Dissertation/Thesis Abstract

Determination of Laser Generated Air Contaminant Emission Rates in a Simulated Surgical Procedure
by Lippert, Julia Ford, Ph.D., University of Illinois at Chicago, 2013, 120; 3573411
Abstract (Summary)

The Occupational Health and Safety Administration (OSHA) estimates that half a million surgical staff are exposed to laser smoke or plume each year. It has been suggested that the type and intensity of exposure is dependent in part on the way a laser is used during surgery. The purpose of this study was to estimate emission rates of the gas phase constituents of laser generated air contaminants using a validated emission chamber methodology while differentiating the effects of the laser operational parameters power, pulse-repetition frequency, and beam diameter, and ultimately to model a set of plausible occupational exposures.

An emission chamber was designed, fabricated, and validated to quantify the emission rates of gases and particles associated with laser generated air contaminants (LGACs) during a simulated surgical procedure. The emission chamber was built of inert materials, including a glass hood section connected to a duct section for collection and allowing for lasing of tissue. The performance, plume capture, and air flow of the emission chamber system were validated. This validated emission chamber and methodology enabled accurate estimation of emission rates with low experimental variability that can be used in mathematical modeling of exposure.

Two medical lasers (Holmium Yttrium Aluminum Garnet [Ho:YAG] and carbon dioxide [CO2]) were set at varying operational parameters in a simulated laser surgery on porcine skin to generate a plume in an emission chamber. Porcine skin was pyrolyzed with a medical laser set to a range of surgically plausible operational parameters. Consistency in the rate and depth of incision was established by a system to control the speed of laser movement and aim angle of the laser tip, and was validated by measurement of tissue loss. The plume was sampled for seven gas phase contaminants of combustion products (volatile organic compounds [VOC], formaldehyde, hydrogen cyanide [HCN], carbon dioxide (CO2), carbon monoxide [CO]). The effect of each operational parameter was determined using a fractional factorial design coupled with a sequential screening process that evaluated the parameters for their influence on emission rates.

Measured concentrations of the gas phase contaminants were below the limit of detection (LOD). Confined to the experimental conditions of this investigation, results indicated that beam diameter was significantly influential to emission rates when using the Ho:YAG laser but not with the CO2 laser. Power and pulse repetition frequency were not influential to emission rates of these gas phase contaminants.

Emission rates of LGAC from the experimentally determined concentrations were used to estimate a range of physically plausible occupational exposures to surgical staff. A two-zone semi-empirical model was implemented with input variables varied over a range based on the general requirements of a laser surgical suite in compliance with regulatory agencies. Twenty-minute time weighted averages were developed for the near- and far-field zones within the surgical suite as estimates of the occupational exposure to LGAC. These values were compared to relevant occupational exposure limits; estimated exposures were at least three times in magnitude less than the exposure limits and thus do not appear to present an occupational hazard.

Indexing (document details)
Advisor: Lacey, Steve
School: University of Illinois at Chicago
School Location: United States -- Illinois
Source: DAI-B 74/12(E), Dissertation Abstracts International
Subjects: Occupational health, Medicine, Public health, Environmental science
Keywords: Air contaminants, Emission rates, Laser smoke, Medical lasers, Surgical procedures
Publication Number: 3573411
ISBN: 9781303435867