Surgeon's occupational exposure to nitrous oxide and sevoflurane during pediatric surgery

Nitrous oxide abuse direct measurement for diagnosis and follow-up: update on kinetics and impact on metabolic pathways

Recreational use of nitrous oxide (N2O) has become a major health issue worldwide, with a high number of clinical events, especially in neurology and cardiology. It is essential to be able to detect and monitor N2O abuse to provide effective care and follow-up to these patients. Current recommendations for detecting N2O in cases of recreational misuse and consumption markers are lacking. We aimed to update current knowledge through a review of the literature on N2O measurement and kinetics. We reviewed the outcomes of experiments, whether in preclinical models (in vitro or in vivo), or in humans, with the aim to identify biomarkers of intoxication as well as biomarkers of clinical severity, for laboratory use. Because N2O is eliminated 5 min after inhalation, measuring it in exhaled air is of no value. Many studies have found that urine and blood matrices concentrations are connected to ambient concentrations, but there is no similar data for direct exposure. There have been no studies on N2O measurement in direct consumers. Currently, patients actively abusing N2O are monitored using effect biomarkers (biomarkers related to the effects of N2O on metabolism), such as vitamin B12, homocysteine and methylmalonic acid.

Occupational Exposure to Halogenated Anaesthetic Gases in Hospitals: A Systematic Review of Methods and Techniques to Assess Air Concentration Levels

Objective During the induction of gaseous anaesthesia, waste anaesthetic gases (WAGs) can be released into workplace air. Occupational exposure to high levels of halogenated WAGs may lead to adverse health effects; hence, it is important to measure WAGs concentration levels to perform risk assessment and for health protection purposes. Methods A systematic review of the scientific literature was conducted on two different scientific databases (Scopus and PubMed). A total of 101 studies, focused on sevoflurane, desflurane and isoflurane exposures in hospitals, were included in this review. Key information was extracted to provide (1) a description of the study designs (e.g., monitoring methods, investigated occupational settings, anaesthetic gases in use); (2) an evaluation of time trends in the measured concentrations of considered WAGs; (3) a critical evaluation of the sampling strategies, monitoring methods and instruments used. Results Environmental monitoring was prevalent (68%) and mainly used for occupational exposure assessment during adult anaesthesia (84% of cases). Real-time techniques such as photoacoustic spectroscopy and infrared spectrophotometry were used in 58% of the studies, while off-line approaches such as active or passive sampling followed by GC-MS analysis were used less frequently (39%). Conclusions The combination of different instrumental techniques allowing the collection of data with different time resolutions was quite scarce (3%) despite the fact that this would give the opportunity to obtain reliable data for testing the compliance with 8 h occupational exposure limit values and at the same time to evaluate short-term exposures.

Analytical Approaches and Trends in the Determination of Psychoactive Drugs in Air

Understanding of the levels of psychoactive drugs in air is important for assessing both occupational and environmental exposure. Intelligence on the usage and manufacture of illegal drugs can also be gained. Environmental analysis and determination of air quality has recently expanded from its traditional focus to new pollutant categories that include illicit and psychoactive drugs. This is attributed to a greater part on the development of new, advanced techniques, such as liquid chromatography/mass spectrometry (LC/MS), allowing for the trace determination of such compounds down to the parts-per-trillion (ng/L) levels generally reported in air. Studies have also investigated the effects of firsthand and secondhand smoking of drugs, such as cocaine, cannabis and opium. Generally, these have shown secondhand smoke effects to be limited, apart from in the case of opium. Some studies have highlighted ill effects resulting through the exposure of vapors and dusts from the storage of drugs, but this has been shown to result from mould and other fungal contaminates. Investigations into the possible occupational exposures resulting from the use of anesthetic drugs in surgery and accident and emergency have focused on nitrous oxide, sevoflurane, methoxyflurane, isoflurane, propofol and fentanyl. This review focuses on developments and applications for the determination of psychoactive drugs in air.

A health-based recommended occupational exposure limit for nitrous oxide using experimental animal data based on a systematic review and dose-response analysis

BACKGROUND

Nitrous oxide (N₂O) is a common inhalation anaesthetic used in medical, paramedical, and veterinary practice. Since the mid 1950's, concerns have been raised regarding occupational exposure to N₂O, leading to many epidemiological and experimental animal studies. Previous evaluations resulted in the classification of N₂O as a possible risk factor for adverse reproductive health outcomes based on animal data. Human data were deemed inadequate primarily because of simultaneous co-exposures to other risk factors for adverse reproductive and developmental outcomes, including other anaesthetic gases. Since previous evaluations, controversies regarding N₂O use remained and new approaches for dose response modelling have been adopted, calling for an update and re-evaluation of the body of evidence. This review aims to assess available animal evidence on N₂O reproductive and developmental outcomes to inform a health-based recommended occupational exposure limit (OEL) for N₂O with a benchmark dose-response modelling (BMD) approach.

METHODS

Comprehensive searches in PubMed, EMBASE, and Web of Science were performed to retrieve all relevant studies addressing reproductive and developmental outcomes related to inhalation of N₂O in animals. The articles retrieved were screened based on title-abstract and full text by two independent reviewers. After data extraction, an overview of all studies was created for the different endpoints, namely foetal outcomes (e.g., resorption), female outcomes (e.g. implantations), and male outcomes (e.g. sperm count). A subset of studies reporting on exposure relevant to workplace settings and with a sufficient number of tested doses were included in dose-response modelling using the BMD approach.

RESULTS

In total, 15.816 articles were retrieved, of which 47 articles were finally included while 4 of those were used for the quantitative data synthesis. The overall risk of bias was judged to be probably high (using OHAT risk of bias tool) and unclear (using SYRCLE's risk of bias tool). From eligible rat studies, three studies provided an acceptable result by fitting a Hill model to the dose-response data. The resulting benchmark dose lower bounds (BMDLs) from three studies converged to an average (±sd) exposure level of 925 ± 2 mg/m³ at an additional risk of one standard deviation of implantation losses above those observed in the control group (i.e. reduced number of live foetuses/mother). For extrapolation from rats to humans, an uncertainty factor of 10 was used and an additional factor of 5 was applied to account for interindividual variability within the population of workers.

CONCLUSION

With this systematic review, all available evidence for reproductive toxicity and adverse developmental outcomes in animals resulting from inhalation exposure to N₂O was used to derive a health-based OEL recommendation of 20 mg/m³ as 8-h time-weighted average.

Risk assessment of occupational exposure to anesthesia Isoflurane in the hospital and veterinary settings

Despite the modern ventilation and waste anesthetic gas (WAG) scavenging systems, occupational exposure to common volatile anesthesia, isoflurane, can occur in the hospital and veterinary settings, but limited information exists on potential exposure and health risk of isoflurane. We assessed exposure dose rates and risks among clinicians and veterinary professionals from occupational exposure to isoflurane. Through a critical review of open literature (1965 to 2020), we summarized potential adverse effects and exposure scenarios of isoflurane among the professional groups, including anesthetists, nurses, operating room personnel, researchers, and/or veterinarians. Deterministic United States National Research Council/Environmental Protection Agency's risk assessment framework (hazard identification, dose-response relationship, exposure assessment and risk characterization) was used to compute inhalation Reference Doses (RfDs), Average Daily Doses (ADDs), and Hazard Quotient (HQ) values-an established measure of non-carcinogenic (systemic) risks-from exposure to isoflurane to workers in hospital and veterinary settings. We identified the central nervous system as the main target for isoflurane, and that isoflurane has dose-dependent effects on cardiac hemodynamics, can impair pulmonary functions and potentially cross the utero-placental barrier leading to congenital malformation in fetus. Based on the modelled RfDs (range 0.8003-7.55 mg/kg-day) and ADDs (range 0.071-1.9617 mg/kg-day), we estimated 56 different HQ values, of which 5 HQs were higher than 1 (range 1.099-2.4512) under high exposure scenarios. Our results suggest a significant non-carcinogenic risk from isoflurane exposures among workers in the occupational settings. The findings underscore the need to significantly minimize isoflurane release to protect workers' health in the hospital and veterinary environments.

Inhaled Anesthetics: Environmental Role, Occupational Risk, and Clinical Use

Inhaled anesthetics have been in clinical use for over 150 years and are still commonly used in daily practice. The initial view of inhaled anesthetics as indispensable for general anesthesia has evolved during the years and, currently, its general use has even been questioned. Beyond the traditional risks inherent to any drug in use, inhaled anesthetics are exceptionally strong greenhouse gases (GHG) and may pose considerable occupational risks. This emphasizes the importance of evaluating and considering its use in clinical practices. Despite the overwhelming scientific evidence of worsening climate changes, control measures are very slowly implemented. Therefore, it is the responsibility of all society sectors, including the health sector to maximally decrease GHG emissions where possible. Within the field of anesthesia, the potential to reduce GHG emissions can be briefly summarized as follows: Stop or avoid the use of nitrous oxide (N2O) and desflurane, consider the use of total intravenous or local-regional anesthesia, invest in the development of new technologies to minimize volatile anesthetics consumption, scavenging systems, and destruction of waste gas. The improved and sustained awareness of the medical community regarding the climate impact of inhaled anesthetics is mandatory to bring change in the current practice.

Effects of sevoflurane exposure on apoptosis and cell cycle of peripheral blood lymphocytes, and immunologic function

BACKGROUND

Waste anesthetic gases (WAGs) leaked from new-type halogenated inhalational anesthetics such as sevoflurane have been were reported to pose a risk for the health of operating room personnel. The effects of WAGs on peripheral blood lymphocytes, however, remain yet controversial. The present study was undertaken to examine the effects of occupational sevoflurane exposure on the peripheral blood lymphocytes of medical personnel who work in the operating room.

METHODS

A cohort of 56 medical residents were divided into exposed group (n = 28) and control group (non-exposed group) (n = 28). Gas chromatography was used to measure the concentration of sevoflurane in the medical resident's breathing zone during surgeries under inhalation anesthesia in the exposure group. The gas collection lasted an hour. Peripheral blood lymphocytes were isolated from venous blood, and then apoptosis and cell cycle were analyzed by flow cytometry. EDTA-anticoagulated whole blood was harvested to analyze the lymphocyte subsets by flow cytometry. Immunoglobulins (IgA, IgM, IgG) were quantified by immunoturbidimetry.

RESULTS

The average concentration of sevoflurane in the exposed group was 1.03 ppm with a range from 0.03 ppm to 2.24 ppm. No significant effects were found on the apoptosis rates or cell cycles of peripheral blood lymphocytes in the exposed group relative to the control group (P > 0.05). Similarly, there were no significant differences in the lymphocyte subsets or the levels of immunoglobulins (IgA, IgM, IgG) between the two groups (P > 0.05).

CONCLUSIONS

Occupational exposure to low-level sevoflurane has no significant effect on the peripheral blood lymphocytes of operating room staff, but this conclusion needs to be confirmed by multicenter and long-term follow-up studies with large samples.

TRIAL REGISTRATION NUMBER AND DATE OF REGISTRATION

ChiCTR2000040772 , December 9, 2020 (Retrospective registration).

Photoacoustic gas monitoring for anesthetic gas pollution measurements and its cross-sensitivity to alcoholic disinfectants

Background

Real-time photoacoustic gas monitoring is used for personnel exposure and environmental monitoring, but its accuracy varies when organic solvents such as alcohol contaminate measurements. This is problematic for anesthetic gas measurements in hospitals, because most disinfectants contain alcohol, which could lead to false-high gas concentrations. We investigated the cross-sensitivities of the photoacoustic gas monitor Innova 1412 (AirTech Instruments, LumaSense, Denmark) against alcohols and alcoholic disinfectants while measuring sevoflurane, desflurane and isoflurane in a laboratory and in hospital during surgery.

Methods

25 mL ethyl alcohol was distributed on a hotplate. An optical filter for isoflurane was used and the gas monitor measured the ‘isoflurane’ concentration for five minutes with the measuring probe fixed 30 cm above the hotplate. Then, 5 mL isoflurane was added vaporized via an Anesthetic Conserving Device (Sedana Medical, Uppsala, Sweden). After one-hour measurement, 25 mL isopropyl alcohol, N-propanol, and two alcoholic disinfectants were subsequently added, each in combination with 5 mL isoflurane. The same experiment was in turn performed for sevoflurane and desflurane. The practical impact of the cross-sensitivity was investigated on abdominal surgeons who were exposed intraoperatively to sevoflurane. A new approach to overcome the gas monitor’s cross-sensitivity is presented.

Results

Cross-sensitivity was observed for all alcohols and its strength characteristic for the tested agent. Simultaneous uses of anesthetic gases and alcohols increased the concentrations and the recovery times significantly, especially while sevoflurane was utilized. Intraoperative measurements revealed mean and maximum sevoflurane concentrations of 0.61 ± 0.26 ppm and 15.27 ± 14.62 ppm. We replaced the cross-sensitivity peaks with the 10th percentile baseline of the anesthetic gas concentration. This reduced mean and maximum concentrations significantly by 37% (p < 0.001) and 86% (p < 0.001), respectively.

Conclusion

Photoacoustic gas monitoring is useful to detect lowest anesthetic gases concentrations, but cross-sensitivity caused one third falsely high measured mean gas concentration. One possibility to eliminate these peaks is the recovery time-based baseline approach. Caution should be taken while measuring sevoflurane, since marked cross-sensitivity peaks are to be expected.

[Comparison of waste anesthetic gases in operating rooms with or without an scavenging system in a Brazilian University Hospital]

BACKGROUND AND OBJECTIVES

Occupational exposure to waste anesthetic gases in operating room (OR) without active scavenging system has been associated with adverse health effects. Thus, this study aimed to compare the trace concentrations of the inhaled anesthetics isoflurane and sevoflurane in OR with and without central scavenging system.

METHOD

Waste concentrations of isoflurane and sevoflurane were measured by infrared analyzer at different locations (near the respiratory area of the assistant nurse and anesthesiologist and near the anesthesia station) and at two times (30 and 120minutes after the start of surgery) in both OR types.

RESULTS

All isoflurane and sevoflurane concentrations in unscavenged OR were higher than the US recommended limit (2 parts per million), regardless of the location and time evaluated. In scavenged OR, the average concentrations of isoflurane were within the limit of exposure, except for the measurements near the anesthesia station, regardless of the measurement times. For sevoflurane, concentrations exceeded the limit value at all measurement locations and at both times.

CONCLUSIONS

The exposure to both anesthetics exceeded the international limit in unscavenged OR. In scavenged OR, the concentrations of sevoflurane, and to a lesser extent those of isoflurane, exceeded the recommended limit value. Thus, the OR scavenging system analyzed in the present study decreased the anesthetic concentrations, although not to the internationally recommended values.

Occupational Chronic Sevoflurane Exposure in the Everyday Reality of the Anesthesia Workplace

BACKGROUND

Although sevoflurane is one of the most commonly used volatile anesthetics in clinical practice, anesthesiologists are hardly aware of their individual occupational chronic sevoflurane exposure. Therefore, we studied sevoflurane concentrations in the anesthesiologists' breathing zones, depending on the kind of induction for general anesthesia, the used airway device, and the type of airflow system in the operating room. Furthermore, sevoflurane baselines and typical peaks during general anesthesia were determined.

METHODS

Measurements were performed with the LumaSense Photoacoustic Gas Monitor. As we detected the gas monitor's cross-sensitivity reactions between sevoflurane and disinfectants, regression lines for customarily used disinfectants during surgery (Cutasept®, Octeniderm®) and their alcoholic components were initially analyzed. Hospital sevoflurane concentrations were thereafter measured during elective surgery in 119 patients. The amount of inhaled sevoflurane by anesthesiologists was estimated according to mVA = cVA × V × t × ρVA aer.

RESULTS

Induction of general anesthesia stopped after tracheal intubation with the patient's expiratory sevoflurane concentration of 1.5%. Thereby, inhalational inductions (INH) caused higher sevoflurane concentrations than IV inductions (mean [SD]: (Equation is included in full-text article.)[ppm] INH 2.43 ± 1.91 versus IV 0.62 ± 0.33, P < 0.001; mVA [mg] INH 1.95 ± 1.54 versus IV 0.30 ± 0.22, P < 0.001). The use of laryngeal mask airway (LMA™) led to generally higher sevoflurane concentrations in the anesthesiologists' breathing zones than tracheal tubes ((Equation is included in full-text article.)[ppm] tube 0.37 ± 0.16 versus LMA™ 0.79 ± 0.53, P = 0.009; (Equation is included in full-text article.)[ppm] tube 1.91 ± 0.91 versus LMA™ 2.91 ± 1.81, P = 0.057; mVA [mg] tube 1.47 ± 0.64 versus LMA™ 2.73 ± 1.81, P = 0.019). Sevoflurane concentrations were trended higher during surgery in operating rooms with turbulent flow (TF) air-conditioning systems compared with laminar flow (LF) air-conditioning systems ((Equation is included in full-text article.)[ppm] TF 0.29 ± 0.12 versus LF 0.13 ± 0.06, P = 0.012; mVA [mg/h] TF 1.16 ± 0.50 versus LF 0.51 ± 0.25, P = 0.007).

CONCLUSIONS

Anesthesiologists are chronically exposed to trace concentrations of sevoflurane during work. Inhalational inductions, LMA™, and TF air-conditioning systems in particular are associated with higher sevoflurane exposure. However, the amount of inhaled sevoflurane per day was lower than expected, perhaps because concentrations in previous measurements could be overestimated (10%-15%) because of the cross-sensitivity reaction.

Breath gas concentrations mirror exposure to sevoflurane and isopropyl alcohol in hospital environments in non-occupational conditions

Anaesthetic gases and disinfectants are a primary source of air contamination in hospitals. A highly sensitive sorbent-trap methodology has been used to analyse exhaled breath samples with detection limits in the pptv range, which allows volatile organic compounds (VOCs) to be detected at significantly lower levels (5-6 orders of magnitude below) than the recommended exposure limits by different organizations. Two common VOCs used in hospital environments, isopropyl alcohol (IPA) and sevoflurane, have been evaluated. Forced-expiratory breath samples were obtained from 100 volunteers (24 hospital staff, 45 hospital visitors and 31 external controls). Significant differences for IPA were found between samples from volunteers who had not been in contact with hospital environments (mean value of 8.032 ppbv) and people staying (20.981 ppbv, p  =  0.0002) or working (19.457 ppbv, p  =  0.000 09) in such an environment. Sevoflurane, an anaesthetic gas routinely used as an inhaled anaesthetic, was detected in all samples from volunteers in the hospital environment but not in volunteers who had not been in recent contact with a hospital environment. The levels of sevoflurane were significantly higher (p  =  0.000 24) among staff members (0.522 ppbv) than among visitors to the hospital (0.196 ppbv). We conclude that highly sensitive methods are required to detect anaesthetic gas contamination in hospital environments.

Multi-capillary column-ion mobility spectrometry (MCC-IMS) as a new method for the quantification of occupational exposure to sevoflurane in anaesthesia workplaces: an observational feasibility study

Background

Occupational exposure to sevoflurane has the potential to cause health damage in hospital personnel. Workplace contamination with the substance mostly is assessed by using photoacoustic infrared spectrometry with detection limits of 10 ppbv. Multi-capillary column-ion mobility spectrometry (MCC-IMS) could be an alternative technology for the quantification of sevoflurane in the room air and could be even more accurate because of potentially lower detection limits. The aim of this study was to test the hypothesis that MCC-IMS is able to detect and monitor very low concentrations of sevoflurane (<10 ppbv) and to evaluate the exposure of hospital personnel to sevoflurane during paediatric anaesthesia and in the post anaesthesia care unit (PACU).

Methods

A MCC-IMS device was calibrated to several concentrations of sevoflurane and limits of detection (LOD) and quantification (LOQ) were calculated. Sevoflurane exposure of hospital personnel was measured at two anaesthesia workplaces and time-weighted average (TWA) values were calculated.

Results

The LOD was 0.0068 ppbv and the LOQ was 0.0189 ppbv. During paediatric anaesthesia the mean sevoflurane concentration was 46.9 ppbv (8.0 - 314.7 ppbv) with TWA values between 5.8 and 45.7 ppbv. In the PACU the mean sevoflurane concentration was 27.9 ppbv (8.0 – 170.2 ppbv) and TWA values reached from 8.3 to 45.1 ppbv.

Conclusions

MCC-IMS shows a significantly lower LOD and LOQ than comparable methods. It is a reliable technology for monitoring sevoflurane concentrations at anaesthesia workplaces and has a particular strength in quantifying low-level contaminations of sevoflurane. The exposure of the personnel working in these areas did not exceed recommended limits and therefore adverse health effects are unlikely.

Long-term allergic dermatitis caused by sevoflurane: a clinical report

BACKGROUND

Allergy to volatile anaesthetics is extremely rare, but capable of damaging the professional career.

METHODS

This article presents the case of a 60-year-old surgeon who developed a skin rash on the reverse of hands, which progressively worsened and extended to distant fold areas. Blood tests were normal but for eosinophilia and risen total IgE, with normal specific globulins and skin prick tests for common allergens. After 8 years, a malfunction in the anaesthetic gas scavenging system was found, and symptoms remitted within a week following its replacement. Repeated open application test with sevoflurane led to the appearance of the same lesions in the tested areas and in distant body folds.

RESULTS

We hypothesize that the most probable mechanism for the reaction in our patient is systemic allergic contact dermatitis, which is caused by repeated systemic exposure to a hapten that reaches the skin through haematogenous transport in a sensitized patient.

CONCLUSIONS

The report aims to warn about the potential aetiological relationship between exposure to inhaled anaesthetics and allergic manifestations with cutaneous symptoms.

Quantitative chemical analysis of surgical smoke generated during laparoscopic surgery with a vessel-sealing device

BACKGROUND

Exposure to surgical smoke in the operation room has been a long-standing concern. Smoke generated by the interaction between lasers or electrocautery devices with biological tissue contains several toxic and carcinogenic substances, but only a few studies so far have provided quantitative data necessary for risk assessment.

METHODS

With laser and Fourier-transform infrared spectroscopy, we investigated the chemical composition of smoke produced with a vessel-sealing device in an anoxic environment during laparoscopic surgery.

RESULTS

Harmless concentrations of methane (<34 ppm), ethane (<2 ppm), and ethylene (<10 ppm) were detected. Traces of carbon monoxide (<3.2 ppm) and of the anesthetic sevoflurane (<450 ppm) were also found. CONCLUSIONS. Gas leaking or gas being released from the pneumoperitoneum could therefore increase pollution by waste anesthetic gas in the operating room. Most toxic compounds found in earlier studies remained undetected. Adverse health effects for operating room personnel due to some of those substances (e.g., toluene, styrene, xylene) can be excluded, assuming no significant losses or changes in the chemical composition of the samples occurred between our sampling and measurements.

Firstborn offspring sex ratio is skewed towards female offspring in anesthesia care providers: A questionnaire-based nationwide study from United States

BACKGROUND

A parental occupation such as anesthesia care provider can involve exposure of the parent to various chemicals in the work environment and has been correlated to skewed offspring sex ratios.

OBJECTIVES

The objective was to conduct a nation-wide survey to observe (a) whether firstborn offspring sex ratio (OSR) in anesthesia providers is skewed towards increased female offspring, and (b) to identify potential factors influencing firstborn OSR, particularly those relating to the peri-conceptional practice of inhalational anesthesia induction among anesthesia providers.

MATERIALS AND METHODS

After institutional review board approval, a questionnaire was uploaded on SurveyMonkey and sent to anesthesia providers through their program coordinators in United States (US) to complete the survey.

RESULTS

The current US national total-population sex ratio is 0.97 male (s)/female with an at-birth sex ratio of 1.05 male (s)/female; comparatively, the results from anesthesia providers' survey respondents (n = 314) were a total OSR of 0.93 male (s)/female (P = 0.61) with firstborn OSR 0.82 male (s)/female (a 6% increase in female offspring; P = 0.03), respectively. The only significant peri-conceptional factor related to anesthesia providers' firstborn OSR's skew was inhalational induction practice by anesthesia care provider favoring female offspring (P < 0.01).

CONCLUSION

Based on the results of this limited survey, it can be concluded that anesthesia care providers who practice inhalation induction of anesthesia during the peri-conceptional period are significantly more likely to have firstborn female offspring.

Occupational exposure to nitrous oxide – The role of scavenging and ventilation systems in reducing the exposure level in operating rooms

OBJECTIVES

The aim of this study was to assess the level of occupational exposure to nitrous oxide (N(2)O) in operating rooms (ORs), as related to different ventilation and scavenging systems used to remove waste anaesthetic gases from the work environment.

METHODS

The monitoring of N(2)O in the air covered 35 ORs in 10 hospitals equipped with different systems for ventilation and anaesthetic scavenging. The examined systems included: natural ventilation with supplementary fresh air provided by a pressure ventilation system (up to 6 air changes/h); pressure and exhaust ventilation systems equipped with ventilation units supplying fresh air to and discharging contaminated air outside the working area (more than 10 air changes/h); complete air-conditioning system with laminar air flow (more than 15 air changes/h). The measurements were carried out during surgical procedures (general anaesthesia induced intravenously and maintained with inhaled N(2)O and sevofluran delivered through cuffed endotracheal tubes) with connected or disconnected air scavenging. Air was collected from the breathing zone of operating personnel continuously through the whole time of anaesthesia to Tedlar((R)) bags, and N(2)O concentrations in air samples were analyzed by adsorption gas chromatography/mass spectrometry.

RESULTS

N(2)O levels in excess of the occupational exposure limit (OEL) value of 180mg/m(3) were registered in all ORs equipped with ventilation systems alone. The OEL value was exceeded several times in rooms with natural ventilation plus supplementary pressure ventilations and twice or less in those with pressure/exhaust ventilation systems or air conditioning. N(2)O levels below or within the OEL value were observed in rooms where the system of air conditioning or pressure/exhaust ventilation was combined with scavenging systems. Systems combining natural/pressure ventilation with scavenging were inadequate to maintain N(2)O concentration below the OEL value.

CONCLUSION

Air conditioning and an efficient pressure/exhaust ventilation (above 12 air exchanges/h) together with efficient active scavenging systems are sufficient to sustain N(2)O exposure in ORs at levels below or within the OEL value of 180mg/m(3).

Exposition des Personals gegenüber Sevofluran

BACKGROUND

Occupational exposure to volatile anaesthetics cannot be completely avoided even in modern operating theatres. In 1997, the staff exposure during balanced anaesthesia in our hospital was low (sevoflurane 0.49 ppm; N(2)O 11.5 ppm). In 1999, N(2)O was completely omitted at our hospital, therefore, exposure to volatile anaesthetics, namely sevoflurane, might have increased.

METHODS

Environmental exposure was measured by photoacoustic infrared spectrometry. To determine the personal exposure and to compare it with environmental exposure, 14 anaesthetists wore diffusion samplers near their breathing zones for 1 week.

RESULTS

The median environmental concentration of sevoflurane was between 0.09 and 0.21 ppm in central operating theatres and between 0 and 24.8 ppm in intervention rooms. The median personal concentration was 0.19 ppm.

CONCLUSION

The occupational exposure to volatile anaesthetics is not higher using sevoflurane alone compared to the combination of sevoflurane and N(2)O. In addition, the data acquired from environmental and personal measurements showed similar results.