Biological monitoring of occupational exposure to isoflurane by measurement of isoflurane exhaled breath

Breath analysis: technical developments and challenges in the monitoring of human exposure to volatile organic compounds

At present, there is a growing concern about human quality of life. In particular, there is an awareness of the impact of volatile organic compounds (VOCs) on the environment and human health, so the monitoring of human exposure to VOCs is an increasingly urgent need. Biomonitoring is theoretically more accurate compared with traditional ambient air monitoring, and it plays an essential role in human environmental exposure assessment. Breath analysis is a biomonitoring method with many advantages, which is applicable to assessments of human exposure to a large number of VOCs. Techniques are being developed to improve the sensitivity and precision of breath analysis based on in-direct and direct measurements which will be reviewed in this paper. This paper briefly reviews the frequently used methods in both of these categories, specifically highlighting some promising new techniques. Furthermore, this review also provides theoretical background knowledge about the use of breath analysis as a biomonitoring tool for human exposure assessment. A review of the application of breath analysis to human exposure monitoring during last two decades is also provided according to occupational/non-occupational exposure. Obstacles and potential challenges in this field are also summarized. Based on the gradual improvements in the theoretical basis and technology reviewed in this paper, breath analysis is an enormous potential approach for the monitoring of human exposure to VOCs.

Application of mathematical models in combination with Monte Carlo simulation for prediction of isoflurane concentration in an operation room theater

Applicability of two mathematical models in inhalation exposure prediction (well mixed room and near field-far field model) were validated against standard sampling method in one operation room for isoflurane. Ninety six air samples were collected from near and far field of the room and quantified by gas chromatography-flame ionization detector. Isoflurane concentration was also predicted by the models. Monte Carlo simulation was used to incorporate the role of parameters variability. The models relatively gave more conservative results than the measurements. There was no significant difference between the models and direct measurements results. There was no difference between the concentration prediction of well mixed room model and near field far field model. It suggests that the dispersion regime in room was close to well mixed situation. Direct sampling showed that the exposure in the same room for same type of operation could be up to 17 times variable which can be incorporated by Monte Carlo simulation. Mathematical models are valuable option for prediction of exposure in operation rooms. Our results also suggest that incorporating the role of parameters variability by conducting Monte Carlo simulation can enhance the strength of prediction in occupational hygiene decision making.

Application of solid-phase microextraction and gas chromatography–mass spectrometry to the determination of volatile organic compounds in end-exhaled breath samples

Analysis of exhaled air is of particular interest as an indicator of health as well as a tool for the diagnosis of diseases. It is also a very attractive procedure for the biological control of the exposition to hazardous solvents. This kind of analysis presents numerous advantages over other methods, the most important being that it is not an invasive procedure and, therefore, it is well accepted and can be applied to a wide range of compounds. Furthermore, the analysis is simplified since the matrix is less complex that in the case of blood or urine. In spite of these obvious advantages and the good results obtained, analysis of exhaled air is not in daily use, probably due to the fact that there are no normalized systems of sampling, thus making the interpretation of the results difficult. In this paper, a method for the determination of tetrachloroethylene in exhaled air using solid-phase microextraction is presented. This method, which can be applied to other volatile organic compounds, was developed with special emphasis of end-exhaled breath sampling. The sample is collected in a glass tube whose ends are closed once the exhalation is finished. The tube has an orifice sealed with a septum through which the fiber is inserted. Then, the fiber is desorbed in the injector of a gas chromatograph and the analysis is accomplished using mass spectrometry for the identification and quantification of the components. The proposed system avoids the need of complex sampling equipment and allows analysis of the alveolar fraction. Additionally, the system is economical and easy to handle, thus facilitating the development of normalized methods and its routine use in field studies.

Phase II collaborative pilot study: preliminary analysis of central neural effects from exposure to volatile anesthetics in the PACU

Nurses working in the PACU are occupationally exposed to volatile anesthetics that are exhaled by patients. Few studies have quantified this exposure using breath analysis or have characterized biological effects associated with this exposure. Isoflurane is a widely used anesthetic and is a strong respiratory depressant. Exposure to isoflurane has been shown to cause changes in breathing patterns at low doses. However, biological effects of isoflurane exposure have never been addressed in the occupational setting. This study investigates whether occupational exposure to anesthetic gases has a depressive effect on central neural control of breathing. In this study, concentrations of halogenated anesthetics were quantified in pre- and postshift breath samples of nurses working in the PACU on a Friday and the following Monday. After each breath sample was collected, an occlusion pressure measurement was taken as an indicator of central inspiratory drive. Cumulative nitrous oxide and halogenated anesthetics exposure was measured each day using personal sampling monitors placed close to the nurse's mouth. Exposure to nitrous oxide and isoflurane was significantly higher on Monday than on Friday (P <.001). Monday breath isoflurane concentrations (mean +/- SD) increased significantly from 43 +/- 30 parts per billion (ppb) in preshift breath samples to 124 +/- 57 ppb in postshift breath samples (P <.002). On Monday, there was a significant decrease in occlusion pressure from 1.2 +/- 0.37 cm H(2)O in preshift samples to 0.85 +/- 0.43 cm H(2)O in postshift samples (P =.05). There was no statistical difference in pre- versus postbreath isoflurane or occlusion pressure on Friday. These data indicate that after increased exposure to isoflurane, central neurorespiratory activity was depressed.

New technologies in the use of exhaled breath analysis for biological monitoring

Breath analysis is an attractive non-invasive procedure for screening workers exposed to solvents. It has been used in numerous laboratory based studies and for field research. Despite the obvious advantages in routine biological monitoring it has failed to become widely accepted as a tool in occupational hygiene. Recent advances in breath sampling and analysis are such that it is likely to become more widely used in the future. In this paper, the past 5 years have been reviewed to try to assess what developments might now contribute to the increased use of breath analysis in biological monitoring; in particular, the development of a selected ion flow tube mass spectrometer for real time direct analysis of trace gases in breath and the more immediately available and less expensive indirect methods involving collection devices with adsorbent tubes is important. The introduction of guidance values for biological monitoring with clear advice on sampling times and the recognition of the importance of quality assurance programmes will help improve confidence in the technique.

Solid-phase microextraction gas chromatographic-mass spectrometric method for the determination of inhalation anesthetics in urine

Solid-phase microextraction (SPME) has been applied to the headspace sampling of inhalation anesthetics (i.e. nitrous oxide, isoflurane and halothane) in human urine. Analysis was carried out by gas chromatography-mass spectrometry using a capillary column with a divinylbenzene porous polymeric stationary phase. A SPME divinylbenzene-Carboxen-polydimethylsiloxane coated fiber, 2 cm long, was used, and its performances were compared with those of a Carboxen-PDMS in terms of sensitivity, extraction efficiency, extraction time, fiber coating-urine distribution coefficient. For both fibers, linearity was established over four orders of magnitude, limits of detection were below 100 ng/l for nitrous oxide and below 30 ng/l for halogenated. Precision calculated as %RSD was within 3-13% for all intra- and inter-day determinations. The method was applied to the quantitative analysis of anesthetics in the urine of occupationally exposed people (operating room personnel).