Cause of Device-Related Incident
Device factors; User errors

Clinical Specialty or Hospital Department
Clinical/Biomedical Engineering; 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)

Support System Failures
*Not stated

Tampering and/or Sabotage
*Not stated

User Errors
Incorrect control settings

Electrosurgical Units [11-490]; Electrosurgical Units, Bipolar [18-230]; Electrosurgical Units, Monopolar [18-229]; Electrosurgical Units, Monopolar/Bipolar [18-231]

Electrosurgical Unit Activation Tone Control

Hazard [Health Devices Nov 1985;14(13):407]


ECRI continues to receive problem reports and investigate incidents of burns caused by inadvertent activation of electrosurgical units (ESUs). Liability and malpractice litigation often follow such injuries. The frequency and severity of these incidents can be greatly reduced if the volume control for the ESU activation tone is maintained at an audible level. Some surgeons are disturbed by the tone and turn the volume down to an inaudible level, risking undetected activation of the ESU and possible injury to the patient. The activation tone on ESUs is an important safety feature that should never be neglected or disabled, regardless of the personal preferences of surgeons or other members of the operating team.

Manufacturers have tried to resolve this dilemma in two ways. The first approach, used by some manufacturers, is to produce ESUs with an adjustable-volume tone that cannot be silenced. These manufacturers can provide a modification that will silence the activation tone. However, the hospital must sign a document that releases the manufacturer from responsibility for accidents resulting from this modification. Thus, the manufacturer-installed tone that cannot be silenced ensures that the device will be safeguarded against inadvertent, undetected activation unless the hospital chooses to override this safety feature.

The second approach, used by those manufacturers who produce ESUs that can be silenced, is to provide, upon request, modification instructions to set a low-volume limit to ensure that the tone remains audible. This approach is less desirable since it requires the initiative of the surgeon or clinical engineer.

In addition to ECRI, both the Association for the Advancement of Medical Instrumentation (AAMI) and the International Electrotechnical Commission (IEC) support low-volume limits on ESU activation tones. But their recommendations are routinely ignored. Some surgeons claim that the activation tone upsets conscious patients undergoing surgery. However, simply explaining the tone to the patient should reduce this anxiety. We acknowledge that during microsurgery on a conscious patient, the onset of the activation tone may startle the patient and possibly lead to a surgical mishap. (One surgeon reports that he provides his patients with headphones to mask disturbing noises, enabling him to maintain an audible activation tone volume.)

The majority of surgeons opposed to the activation tone are irritated by the quality of the tone. Some individuals have suggested that a less annoying tone would be more acceptable. However, surgeons must be made aware that disabling this safety feature exposes their patients to the possibility of accidental electrosurgical burns. One burn incident we investigated occurred when a patient's leg was moved during surgery. The patient's heel was mistakenly placed on the electrosurgical pencil, activating the unit and causing third- and fourth-degree burns on the foot. Had the activation tone been audible, the severity of this accident would have been greatly reduced.


  1. Alert all users of ESUs to this report. Discuss the importance of using the activation tone during electrosurgery with your hospital's administrator and risk manager, and ask them to advise your hospital's chief of surgery about the risks related to the reported problem.
  2. Placard a warning on ESUs that can be silenced; for example "WARNING: The activation tone is an important safety feature. DO NOT turn it down to an inaudible level."
  3. Listening to music in the OR risks masking the audible alarms of ESUs and other devices. If music is permitted, be sure that alarms can still be heard.
  4. Contact the manufacturer of your ESUs to determine what modifications are needed to set a low-volume limit to ensure that the tone remains audible.
  5. Verify that the activation tone functions at the minimum control setting during all acceptance and routine ESU inspections. Check the ESUs in inventory to be sure the activation tone is functioning properly.


  • Electrosurgical Units [11-490]
  • Electrosurgical Units, Bipolar [18-230]
  • Electrosurgical Units, Monopolar [18-229]
  • Electrosurgical Units, Monopolar/Bipolar [18-231]

Cause of Device-Related Incident

Device factor: Design/labeling error

User error: Incorrect control settings

Mechanism of Injury or Death


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