Mean absence rates of nursing staff from work is currently running at more than 20 days per annum in Germany. This figure is more than three times higher than for the least affected occupations (e.g. pharmacists: 5.2 days, medical profession: 6 days).

Musculo-skeletal disorders are the principal reason for the high absentee rate of nurses.

There is a close association between the health impairments suffered by nurses and the desire to seek another occupation [1,2]. Evanoff et al. [2] rate back pain as the principal motive for leaving the nursing profession. Very few nurses stay in this occupation for longer than ten years.

Other relevant factors include demographic change, which lies behind various trends currently discernible in the labor market [3], and this also applies to members of the nursing profession. The aging society is influencing not only the employment opportunities for nurses. It also means that demand for nursing services will continue to grow. The trend to shorter patient stays in hospitals is another factor increasing stress on nurses.

These trends make it all the more important to ensure that nursing staff are working under conditions favoring health care and protection and encouraging longest possible commitment to work in the nursing profession. Every feasible means of keeping experienced nurses in the profession should be used. Studies of musculo-skeletal disorders and design of effective programs to prevent or minimize these are essential.

Current status of research

Job analyses in hospitals and senior citizens ‘homes confirm that nursing work involves seriously stressful physical activities. This is confirmed by surveys of the literature (Cf. Synopsis by Stern et al. [4]). These include transfer and positioning of patients, bed changing and making, and various other carrying activities. These regularly involve unfavourable body postures (e.g. bent postures for as much as two hours per shift, 1500 bending movements per shift), high compressive forces on inter-vertebral discs, as well as strains in the shoulder-neck and knee regions, especially during patient transfers, i.e. carrying or assisting patients from a bed to another horizontal surface or to a chair, which are regarded as the principal causal factors of back pain in nurses [5-8], especially in cases where the nurse is not using a technique reducing back stress. In such cases, disc compressive forces can rocket to levels as high as 9 kN during patient transfers, i.e. in many cases significantly above recognized upper continuous strain limits [9].

In Germany, it has only proved possible to attain the high scientific standard of international physiological and epidemiological studies of musculo-skeletal disorders in nurses and the resulting health risks in isolated cases. Most of the work is reports on studies organized by employers’ liability associations and trade unions. Controlled intervention studies in this area are rather rare (e.g. [9-11]). Jäger et al. [12] succeeded in obtaining alleviation of lumbar spine stresses in nurses during patient transfer with the help of spine-protecting techniques and use of small aids. Michaelis [10] reported improvement in back condition and alleviation of physical stresses in nurses following introduction of various ergonomic techniques (Cf. Also [13-15]). Intervention studies on job design and behavioral ergonomics during patient handling tend to come mainly from Anglo-Saxon countries, Scandinavia and the Netherlands (Cf. Synopsis of these projects by Fray und Hignett [16]). But there are no known studies identifying specific techniques for handling of totally dependent patients, e.g. patients in trance coma.

Consequently, the authors of this report decided to conduct an intervention study on fitness for employment of nursing staff caring for totally dependent patients. The objective of this project was to reduce stresses on nurses during patient transfers to a level, at which their health care and protection was guaranteed for as long a period as possible, and the work could still be performed by older nurses.

The working hypothesis was defined as follows:

An ergonomically correct method of working in transfer of totally dependent patients yields a reduction in musculo-skeletal disorders and, consequently, a reduction in health risks for the nurses.

After extensive analysis of the stress-strain status of the study and control groups, various training exercises were practiced and then followed by repeat analyses.

Ergonomic and safety-compatible work processes

The focus of the intervention study conducted from 2011 to 2013 was on training in work techniques using ergonomically correct methods of working in the study group. Muscle development and functional training enabling the nurses to optimize their physical proficiency in patient transfer was also offered.

The control group continued to use conventional and mainly manual patient handling techniques. No muscle development and functional training was offered to the nurses in the control group.

A specimen graph plotting the physical stresses on a nurse over a time axis and a rating of the ensuing potential health risk showed that transfers of totally dependent patients expose nurses to a high health risk. Other physical work (e.g. bed baths) lies within the medium risk range; work in a sitting position (e.g. documentation) or therapyassociated operations (e.g. administering medication) generally involve no health risk (Figure 1).

Figure 1: Specimen graph of physical stresses on a nurse on early shift and rating of health risk (control group).

We have workplace design and behavioral ergonomics at our disposal for assessment of health risk. Workplace design ergonomics, also known as workplace ergonomics, includes a large number of job design items, e.g. modifying the workplace to fit the dimensions of the human body; other items include technically safe job design and work organization. In the case of transfers of totally dependent patients this kind of job design modification is, for a variety of reasons, (e.g. limits to use of technical aids with trance coma patients) not enough to minimize nurses’ health risk. Behavioral ergonomics have to be added in. These require the nurse to adapt her work behavior to comply with anthropometric, biomechanical and physiological laws. The behavioral adjustments recommended in this case are of a very prophylactic nature.

A checklist was used to assess the ergonomics of the patient transfer processes (Table 1).

Table 1: Checklist for assessment of ergonomics of transfer procedures.

The transfer training aims primarily to generate awareness of stressoptimized behavior and also to instill a routine into work procedures. It was split into five units of approx. one hour each. The trainee groups consisted of not more than 6 nurses, plus two experienced ergonomics trainers and one accompanying member of the project team. The first four units were held around a hospital bed without patient. Only the fifth unit had a patient in the bed. The units were structured to start with the nurses performing their normal working procedures, which were then ergonomically corrected.

The five training units were organized as follows:

1. Transfer from lying to sitting: transfer from bed to wheelchair without aids

2. Transfer from sitting to lying: transfer from wheelchair to bed without aids

3. Further work on items 1 and 2

4. Transfer from lying to lying: transfer from bed to shower recliner alone/with two nurses

5. Transfer with actual patient.

During the course of the five units the nurses were confronted in each lesson with ergonomic rules and correct ergonomic behavior. First priority was compliance with these and avoidance of wrong working methods.

The main aim of the muscular development and functional training also offered through the project was improvement of spinal stability, which is of key importance for risk limitation in patient transfer. Agerelated decline in functional efficiency and the accompanying risk of work-related disorders can be counteracted by regular physical training [17].

A training program specifically designed for this project by two sports scientists was used to improve spinal stability. This program started with a short warm-up phase followed by the main training workout. It was held in a separate room of the Intensive Care building and was led by either a PE specialist or a physiotherapist. The aim was to have each nurse attending the workouts twice weekly over a period of five months, but this was not always possible because of absences on vacation, free days and night shift duties.

The training was in small groups of not more than six nurses and was timed to follow immediately after the early shift or before the start of the late shift. It was treated as work time and lasted approx. 20 minutes per unit, plus the time for changing in and out of training gear. Exercises were alternated regularly to maintain interest and enhance training performance.

Nurses’ body movements during patient transfer were recorded by digital video camera. Incorrect postures and movements and ergonomically correct alternatives were analyzed with Motion Toolbox software [18]. This software can track body movements, display angle data and calculate distance data. The video analysis was used to prepare an ABC analysis [19] of ergonomically incorrect and correct working methods. This was used to classify the urgency of redesign work.

Work flow studies based on REFA [20] were used to collect data on transfer frequencies, overall transfer duration and duration of individual operations. This made it necessary to accompany the nurses over the full period of their shift. It goes without saying that violation of the patient’s private sphere was avoided. Data collection was subdivided into three sections: transfer preparation, actual transfer performance and transfer completion.

A biomechanical model was used for microanalysis of stresses (Cf. [21]), because this model focuses on inter-vertebral disc L5/S1, which is highly relevant and critical for members of the nursing profession (Cf. [22-24]). The available software enabled us to record snap shots of critical manual load handling operations and body postures. The software analyzed compressive and shear forces on disc L5/S1.

Ergonomic Assessment Worksheet (EAWS) was used to make summary risk assessments of physical stresses occurring during transfer. These assessments were based on analyses of video recordings of various transfers performed without any technical aids. EAWS [25] is an ergonomic tool for assessment of physical stresses acting on the whole body. Trained analysts were used to classify Sections 1 to 3 of the EAWS. These contain data on body postures and movements involving low external loads or force expenditure, static and dynamic applied forces and additional stresses and load handling operations. Section 4, which uses a ‘microscopic’ approach designed for planners, was dispensed with.

The NASA Task Load Index TLX [26] was used to collect data on strains perceived by the nurses during transfers. These subjectively perceived physical strains and time demands were classified after each transfer as either very high or very low. Physical strains relate to the extent to which physical activities were required (e.g. pressing, pulling, turning, controlling, activating etc.). Was the performed task easy or hard, calm or busy, relaxing or energy-consuming, recreational or laborious? Time demands relate to the nurses’ perceived impression of time pressure dictating speed of task execution. Was it performed slowly and in a leisurely way or hurriedly?

The computer-assisted Trunk Stability Test (Pegasus Software) [27] was used to collect data on power profiles of spine-stabilizing muscles (spinal stability). Maximum isometric power of spine-stabilizing muscles was determined at three body levels, namely

• abdominal (trunk flexion) and dorsal (trunk extension) muscles

• lateral flexors of the trunk (leaning sideways left and right)

• rotator muscles of the trunk (turning left and right).

The muscle groups listed above are the main ones responsible for spine stabilization in both static and dynamic stress situations.

Study participants

The study group consisted of 21 nurses, nurse assistants and teaching nurses working at the Specialist Facility for Intensive Care in Germany’s state of Saxony. The control group worked in a hospital department responsible for care of rehabilitation patients requiring intensive nursing care. 56 nurses were employed there.

In both the study and the control group two thirds of the staff is less than 30 years of age. The mean duration of stay in the nursing profession of the younger nurses is less than 6 years. The equivalent figure for the older nurses (over 41 years of age) lies between 16 and 40 years.

The study group was caring for up to 20 patients either in trance coma or suffering a similarly severe sickness living in two residential facilities. The trance coma patients were either adults or adolescents of adult-equivalent stature and bodyweight. The trance coma patients cared for by the study group were in apallic state and classified in each case in the highest relevant rating of Barthel Index (FRB) for nursing service requirements [28].

The control group was selected because of its responsibility for care of similarly totally dependent patients. The nursing services and care provided by this group were less extreme than those required from the study group for its trance coma patients. Most of its patients were postoperative organ transplants or paraplegics, with whom communication was normally possible. The 51 patients undergoing rehabilitation remained there for varying periods of time.

Mean patient weight in the transfers observed in the control group was 76.6 kg (min. = 61.4 kg, max. = 85.0 kg), in the study group 71.4 kg (min=60.7 kg, max.=88.5 kg).

In addition to the difference in degree of help required between the patients in the two groups, the study group patients had to be transferred kinesthetically, while most of the control group patients could be transferred conventionally.

Ergonomically incorrect and correct methods of working

With due regard to the risk factors listed in EAWS, comparisons were made of the essential elements of ergonomically incorrect and correct methods of working. These were based on the video analyses obtained with the Motion Toolbox software. An ergonomically incorrect method of working in patient transfers was characterized by prolonged moderate to extreme forward inclination of the trunk, lateral inclination and twisting of the trunk, working at an unnecessarily long distance from the patient’s body, frequent holding, lifting and pulling of high percentages of the patient’s weight, extreme and prolonged wrist positions and extreme and prolonged use of high finger forces. High-stress body postures and movements resulted, inter alia, from unfavorable workplace conditions and nurses’ failure to coordinate properly. One frequently observed incorrect method of working resulted from subjectively perceived time pressure. Others were often attributable to lack of understanding of ergonomics. Other problems included, for example, defective or incorrectly worn protective clothing, failure to use wheelchair brakes creating risks for both patients and nurses, and were classified as ergonomically incorrect. Urgency of correction was defined by classification as either A priority for items constituting a high risk of overload of the musculo-skeletal system. Immediate improvement was recommended in these cases. B priority items were those considered to constitute a potential overload risk. Although less urgent than the former group, improvement as soon as possible was recommended here. Items classified as C priority were regarded as constituting only a minor risk of overload of the musculoskeletal system (Cf .Figure 2).

Figure 2: Ergonomically incorrect and correct methods of working.

Duration of transfers

Figure 3 shows the duration of the whole transfer operations, broken down into preparation, actual patient transfer and completion, as performed by one nurse either working alone or assisted by a colleague (in both cases without technical aids).

Figure 3: Comparison of transfer duration (a) one nurse (b) two nurses (with nurse in charge) between study and control group. n.s.: not statistically significant, *: statistical significance p ≤ 0.05.

The overall times for transfers by one nurse working alone ranged from 1 minute to approx. 4 minutes for the control group and between 4 minutes and 12 minutes for the study group. Mean duration was approx. 3 minutes and approx. 7 minutes for the control group and the study group respectively (Figure 3). These differences are significant (p < 0.05) (Table 2).

Overall transfer duration for transfers with assistance from a colleague was also investigated with an eye to time efficiency. The difference between the two groups in this case was also significant (p<0.05) (Table 2). Although the minimum overall duration for the study group declined sharply from 4 minutes alone to only 1 minute with assistance from a colleague, the mean overall duration remained at approx. 7 minutes in both cases (Figure 3).

Table 2: Descriptive statistics of duration of patient transfer (min.). C=control group; S=study group.

One notable finding was the remarkably high proportion of time taken up by preparation and completion of the transfers and the relatively short time required for the actual transfer itself (Figure 3). Although the time differences between control group and study group for preparation and completion were statistically significant (Table 2) irrespective of whether the nurses were working alone or in pairs, no significance could be shown for the differences in performance of the actual transfer (Table 2).

It was observed that the time requirement for preparation by one nurse alone can take longer than when a colleague is assisting.

Biomechanical calculation of stresses on lumbar spine

The results obtained with the biomechanical model revealed considerable stresses on the lumbar spine when ergonomically incorrect methods were used for patient transfer. One such example of incorrect working is failure to raise the head section of the bed (Cf. Figure 4), which increased lumbar spine stresses to quite unacceptable levels and make urgent action essential. Patients in trance coma are totally incapable of acting on their own initiative and their bodies are frequently either unnaturally limp or unnaturally tense. This places even higher demands on the nurses. The ergonomically correct procedure in this case is to raise the bed’s head section, thereby eliminating the need to lift the patient’s full body weight from the lying position. This yielded a decrease of roughly one third in stress on the lumbar spine.

Figure 4: Comparison of stresses on lumbar spine from incorrect and correct methods of working.

Risk assessment

Given a mean patient bodyweight of more than 70 kg in both the study group and control group and a frequency of more than five patient transfers per nurse per shift – in addition to all other physically demanding tasks like positioning patients in bed, changing and making beds and other carrying duties, it is not surprising that the EAWS assessments yielded results showing either a possible or a high risk of biomechanical overload on the musculo-skeletal system. Unless risk limitation action is taken, it is impossible to exclude the possibility that these high stress levels will cause musculo-skeletal disorders.

The assessment showed that the risks arising from transfers were higher in the control group than in the study group (Figure 5). The reason for this was the transfer techniques used during the actual transfer. The study group’s use of kinesthetic techniques brought a reduction in patient bodyweight actually lifted and held. Ergonomically undesirable postures and movements were also observed and evaluated during the preparatory and completion phases in both groups.

Figure 5: Comparison of EAWS risk points for lying-to-sitting transfer in study group and control group. *: statistically significant at p=0.05 level.

Patient transfers recorded in six videos were evaluated with EAWS for ergonomically incorrect methods of working. Six videos of ergonomically correct methods of working were also available. The ergonomically correct method of working significantly reduced the risk of musculo-skeletal system overload by nearly half. The high or possible risk predicted for the ergonomically incorrect method was reduced to possible or low risk for the ergonomically correct method.

Subjectively perceived strains and demands during transfers

Both the subjectively perceived physical strains as reported to the investigators and the time demands governing the transfer (as calculated directly from the video recordings) were higher in the study group than in the control group (Figure 6). It was, however, impossible to confirm this statistically (p>0.05).

Figure 6: Comparison of subjectively perceived physical strains (a) and transfer duration (b) in study and control groups. Method: NASA TLX. n.s.=not statistically significant

Spinal stability

Before-after physical status of ten nurses taking part in the study was verified with the trunk stability test at the start of the study and after an interval of approx. 6 months, i.e. after they had completed the muscular development and functional training course.

The trunk stability test revealed that the training course had in nearly all cases raised the functional efficiency of the extension muscles (backward) and the flexion muscles (forward), and also of the muscles enabling lateral inclination to above the generally recognized target levels. Tone of the muscles enabling left and right rotation of the trunk also showed before-after improvement (Figure 7).

Figure 7: Max. isometric force on trunk in study group and control group before and after redesign (n=10).

Analysis of the data obtained for the study group and control group shows that the level of risk of musculo-skeletal system overload, to which nurses are exposed during patient transfers, is unacceptably high and that the transfer techniques are in need of redesign. EAWS stress evaluation revealed high or possible risk for the musculoskeletal system. This was confirmed by calculations obtained with the biomechanical model. Stress bottlenecks in the musculo-skeletal system were identified and visualized with Motion Toolbox software. The data obtained made it possible to compare ergonomically incorrect and correct work techniques and design a comprehensive training program that makes due allowance for the risk factors involved. Work flow and time studies have shown that the training program should not focus solely on the actual patient transfer, but should also address the time-intensive preparation and completion phases, where training is also needed.

The training program had enabled the study group to almost halve the risk of musculo-skeletal system overload from biomechanical stresses caused by incorrect methods of working. The risk predictions obtained from the EAWS evaluation are statistically significant. Calculations with the biomechanical model showed that even quite minor corrections of ergonomic behavior, e.g. raising of the head section of the bed before starting the transfer, yield substantial reduction of stresses on the lumbar spine.

Although this training in transfer techniques minimized the risks for the musculo-skeletal system, it did not eliminate them completely. The principal reason for this lies partly in the nature of the general nursing duties themselves, which inevitably include demanding tasks (e.g. patient transfer and positioning in bed) that are often aggravated by lack of personnel, but also in basic human nature, which makes it more or less impossible to totally eliminate behavioral errors. This is the reason why muscular development and functional training aimed at optimizing spinal stability is so important. Optimal spinal stability is a key factor in helping to reduce the risk of potentially injurious stresses during patient transfer and making that procedure safe for the nurses. Measurements of spinal stability before and after participation in the muscular development and functional training course confirmed that this yielded tangible improvements.

The survey of subjectively perceived physical strains in the study group did not yield statistically significant higher results. It is assumed that patient passivity is the principal reason for this.

In summary, the study results do not refute the working hypothesis on which the study was based. Ergonomically correct methods of working when transferring totally dependent patients are capable of reducing musculo-skeletal stresses and, consequently, health risks for the nurses. The areas of ergonomic design most closely associated with avoidable physical stresses are optimization of load handling, avoidance of prolonged, high-stress body postures, provision of adequate work space and avoidance of accidental falls.

Specifically-designed muscular development and functional training to optimize trunk stability is also essential for reducing health risk in nurses performing patient transfers.

The question whether use of technical aids would further improve the results obtained with the aforementioned solutions needs to be investigated. Seminars on work organization should also be introduced as a supporting measure.

Bos et al. [29] demonstrate the favourable impact of training and educational measures, combined with intervention by qualified ergonomists during actual task performance, on incidence of back pain in nursing staff, thereby supporting our findings. As already stated under the heading Current status of research, there are very few controlled intervention studies in Germany indicating that correct back postures and appropriate work aids help to alleviate spinal stresses [9- 11]. This is not the case in Anglo-Saxon countries, Scandinavia and the Netherlands [16]. The authors have analyzed this literature in greater detail in a research study for out-patient nursing care. The findings are more or less totally congruent with those for the patient group in our study [30]. It can only be assumed that certain other countries attach greater importance to healthy working conditions for their nursing staff, because they have issued guidelines for load handling containing instructions entitled, for example, No manual patient lifting, No lift program and Safe patient handling [31]. Politicians and associations actively ensure that these instructions are enforced. The following measures to achieve application of ergonomically correct work behaviour based on descriptions in the literature are recommended:

• The basic conditions of nursing work must be properly designed, i.e. technical aids must be made available [32] and adequate allowance must be made in nurses’ work schedules for paid training periods [33].

• Introduction of ergonomically correct ways of working must be organised systematically and properly structured in the form of a project. It must include an analysis of actual preproject status, planning of actions to be taken, implementation of these plans and, finally, project evaluation. Reference can be made to examples in the following bibliography [34].

• Training courses explaining ergonomically correct ways of working to nurses must be multidimensional and comprehensive. Training exercises alone do not always have long-lasting effects. Reference can be made to examples of multidimensional training courses in the following bibliography [35].

• To obtain long-lasting effect of a training course, a suitably qualified member of the employer institution’s own staff should be appointed Health Officer or Ergonomics Officer [36].

• Follow-up refresher training courses are essential [37].

• Promotion of staff health must be recognised as one of the employer institution’s corporate objectives [38].

Sponsored by the European Social Fund (EFS) and the Free State of Saxony.