femorisd 25.5 13.6 33.0 24.1 42.7 25.2
32.5 21.5a 45.3 23.5 54.1 25.2
76.2 15.3 63.7 23.1 60.4 21.6
87.9 7.1a 74.0 21.6 61.6 18.9c
61.2 16.2 50.8 18.5 49.6 20.5
52.7 20.4 59.6 23.5 55.0 18.4
Left
Right
Task 1 Novice-U Novice-T Experienced
21.7 10.4a 12.3 5.8b 38.8 17.1c
35.0 7.5 32.4 20.9 51.9 21.2c
Task 2 Novice-U Novice-T Experienced
17.9 12.3 13.6 5.8b 39.7 31.2
Task 3 Novice-U Novice-T Experienced
45.2 23.1a 27.1 18.2 41.2 25.6
a b c d
Significant difference between untrained and trained novices (p < 0.05). Significant difference between trained novices and nurses (p < 0.05). Significant difference between untrained novices and nurses (p < 0.05). Rectus femoris collected for Task 3.
Trained novices had significantly lower muscle activity than nurses for the LTR (26.1% MVE; F1 ¼ 6.8, p ¼ 0.019), LEO (11.7% MVE; F1 ¼ 4.8, p ¼ 0.043) and REO (16.2% MVE; F1 ¼ 5.7, p ¼ 0.029; Table 1). Experienced nurses had significantly lower sagittal ROM than both untrained and trained novices by 7.0 (F1 ¼ 5.7, p ¼ 0.028) and 3.8 (F1 ¼ 4.3, p ¼ 0.05), respectively (Table 2). Nurses also showed significantly less twist ROM than both trained (F1 ¼14.3, p ¼ 0.001) and untrained (F1 ¼10.6, p ¼ 0.005; Table 2). Interestingly, nurses had significant greater left twist than both untrained (F1 ¼14.4, p ¼ 0.001) and trained (F1 ¼ 7.9, p ¼ 0.012) novices, indicating that they were biased in the left direction (Table 2).
3.3.2. Novice participants versus experienced nurses Nurses had lower RES activity (61.6 18.9% MVE) than untrained (87.9 7.1% MVE) and trained (74.0 21.6% MVE) novices, however the difference was only significant between nurses and untrained novices (F1 ¼16.9, p ¼ 0.001; Table 1). LEO activity was about 12% MVE lower in nurses than untrained novices (49.6 versus 61.2% MVE) while both LRF and RRF were 17.2–21.6% MVE larger than untrained and 8.8 - 9.7% MVE larger than trained novices; however, none of these were significant due to high variability (Table 1). Maximum twist ROM was significantly less for experienced nurses (11.1 5.4 ) than untrained (16.9 5.2 ; F1 ¼ 5.6, p ¼ 0.03) and trained (20.8 8.8 ; F1 ¼ 8.1, p ¼ 0.011) novices (Table 2).
3.3. Task 3: patient transfer from bed to wheelchair 4. Discussion 3.3.1. Effects of training on novice participants Training significantly reduced peak LTR from 45.2 23.1% MVE prior to training to 27.1 18.2% MVE after training (F1 ¼ 7.2, p ¼ 0.025). Although not significant, LES activity was lower after training (76.2 15.3% MVE to 63.7 23.1% MVE; Table 1). A significant increase was found for the RRF, with novices having a mean peak of 10.5 7.4% MVE prior to training and 13.8 7.4% after training (F1 ¼ 6.12, p ¼ 0.035; Table 1). There were no significant differences in trunk posture due to training in novices (Table 2).
Low back disorders have plagued the nursing profession for decades (Owen and Garg, 1991). While ‘‘no lift’’ policies have significantly reduced injuries (Li et al., 2004; Zhuang et al., 1999), mechanical lift assists have not always been deemed feasible for many reasons such as patient condition that limit sling use, and constraints on economic resources and physical space. Safe transfer training has been used as a cost effective intervention (Hignett et al., 2007; Johnsson et al., 2002; Garg et al., 1991) and the BIPP, used in the current study, follows many of the aspects that are key
Table 2 Mean LMM angular displacements with standard deviation (deg) averaged for untrained novices (Novice-U), trained novices (Novice-T) and experienced participants (Experienced). Negative values indicate displacement was opposite direction of column heading. Lateral Bend (deg) Left
Right
Task 1 Novice-U Novice-T Experienced
1.6 2.9 3.7 2.2 4.8 4.2
4.5 4.7 1.0 4.8 0.2 4.7c
Task 2 Novice-U Novice-T Experienced
3.3 4.0 1.6 2.6 2.3 4.1
Task 3 Novice-U Novice-T Experienced
4.8 3.4 5.9 3.1 3.1 5.0
a b c
Sagittal Bend (deg) ROM
Axial Twist (deg)
Ext
Flex
ROM
9.7 7.2 5.7 4.3 5.9 3.0
2.3 8.6a 10.6 8.3 5.0 8.4
4.4 11.4a 5.3 7.6 2.7 9.7
10.3 6.6 6.5 7.9 3.4 2.8c
6.0 5.6 7.4 2.9b 2.1 6.9
2.4 6.7 0.4 6.1 1.5 6.6
12.7 4.9 11.2 6.6 6.7 4.9c
10.9 7.6a 4.2 4.6b 0.3 3.8c
16.1 9.5a 10.1 3.5b 4.6 2.5c
3.1 6.5 2.7 10.5 4.1 9.9
13.6 11.7 6.2 10.2 10.2 10.5
15.5 8.2 12.2 4.5b 8.5 3.2c
1.3 6.4a 3.1 3.8b 8.1 4.0c
10.0 5.1 8.3 3.3 11.3 3.4
13.2 7.6 11.3 4.8b 4.6 2.5c
2.0 3.0 8.6 9.0 3.3 5.2
2.0 2.9 8.6 9.0b 3.3 5.2
11.0 2.9 12.2 8.1 6.1 5.2
14.9 9.8 13.2 9.0 10.1 10.6
17.6 4.8 19.9 7.0 13.8 3.7
3.4 5.7 5.0 5.9 3.1 4.1
11.0 2.9 12.2 8.2 6.1 5.2
16.9 5.2 20.8 8.8b 11.1 5.4c
Significant difference between untrained and trained novices (p < 0.05). Significant difference between trained novices and nurses (p < 0.05). Significant difference between untrained novices and nurses (p < 0.05).
Left
Right
ROM
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to a successful training program (Hignett et al., 2007; Bouchier, 1996). These features include assessment tools, incorporating patient handling skill instruction into curriculum and clinical practice, as well as providing simple equipment such as the drawsheets used in this study. The aim of this study was to quantify the postural changes that occur with BIPP. Previous investigations have examined the effectiveness of various patient transfer training using quantitative techniques such as video analysis, ground reaction forces, LMM and EMG (Skotte and Fallentin, 2008; Garg et al., 1991; Gagnon et al., 1987), as well as qualitative techniques (Kee and Seo, 2007; Johnsson et al., 2002). In the current study, spine kinematics and muscle activity was used to quantify the postural changes that occurred as a result of being taught the transfer techniques in BIPP. While training improved muscle activity and back posture during the repositioning task from the side of the bed (task 1), the results were modest. The initial postures adopted by the novices prior to training approximated neutral, thus there was little room for improvement (Table 2). The increase in spine extension after training was not expected and may be a strategy of the novices to maintain an upright posture while attempting to master the side-toside weight shift (Table 2). The thoracolumbar spine positions and displacements for the trained novices and experienced nurses are below those considered to be correlated with low risk, with the exception of left bend (Marras et al., 1995). Reductions in peak muscle activity after training, ranged from 2.1% to 11.3% MVE depending on the muscle, indicating a modest reduction in maximal spinal loading due to the training provided. Nurses used a more neutral spine posture and a smaller range of motion than novice participants yet they had greater muscle activity for all muscles except the right EO, than the novices (Table 1). Similar results were reported by Keir and MacDonell (2004), who found that, regardless of the side of the bed or the transfer technique used, experienced handlers consistently had higher TR activity levels. They theorized that the increase was due to experienced patient handlers preferentially loading their shoulders as a protective strategy for their backs. However, adjusting postures to minimize low back pain has been previously acknowledged to transfer loads to other joints, such as the shoulders, thus increasing the risk of injury to tissues other than those of the back (Gagnon et al., 1987; MacKinnon and Vaughan, 2005). Recently, Kee and Seo (2007) found that the shoulder was the most prevalent site of injury symptoms in their study of musculoskeletal disorders in 162 Korean nursing personnel. Thus, future improvements to BIPP should consider the effects on the shoulder joint during patient transfer training. For the second task, repositioning the patient while at the head of the bed, training decreased novice participants maximum muscle activity in all muscles except right TR (Table 1). Training also reduced peak lateral and sagittal spine angles in novices by a small but significant amount (Table 2). BIPP training appeared to have a greater impact on novice participants for this task compared to the reposition from the side of the bed, likely due to the increased mechanical advantage learned for this technique, resulting less muscular effort after training. Repositioning while at the head of the bed found nurses to have higher muscle activity than untrained and trained novices, with the exception of the left TR (Table 1). Although experienced nurses were slightly more flexed and twisted than novices, they tended to use less range of motion perhaps suggesting some form of abdominal and back bracing (likely learned through experience). The LMM angular displacements and ranges for the trained novices and nurses were found to be lower than the low risk values of Marras et al. (1995), with the marginal exception of left bend. When transferring the patient from the bed to the wheelchair, training the novice participants resulted in reduced all peak muscle activity except for the RF (Table 1). The BIPP technique for this
287
transfer promotes involvement of the legs by shifting weight between the legs, thus increased in RF activity would indicate compliance. This task was considered the most complex performed and had the highest variance in all participants, regardless of training. However, novices had lower TR and ES activity after training (Table 1), which combined with a reduction in lateral displacement (Table 2), and suggests that training resulted in a more neutral spine posture and better (closer) load location. Experienced nurses exhibited higher muscle activity in their right trapezius than novices regardless of training. Higher trapezius (TR) activity may again be indicative of a protective strategy to redistribute load away from the lumbar spine (Keir and MacDonell, 2004). This is further supported by the nurses’ significantly lower erector spinae (ES) activity and higher rectus femoris (RF) activity. Although modest in magnitude, both nurses and trained novices had less twist and flexion/extension than those who had not received previous training in the weight shifting technique. Previously, during a bed to chair transfer working nurses were found to have peak trunk flexion angles around 40 greater than the trained participants in the current study (Garg et al., 1991). After training, both nurses and novices had peak spine angular displacements that would be termed ‘‘low risk’’ in all axes, providing support for the techniques taught by BIPP (Marras et al., 1995). There are a few limitations to the current study. First, while we chose to report peak, rather than mean, posture and EMG data, the interpretation of the mean data was consistent with the data presented in this paper. In addition, previous literature has shown that trunk flexion angle is a major contributor to back loading and a good predictor of injury risk (Nelson and Hughes, 2009; Hoozemans et al., 2008), thus peak posture should reflect the greatest risk. The BIPP training, whether recent (novices) or within the past two years (experienced nurses), reduced peak muscle activity and spine angles for the tasks analyzed. Second, due to being observed, the nurses may have been more mindful of their posture than during a typical work shift, thus their lumbar motion and muscle activity may not be representative of actual work. Third, normalizing muscle activity to their maximal effort may have increased variability as the novices were likely more familiar with performing maximal efforts than the nurses. It is not clear whether the high peak activities seen in the nurses was due to lower maximal efforts or were due to altered motor strategies. It should be noted that both the trained novices and nurses had large variance in muscle activation levels and trunk kinematics. Thus individual differences in anthropometrics, strength and subtle differences in technique play a major role in the current assessment. Although not the focus of the current study, consideration should be given to the frequency of re-training in order to optimize learning retention. Finally, separate ANOVA’s were used to compare groups despite some borderline normality due to the nature of some variables. 5. Conclusion Overall, training reduced spine deviation and peak muscle activity, thus reducing the load on the back and injury risk. In all three tasks, the BIPP training provided to novices resulted in more favourable muscle activities and lumbar motions. Nurses appeared to retain the training as their kinematics were similar to the trained novices but their EMG may suggest some learned or protective behaviours. There is a continuing need to ensure that nurses are trained in the proper biomechanical theories and practical motions to protect themselves and their patients when mechanical lifts are not available such as in repositioning a patient in bed. Issues such as evaluating other susceptible joints such as the shoulder, onsite evaluation, and training retention by nurses and nursing aides should be further evaluated.
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Acknowledgements The authors would like to thank Michael Holmes and Stephen Mills at Memorial University for their assistance during data collection. As well as the BIPP trainers from Eastern Health, formerly the Health Care Corporation of St. John’s, for their dedication to this study.
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