Determining the space needed to operate a mobile and an overhead patient hoist

The effectiveness of health-care delivery is determined, in part, by the design of the physical environment and the spatial organisation of work (Reizenstein, 1982; Gadbois et al., 1992). The factors affected by design include confidentiality, cross-infection and travel time. A recent survey found that nurses base their decision to join a trust on a variety of factors, one of these being the workspace available in wards (Harrison, 2004). In particular, the logical and rational organisation of space and equipment was seen as highly important for staff retention, from too little space to work in and doors too small to allow easy movement of beds, to the location of equipment and insufficient electrical points (Commission for Architecture and the Built Environment, 2004a; 2004b).

When the NHS was established in 1948 it inherited around 3000 hospitals and clinics. By 1988 about one-third of the beds were located in accommodation built or converted since 1948, with just over half the buildings having been built before 1918 (Rogers and Salvage, 1988. However, this was not always described as a negative factor as 'the design and layout of much of the 1960s and 1970s buildings was excessively generous in terms of space provision' (NHS Executive, 1993).

In the early 1980s, the Department of Health and Social Security (DHSS) developed an ergonomic database in the form of published Health Building Notes to act as guidance in the design of new hospitals and the adaptation of old buildings.

In 1986 (DHSS, 1986), the minimum dimensions of each cubicle bed space were recommended to be 2500mm x 2900mm (long axis of bed), giving an area of 7.25m2. The recommended width of the bed space was increased to 2700mm in 1995, as shown in Figure 1, an area of 7.83m2 (NHS Estates, 1995). For a single room, a range of layouts and dimensions was given, resulting in floor areas ranging from 11.28m2 to 13.32m2 (NHS Estates, 1995). Although these dimensions were developed with experts, no user data were included (Stanton, 1983).

Bed-space envelopes are found in a range of configurations, from multi-bed bays to single rooms. As part of a risk-management programme (Hignett, 2001), 12 wards at an acute hospital identified that the restriction in bed space was contributing to an increased risk of back injury. The bed spaces were measured and were found to range from 1800mm to 2350mm in width (recommended minimum 2500mm) and 2100mm to 2600mm in length (recommended 2900mm).

The picture alongside shows the functional impact of a restricted 'bed-space envelope'.

Studies by Meyer (1995) and McGuire et al (1996) identified that the use of mobile hoists is affected by the available bed space. Meyer (1995) found that 41% of the respondents found hoists too large or that they had insufficient space in which to use them. McGuire et al (1996) investigated nurses' perceptions towards mechanical aids. They found that almost half of the nurses who responded (49%, n=91) reported that they had difficulty using mechanical aids because of space constraints in wards, bathrooms and toilets.

One suggestion made to minimise the amount of space required for manual handling had been to install overhead tracking hoists rather than using mobile hoists. We set out to measure and compare the minimum space required to operate a mobile hoist and an overhead (gantry) hoist in a single bed space for two patient-handling tasks.

Study
This study used a repeated measures experimental protocol to compare directly the space required for the two tasks (dependent variable) using two different hoists (independent variable).

The university ethics committee at Loughborough University granted ethical approval for the experimental protocol.

Two patient-handling transfers were simulated: chair-to-bed and floor-to-bed. Each participant carried out only one of the tasks using both hoists. Video data were collected to plot and measure the space required for each task. The order of hoist use was changed for every other participant so as to counterbalance learning order effects.

Participants
The project recruited 20 novice handlers (students) aged 18 to 25 years from the Department of Human Sciences, with equal numbers of men and women. They were all given information sheets and signed consent forms.

Training was given in the use of both hoists in line with the manufacturer's recommendations. Specific safety and emergency issues were highlighted; for example, the importance of holding the sling bar away from the patient's head and the position of the emergency stop button.

Participants from the same student population simulated the 'patient'. They were given instructions about their role and asked not to assist except by moving their legs as they approached the bed.

Equipment
A mobile hoist and an overhead gantry system were used for this experiment. The mobile hoist had an adjustable base leg width from 750-1020mm and a base length of 1310mm. It occupied a floor space between 0.98 and 1.34m2. The overhead lifting unit had a lifting range (height) of 2100mm and did not occupy any floor space.

The hospital ergonomics and patient safety unit has an experimental laboratory with a full-size hospital room mock-up. For this experiment, floor lines were installed to measure the space used at 100mm intervals from 2700mm, the minimum cubicle bed-space for hoist use (NHS Estates, 1995) to 3600mm, the recommended inter-bed width for infection control (NHS Estates, 2002). Each hoist had a designated starting point, and the task was complete when the sling was unhooked with the patient on the bed.

Results
The maximum space used for each hoist and each task was measured from the video recording. It was found that the mobile hoist exceeded the current recommended minimum space for a single room (3200mm) by requiring an additional 400mm to (a) turn the hoist (with the patient) during task one when it was moved away from the chair to approach the bed and (b) position the hoist legs around the patient on the floor in task two (Table 1).

The route and maximum space used for each of the two tasks were plotted for each participant and then combined for each task and hoist to produce average routes for each task. The average routes for both the mobile and overhead hoists from chair-to-bed are shown in Figure 2. The dotted lines show the pathway of the hoists from the starting position to the patient and the solid lines show the pathway of the hoists with the patient from the chair to the bed.

The average space used for the overhead hoist was 2610mm for task one and 2890mm for task two. The second dimension exceeds the current recommendation of 2700mm (NHS Estates, 1995). The mobile hoist required an average bed space width of 3360mm for task one and 3570mm for task two, with nine of the participants recording a maximum width of 3600mm.

The space required for the two hoisting options was compared for each task using a one-tailed t-test for related samples to test the null hypothesis that there will be no difference in the amount of space required to operate the two hoists for the two tasks.

Both tests resulted in the null hypothesis being rejected (p< 0.01) and the conclusion was that significantly more room is needed to operate a mobile hoist than an overhead hoist for both chair-to-bed and floor-to-bed transfers.

Discussion and conclusion
The results from this experiment indicated that a considerable increase is needed on the recommended width of 2700mm to use mobile hoists (NHS Estates, 1995), with a new recommended width of 3600mm. The alternative would be to design new and refurbished bed-space envelopes with overhead tracks. Although this would be a suitable solution for the two tasks in this experiment, it would not be an answer for lifting patients in other areas of the ward or hospital.

A separate workshop was held with resuscitation experts to investigate the critical bed-space dimensions for providing a safe clinical environment for resuscitation.

The findings from the workshop identified that the bed-space length was critical for resuscitation tasks. The approximate length required is 2835mm - bed length with bed stripper extended (NHS Estates, 1995) plus 889mm (bed-head clearance for a 95 percentile British male kneeling, 18-65 years population data (Peoplesize, 1995)) plus 500mm (trolley width) plus 500mm (clearance for passage of additional equipment), which gives a total of 4724mm.

Combining the results from the hoist experiment and the resuscitation workshop produces a bed-space envelope 3600mm (width) x 4700mm (length). This is close to the recommendation from Reiling et al (2003) of 3800mm x 4700mm.

The limitations for this project include the exclusion of the space for hygiene (en suite facilities) and staff activities (administration and hygiene). Other critical factors for a bed-space envelope to be included in future analyses are infection control requirements and disability equipment access.

A possible further limitation is that participants were not experienced nursing staff, although the training received in the use of the hoists was equivalent to that provided for newly employed unqualified health-care assistants.

The effect of restricted bed spaces has been to impinge on an adjacent bed space or corridor. Whenever a mobile hoist is being used in a restricted space there needs to be a method of warning patients and staff in adjacent cubicles that there is an increased risk to their safety. As the provision of single rooms is likely to increase, it is extremely important that the minimum dimensions for a bed space are ensured.

KEY POINTS
- Provision of sufficient and appropriate space is an important requirement in staff recruitment and retention

- Use of mobile hoists is restricted by insufficient bed space

- Overhead hoists use significantly less operational space than mobile hoists for chair-to-bed and floor-to-bed transfers

- The minimum bed space required to accommodate mobile hoists and resuscitation tasks is 3600mm x 4700mm.

Acknowledgements
We would like to thank Liko (UK) for the loan of the equipment and the annual student sponsorship from Bob Parsons and Pam Rose at Liko (UK) which supported this project.

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