JOURNAL OF OPTOELECTRONICS AND ADVANCED MATERIALS Vol. 14, No. 7- 8, July – August 2012, p. 664 - 670 Quantitative in vitro analysis of surgical smoke by laser photocoustic spectroscopy M. PETRUS a , C. MATEI a , M. PATACHIA a,b , D.C. DUMITRAS a a Department of Lasers, National Institute for Laser, Plasma and Radiation Physics,409 Atomistilor St., PO Box MG-36, 077125, Bucharest, Romania b University of Bucharest, Faculty of Physics, 36-46 Mihail Kogalniceanu Blvd., 050107, Sector 5, Bucharest, Romania CO 2 laser photoacoustic spectroscopy is used to detect and monitor gases at low concentrations, in the range of ppb (part per billion) or even lower. In the present paper, chemical compounds of surgical smoke produced in vitro by CO 2 laser ablation of fresh animal tissues, in nitrogen or synthetic air atmospheres, were investigated by CO 2 laser photoacoustic spectroscopy. A quantitative analysis of some gases from surgical smoke was achieved. Traces in ppm (part per million) range of benzene, ethylene, ammonia, and methanol were detected in the samples which consisted mostly of carbon dioxide and water vapors. The relationships between gas concentrations and laser power, exposure time, atmosphere and the type of tissue were investigated. The CO 2 laser photoacoustic spectroscopy system proved once again its efficiency in gas concentration measurement with high sensitivity, over a large span of concentration values. (Received May 23, 2012; accepted July 19, 2012) Keywords: Laser photoacoustic spectroscopy, CO 2 laser, Surgical smoke, Benzene, Ethylene, Ammonia, Methanol 1. Introduction The use of thermal instruments for surgical applications has grown significantly over the past three decades. Unfortunately, when any type of thermal or ultrasonic surgical instrument, such as laser energy, electrosurgery, argon, ultrasonic/harmonic scalpel, or plasma is applied to human tissue, an unwanted by- product is produced which is commonly known as surgical smoke plume [1-5]. Surgical smoke has been shown to be a viable transport mechanism for viruses [1–5], blood and cell containing aerosols [5–7] and tissue fragments [8, 9]. There are several ways by which surgical smoke affects patients and health care professionals present in the operating room, depending on the size, nature and concentration. For example, laser produced smoke is characterized by small particles with a diameter of approximately 0.3 µm [10] that generally pose a chemical hazard. Therefore, from the health safety perspective, the chemical and biological composition of surgical smoke is of great interest. The toxicity and mutagenicity of surgical smoke has been said to be at least as severe as that of cigarette smoke [6-9]. In fact, the smoke issued from laser ablation of 1 gram of tissue can be compared to the burden derived from 3 cigarettes; for electrocautery, the number is 6 cigarettes [9]. In this work, we present the results of quantitative analysis of trace gas concentrations (ethylene, benzene, ammonia, and methanol) and water vapors content from surgical smoke produced in vitro in our laboratory on fresh animal tissue, in nitrogen or synthetic air atmosphere, analyzed with CO 2 laser photoacoustic spectroscopy. We also investigated the relationship between smoke composition and laser irradiation power, exposure time, atmosphere and type of the tissue. The CO 2 laser photoacoustic spectroscopy technique has the advantage of high selectivity, necessary to distinguish the gas species present in a multicomponent gas mixture, such as surgical smoke, together with a high sensitivity to detect very low concentrations of gases. Detection limits in the bands of ppb and ppt, good selectivity, and a relative experimental simplicity are some aspects that make photoacoustic spectroscopy a great tool for the detection of trace gases [11-14]. Moreover, the CO 2 laser photoacoustic spectroscopy technique holds a great potential for medical diagnostics and monitoring of human breath biomarkers [15]. The smoke was produced by CO 2 laser irradiation; one of the most frequently used lasers in medicine. The interaction of the laser beam with the tissue is purely thermal and, as a consequence, the production of smoke is rather high. From the multitude of volatile compounds present in the CO 2 laser surgery smoke, the four gases under observation were chose based on their high absorption coefficient in the CO 2 laser wavelength range, as well as due to their influence on the immediate and long-term health of those who inhale them. Benzene is a mutagen which can lead to headaches, as well as irritation and soreness in the eyes, nose and throat. Benzene targets liver, kidney, lung, heart and the brain causing cancer or increasing the risk of cancer, DNA strand breaks, and chromosomal damage [16-19]. Ethylene is considered a human carcinogen and can be metabolized to ethylene oxide, which is a respiratory irritant and cause pulmonary edema, much more than other irritant gases do. Ethylene have been shown to present a mutagenic and carcinogenic potential similar to that of the