Cause of Device-Related Incident
Device factors; Support system failures; User errors

Clinical Specialty or Hospital Department
Anesthesia; Cardiology / Cardiac Catheterization; CCU / ICU / NICU; Clinical/Biomedical Engineering; Emergency Medicine; Home Healthcare; Nursing; Obstetrics and Gynecology; OR / Surgery

Device Factors
Design / labeling error

Document Type
Hazard Reports

External Factors
*Not stated

Mechanism of Injury or Death
Burn (electrical, thermal, chemical); Electrical shock / electrocution

Support System Failures
Use of inappropriate devices

Tampering and/or Sabotage
*Not stated

User Errors
Improper connection

UMDNS
Cables/Leads, ECG [15-754]; Apnea Monitors [12-575]; ECG Monitors [12-599]

Risk of Electric Shock from Patient Monitoring Cables and Electrode Lead Wires



Hazard [Health Devices May-Jun 1993;22(5-6):301-2]

Problem

In 1987, we published a Hazard Report on patients who received electric shocks when they were inadvertently connected to line power (120 VAC). These incidents occurred when electrode lead wires, which should have been attached to the patient cables connected to ECG or home apnea monitors, were instead plugged into energized detachable power-line-cord plugs (see "Connection of Electrode Lead Wires to Line Power," Health Devices 16[2], Feb 1987).

Since that time, we have become aware of several additional cases of patient injury, apparently also the result of electric shock from misconnection of electrode lead wires into line-cord plugs (120 VAC). The reported incidents have occurred in hospitals and homes, and the misconnection has been made by clinicians (e.g., nurses) and caretakers (e.g., parents), as well as children (usually siblings). This ongoing problem has prompted us to update our report.

Discussion

The mechanism for this hazard is inappropriate connection of two medical device components—unprotected patient electrode lead wires and detachable device line cords. A typical misconnection occurs when the thin, round, conductive male pins located at the cable end of electrode lead wires are inserted into the slotted female connectors of an energized line cord or extension cord; these connectors are intended to receive the plug blades of an electrical device, not the lead wires.

Typically, misconnection is caused by confusion about the cables used in ECG (heart electrical activity) and apnea (heart and respiratory activity) monitors. The problem may be exacerbated by the coincident color coding (e.g., black, white, green) of electrode lead wires and line-cord wires. Line-cord wires, whose color coding typically matches that of the electrode lead wires, can frequently be seen through transparent female power connectors on the detachable power cords used on many hospital devices.

Conclusions and manufacturer responses

ECRI recommends that all unprotected patient cables and electrode lead wires be immediately removed from service; we also recommend that manufacturers and equipment lessors supply only safe monitoring cables and lead wires. Safe or "protected cable/lead system" connectors are constructed in a lock-and-key configuration that conceals the electrically conductive junctions to prevent insertion into line cords and electrical outlets.

In our evaluation of infant apnea monitoring systems (see "Infant Home Apnea Documentation Monitors," Health Devices 21[10], Oct 1992), we discovered that all apnea monitor manufacturers now provide only protected cable/lead systems to home users; however, at least one manufacturer offers unprotected cable/lead systems to hospitals. Most ECG monitor manufacturers still offer both protected and unprotected cable/lead systems; however, one manufacturer has recently informed us that it will discontinue the manufacture and sale of all unprotected systems.

Hospitals that operate equipment-leasing programs, as well as all nonhospital-based equipment lessors, should ensure that they supply safe patient monitoring cables and electrode lead systems.

Recommendations

  1. Immediately locate and discard all patient monitoring cables and electrode lead wires that do not protect against accidental connection to line cords; also, purchase electrode lead wires with compatible patient cables and protected connectors for all ECG and respiration/apnea monitoring systems.
  2. If it is not possible to immediately remove unsafe patient cables and electrode lead wires from service, take the following precautions during the transition period to help minimize the risk of connecting patients to line power:
  • Warn clinical and housekeeping personnel of the potential for patients to receive electric shocks, as described in this report.
  • When temporarily disconnecting a patient from a monitor, either disconnect the cable from the monitor, or disconnect the lead wires from the electrodes. Do not disconnect the lead wires from the patient cable.
  • Hard-wire or secure (e.g., with a cable clamp) detachable medical device line cords to the device. If this is not practical or if the cord must be removed for transport, consider attaching a warning label to the female connector end of the remaining detachable line cords that states "120 VOLTS." We recommend placing the label immediately next to the female connector, rather than some distance up the line cord.
  • Never leave a detached line cord or unused extension cord plugged into an AC receptacle.
  • Avoid use of extension cords in the vicinity of monitoring devices.
  • Store unused electrode lead wires out of the reach of children; cut up and discard defective lead wires.
  • Consider using childproof outlet caps in pediatric departments that do not have tamperproof receptacles and in homes with children under six years old.
  • Alert home care dealers to this report; also alert parents who have a child on a cardiorespiratory monitor at home or who have permission to disconnect the child from or reconnect the child to a monitor in the hospital.

UMDNS Terms

  • Cables/Leads, ECG [15-754]
  • Apnea Monitors [12-575]
  • ECG Monitors [12-599]

Cause of Device-Related Incident

Device factor: Design/labeling error

User error: Improper connection

Support system failure: Use of inappropriate devices

Mechanism of Injury or Death

Burn (electrical); Electrical shock/electrocution


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