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Surgical Suite
Use of Medical Lasers

Employees are exposed to lasers used in healthcare facilities during diagnostic, cosmetic, preventive, and therapeutic applications. Lasers used in these applications are incorporated into an apparatus, which includes:
  1. a delivery system to direct the output of the laser,
  2. a power supply with laser control and calibration functions,
  3. mechanical housing with interlocks, and
  4. associated liquids and gases if required for the operation of the laser.
Although there are hundreds of different types of lasers, only about a dozen laser systems are found in everyday clinical use. Nearly all treatment laser products used in surgery are Class 4 as they are designed to deliver laser radiation for the purpose of altering biological tissue. The following provides information regarding the use of lasers: The Food and Drug Administration regulates all medical lasers under regulations issued under the Medical Device Amendments to the Food and Drug Act [21 CFR Parts 800-1299 Note: Enter terms in the search boxes], and the Federal Laser Product Performance Standard [21 CFR Part 1040].

For additional information on Potential Hazards and Possible Solutions, see Surgical Suite - Laser Hazards.
 
Laser Classifications

Note: Class 2 and higher must have the laser radiation warning label.
Note: Class 2 and higher
must have the laser
radiation warning label.
Federal regulations require manufacturers to classify medical laser systems based primarily on their ability to cause damage to the eye and skin. This classification must be indicated on the laser systems label.









Class 1

A Class 1 laser system is considered to be incapable of producing damaging radiation levels during normal operation, and is exempt from any control measures or other forms of surveillance. Although some Class 1 lasers emit very weak, non-hazardous beams, most Class 1 laser systems incorporate "embedded" higher-power lasers, which can be accessed only if important safety features such as interlocks are defeated or deliberately bypassed as is sometimes done during servicing. In this case, the system temporarily reverts back to the original laser classification (requiring special safety procedures). NOTE: Products which have been previously classified as Class 2a should be treated the same as Class 1.
 
Class 1M

A Class 1M laser system is considered to be incapable of producing hazardous exposure conditions during normal operation unless the beam is viewed with an optical instrument such as an eye-loupe (diverging beam) or a telescope (collimated beam), and is exempt from any control measures other than to prevent potentially hazardous optically aided viewing; and is exempt from other forms of surveillance.

Class 2 A Class 2 laser system emits in the visible portion of the spectrum (400-700 nm), and eye protection is normally afforded by the aversion response. The aversion response is the closure of the eyelid, eye movement, pupillary constriction, or movement of the head to avoid an exposure to a bright light stimulant. The aversion response to a bright visible laser source is assumed to limit the exposure of the retina to 0.25 seconds or less.
 
Class 2M A Class 2M laser system emits in the visible portion of the spectrum (400-700 nm), and eye protection is normally afforded by the human aversion response for unaided viewing. However, Class 2M is potentially hazardous if viewed with certain optical aids.
 
Class 3R

A Class 3R laser system is potentially hazardous under some direct and specular reflection (shiny or mirror-like) viewing conditions if the eye is appropriately focused and stable, but the probability of an actual injury is small. This laser will not pose either a fire hazard or diffuse reflection hazard. NOTE: Products which have been previously classified as Class 3a should be treated the same as Class 3R.
 

Class 3B

A Class 3B laser system may be hazardous under direct and specular viewing conditions, but is normally not a diffuse reflection or fire hazard.
 

Class 4

A Class 4 laser system is a hazard to the eye and skin from the direct beam, and may pose a diffuse reflection or fire hazard, and may also produce laser-generated airborne contaminants and hazardous plasma radiation.


Laser Wavelength and the Eye's Response
Different laser wavelengths affect various parts of the human eye and may cause serious injury at high power levels. The following describes these wavelengths and the parts of the eye that are affected.

Ultraviolet (Invisible to the Human Eye)
  • Lasers operating in the ultraviolet spectrum (315nm to 390nm) are absorbed by the lens. An excimer laser is a typical ultraviolet medical laser.
Illustration of where Near-Ultraviolet Radiation (315nm-390nm) is absorbed in the eye.
Figure 1. Illustration of where Near-Ultraviolet Radiation
 (315nm-390nm) is absorbed in the eye.
Visible
  • Laser radiation in the visible region of the spectrum (400-700nm) is absorbed primarily within the retina. An ideal eye can focus a collimated visible beam by as much as 100,000 times. Argon and KTP lasers are typical visible medical lasers.
Illustration of where Visible and Near-Ultraviolet Radiation (400-1400nm) is absorbed in the eye.
Figure 2. Illustration of where Visible and Near-Infrared
(400-1400nm) Radiation is absorbed in the eye.


Near-Infrared (Invisible to the Human Eye)
  • Laser radiation in the near-infrared region of the spectrum (700-1400nm) is absorbed by the retina. The eye can concentrate a laser beam on the retina as much as 100,000 times.  For example, a 1 mW/cm2 irradiance (power density) at the cornea will be 100 W/cm2 at the retina. Since the eye does not have an aversion response in the near- or far-infrared portion of the spectrum we will not know that we have been overexposed until the injury occurs. This is why this portion of the spectrum is very dangerous.

Far-Infrared

  • Laser radiation in the far-infrared region of the spectrum (1400nm-1mm) and the mid-ultraviolet (180-315nm) primarily affects the cornea. CO2 laser is a typical far-infrared medical laser.
Illustration of where Mid-Infrared and Far Infrared (14nm-1mm) and Middle-Ultraviolet (180nm-315nm) Radiation is absorbed in the eye.
Figure 3. Illustration of where Mid-Infrared and Far Infrared (1400nm-1mm) and Middle-Ultraviolet (180nm-315nm) Radiation is absorbed in the eye.
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Laser-Generated Airborne Contaminants (LGAC)

In operations using lasers that vaporize tissue through disruption of cells, laser generated airborne contaminants (LGAC) result as an airborne hazard requiring appropriate management. Analysis of these contaminants produced during laser surgical procedures has shown the presence of:
  • gaseous toxic compounds.
  • bio-aerosols.
  • dead and live cellular material.
  • viruses.
In orthopedics, dentistry, plastic surgery and other fields, it is also possible to generate particulates and metal fumes. At certain concentrations some of the LGAC may cause ocular and upper respiratory tract irritation, have unpleasant odors, create visual problems for the user, and have been shown to have mutagenic and carcinogenic potential. It has been shown that laser smoke production is a function of increased irradiance levels. Therefore, laser surgical procedures requiring high irradiance levels are more likely to produce LGAC.

Possible Solutions
  • Airborne contaminants should be controlled by the use of local exhaust ventilation, respiratory protection or a combination of both. [ANSI Z136.3]
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Detailed training in laser safety should be provided for those healthcare personnel using, or working in the presence of, Class 3B and Class 4 health care laser systems. All training activities should be documented and retained on file. Laser safety training should be presented to the following healthcare personnel: [ANSI Z136.3]
  1. Laser Safety Officer (LSO)
  2. Users
  3. Laser technical support staff
  4. Nurses and allied health personnel
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Credentialing
Each medical specialty has evolved its own procedures for bringing in new techniques and new surgical procedures. In all cases, the laser user should use the laser for its intended purpose within the user's scope of practice, training and experience. All credentialing processes must require training in the safe clinical use of the laser, as well as the maintenance of a safe environment in compliance with defined standards, and local, state and Federal requirements.
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