PubMed · 15303620
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2004. Calling all experts.. https://pubmed.ncbi.nlm.nih.gov/15303620/
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Bedside safety rails are used extensively throughout hospitals and residential care environments as a safety device to protect people against the risk of falling out of bed. However, several adverse incidents involving body entrapment have been linked to their use, which have resulted in serious injury to the bed occupants and, in more extreme cases, fatalities. Internationally agreed standards (i.e. European Committee for Standardisation (CEN) standards) for the design and testing of bed rails have recently been developed and are targeted at improved safety requirements (European Committee for Standardisation 19972000). The purpose of the present study was to: 1) determine whether the CEN test procedure for assessing bed rail strength and rigidity requirements is consistent with human force exertions to which bed rails may be exposed; 2) carry out loading tests on bed rails currently in use throughout the UK to determine whether they comply with the current safety recommendations proposed by the CEN standards.A laboratory study was conducted to determine the force exertions of 20 participants performing seven tasks (including activities of both bed occupants and care providers), which were considered representative of the forces to which bed rails could be exposed during normal use. Forces exerted by participants were measured using a force platform and distortions of the bed rails leading to potential entrapment zones were measured using linear displacement transducers. Static load tests were then conducted, in which incremental point loading was applied at the most adverse points on each of nine different bed rails (commonly used in UK nursing and residential care homes) in accordance with the test procedure detailed in the current CEN standards. Maximum static forces exerted by participants were found to range between 250 N and 350 N, which were within the 500 N force tolerance requirements set by the standards. Dynamic tasks involving 'rolling aggressively' against the bed rail produced the highest peak force of 722 N. None of the bed rails included in this study met the requirements of the CEN test procedures, principally due to horizontal lateral displacements being in excess of 50 mm for a 500 N applied force and/or the bed rails' inability to withstand inward horizontal forces of 500 N. Bed rails used with divan beds were often unable to withstand forces greater than 300 N due to turning moments exceeding the bed rail's restraining mechanism. Current CEN standards for assessing the strength and rigidity of bedside safety rails appear to be consistent with the human forces that might arise as a consequence of the normal movement and activities of a bed occupant or care provider. Although compliance with existing standards is not compulsory, findings from the tests carried out on the selection of bed rails in current use throughout the UK highlight the need for improvements in the design and manufacture of bed rails.
The variety of sometimes contradictory results of studies of the impact of secondary cognitive tasks on postural balance may be attributed to the heterogeneity of balance challenges and tasks deployed and frequent lack of quantitative comparability of tasks. We deployed a wide range of quantitatively graded difficulties of both balance challenge and cognitive tasking to obtain an overview of the spectrum of their interactions in a multi-tasking situation. A differential comparison of the effects of verbally versus spatially loaded tasks, balanced for difficulty, was made and unlike any other study, we contrived to incorporate falls as an experimental variable. In the first study subjects stood in tandem on beams of either 2, 3 and 6 cm or 3, 6 and 8 cm width (according to 'best performance' ability) while performing mental verbal or spatial 'Stroop' tasks. The design was a between groups (sixteen subjects each) comparison (to reduce learning effect) of sway, fall rate and task error, balanced for order. Measurements were taken of centre of pressure, sway velocity at the hip and head displacement. For any beam width there were no within-subject correlations between sway magnitudes and frequency of falls. Spatial task errors increased with balance challenge (hence with magnitude of sway) but verbal performance was maintained independently of balance challenge. The results of the first study provided statistical power estimates for the design of the second focussed experiment which made a within group (twenty four subjects) comparison of the impact of spatial versus verbal tasks on balancing on the hardest beam. The spatial task significantly elevated the incidence of falls whereas the verbal task had no effect on fall rate. The spatial task raised the incidence of falling by 50% (P = 0.0008) in comparison with 'no task'. The verbal task had no effect (P = 0.07). We conclude that sway magnitude is a poor index of multi-task load. Multi-tasking can increase the chance of falling and spatial processing may have a specific impact on balance. The significant elevation of fall frequency during cognitive tasking shows that the 'posture first' principal can be transgressed although the necessary condition for transgression may be that the subject is willing to take risks believing that he can arrest any fall.
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