The Effects of Restricted Space in SPH Task

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38 PROFESSIONAL SAFETY JULY 2010 www.asse.org

Safety ResearchSafety Research

The Effects ofRestricting Space

A study involving a patient-handling taskBy Grady T. Holman, Troy Blackburn and S. Maghsoodloo

FOR MORE THAN 5 YEARS, nurses and healthcareworkers have had the second highest injury and

severity rates among listed professions in the U.S.(BLS, 2005). Consequently, many nurses may con-sider alternate careers, decreasing the average careerlife span of practicing nurses during this period.

One reason for the short career span of nursesmay be the high incidence of severe injuries, espe-cially to the lower back. The latest BLS (2005) datanote that in 2003 42% of all nursing injuries wereback related. Some experts estimate that most of theinjuries were attributed to patient transfer tasks(Evanoff, Wolfe, Aton, et al., 2003; Nelson, Matz,Chen, et al., 2006).

For the past 20 years, much of the back-injury-related research has focused on techniques and meth-

ods to reduce lower back injury. In the past 10 years,devices have been developed for patient handling, aprimary contributor to lower back injury (Marras,2005; Nelson, et al., 2006).

A review of literature found notable studies inmodeling nurses perceptions of on-the-job influ-ences (Hignett & Richardson, 1995); analysis ofmechanical devices such as slings (Elford, Straker &Strauss, 2000); long-term ergonomic program evalu-ation (Owen, Keene & Olson, 2002); and biomechan-ical analysisof manual handling techniques (Schibye,Hansen, Hye-Knudsen, et al., 2003).

The strength of these stud-ies is that they approach the

low back issue from differentperspectives. The weakness isthat none consider the taskenvironment and/or physicalrestrictions (i.e., space) orcon-ditions affecting the patienttransfer task.

The research presentedhere is the third part of a three-part, 3-year study investigat-ing the physical restrictionsand conditions affecting pa-tient handling. Part one was adescriptive study using litera-ture and focus group informa-

tion to define and map the interaction of known fac-tors affecting patient handling (Holman, 2006). Part

two used a survey to examine the personal health ofnurses and determined what environmental factorshave the most influence on a patient transfer basedon the opinions of working nurses.

Part three was a biomechanical study based onfindings from parts one and two, which dictated thatthe worst location to perform a transfer was in thebathroom (Nelson, 2005) while transferring a patientfrom the floor to toilet given that a fall had occurredin the main bathroom or shower. The rationale forthis finding was that space was restricted and/orcongested, thus not allowing for team lifts or use ofpatient-handling equipment (a common problem).

Related specific physical and/or psychological

stressors identified by nurses were: 1) lowering orlifting heavy loads; 2) pushing or pulling heavyloads; 3) twisting of the back; 4) bending forward/toward work (stooped posture); 5) carrying heavyloads; 6) highly repetitive motion; and 7) pace orduration. The goal of this study was to quantify theeffects of space restriction on a patient transfer.

Study MethodologyThe research team recognized that for this study

to succeed the setting had to replicate a true to lifehospital bathroom environment. To accomplish this,the team constructed a mock-up bathroom in a bio-mechanics laboratory. Attention to detail was high to

ensure the fidelity of the recreated environment.Only participant safety was considered more impor-tant during the execution of the study.

Biomechanics LaboratoryThe biomechanics laboratory is equipped with a

five-camera PEAK motion capture system (Motus8.5), an AMTI OR6-7 1000 forceplate, four lumbarmotion monitors and a pressure pad system.General lab specifications include variable levelremote lighting, synchronized time encoding, anti-glare flooring, blackout curtains and 80 sq ft of cap-ture area. For this study, only the five-camera motioncapture system with integrated forceplate samplingat 60 Hz would be utilized.

Grady T. Holman, Ph.D., is an assistant

professor of industrial engineering at the

University of Louisville. He holds a Ph.D. inIndustrial and Systems Engineering from

Auburn University.

Troy Blackburn, Ph.D., is an assistant professor

in the Department of Exercise and Sport Science

at the University of North Carolina at Chapel

Hill. He holds a Ph.D. in Human Movement

Science from University of North Carolina at

Chapel Hill.

S. Maghsoodloo, Ph.D., is an emeritus

professor in the Department of Industrial and

Systems Engineering at Auburn University. He

holds a Ph.D. in Applied Mathematics from

Auburn University.
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www.asse.org JULY 2010 PROFESSIONAL SAFETY 39

weight based on cadaver studies (Kroemer, Kroemer& Kroemer-Elbert, 1997). The dummy was weightedto a target weight of 110 lb with the final weightbeing 113.7 lb. The target weight was considered tobe representative of a fifth percentile female basedon a combination of multiple anthropometric tablesexamining body weight by nationality (Kroemer, et

al., 1997; Roebuck, 1995) and military tables(Gordon, Churchill, Clauser, et al., 1989). The use ofthis weight was viewed by the committee as both asafety precaution and testing under best-case sce-nario. Figure 2 illustrates the dummys weight dis-tribution by body segment.

A limitation with the dummy was that it was 71

EquipmentTo expedite the motion capture process and to

standardize clothing and footwear between subjects,participants wore full-body motion capture suitswith a black hairnet and black latex gloves.

Footwear included form-fitting black diving bootswith polymer treaded soles to ensure firm, stablefooting (i.e., no slipping). For tracking, a series of 30markers were placed on the subjects using anthro-pometric landmarks as guides, thus allowing for afull body spatial model representation (Daynard,Yassi, Cooper, et al., 2001). Figure 1 presents a gener-al diagram of marker placements and the subse-quent spatial model rendered.

Testing ApparatusThe testing apparatus was constructed from

dimensions provided by a collaborating Missourihospital. The objective was to emulate a privateroom bath fitted with standard hardware, including

a toilet measuring 16 in. in height, and threehandrails, one for each wall. The unique feature ofthis bathroom was that it was made of Plexiglas toallow for motion capture through the walls. Thewalls were made of 38-in. Plexiglas with clarity of0.92 with clear Lexan angle strips to reinforce thecorners. Both upper and lower track supports wereused to ensure structural stability, and no door wasused as though a pocket door was installed.

The design was modular, allowing for the bath-room to be assembled or disassembled in 25 min-utes. This allowed for testing of restricted versusunrestricted space for the same subject. Photos 1 and2 show the bathroom apparatus in the biomechani-

cal laboratory.Other apparatus employed included a dummy to

simulate a human. The decision to use a transferdummy instead of a live person was based on sever-al criteria. First, the introduction of uncontrollablevariables associated with a person, such as level ofpatient assistance, was seen as unneces-sary since the team was evaluating theeffect of restricted space not patient coop-eration (which can affect a transfer eitherpositively or negatively). Second, partici-pant availability could have become prob-lematic and an uncontrollable factor in testscheduling. Third, the conditions for

which each trial was performed must berepeatable. Finally, based on the activity,safety issues for the person being trans-ferred were viewed as unacceptable.

The grappling dummy used was de-signed to be durable with a metal rod andcable reinforced frame. It was first con-structed using a human mold, then sculpt-ed to give representative range of motionin the joints. In addition, its outer shell is alifelike polymer skin that gives it a natur-al feel.

Initial weight was 60 lb, but thedummys design allows for it to be load-weighted by body segment to a desired

Photos 1 and 2: The biomechanics laboratory and the mock-up

bathroom apparatus.

Figure 1Figure 1Tracking Marker Transitioning

From Subject to Spatial Model

Abstract: Nurses consti-

tute the largest propor-

tion of the healthcare

industrys workforce.

Understanding job facto

that impact their health

and subsequent working

life is essential. In generaindustry, work is often

performed where space

restricted. Understanding

how this factor changes

the demand on a worker

is key to maintaining

both a safe work environ

ment and an efficient

workplace. This study

evaluated the influence

of space restriction on

patient transfer.


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toilet. The dummy is laying/placed in a standard-ized position.

Dependent measures were determined based onfour categories:

1) Time. Time to complete a task is an accurateindicator of the effect sustained by a persons body rel-ative to conditions. Time is also a strong indicator oftask efficiency and/or performance. Time intervalswere measured via frame rate or time encoding.

2) Posture. The posture that a persons bodyassumes while completing a given task is normallydirectly correlated to the requirements of the taskand the immediate surroundings (Chung, Lee &

Kee, 2003). Therefore, two methods of postural eval-uation were needed to accurately depict the effectsof restricting space:

Rapid Entire Body Assessment (REBA) (Hignett& McAtamney, 2000). This tool was selected due toits ability to account for most joint angles and bodypositions required when transferring a patient(Chung, et al., 2003). Its ability to provide a singlecomposite score for each individual video framecaptured made it ideal for use in a biomechanicallaboratory setting. Additionally, this applicationeliminates the two most common causes of errorpreviously experienced when performing evalua-tions in workplace settings: lack of a sufficientnumber of samples to gain validity and single per-

in. tall, roughly 5 in. taller than preferred,and with the stature of a medium-buildmale, rather than a small female.However, these characteristics were stan-dardized across subjects and conditions,

thus the influence on the results was neg-ligible compared to using a live subject,whose ranges of height, weight andanthropometric dimensions would addconsiderably more variation to the study.

SubjectsThe universitys Institutional Review

Board for Human Subjects in Researchapproved the study prior to subject re-cruitment. Based on the statistical model, apriori power analysis showed 10 licensednurses were needed for this study toobtain a power of at least 0.80. All partici-pants were compensated. Potential sub-jects had to clear both a telephoneprescreen and physical activity question-naire before participating.

The screening criteria were as follows:Participants must have been licensed

for at least 1 year with the Alabama Boardof Nursing as a licensed practical nurse,which was set as the minimum degree forparticipation.

Participants must have been currentlyemployed for a period of greater than 3months as a nurse with patient handlingduties composing at least 15% of theirdaily regimen.

Participants must have been betweenages 20 and 50 with a body mass index of less than30.0.

Participants must have been in good health withno current injuries or illnesses.

Participants must have use of and full range ofmotion in joints and extremities.

Participants could not have been on medica-tions that could affect mood, thought process, pos-tural stability, physical strength or impair judgment.

Participants must verbally indicate, then demon-strate that they can successfully transfer the dummy.

Statistical Model

The statistical model for this portion of the studywas a randomized complete block with a replicate.The independent measure was restricted versusunrestricted space and the mechanism for testingwas determined to be the floor-to-toilet transfer,which the surveyed nurses identified as the worsttransfer to perform. Simple definitions of spacerestriction are:

Unrestricted space. Only the toilet and thedummy are present in an open floor space allowingfor maximum access to the dummy for transfer. Thedummy position/posture is standardized betweenall transfers, both restricted and unrestricted.

Restricted space. The space is representative ofreal life, with walls, handrails, doorway access and a

Figure 2Figure 2Weight Distribution

by Body SegmentPatient transfer dummy with distribution of load-weight bybody segment.

The grappling dummy

used was designed to

be durable. It was

first constructed using

a human mold, then

sculpted to give rep-resentative range of

motion in the joints.

In addition, its outer

shell is a lifelike poly-

mer skin that gives it

a natural feel.


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ProceduresTesting procedures were defined in detail

through pilot studies prior to testing. They weredesigned with three objectives in mind: participantsafety, study repeatability and standardization of

data collection through use of protocol. Therefore,the following activities were undertaken in eitherthe introduction or testing phases of this study:

Familiarization.After prescreening was complet-ed and the IRB consent signed, participants wereasked to watch a 10-minute video summarizing theresearch to date and finishing with the purpose ofthe laboratory study in which they were to partici-pate. Following the video, each participant was re-quired to examine the bathrooms handrails, toiletposition and sturdiness. They were then asked toperform a trial transfer to gain perspective of thedummys weight and motion when being moved.Finally, they were instructed on what to do in the

event of interruption, marker loss or if somethingjust did not feel right.

The goal of these procedures was to ensure thatall participants received the same instructions and toreduce the learning curve relative to transferring adummy instead of a human. However, nurses werenot instructed how to perform the transfer, as this isa function of the individuals training and experi-ence and, therefore, procedurally, a best-case sce-nario for the nurse.

Recovery time. It was noted during prior pilottesting that while a patient transfer is a relativelybrief task, consisting of only seconds, a patient trans-fer requires a high percentage of the maximum vol-

untary contraction (MVC) capability of most of theactive muscles used due to the weight being trans-ferred. Therefore, it was determined a minimumrecovery period of 5 minutes would be requiredbetween transfers to minimize fatigue (Hebestreit,Mimura & Bar-or, 1993; Holbein & Chaffin, 1997;Burnley, Doust & Jones, 2006).

Patient transfer belt. A common patient-han-dling device recommended by most hospital pro-grams and nursing professionals is a patient transferbelt, sometimes called a gait belt (Menzel, Brooks,Bernard, et al., 2004; Nelson, et al., 2006). For mostcircumstances where normal lift/transfer equip-ment cannot be used, these belts are recommended.They are described as easy to use, allowing the userhandles to better maintain grip and leverage duringthe transfer process. Thus, the research team decid-ed in the interest of participant safety to use a patienttransfer belt during the laboratory trials. In addition,the belts provided a standardized handhold thatproved to be beneficial in testing.

Best-case scenario. An item not controlled in thestudy was the participants approach and/ormethod to the transfer. Since no standardized trans-fer procedure is consistently taught to all nurses inevery nursing school, the research team decided, inlight of the subject pool being experienced nurses, toallow participants to accomplish the transfer by themethod they knew best. This reasoning was sup-

spective user error in which joint angles are inaccu-rately determined.

Ovako Working Analysis System (OWAS)(Karhu, Kansi & Kuorinka, 1977). This well-knownclassification tool has been used extensively for eval-

uation of nurses working postures (Engels, Lande-weerd & Kant, 1994; Lee & Chiou, 1995). Itslimitation is that its sensitivity only allows for bulkclassification of samples taken from a single event.However, this should be adequate when coupledwith the REBA analysis.

3) Joint moment. In light of abundant literaturerelating to the prevalence of back injuries in nursing(Hignett, Fray, Rossi, et al., 2007; Nelson, et al., 2006;Waters, Collins, Galinsky, et al., 2006), it is reason-able to include an estimated measure of momentabout the L5 vertebra in this study. For this purpose,the revised Utah Back Compressive Force Equationwas used.

Utah Back Compressive Force Equation(Loertscher, Merryweather & Bloswick, 2006). Thisgender-specific equation predicts the peak momentabout the L5 given specific body angles and theweight of the load being transferred. Body anglesused in the equation are specific and were measuredbased on anatomical landmarks, coordinate axis orreference planes. Initial testing of the equationshowed an r2 = 0.96 and r2 = 0.95, for males andfemales, repetitively (Loertscher, et al.).

For the current study, the Utah equation was uti-lized both statically and dynamically. The staticequation had a constant load, which was introducedinto the system as a constant. The constant load was

determined using a push/pull dynamometer priorto laboratory testing. The dynamic equationreceived the calculated hand moment directly fromthe forceplate, which allowed for direct samplingand a second load estimate for analysis. The handmoment was calculated using upward inversedynamics from the resulting forceplate moment lessthe mass of the subject, yielding a resulting momentrelated to only the dummys mass.

4) User perception. User perception and per-ceived ratings were important parts of this research.The objectives were to understand what the subjectswere feeling (e.g., stress/fatigue/difficulty) (Chung,et al., 2003), and whether they felt the testing sce-nario corresponded to real-world environments andsituations (Hignett, et al., 2007).

An underlying premise of this study was thatworking nurses were involved in each aspect of thestudy design based on information provided in ear-lier studies. Therefore, surveying user perceptionwas a critical step in the overall evaluation of thestudy. Not doing so would leave out an importantstep in the validation of this research. Thus, surveyswere given for each individual trial after completion,then for the study after all trials were complete. Eachsurvey consisted of seven questions using a six-point Borg scale with verbal anchors. Informationcollected related to transfer planning, execution, dif-ficulty, equipment and resemblance to real life.

User

perceptions

and perceived

ratings were

important to

understand

what the

subjects were

feeling and

whether they

felt the

testing

scenario

corresponded

to the real

world.


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3) a previous back injury thatwas flaring up from time totime (thus, in the candidatesbest interest to not participate).

Subject testing time from

entry into the biomechanicslaboratory until exit was ap-proximately 4 hours.

Analysis of participantsbodys positioning, accelera-tions and velocities relative tothe subjects transfer techniqueshowed three distinct activi-ties/stages in the floor-to-toilettransfer task.

Stage 1. This was the posi-tioning stage. A participantwould enter the bathroom/testing area and position him-

self/herself in preparation toperform the transfer. No load-ing occurred in this stage.

Stage 2. This was the verti-cal lift portion of the transfer. Itbegan immediately after theframe/point where the partici-pant gained control of the trans-fer belt handles and the wristmarker initiated a positivez-axis (i.e., vertical, increase/displacement in position).

Stage 3. This was the hori-zontal repositioning portion of the transfer. It beganimmediately after the frame/point where the ratioof z-axis displacement divided by the resultant ofthe x and y axis displacement became less than one.Stage three continued until the dummy was station-ary on the toilet with no load present on the handsdue its weight.

As testing proceeded through each stage, bodyposture and force were continuously captured rele-vant to time by the labs various data acquisition sys-tems (Daynard, et al., 2001; Zhang & Chaffin, 1999;Zhang, Nussbaum & Chaffin, 2000). Statistical testsconducted on the resulting data included balancedANOVA and paired t-test. Tests were performed at asignificance level of 0.05. In addition to testing eachstage, the entire transfer (i.e., the event) and loading

stages (i.e., combining stages 2 and 3) were tested.Detailed results for each of the four dependent meas-ures are explained in the following sections.

TimeThe difference in the average time required for

lifting in unrestricted as opposed to restricted spacewas found to be significant using a paired t-test forboth the vertical lifting stage (p = .036) and the com-bined stages 2 and 3 (p = .049). For the stage 2 verti-cal lift, time increased 28.20% from 2.357 seconds to3.022 seconds, when the space was restricted. Whenexamining the combination of the two stages, timewas found to increase 14.02% from 5.313 seconds to6.058 seconds when space was restricted.

ported by the logic that the study was assessing theeffects of restricting space on the task based on theperson, not the procedure.

Consequently, the goal was to permit each partic-ipant to use the method most beneficial to them,while still accomplishing the task (i.e., the best-casescenario for the nurse). Additionally, from a statisti-cal standpoint, allowing subjects to use their pre-ferred lifting technique will improve within-subjectreliability. As the design of the study with respect tospace restriction is completely within-subjects, thiswill improve the internal and external validity.

User PerceptionEvaluation of testing status, procedures and envi-

ronment were conducted throughout to moni-

tor/gauge the studys validity and participantssafety. As noted, participants completed a question-naire after each transfer performed, then again afterall transfers were complete.

Study ResultsTesting was performed from March 2007 to June

2007. During that time, more than 100 potential sub-jects were contacted and 14 were invited to the labo-ratory. Of the 14, 10 cleared all screening protocolsand were allowed to participate. The other fourpotential participants did not clear the screeningprocess for various reasons, including 1) currentposition does not involve transferring adult patients;2) could not physically perform the transfers; and

Table 1Table 1OWAS Distribution by Back PositionOWAS distribution by back position with percentage of time posture was loaded per catego-

ry for the transfer event.

Table 2Table 2

Utah Back Compressive Force EquationsAverage Peak EstimationUtah Back Compressive Force Equations average peak estimation of the L5 moment for therestricted and unrestricted patient transfers using both static and dynamic loading.

OWAS is a well-known

classification tool that

has been used exten-

sively for evaluation

of nurses working

postures. The Utah

equation is a gender-

specific tool that pre-

dicts the peak moment

about the L5 given

specific body angles

and the weight of the

load being transferred.


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ed at the level of a fifth percentile female. Table 2shows the Utah Back Compressive Force Equationsaverage peak estimated moment about the L5 verte-bra for both static and dynamic loads.

Additionally, in three individual trials, shock/spring loading of the transfer occurred when theparticipant generated momentum prior to the begin-ning of the vertical lift (i.e., jerking motion) (Com-missaris & Toussaint, 1997). In at least one case, themoment predicted about the L5 vertebra was greater

than two times the gold standard, which has thepotential to cause an acute low back injury. How-ever, this result is only preliminary due to samplesize not having sufficient statistical power.

User PerceptionParticipants opinions were collected via survey

after each trial, then again after all trials were com-pleted. Results for individual trials showed that only68% of the time did participants believe that they per-formed the transfer correctly during the trial and 73%of the time did they believe the transfer was per-formed the way they planned to do it. Further, 73% ofthe time they believed that the transfer was difficult,

but 90% of the time they still believed real-life trans-fers were more difficult than the trials. Time to com-plete the task was considered to be consistent with reallife, receiving 2.9 out of 6.0 on a scale using the verbalanchors took more time in real life and took lesstime in real life. Overall, it was believed that 80% oftrials were realistic compared to the real world with acombined effectiveness rating of 4.1 out of 6.0.

For the study, 90% believed both body and backstress increased when space was restricted. Addi-tionally, 100% of participating nurses stated theybelieved restricting the space made the transfermore costly in terms of time to complete and diffi-culty. Other results showed that 90% of participantsbelieved the study was representative of real life,

PosturePostural differences were found to be significant

in one of the two postural analysis tools used whencomparing restricted to unrestricted transfers. REBAshowed significant differences using a paired t-testto analyze the horizontal repositioning (p = .002),stage 3. During the horizontal repositioning of thedummy, the REBA composite score decreased19.70% from 5.33 to 4.28 when the space was restrict-ed. Hence, REBA scoring is the lower the score, the

better the posture. However, both scores are consid-ered to be a medium risk factor, where action wasnecessary to reduce the risk level is recommended.

Testing using OWAS did not yield any statisticallysignificant results. However, it was used in a slightlydifferent way in this experiment. The normal applica-tion of OWAS is to classify position of the entire body.However, this teams focus was limited to evaluationof the back. Therefore, only the distributions of thethousand category ranges (i.e., back position) and thepercentage of time the task was loaded during thatcategory were charted and analyzed.

While there were no significant results, the chart-ing provided insight into the manipulation and

loading of the spine required to complete the patienttransfer. Table 1 shows the average distribution ofOWAS classifications, by restriction, for a patienttransfer from the floor to toilet.

Joint MomentPeak moment about the L5 vertebra of the spine

was not found to be significantly different based onrestriction in the floor-to-toilet transfer. However,the average peak load was approximately 2,880 N ofcompressive stress on average, which is substantialconsidering the gold standard is to not exceed3,400 N (Marras, 2005). This conclusion is also basedon the fact that this study was designed to be thebest-case scenario with the transfer dummy weight-

Of the nurses who

participated, 100%

stated that restricting

the space made the

transfer more costly

in terms of time to

complete and more

difficult. In addition,

9 of 10 participants

felt the overall study

was a good represen-tation of real life.

Table 3Table 3Participating Nurses Average ResponsesParticipating nurses average responses to user perception questions.


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The final physical component based on task time,posture, and force was a measure of the stress on thelow back. Since back injuries were the most preva-lent injury seen among nurses in statistical reportsand literature (BLS, 2005), the moment about the L5

vertebra was evaluated. However, no significant dif-ference in back moment was found when comparingthe restricted and unrestricted transfers, but this wasnot the only goal. The goal was to determine themoment under the best-case scenario, then analyzefor differences.

The average combined peak moment at the L5was estimated by the Utah Back Compressive ForceEquation at approximately 2,880 N. This level ofmoment is considered to be substantial, since thetransfer weight was only 113.7 lb. Since mostAmerican males weigh at least 1.5 times thisamount, it is reasonable to conceive that the 3,400 Nlimit would be exceeded in a typical patient transfer.

In addition, this moment does not include estima-tions of spring/shock loading, which could help anurse perform a transfer but could more than dou-ble the normal stress/moment on the low back.

An overall assessment for the physical character-istics was performed by examining the posturalresults in stages over time for both restricted andunrestricted transfers. The purpose was to examineevents such as the participants posture when load-ing was initiated. In Figure 3, vertical event lines areused to show the beginning and ending of eachtransfer stage.

Analysis of this graph shows initial loading (i.e.,stage 2 vertical lift) begins with the participant in the

worst posture given the event. For the unrestrictedtransfer, the participant quickly transitions from thestage 2 vertical lift into the stage 3 horizontal reposi-tioning before resuming a more upright posture.

This event can be seen byexamining the intersection ofthe start stage 3 unrestrictedevent line and the unrestrictedtransfer, which is at the top ofthe declining slope.

Further, this gives insightinto why time was significant.Specifically, if the participantswere not allowed (due to spaceor other restriction) to transi-tion to the horizontal reposi-tioning as they normallywould before being required tocome to a complete uprightposition, then additional timewould be required to completethe stage 2 vertical lift, account-ing for the significant time dif-ference. This comparison canbe seen visually in the figure bycomparing the slope intersec-tion point of start stage 3event lines with the correspon-ding REBA line plot. However,

giving it an overall effectiveness rating of 4.9 out of6.0. Table 3 (p. 43) gives the average ratings andresponses to each question.

Discussion

The goal of this study was to evaluate the effectsof restricted space on a patient transfer that involvedmoving a patient from the floor to a toilet while inthe main bathroom or shower. Responses examinedincluded the time to complete the lift, body postureand joint moment about the L5 vertebra.

Of these, time was the most affected, showing anincrease of 28.20% for the vertical lifting stage and a14.02% increase during both vertical and horizontalloaded stages combined. This was particularlyimportant since these are the two stages of the trans-fer that the nurse was lifting/carrying a load. Hence,the obvious implication is that working in a restrict-ed space such as a bathroom substantially increases

the time during which the person (nurse) executingthe transfer is exposed to an associated high-riskposture while lifting/carrying a heavy load.

For posture, results showed that the REBA pos-ture score improved slightly overall for the hori-zontal repositioning when space was restricted.However, it is believed that this improvement wasdue to the restriction limiting the ranges of motion ofthe participants body. Further, neither score forrestricted nor unrestricted transfers was found to bebelow a medium risk level, which is considered to bean action necessary level for REBA. Additionally,both the average restricted and unrestricted transferscores for the vertical lift stage were at the high risk

level, an action necessary soon level. Figure 3 illus-trates the average REBA postural score by time forboth restricted and unrestricted transfers withdefined risk levels.

REBA is able to

account for most

joint angles and

body positions

required when trans-

ferring a patient. Its

ability to provide a

single composite

score for each indi-

vidual video frame

captured made itideal for use in a

biomechanical

laboratory setting.

Figure 3Figure 3REBA Postural ScoreAverage REBA postural score for both restricted and unrestricted transfers.


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the dummy was taller than desired, and its staturewas that of a medium-build male.

Another limitation was based on experience frompilot trials. There was no way to ensure participantswould keep their foot/feet completely on the force-

plate for the duration of a transfer. Therefore, therecently published revised Utah Back CompressiveForce Equation was used to estimate the peakmoment about the L5. The research team believed,based on the literature, the equation would provideaccurate moment estimates for the study, as well as,allow for an external validation of the equation itself.However, the choice to use the equation meant los-ing the ability to measure dynamic spring/shockloading, since it is a static predictor.

ConclusionMethods that nurses in Alabama use to handle

patients are substantially influenced by several fac-

tors, and these factors facilitate either positive ornegative perceptions of job duties/tasks. One nega-tive perception is that the floor-to-toilet transfer isthe most difficult of the patient-handling transfersdue to the conditions and restrictions that dictate thetask. Consequently, they also regard the location ofthe transfer as important, perceiving bathrooms asthe most undesirable area for a transfer.

Despite these negative perceptions, the studyparticipants were asked to perform a series of floor-to-toilet transfers in order to quantify the effects ofrestricted space. Results showed that restricting thespace, as it occurs in a hospital environment, doesnot place any significant additional moment on the

low back. It does, however, alter how the nursemoves when transferring a patient, thus significant-ly increasing the transfer time during the loadedportions of the transfer.

The time needed for a restricted transfer in-creased by an average of 14% when compared to theunrestricted. In this context, this is 14% more time ina medium- to high- risk postural position for whichthe best-case scenario estimates the moment on thelow back at an average of 2,880 N. Simply put, spacerestriction increases exposure to a high-risk eventknown to cause injury in literature. Hence, the neg-ative perceptions nurses have of this transfer seem tobe justified.

Information presented here comprises only oneset of variables relating to one transfer performed inone location. Additional studies of this type areneeded before valid multilevel recommendationscan be made. Results of this study suggest that fewreal-world floor-to-toilet transfers would producelow back stress (i.e., a peak L5 moment, less than the3,400 N limit). Therefore, mechanical assistanceshould be required for this transfer.

Unfortunately, this is a statement made all toooften, since it is both understood and acceptedamong nurses, administration and professionals thatpatient handling is a complex problem that will notbe solved simply by one catch-all solution. Advanceswill only occur when the problem is defined from

given the estimated average moment present duringthe loaded stages, it is believed that neither floor-to-toilet transfer tested here would be capable of pro-ducing an L5 moment less than the 3,400 N limit,while transferring a person of average (50% per-

centile) height and weight.Finally, user perception of this study was found

to be positive. In general, participants believed timeto perform the task was consistent with real life.However, laboratory simulations were still believedto be less difficult due to the weight transferred, acomment stated by most participants during thestudy debriefing. The transfer belt was viewed asbeneficial by 9 of 10 participants when performingthe floor-to-toilet transfer, but 90% believed bothbody and back stress increased when space wasrestricted.

Additionally, as noted, 100% of participating nurs-es stated that restricting the space made the transfer

more costly in terms of time to complete and moredifficult. However, results only show that time tocomplete the task increased, but difficulty remainedstatistically constant. Thus, the true reasoning for thisresponse is unknown, but speculation suggests that itcould possibly be attributed to psychosocial factorsrelated to nursing or that it is a conditioned responsebased on education and/or experience. Also asnoted, 80% found each individual trial to be realistic.Further, 9 of 10 participants felt the overall study wasa good representation of real life, giving an effective-ness rating of 4.9 out of 6.0.

Potential LimitationsRestriction in workspace is normally categorized

as an environmental situation or condition thataffects work being performed both from a workersafety and efficiency perspective. While this studyfocused on the effects of restricting space when per-forming a patient transfer, many other industrieshave similar tasks for which restricted, confined orcongested space is a known problem.

However, no published literature was found for acomparison or basis that attempted to quantify thiscondition. This absence in literature is likely due tothe large number of variables that must be controlledin order to get valid, reliable research data. Some ofthe variables are spring/shock loading of the trans-fer, directional forces generated from brushing, hit-

ting or leaning on an obstruction such as a wall orhandrail, unilateral and/or unbalanced lifting,feet/foot not being completely on the forceplate, etc.

For this study, efforts were made to design andbuild a high-fidelity representation of an actual hos-pital bathroom. Protocols and procedures weredeveloped to ensure uniform instruction in order tominimize the number of confounding variables.However, as with all laboratory studies, there is alimit to what can be recreated from real life.

A limitation of the study was that a weighteddummy was used for transfer and not an actual per-son. The dummy met desired criteria including skintexture, weight, weight distribution and proper jointmovement and range. However, given the weight,

Methods

that nurses

use to handle

patients are

substantially

influenced

by several

factors, and

these factors

facilitate

either

positive or

negative

perceptions

of job

duties/tasks.


9/9


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AcknowledgmentsThis study is a collaboration of Auburn Universitys Department ofIndustrial and Systems Engineering, University of North CarolinasDepartment of Exercise and Sport Science, University of UtahsDepartment of Mechanical Engineering, Auburn Universitys Schoolof Nursing, University of Alabama, Birminghams School of Nursingand the NIOSH Deep South Education and Research Center (Grant 5T42 OH008436). An ASSE Foundation research grant also helpedfund this study.

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patient transfer situations (Nelson, 2003).

Future ResearchThis study has shown that the conditions and

restrictions of the job environment play a large rolein the selection of methods nurses use to performpatient-handling tasks. The results quantified theeffects of restricting space on one of the two transfersregularly performed in a hospital bathroom. Thissuggests that if the second transfer could be quanti-fied in future research, an overall risk factor couldbe developed based on the unrestricted transfer,which could ultimately lead to understandinghow risk changes when work areas are increased

or decreased.

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