Figure 3-17

Mistake-Proofing the Design of Health Care Processes -

Figure 3.17. Benign failure: Wheelchair will not roll

Fault tree of a benign failure, 'Wheelchair will not roll,' is used to demonstrate migration of one element, 'Armrest used for support, seat vacant,' from the undesirable event fault tree after addition of an automatic brake to a wheelchair. The top item, 'Wheelchair will not roll,' leads to split at an OR symbol into three branches. The center branch (1-B) terminates at the first element, 'Obstruction in front of wheel.' The left branch (1-A), 'Excessive friction,' proceeds to an OR symbol and splits into two branches: 'Bearings not functional' and 'Inadequate lubrication.' 'Bearings not functional' splits at an OR symbol into two terminal elements: 'Corrosion' and 'Worn out'. 'Inadequate lubrication' splits at an OR symbol into two terminal elements: 'No preventive maintenance' and 'Adverse environment'. The right branch (1-C), 'Brake engaged,' splits at an OR symbol into two elements: a terminal element (right), 'Armrest used for support, seat vacant' (highlighted for emphasis), and an element (left), 'Handbrake engaged,' which progresses to an AND symbol and splits into two terminal elements: 'Patient engages brake' and 'Patient forgets to disengage brake.'

Current as of May 2007

Internet Citation: Figure 3-17: Mistake-Proofing the Design of Health Care Processes -. May 2007. Agency for Healthcare Research and Quality, Rockville, MD. http://www.ahrq.gov/professionals/quality-patient-safety/patient-safety-resources/resources/mistakeproof/mistakefig3-17.html