Cause of Device-Related Incident
Device factors; User errors

Clinical Specialty or Hospital Department
Clinical/Biomedical Engineering; CSR / Materials Management; Obstetrics and Gynecology; OR / Surgery

Device Factors
Device failure

Document Type
Hazard Reports

External Factors
*Not stated

Mechanism of Injury or Death
Burn (electrical, thermal, chemical); Failure to deliver therapy; Fire

Support System Failures
*Not stated

Tampering and/or Sabotage
*Not stated

User Errors
Failure to perform pre-use inspection

UMDNS
Cables/Leads, Electrosurgical Unit [11-496]; Electrodes, Electrosurgical, Active, Hand-Controlled [11-499]; Electrodes, Electrosurgical, Active, Foot-Controlled [16-206]; Electrodes, Electrosurgical, Return [11-500]; Electrosurgical Units [11-490]

Sparking from and Ignition of Damaged Electrosurgical Electrode Cables



Hazard [Health Devices Aug 1998:27(8):301-3]

Problem

ECRI has received reports from several member hospitals describing incidents of sparking from or ignition of electrosurgical electrode cables used during various surgical procedures. In some cases, sparking severed the electrode cable. In others, the cable ignited, starting a fire that spread to nearby surgical drapes. These incidents caused delays in treatment and, in a few cases, injuries to staff members and to the patient. Medical device reporting databases contain numerous recent reports of other such events.

Discussion

Understanding the Problem

Electrosurgical electrode cables connect the electrosurgical generator either to the active handpiece (e.g., forceps) used to treat the patient or to the return electrode used to complete the circuit between the patient and the generator. These cables can be damaged in many ways—some that result in only superficial damage to the cable insulation (e.g., cracks, tears), and others that result in the breaking of some or all the conductor wires within the insulation. Damage to only the cable insulation is unlikely to cause significant problems. For one thing, it may be noticed by staff before the cable is used. In addition, it is unlikely (although possible) that gaps in the cable insulation alone will result in the types of problems described in this report. Rather, sparking and ignition are most likely to occur as a result of damage to the cable's conductor wires—damage that, as discussed below, is not always easy to detect.

When conductor wires within a cable become severed, current may be able to arc across the break. Because the arcing may allow the device to continue operating—albeit on an intermittent basis (as the severed wires move into and out of close proximity)—staff may not notice the break. The arcing can quickly generate sufficient heat to melt the insulation and, in some cases, could even cause the cable to ignite. With less severe breaks, in which only a few strands of the conductor wires have been severed, sparking and ignition can still occur because the current passing through the unaffected wires may be sufficient to melt these remaining strands, severing the wire. In both situations, the problems reported by our member hospitals can result.

Unfortunately, damage to the cable's conductor wires will not necessarily result in any outward sign that the cable has been compromised. For example, reusable cables are subjected to repeated flexing and sterilization, two processes that can damage the conductor wires without causing a break in the cable's insulation. And any type of cable (single-use or reusable) can be subjected to physical abuses, such as being pinched between the edges of two carts, that can cause the conductor wires to break in places along the cable's length while the insulation that encases the wires remains intact. Thus, avoiding the types of problems described in this report will require that relevant staff know how to identify potentially damaged cables, preferably before they are used (see Dealing with the Problem, below).

Staff should note that incidents of cable damage resulting in sparking and fire are much less likely to occur with cables that connect the return electrode to the electrosurgical unit (ESU) than with cables that are connected to the active electrode for two reasons: 1) Most return electrode cables are integral to the dispersive electrode and thus are disposable; as such, they are not subjected to the actions—most notably repeated flexing and sterilization—that are most likely to result in cable damage. 2) If a return electrode cable breaks, the ESU's return electrode contact quality monitor or cable continuity monitor will shut off any current and then alarm, reducing the likelihood of sparking or fire.

Dealing with the Problem

Detecting damaged cables before they are used requires routine inspections—both during cleaning (for reusable cables) and before use. As part of the inspection, personnel should do the following:

  • Visually examine the cable. A visual examination should reveal any significant insulation damage, which will usually take the form of cracks, nicks, abrasions, holes, or tears in the covering of the cable. Although insulation defects themselves are not likely to result in sparking or fire, they could be a sign that the conductor wires have also been compromised, and thus should not be ignored.
  • Manually flex the cable. This manual inspection is needed to help identify breaks in the conductor wires, which may not be accompanied by corresponding breaks in the insulation. Conductor wire breaks are evidenced by increased flexibility of the cable at the break point, which is often the point where the cable joins an end connector.

Another way to avoid the problem is to recognize that reusable cables have a finite lifetime and should be replaced before they cause a problem. This lifetime will vary depending on the cable's usage, but can be determined from tracking, routine inspection, inventory control, and purchasing records. The presence of adequate strain relief (e.g., flexible boots around the point of greatest strain on the end connector and cable) will lengthen the amount of time that reusable cables can be used before they become susceptible to failure.

Supplier Recommendations

Most suppliers of ESUs, active electrodes, cables, and associated devices specifically warn users to inspect cables before use and before sterilization for damage such as breaks, cracks, or nicks in the insulation or for loose connectors. If such damage is found, the cable should not be used.

Some suppliers recommend that a pre-use activation test of the setup be performed just before patient use. This test will identify broken cables or intermittent connections. Readers should recognize, however, that these tests may not uncover cables that are damaged slightly enough to still allow low-power operation but that will melt or arc during high-power use.

Conclusion

While damaged or broken cables are a known risk, the recurrence of these problems suggests that some hospitals are not routinely performing pre-use (and cleaning) inspections of reusable cables.

Recommendations

  1. Alert electrosurgical device users and central supply personnel to the need to inspect reusable electrosurgical cables, as discussed in this report, before use and during cleaning.
  2. Instruct users to inspect cables before use and to perform an activation test of the setup just before application to the patient. (User manuals or instructions for the ESU or handpiece typically provide details of such activation tests.)
  3. Instruct central supply personnel to inspect cables before sterilization for excessive cable flexibility, for loose or broken connectors, and for nicks, breaks, cracks, holes, or other damage.Cables that are damaged—or that appear to be damaged—should be removed from service and either repaired or replaced. (NOTE: We focus on reusable cables in this report because single-use cables are not likely to be subjected to the repeated actions that are most likely to result in cable damage. However, any type of cable can be damaged by one-time physical abuses, and single-use cables should likewise be examined before use.)
  4. Track reusable cables and determine their expected lifetimes based on their use, replacement rate, and failure rate. Replace reusable cables when they reach their expected lifetime (e.g., three months when used three or more times weekly).

UMDNS Terms

  • Cables/Leads, Electrosurgical Unit [11-496]
  • Electrodes, Electrosurgical, Active, Hand-Controlled [11-499]
  • Electrodes, Electrosurgical, Active, Foot-Controlled [16-206]
  • Electrodes, Electrosurgical, Return [11-500]
  • Electrosurgical Units [11-490]

Cause of Device-Related Incident

Device Factor: Device failure

User Error: Failure to perform pre-use inspection

Support System Failure: Lack or failure of incoming and pre-use inspections

Mechanism of Injury of Death

Failure to deliver therapy; Fire; Burn (thermal)


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