Hazard [Health Devices Jun 1986;15(6):184]
Many electronic medical devices have membrane (touch-panel) control
switches. These switches offer resistance to fluid entry, thereby reducing the possibility
of electrical shock and switch malfunction. To avoid inadvertent activation, many
manufacturers have designed these switches so that they require greater force to activate.
ECRI received several reports of membrane switch failures due to operator abuse. Personnel
have damaged the membrane switches by using sharp instruments to activate them.
A damaged switch may cause a device to operate in a hazardous manner. For
example, a member hospital reports that the clear volume membrane switches on 4 of its 15
patient-controlled analgesic infusion pumps have been damaged by user abuse. When the
switch has been punctured or bent inward by sharp instruments, it often remains closed,
causing the pump to continuously clear the volume infused display. Because no alarms
indicate this malfunction, a user who has set the pump to infuse a selected-volume dose
may later find no indication on the display that any medication was administered. This may
cause the user to inadvertently repeat the dose.
ECRI is aware of another common clinical situation in which membrane
switches are abused. To avoid breaking sterile technique, a surgeon may activate nearby
nonsterile electronic equipment with a sharp, sterile hemostat or scalpel and then discard
the instrument. At one hospital, the membrane switches on an electrosurgical unit (ESU)
were damaged because surgeons routinely used hemostats to reset the energy levels. The
switches were riddled with puncture holes and lost the capability to set the energy
levels. Fortunately, these switch failures did not cause the unit to operate in a
hazardous manner. If the switch failures had resulted in intermittent contact, the set
energy level might have spontaneously changed, leading to the use of inappropriate energy
levels during a specific procedure and possible patient injury.
ECRI encourages the use of fail-safe medical device designs. However, we
believe that the described failures are not due to an inherent design or manufacturing
defect, but to operator error. The aforementioned problems are not limited to infusion
pumps and ESUs, but include all electronic equipment with membrane switches.
- Advise all hospital personnel not to use
instruments to activate membrane switches on electronic equipment, and alert
them to potential problems associated with membrane switch damage.
- Incorporate this information into in-service
training programs for hospital staff.
- Alert surgeons and other operating room staff
members to the danger of using surgical instruments to activate any
electronic equipment controls. Remind surgeons to ask the circulating nurse
to adjust nonsterile equipment controls.
- Check membrane switches visually and functionally during routine
equipment inspections. In addition to repairing abused switches, bring this
situation to the attention of users, and determine why the abuse has
occurred and how to avoid it.
Cause of Device-Related Incident
Device factor: Device failure
User error: Abuse of device
Mechanism of Injury or Death
Failure to deliver therapy