ABSTRACT
The crashworthiness of occupied proprietary wheelchairs, which are transported in motor vehicles, is currently assessed by physical crash testing in accordance with ISO 7176-19. If such wheelchairs are modified to meet the needs of the occupant, e.g. the addition of special seating, environmental control systems or life support equipment, then those making the modifications take on the manufacturer's responsibilities, one of these being the assessment of the modified wheelchair's ability to withstand vehicle crash forces. Destructively testing bespoke wheelchair designs is not practical so, currently, the transport-related risk is assessed using best engineering judgement. To improve this process virtual crash testing of the wheelchair and occupant was used. A modified crash criteria from ISO 7176-19 is proposed to enable assessment of the wheelchair's crashworthiness and provide the clinical engineer with an informed judgement of how both wheelchair alone and occupant and wheelchair together will behave in a crash.
Subject(s)
Transportation of Patients , Wheelchairs , Accidents, Traffic , Biomedical Engineering , Computer Simulation , Computer-Aided Design , Humans , Motor Vehicles , Risk Assessment/statistics & numerical data , Risk Management , Transportation of Patients/standards , User-Computer Interface , Wheelchairs/adverse effects , Wheelchairs/standardsABSTRACT
Intensive care often requires the simultaneous administration of high potency short half-life intravenous drugs. Numerous reported instances of unwanted transient flow characteristics such as bolus flow, slow start-up at set rate and fluid reflux-where fluid is found to flow away from the infusion site-have indicated a need for better understanding of the system dynamic. This article introduces a simple mathematical model of an infusion pump system, highlighting system mechanical compliance as a major contributory factor for flow error. The model is verified as correctly predicting flow variation caused by pump height change and is offered as an aid in the development of more accurate infusion devices. The accurate delivery of low flow rates requires small volume rigid components. This study also suggests that the current design of syringe infusion devices makes them susceptible to flow error caused by change in patient venous pressure.
