FDA Safety Tip: External Defibrillators With “Hands-Free” Capabilities, Preventing Defibrillator Cable and Connector Malfunctions
MedSun: Newsletter #12, February 2007
Problem Descriptions: Many reported malfunctions with external defibrillators, particularly those with “hands-free” configurations, indicate failures in the cables and their connectors. These failures were not discovered during routine functional tests but only when an attempt was made to use them on a patient. The failure to deliver possible life-sustaining electrical energy to the patient’s heart in a timely manner may contribute to an adverse event.
In brief, a defibrillator is a device that delivers an electrical shock of energy for defibrillating (restoring normal heart rhythm to) the atria or ventricles of the heart or for terminating other cardiac arrhythmias. The device may either synchronize the shock with the proper phase of the electrocardiogram or may operate asynchronously. There are two basic patient contact configurations, the paddles and the hands-free. With the paddles, the health care professional or device user holds the wired contact paddles on the patient while the shock is delivered through them to the heart. With the hands-free configuration, disposable pads connect to the defibrillator unit by a cable and connectors to deliver energy to the patient. The hands-free terminology refers to the fact that the user’s hands are not needed to hold the pads in place when the shock is delivered from the defibrillator power unit.
Reported Incidents: The Medical Product Safety Network (MedSun) has received several adverse event reports describing external defibrillator malfunctions attributable to cables and their connectors. These failures are not product- or source-specific but occur across defibrillator manufacturers. Summaries of several of these reports follow here.
•On one occasion, a nurse tried to attach the hands-free pad to the hands-free interface cable. It would not attach. The nurse found that the defibrillator hands-free electrode cable end was broken and would not align with the connector of the external multifunction electrode pad. The interface cable had to be replaced. It was believed that the twisting motion used during removal of the test load (testing done daily) put stress on the connector, causing the break.
•In another case, a nurse was unable to defibrillate a patient using the hands-free pads and interface cable. A switch was made to the paddles-cable, and defibrillation was achieved. A second defibrillator was later requested, and it also failed to work in the hands-free mode but did work when the paddles were attached. The last self-test on the original defibrillator unit had been performed the day before the failure, but the last time the pad interface cable was tested with this defibrillator was about a month before. The underlying causes of the hands-free failure were that the staff was unaware that an audible click would confirm the proper seating of each connector, and they were unable to recall (seeing) a system or momentary error message on the unit’s display.
•In a third instance, a patient was brought into the ER with no vital signs present. The ER staff attempted to defibrillate using the hands-free pads, but the device failed to operate. A second unit was tried [with the same pads], and it also failed. Paddles were brought in, but they would not plug into the defibrillator. Finally, a defibrillator from another unit was brought in and it worked. The original defibrillator was inspected by Biomedical Engineering staff, and it was discovered that the hands-free cable had a pin that had broken off in the defibrillator connector. This prevented the other pads (cable) that were tried from making proper connection and also damaged the paddle’s connector so it would not work in another unit.
Recommendations: Cables and their connectors are often the source of hands-free defibrillator failures. The following recommendations are designed to assist user facilities and staff in minimizing these types of occurrences during both testing and patient defibrillation.
•Perform a functional test of the defibrillator at least once a day or per the facility’s or manufacturer’s protocol.
-Be sure to test the unit on battery power only.
-Be sure that all accessories such as ECG electrodes, lead wires, hands-free pads, cables, and paper are present.
-Check for expiration dates on disposable products such as electrodes and hands-free pads.
-Keep records of these tests.
-Report within the facility any failures including mechanical faults such as bent or broken connector pins and/or cables, and electrical malfunctions such as open circuits or failure to deliver selected energy level.
•Include testing with an external test load with the interface cable.
-Keep the hands-free interface cables plugged into the test load as a protective measure when the device is not in use, if feasible. This measure can reduce the wear and tear from the frequent attaching and detaching of the connectors and the cables. The other ends of the cables can be connected to the defibrillator, if your facility’s protocol allows.
•At no less often than once every 6 months, test to ensure that the system will reliably produce the maximum energy level that will be used on patients.
•Keep in mind that the interface cables (and other included wires) are subject to various mechanical bending and twisting during use.
-Functionally testing and repositioning the cables to simulate actual use conditions may be helpful for early detection of connection issues that may cause intermittent opens/shorts.
•Be sure that the cables and connectors are positioned within easy reach of device users. Overreaching and stretching during a code event may lead to pin bending/breaking and/or incomplete mating of the pins or no connection.
•Train all device users to check the display screen and/or to listen for an audible clicking sound. These are feedback mechanisms from defibrillators that confirm positive connections. Look for possible messages that may indicate a connection has or has not been established.
•Provide the most current instructions for use with each defibrillator model during daily testing and preventive maintenance procedures, including any manufacturer’s suggested checklists.
•Provide adequate staff training according to the user facility’s policies and procedures.
•Provide the manufacturer’s technical support and emergency contact phone numbers near the defibrillator for easy contact if the device does not operate properly.