Connection of Electrode Lead Wires to Line Power
Hazard [Health Devices Feb 1987;16(2):44-6]
In a one-month period, two member hospitals reported incidents in which
nursing staff inadvertently connected patient ECG lead wires to line power (120 VAC). In
both cases, lead wire pins were plugged into the female connector of an energized line
cord that was detached from an infusion device. One incident resulted in death by
electrocution; the other produced severe third-degree burns that required plastic surgery.
In both incidents, ECG electrode lead wires with round male pins were
inserted into a parallel blade-style female connector commonly used on detachable power
cords and extension cords. In one case, however, the line cord emerged from a shelf of
instruments adjacent to the monitor; its connection to a wall AC outlet was concealed. In
the other instance, the line cord was plugged into a visible wall receptacle 46 cm (18 in)
above the floor; both cord and cable had been draped over the bedrail, and it was reported
that the patient cable had slipped off.
One of the two line cords had a molded clear plastic connector that
revealed three colored conductors (black—hot, white—neutral, green—ground)
that coincidentally matched frequently used ECG monitor lead wire colors (black—left
arm, white—right arm, green—reference). The chassis connector on the other line
cord resembled the patient connector both were black and approximately the same size. In
one case, the patient cable and lead wires were the same brand as the monitor, while in
the other case the cable and lead wires were generic. Although four different brands of
line-powered devices were involved in these two cases (two ECG monitors and two infusion
pumps), we do not specifically associate this hazard report with these four devices or
with a particular electrode lead wire.
Similar incidents in which patient leads were connected to line power have
been reported in connection with the use of home apnea monitors. One electrocution and
four cases of electrical burns are discussed in a comprehensive study.(1) In addition to
connecting patient leads to detached energized line cords, patients were exposed to line
power when lead wires were plugged into "live" extension cords and directly into
wall AC receptacles. Some of these connections to line power were made by the pediatric
patient being monitored, and others were made by siblings. The authors speculate that
electrical burn injuries associated with electrode lead wires are very likely
underreported for a number of reasons.
During the past year, manufacturers of home apnea monitors have modified
the connector at the patient cable end of their lead wires. (This has required
manufacturing new patient cables with modified connectors for electrode lead wires.) Most
of the lead wires, however, still have an unprotected pin connector for the electrode, and
the potential for an electrical shock exists for children who attempt to insert this pin
connector into a line voltage source. (Two of the reported cases of electrical burns
allegedly occurred when only one end of a detached lead wire was inserted into a wall AC
Three of the eight units in our evaluation of apnea monitors, currently in
progress, have detachable line cords; when these units are operated on battery power, the
line cord should be disconnected from the AC receptacle and stored. The other units can be
powered by either a detachable plug-mounted low-voltage module or a backup battery. In
general, ECRI questions the value of detachable line cords. While they may be considered
advantageous for devices with battery backup that are frequently used in transport
applications, detachable cords are prone to inadvertent disconnection (leading to battery
depletion), are likely to be used with other devices, or may be left behind during
transport and lost.
We encourage hospitals to request, and manufacturers to supply, electrode
lead wires with a protected connector at the patient cable end. A protected connector
(i.e., one that cannot be inserted into the AC receptacle) at the electrode end is also
desirable for monitoring applications in the home. To maintain flexibility in the purchase
and use of electrode lead wires and patient cables and to encourage competition in
marketing these products, we believe that it is desirable for all manufacturers of these
items to adopt the same protection mechanism. (At present, a round male pin connector is a
de facto standard for connecting physiologic monitoring electrode lead wires to patient
cables.) Although a patient cable with molded (nondetachable) lead wires eliminates the
problem of pin connectors, this solution is more expensive—a single intermittent lead
wire necessitates replacing the entire cable assembly.
One major manufacturer of cables and lead wires states that new lead wires
with protected connectors are currently more expensive than those now used in most
applications. As a result, hospitals may be faced with slightly higher costs during the
period of transition from existing stock to the new-style lead wires and cables. However,
as the sales volume of new lead wires increases, costs can be expected to drop back to
present levels. In addition, the same manufacturer states that cables for the new lead
wires are no more expensive than the cables now in use.
Inform manufacturers and distributors of your needs now to give them a
greater incentive to supply appropriately modified electrode lead wires and patient cables
as soon as possible. Avoid major purchase commitments, and attempt to minimize inventory
of lead wires with unprotected connectors and their associated patient cables so that you
can switch to the new lead wires and cables as soon as they are available. As it may take
manufacturers some time to design, test, produce, and supply the new product line, be sure
not to let inventories drop too low to meet clinical needs.
- When available, purchase electrode lead wires with
protected connectors and compatible patient cables for all ECG and
respiration/apnea monitoring systems.
- Where unprotected electrode lead wires continue to be used as existing
inventories are depleted or until an acceptable alternative is available, do
- Warn clinical and housekeeping personnel of the
potential for electrocution as described above. Post photocopies of the
warning illustration provided here in appropriate places.
- 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.
- Hardwire or secure (e.g., with a cable clamp
attached to the device) detachable medical device line cords. If this is
not practical or 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." Also, request
that suppliers of leased devices with detachable line cords follow this
- Never leave a detached line cord connected to
an AC receptacle.
- Do not routinely use extension cords in the
vicinity of monitoring devices.
- Store unused 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.
- Bring this warning to the attention of parents who will have a child
at home on a cardiorespiratory monitor. This report and warning may be
freely copied for distribution to home care clinical personnel and
- Katcher ML, Shapiro MM, Guist C. Severe injury and death associated with
home infant cadiorespiratory monitors. Pediatrics
Cables/Leads, ECG [15-754]
Cause of Device-Related Incident
Device factor: Design/labeling error
User error: Accidental misconnection
External factor: Power supply
Support system failures: Poor prepurchase
evaluation; Use of inappropriate devices
Mechanism of Injury or Death