Figure 3.16. Fault tree of an undesirable event: "Patient falls during transfer"

Fault tree of 'Patient falls during transfer' shows possible reasons for event. The top item, 'Initial chart element,' leads to split at an OR symbol into two branches. Branch One (left), 'Failure to land on seat during entry or aborted exit,' progresses to split at an AND symbol, with two branches: Branch one-B (right) contains element 'Patient unable to hold wheelchair in position' and does not continue further; Branch one-A (left) goes to element 'Wheelchair rolls away' and progresses to a split at an AND symbol to two elements. The first element (right), 'Armrest used for support, seat vacant,' does not continue. The second element (left), 'Hand brake not engaged,' progresses to a final split at an OR symbol with two final elements, A (left) 'Patient forgets' and B (right) 'Patient untrained.' The Branch Two top element, 'Trip on footplate,' progresses to split at an OR symbol, leading to two sub-branches, Two-A and Two-B. Sub-branch Two-A, 'Patient inadvertently steps on footplate instead of floor,' progresses to an AND symbol, which splits into three branches; the first (right), 'Small initial step,' does not progress further; the second (center), 'Feet placed near edge of seat (behind location of footplate),' does not progress further; and the third (left), 'Footplate present when its should not be,' progresses to an OR symbol, which splits twice. The element labeled '1. Patient omits moving footplate' does not progress further. The element labeled 'Footplate moves back into position for use' progresses to an AND symbol with two branches terminating in elements: '2. Footplate loose' and '3. Patient lifts footplate.' Sub-branch Two-B, 'Patient trailing foot trapped behind footplate,' progresses to an AND symbol, which splits into three branches: the first (right), 'Trailing foot moved below height of footplate,' does not progress further; the second (center), 'Feet placed near edge of seat (behind location of footplate),' does not progress further; and the third (left), 'Footplate present when its should not be,' progresses to and OR symbol, which splits twice. The element labeled '1. Patient omits moving footplate' does not progress further. The element labeled 'Footplate moves back into position for use' progresses to and AND symbol with two branches terminating in elements: '2. Footplate loose'; and '3. Patient lifts footplate.'

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