What are the safety rules for using surgical or therapy laser in the veterinary practice?

Laser is an acronym for Light Amplification by Stimulated Emission of Radiation. In general, laser light focused onto tissues will be absorbed, transformed, reflected and/or scattered. The primary hazards associated with lasers are from inadvertent exposure to the laser beam and from exposure to the smoke stream resulting from the tissue destruction by the laser. Exposure to an individual may occur directly from the laser beam, or when the beam is reflected from a shiny surface such as a mirror, ring, glass picture frame, etc. or in the case of the CO2 laser from metal instruments and other common operative items. The parts of the body at greatest risk are a person’s eyes and skin.

Surgical lasers used in veterinary medicine produce an intense beam of pulsed or continuous invisible infrared light (radiation), which is used for cutting and sealing tissue. The benefits of using laser radiation in surgery include decreased bleeding as smaller blood vessels are sealed, decreased pain in post operative recover and destruction of bacteria. The most commonly used surgical laser in the veterinary profession the CO2 laser used for soft tissue surgery. The CO2 laser wavelength is usually 10.6 micrometers which is highly absorbed by water contained in soft tissue. The CO2 laser uses the principle of Photothermal Ablation (light generated heat to cut or remove).

Unlike surgical lasers, therapy lasers are not designed to destroy tissue, but merely to "excite" them. Although the smoke hazards are not present when using a therapy laser, the eye hazards are still present.

Eye Hazards

Eye damage from a laser beam happens primarily because the cornea and lens focus the light beam to a very small spot on the retina. Vision damage is usually severe, and can result in blindness; therefore, direct viewing of the laser and its reflections should be avoided by all practical means available.

The five main points determine the type of eyewear required for a laser are:

• Wavelength
• Pulse vs. continuous laser
• Laser type (carbon dioxide, ruby)
• Wattage
• Comfort and duration of use

Because of the destructive nature of the laser and it’s ability to be reflected by smooth surfaces, everyone in the room must wear goggles or eyewear that is “tuned” to the frequency of the laser in use.

Laser safety eyewear is a filter/absorber designed to filter out (or absorb) a specific wavelength while allowing light for other wavelengths to pass through. General purpose safety glasses and traditional prescription glasses offer no protection from surgical laser beams. Likewise, sunglasses, even polarized ones are not appropriate safety glasses for laser surgery use.

OSHA endorses the American National Standards Institute (ANSI) Standard Z136.1-2007 as the “definitive authority” on laser safety operations, including eye protection rules. Part of that standard requires all laser eye wear to be clearly labeled with Optical Density (OD) values and wavelengths for which protection is afforded. If the glasses or goggles do not have these markings, they do not meet the safety requirements for use in laser operations.

Bottom line...every person in the room when the laser is fired must wear eye protection clearly labeled as appropriate to the laser and the procedure. These rules must be followed no matter if the laser in use if for surgical or therapeutic purposes.

Smoke Inhalation Hazards

During surgical procedures using a laser or electrosurgical unit, the thermal destruction of tissue creates a smoke byproduct. This smoke plume can contain toxic gases and vapors such as benzene, hydrogen cyanide, and formaldehyde, bioaerosols, dead and live cellular material (including blood fragments), and viruses. At high concentrations the smoke causes ocular and upper respiratory tract irritation in health care personnel, and creates visual problems for the surgeon.

General room ventilation is not sufficient in itself to capture contaminants generated at the source, therefore, process-specific exhaust ventilation is also required. Most practices use a High Efficiency Particulate Absorption (HEPA) filter scavenger to capture the smoke from laser procedures.

The smoke evacuator or scavenger suction hose inlet must be kept within 2 inches of the surgical site to effectively capture airborne contaminants generated by these surgical devices. The scavenger or smoke evacuation system should be activated at all times when airborne particles are produced during procedures. At the completion of the procedure all tubing, filters, and absorbers must be considered contaminated and cleaned, disinfected or disposed of appropriately. Of course, regular maintenance and inspection of the scavenger or evacuator is essential for preventing leaks that could release the harmful smoke back into the room.

Other Hazards

In addition to the smoke and eye protection issues, there are these considerations when using lasers in the veterinary practice:

• A potential explosion hazard may occur from the buildup of high pressures of gases in the flash lamp when it is fired.
• Sometimes cryogenic gases (liquid nitrogen or liquid helium) are used to cool the crystal (ruby, neodymium, etc.). Skin burns can result from contact with these gases. If these cryogenic gases leak into a closed room, they are capable of replacing the oxygen in the air, thus creating an oxygen-deficient atmosphere.
• Electrical shock or electrocution may occur from contact with exposed utility power. Exposures can occur during setup, installation, maintenance and service of the laser. The protective covers are often removed to allow access to the components.
• Fire is also potential hazard with Class 4 laser systems. The use of flame-retardant materials should be encouraged.

Given the ease and results of this tool, it’s easy to see why lasers are becoming more prevalent in the average veterinary practice. Even with the potential risks of using lasers, many practices use them with excellent safety records and clinical results. The key to establishing an effective and safe laser program is to prepare the location properly and follow all the procedural instructions supplied by the manufacturer.

Did You Know...?

The scientific term for
"deep tissue laser therapy" is photobiomodulation!