April 11, 1988

The use of laser to perform surgery has gained wide acceptance in recent years. Carbon dioxide laser is the most frequently used laser in surgery due to its precise cutting ability, coagulating effect on small blood vessels, and low trauma to surrounding tissue areas. The energy supplied at the focal point of the carbon dioxide laser is so great that the tissue and fluid are vaporized. Researchers have suggested that the smoke may act as a vector for cancerous cells which may be inhaled by the surgical team and other exposed individuals.

There have been many studies on this subject. One study in 1987 by Camran Nezhat et. al. (1) examined the compositions of the smoke plume produced during carbon dioxide laser surgery to determine whether the operating room team was at risk from the laser smoke. The authors were interested in calculating the probability that something the size of a whole red blood cell (7.5 um) would be present in the smoke. Particles with an aerodynamic diameter range from 0.1-0.8 um were found in the collected smoke plume samples but no cell-size particles, including cancer cells, were present in the plume (probability 0.000001).

The findings of this study differ from some earlier studies in which intact cells or identifiable cell parts were collected from both carbon dioxide and neodymium: yttrium-aluminum-garnet (YAG) laser radiation of animal tissue. The conclusion of the Nezhat study was that although no identifiable hazard from airborne cancer cells was detected, a significant portion of the particles in the smoke was in the range of 0.5-5.0 um. These particles are too small to be effectively filtered by surgical masks. It was recommended that a mechanical smoke evacuator system with a high-efficiency multi-stage filter be used during smoke generating laser vaporization procedures.

An article by Robert Fisher (2) indicated that although mechanical smoke vacuuming systems were used in carbon dioxide laser surgery, the tube had to be held as close as 1 cm from the target. At 2 cm, the evacuation ratio was down to 50%. The author concluded that prudence should be exercised while the hazards presented by the laser smoke are further investigated.

The most recent study published in February, 1988 by Garden et. al. (3) analyzed the vapor produced by the carbon dioxide laser during vaporization of papillomavirus infected verrucae. This study concluded that intact viral deoxyribonueleic acid (DNA) was liberated into the air with the plume of laser-treated verrucae. Papillomavirus DNA has been demonstrated to be infectious. Therefore, when performing laser therapy on patients infected with viruses such as hepatitis or the human immunodeficiency virus, the smoke plume should be assumed to be infectious and appropriate precautions, such as a well maintained vacuum apparatus should be observed.

"American National Standard for the Safe Use of Laser in Health Care Facilities," ANSI Z-136.3 will be published in June, 1988. The standard provides guidance for safe use of lasers and laser systems for diagnostic and therapeutic uses in health care facilities. The standard takes into consideration the unique problems related to operating rooms, outpatient clinics, and private medical offices. The hazard classification scheme detailed in ANSI Z-136.3 is identical with that in ANSI Z-136.1, "American National Standard for the Safe Use of Lasers" already published and available for use.

Compliance and consultative personnel should be aware of this emerging problem and advise medical personnel of the possible hazard of laser smoke during compliance inspections and consultative visits. Please disseminate this information to Area Offices, State Plan States and Consultation Project Officers.

References:

1. Nezhat C, Winer W, Nezhat F et. al.: Smoke from Laser Surgery: Is there a hazard? "Lasers in Surgery and Medicine" 7: 376-382, 1987.
2. Fisher RW: Laser smoke in the operating room, "Biomedical Technology Today" 191-194, 1987.
3. Garden JM, O'Banion KM, Shelnitz LS et. al.: Papillomavirus in the vapor of carbon dioxide laser - treated verrucae, "Journal of American Medical Association," 259: 1199-1202, 1988.