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

Clinical Specialty or Hospital Department
Clinical/Biomedical Engineering; Dermatology; OR / Surgery

Device Factors
Device interaction

Document Type
Hazard Reports

External Factors
*Not stated

Mechanism of Injury or Death
Burn (electrical, thermal, chemical)

Support System Failures
Use of inappropriate devices

Tampering and/or Sabotage
*Not stated

User Errors
Failure to read label; Incorrect clinical use

UMDNS
Cables, Fiberoptic [15-308]; Light Sources [12-340]; Light Sources, Fiberoptic, Rigid Endoscopic/Multipurpose [16-831]; Microscopes, Operating [12-539]

Patient Burn Caused by Excessive Illumination during Surgical Microscopy



Hazard [Health Devices Aug-Sep 1994;23(8-9):272-3]

Problem

A member hospital reported that a patient suffered a third-degree burn during routine plastic surgery. At the end of the procedure, the burn was discovered on the skin surrounding the surgical site, which had been continuously illuminated for 3 hr by a xenon light source used on a surgical microscope with a high-efficiency fiberoptic illumination cable. It is likely that the reported problem was related to the equipment configuration and the type of surgical procedure, not to this manufacturer's devices.

Discussion

Microscope illumination systems can deliver intense energy to a surgical site. Depending on the type of illumination source (e.g., xenon arc lamp) and the light-transmitting characteristics of the fiberoptic illumination cable, this energy may span a broad portion of the electromagnetic spectrum, including the nonvisible (ultraviolet [UV] and infrared [IR]) wavelengths that can damage human tissue. The light sources used in microscopy and endoscopy are typically designed with UV lens coatings and IR filters to remove the nonvisible light most likely to cause skin burns, eye damage, and surgical site heating. Similarly, the light-attenuation characteristics of fiberoptic illumination cables typically limit the amount of light reaching the surgical site.

Despite such provisions for avoiding tissue damage, burns can occur under certain conditions relating to the intensity of illumination at the surgical site, duration of tissue exposure, and tissue perfusion. Illumination intensity at the site will be affected by the illumination source-to-tissue distance and the light source's intensity setting. In the reported incident, the light source was set to the maximum output level, with the light-emitting lens of the microscope positioned approximately 235 mm (9 inches) from the surgical site for 3 hr.

In addition, the light source and fiberoptic cable involved were replacements for an older-model illumination system that was routinely used at its maximum intensity setting. Drying and heating are known complications of illumination during surgical microscopy; as light sources and fiberoptic illumination cables are replaced with newer models, even greater caution must be exercised. For example, some newer-model light sources may have increased illumination capability to satisfy video camera requirements, or they may have different heat-generation characteristics associated with newly implemented lamps. Similarly, some new fiberoptic cables transmit more light more efficiently than older cables.

Manufacturer Action

The supplier is aware of this incident and has provided warnings to users through a revised instruction manual, which now contains prominent cautions; a customer notification form; and a warning sticker that has been installed on all units by supplier representatives. The manufacturer reported to us that all users received these upgrades by April 1994.

Recommendations

Hospitals using surgical microscope systems should implement the following recommendations along with those supplied by the light source manufacturer:

  1. Inform clinicians when light sources and fiberoptic illumination cables are replaced or updated; alert them to any differences in performance (e.g., illumination intensities) and to any hazards (e.g., tissue heating). In addition, recommend that clinicians do the following:
    • Use the minimum light-level setting that adequately illuminates the surgical site. Maximum intensity should be used with extreme caution and for the shortest duration possible.
    • Avoid keeping the light source focused on the same tissue area for extended periods; when possible, the light source's position should be readjusted or its output intensity should be reduced after approximately 30 min.
    • Use sterile wet gauze to keep the surgical site moist and cool. When possible, irrigation should be directed to the inside and outside of the surgical site.
  2. Perform acceptance and periodic testing on the light sources by verifying that the necessary lens coatings or filters are in place and that the controls are operating properly. This may involve inspecting internal devices and following manufacturer-recommended test procedures.
  3. Replace lamps with manufacturer-approved devices only.

UMDNS Terms

  • Cables, Fiberoptic [15-308]
  • Light Sources [12-340]
  • Light Sources, Fiberoptic, Rigid Endoscopic/Multipurpose [16-831]
  • Microscopes, Operating [12-539]

Cause of Device-Related Incident

Device factor: Device interaction

User errors: Failure to read label; Incorrect clinical use

Support system failure: Use of inappropriate devices

Mechanism of Injury or Death

Burn (thermal)


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