A straightforward method for determination of the sevoflurane metabolite hexafluoroisopropanol in urinary occupational medical samples by headspace-gas chromatography mass spectrometry.

Biological monitoring of the unmodified sevoflurane and its metabolite hexafluoroisopropanol (HFIP) in urine samples was proposed to determine the individual exposure levels of the medical staff. In this study, a method for simultaneous determination of both compounds in urine using static headspace-gas chromatography-mass spectrometry (HS-GC-MS) was developed. The method is linear over a broad concentration range from 1 to 1000 µg/L (r2 > 0.999) and shows high precision. Limits of quantification (LOQ) are 0.6 µg/L for sevoflurane and 3 µg/L for HFIP, representing an excellent sensitivity without the necessity of analyte enrichment. The method was successfully applied in a German pilot-study to monitor both compounds in samples from medical personnel working in operating theatres. Urinary concentrations of HFIP ranged between < LOQ and 145 µg/L, while sevoflurane was below the LOD in all samples.

Pain management & opioid dose reduction with topical sevoflurane instillations in intractable venous ulcers: a case report

Abstract Vascular ulcers (VU) constitute a major cause of pain and disability, and significantly compromise quality of life. VU have a natural tendency to become chronic and in many cases exhibit anunsatisfactoryresponse to many of the standard therapeutic options.The case of a 73 year-old Caucasian female with severe pain and poorly-controlled pain (Visual Analogic Scale-VAS- of 8-9) due to three lower leg long-standing VUs is reported and discussed herein. The patient was treated with topical instillations of undiluted sevoflurane as per institutional off-label protocol (starting doses of 1mL/cm2 twice a day, and up-titrated according to response to a maximum of 7 mL twice daily). The VAS score dropped to 0-1 shortly after initiation of therapy and remained stable throughout treatment up until the closure of the observations. Subsequently, opioid therapy was gradually tapered down and ultimately abandoned.Sevoflurane application resulted on adequate and sustained pain management of refractory VU, with no significant side effects. On account of its beneficial effectivity and safety profiles, topical sevoflurane emerges as an add-on alternative for the long-term management of VU, and potentially other painful conditions.

Probabilistic health risk assessment of occupational exposure to isoflurane and sevoflurane in the operating room.

Risk assessment is an important tool in predicting the possible risk to health. It heightens awareness by estimating the probability of adverse health effects in humans who are exposed to chemicals in the course of their work. Therefore, the present work aims to determine the occupational exposure of operating room staff to the volatile anesthetic gases, isoflurane and sevoflurane, and estimates non-cancer risk using the United States Environmental Protection Agency method. Air samples from the breathing zone of staff members were collected using the Occupational Safety and Health Administration Method 103 and analyzed using gas chromatography-mass spectroscopy. The results indicate that the measured concentrations of isoflurane and sevoflurane are below the National Institute of Occupational Safety and Health standard (2 ppm) for technicians and nurses, but not for anesthesiologists and surgeons. Moreover, the estimated non-cancer risk due to isoflurane is above the acceptable value for anesthesiologists (but acceptable for other occupational categories). A sensitivity analysis indicates that exposure time has the most effect on calculated risk (53.4%). Occupational exposure to anesthetic gases may endanger the health of operating room personnel. Therefore, control measures, such as daily testing of anesthetic devices, ensuring the effectiveness of ventilation systems, advanced scavenging methods, and regular training of staff are highly recommended.

Hepatotoxic and neuroendocrine effects in physicians occupationally exposed to most modern halogenated anesthetics and nitrous oxide.

The lack of data on hepatic and hormonal markers for occupational exposure to most modern halogenated anesthetics has stimulated our research, which assessed liver enzymes, high-sensitivity C-reactive protein (hs-CRP) and neuroendocrine response. The study investigated 106 physicians who were categorized in an exposed group (primarily exposed to isoflurane and sevoflurane and less to desflurane and nitrous oxide) as well as as a control group. Anesthetic air monitoring was performed, and biological samples were analyzed for the most important liver enzymes, hs-CRP, adrenocorticotrophic hormone, cortisol and prolactin. No biomarkers were significantly different between the groups. Exposed males showed significant increases in cortisol and prolactin compared to unexposed males. However, values were within the reference ranges, and 22 % of exposed males versus 5 % of unexposed males exhibited higher prolactin values above the reference range. This study suggests that occupational exposure to the most commonly used inhalational anesthetics is not associated with hepatotoxicity or neurohormonal changes.

Oxidative hydrothermal surface modification of activated carbon for sevoflurane removal.

The emission of waste anaesthetic gas is a growing contributor to global warming and remains a factor in atmospheric ozone depletion. Volatile anaesthetics in medical waste gases could be removed via adsorption using suitable activated carbon materials possessing an enhanced affinity to anaesthetic molecules. In this work, the effects of surface physical and chemical properties on sevoflurane adsorption were investigated by oxidative hydrothermal surface modification of a commercial activated carbon using only distilled water. The hydrothermal surface modification was carried out at different treatment temperatures (150-300 °C) for varying durations (10-30 min), and adsorption was conducted under fixed conditions (bed depth = 10 cm, inlet concentration = 528 mg/L, and flow rate = 3 L/min). The hydrothermal treatment generally increased the BET surface area of the activated carbons. At oxidation temperatures above 200 °C, the micropore volume of the samples diminished. The relative amount of surface oxygen was enriched as the treatment temperature increased. Treatment duration did not significantly affect the introduction of relative amount of surface oxygen, except at higher temperatures. There were no new types of functional groups introduced. However, disappearance and re-formation of oxygen functional groups containing C-O structures (as in hydroxyl and ether groups) occurred when treatment temperature was increased from 150 to 200 °C, and when treatments were conducted above 200 °C, respectively. The ester/acetal groups were enriched under the temperature range studied. The findings suggested that the re-formation of surface oxygen functionalities might lead to the development of functional groups that improve sevoflurane adsorption.

Enrichment of surface oxygen functionalities on activated carbon for adsorptive removal of sevoflurane.

Activated carbons have been reported to be useful for adsorptive removal of the volatile anaesthetic sevoflurane from a vapour stream. The surface functionalities on activated carbons could be modified through aqueous oxidation using oxidising solutions to enhance the sevoflurane adsorption. In this study, an attempt to oxidise the surface of a commercial activated carbon to improve its adsorption capacity for sevoflurane was conducted using 6 mol/L nitric acid, 2 mol/L ammonium persulfate, and 30 wt per cent (wt%) of hydrogen peroxide (H2O2). The adsorption tests at fixed conditions (bed depth: 10 cm, inlet concentration: 528 mg/L, and flow rate: 3 L/min) revealed that H2O2 oxidation gave desirable sevoflurane adsorption (0.510 ± 0.005 mg/m2). A parametric study was conducted with H2O2 to investigate the effect of oxidation conditions to the changes in surface oxygen functionalities by varying the concentration, oxidation duration, and temperature, and the Conductor-like Screening Model for Real Solvents (COSMO-RS) was applied to predict the interactions between oxygen functionalities and sevoflurane. The H2O2 oxidation incorporated varying degrees of both surface oxygen functionalities with hydrogen bond (HB) acceptor and HB donor characters under the studied conditions. Oxidised samples with enriched oxygen functionalities with HB acceptor character and fewer HB donor character exhibited better adsorption capacity for sevoflurane. The presence of a high amount of oxygen functional groups with HB donor character adversely affected the sevoflurane adsorption despite the enrichment of oxygen functional groups with HB acceptor character that have a higher tendency to adsorb sevoflurane.

High concentrations of waste anesthetic gases induce genetic damage and inflammation in physicians exposed for three years: A cross-sectional study.

This cross-sectional study analyzed the impact of occupational waste anesthetic gases on genetic material, oxidative stress, and inflammation status in young physicians exposed to inhalational anesthetics at the end of their medical residency. Concentrations of waste anesthetic gases were measured in the operating rooms to assess anesthetic pollution. The exposed group comprised individuals occupationally exposed to inhalational anesthetics, while the control group comprised individuals without anesthetic exposure. We quantified DNA damage; genetic instability (micronucleus-MN); protein, lipid, and DNA oxidation; antioxidant activities; and proinflammatory cytokine levels. Trace concentrations of anesthetics (isoflurane: 5.3 ± 2.5 ppm, sevoflurane: 9.7 ± 5.9 ppm, and nitrous oxide: 180 ± 150 ppm) were above international recommended thresholds. Basal DNA damage and IL-17A were significantly higher in the exposed group [27 ± 20 a.u. and 20.7(19.1;31.8) pg/mL, respectively] compared to the control group [17 ± 11 a.u. and 19.0(18.9;19.5) pg/mL, respectively], and MN frequency was slightly increased in the exposed physicians (2.3-fold). No significant difference was observed regarding oxidative stress biomarkers. The findings highlight the genetic and inflammatory risks in young physicians exposed to inhalational agents in operating rooms lacking adequate scavenging systems. This potential health hazard can accompany these subjects throughout their professional lives and reinforces the need to reduce ambient air pollution and consequently, occupational exposure.

Comparison of 3 Methods to Assess Occupational Sevoflurane Exposure in Abdominal Surgeons: A Single-Center Observational Pilot Study.

BACKGROUND: Studies demonstrated that operating room personnel are exposed to anesthetic gases such as sevoflurane (SEVO). Measuring the gas burden is essential to assess the exposure objectively. Air pollution measurements and the biological monitoring of urinary SEVO and its metabolite hexafluoroisopropanol (HFIP) are possible approaches. Calculating the mass of inhaled SEVO is an alternative, but its predictive power has not been evaluated. We investigated the SEVO burdens of abdominal surgeons and hypothesized that inhaled mass calculations would be better suited than pollution measurements in their breathing zones (25 cm around nose and mouth) to estimate urinary SEVO and HFIP concentrations. The effects of potentially influencing factors were considered. METHODS: SEVO pollution was continuously measured by photoacoustic gas monitoring. Urinary SEVO and HFIP samples, which were collected before and after surgery, were analyzed by a blinded environmental toxicologist using the headspace gas chromatography-mass spectrometry method. The mass of inhaled SEVO was calculated according to the formula mVA = cVA·(Equation is included in full-text article.)·t·ρ VA aer. (mVA: inhaled mass; cVA: volume concentration; (Equation is included in full-text article.): respiratory minute volume; t: exposure time; and ρ VA aer.: gaseous density of SEVO). A linear multilevel mixed model was used for data analysis and comparisons of the different approaches. RESULTS: Eight surgeons performed 22 pancreatic resections. Mean (standard deviation [SD]) SEVO pollution was 0.32 ppm (0.09 ppm). Urinary SEVO concentrations were below the detection limit in all samples, whereas HFIP was detectable in 82% of the preoperative samples in a mean (SD) concentration of 8.53 µg·L (15.53 µg·L; median: 2.11 µg·L, interquartile range [IQR]: 4.58 µg·L) and in all postoperative samples (25.42 µg·L [21.39 µg·L]). The mean (SD) inhaled SEVO mass was 5.67 mg (2.55 mg). The postoperative HFIP concentrations correlated linearly to the SEVO concentrations in the surgeons' breathing zones (ß = 216.89; P < .001) and to the calculated masses of inhaled SEVO (ß = 4.17; P = .018). The surgeon's body mass index (BMI), age, and the frequency of surgeries within the last 24 hours before study entry did not influence the relation between HFIP concentration and air pollution or inhaled mass, respectively. CONCLUSIONS: The biological SEVO burden, expressed as urinary HFIP concentration, can be estimated by monitoring SEVO pollution in the personnel's individual breathing zone. Urinary SEVO was not an appropriate biomarker in this setting.

Validation of Waste Anaesthetic Gas Exposure Limits When Using a Closed Vaporizer Filling System: A Laboratory-Based Study.

INTRODUCTION: It is desirable to minimise exposure of personnel to halogenated inhaled anaesthetics in the operating room to avoid deleterious short-term and long-term health effects. The objective of this study was to determine whether, while filling anaesthetic vaporizers with sevoflurane using AbbVie's closed vaporizer filling system (Quik-Fil™), concentrations of sevoflurane in ambient air remained at or below recommended levels when measured at different operator heights. METHODS: Nine filling runs were conducted, with measurement heights of 95, 130, 140, 150, 160, and 185 cm. Within each 15-min run, five vaporizers were sequentially filled from bottles of sevoflurane with the closed valving system. Ambient-air sevoflurane concentration in the breathing zone was continuously measured once per second by using a MIRAN SapphIRe 205BXL portable ambient air analyser. RESULTS: The use of the closed filling system maintained a level of waste anaesthetic gas exposure that was well below (mean, 0.10 ppm; maximum, 0.16 ppm) the recommended short-term value of 20 ppm average for 15 min provided by the Swedish Work Environment Authority and also fell below the US limit of a time-weighted average of 2 ppm provided by the National Institute for Occupational Safety and Health. Exposure to sevoflurane appeared to be independent of the height at which the measurement was made. CONCLUSIONS: The presence of sevoflurane in the work environment while using the closed filling system maintains a level of waste anaesthetic gas exposure well below the recommended levels at all tested operator heights.

Studies pertaining to the monitoring of volatile halogenated anaesthetics in breath by proton transfer reaction mass spectrometry.

Post-operative isoflurane has been observed to be present in the end-tidal breath of patients who have undergone major surgery, for several weeks after the surgical procedures. A major new non-controlled, non-randomized, and open-label approved study will recruit patients undergoing various surgeries under different inhalation anaesthetics, with two key objectives, namely (1) to record the washout characteristics following surgery, and (2) to investigate the influence of a patient's health and the duration and type of surgery on elimination. In preparation for this breath study using proton transfer reaction time-of-flight mass spectrometry (PTR-TOF-MS), it is important to identify first the analytical product ions that need to be monitored and under what operating conditions. In this first paper of this new research programme, we present extensive PTR-TOF-MS studies of three major anaesthetics used worldwide, desflurane (CF3CHFOCHF2), sevoflurane ((CF3)2CHOCH2F), and isoflurane (CF3CHClOCHF2) and a fourth one, which is used less extensively, enflurane (CHF2OCF2CHFCl), but is of interest because it is an isomer of isoflurane. Product ions are identified as a function of reduced electric field (E/N) over the range of approximately 80 Td to 210 Td, and the effects of operating the drift tube under 'normal' or 'humid' conditions on the intensities of the product ions are presented. To aid in the analyses, density functional theory (DFT) calculations of the proton affinities and the gas-phase basicities of the anaesthetics have been determined. Calculated energies for the ion-molecule reaction pathways leading to key product ions, identified as ideal for monitoring the inhalation anaesthetics in breath with a high sensitivity and selectivity, are also presented.

Breakthrough analysis of continuous fixed-bed adsorption of sevoflurane using activated carbons.

The inhalational anaesthetic agent - sevoflurane is widely employed for the induction and maintenance of surgical anaesthesia. Sevoflurane possesses a high global warming potential that imposes negative impact to the environment. The only way to resolve the issue is to remove sevoflurane from the medical waste gas before it reaches the atmosphere. A continuous adsorption study with a fixed-bed column was conducted using two commercial granular activated carbons (E-GAC and H-GAC), to selectively remove sevoflurane. The effect of bed depth (Z, 5-15 cm), gas flow rate (Q, 0.5-6.0 L/min) and inlet sevoflurane concentration (C0, ∼55-700 mg/L) was investigated. E-GAC demonstrated ∼60% higher adsorption capacity than H-GAC under the same operating conditions. Varying the levels of Z, Q and C0 showed significant differences in the adsorption capacities of E-GAC, whereas only changing the C0 level had significant differences for H-GAC. Three breakthrough models (Adams-Bohart, Thomas, and Yoon-Nelson) and Bed-depth/service time (BDST) analysis were applied to predict the breakthrough characteristics of the adsorption tests and determine the characteristic parameters of the column. The Yoon-Nelson and Thomas model-predicted breakthrough curves were in good agreement with the experimental values. In the case of the Adams-Bohart model, a low correlation was observed. The predicted breakthrough time (tb) based on kinetic constant (kBDST) in BDST analysis showed satisfactory agreement with the measured values. The results suggest the possibility of designing, scaling up and optimising an adsorption system for removing sevoflurane with the aid of the models and BDST analysis.

[Climate footprint of halogenated inhalation anesthetics]. / Klimateffekterna från anestesin kan minska.

This study estimated the climate footprint of halogenated inhalation anesthetics in Sweden and estimated effects of a decreased use of these compounds. We collected data on sales of desflurane, sevoflurane and isoflurane in Sweden during 2017 and calculated the mass of CO2 equivalents (CO2e) using Global Warming Potential data over 100 years for the compounds. Inhalation anesthetics contributed by 5000 tons of CO2e which corresponds to 0.005 percent of the Swedish climate footprint. By replacing desflurane with sevoflurane the footprint can be reduced by 73 percent. By replacing sevoflurane with intravenous propofol the climate effect can be reduced further by at least 2 orders of magnitude.

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.

The Personnel's Sevoflurane Exposure in the Postanesthesia Care Unit Measured by Photoacoustic Gas Monitoring and Hexafluoroisopropanol Biomonitoring.

PURPOSE: Room ventilation in the postanesthesia care unit (PACU) is often poor, although patients exhale anesthetic gases. We investigated the PACU personnel's environmental and biological sevoflurane (SEVO) burden during patient care. DESIGN: Prospective, observational study. METHODS: Air pollution was measured by photoacoustic gas monitoring in the middle of the PACU, above the patient's face, and on the PACU corridor. Urinary SEVO and hexafluoroisopropanol concentrations were determined. FINDINGS: Mean air pollution was 0.34 ± 0.07 ppm in the middle of the PACU, 0.56 ± 0.17 ppm above the patient's face, and 0.47 ± 0.06 ppm on the corridor. Biological preshift exposure levels were 0.13 ± 0.03 mcg/L (SEVO) and 4.72 ± 5.41 mcg/L (hexafluoroisopropanol). Postshift concentrations increased significantly to 0.20 ± 0.06 mcg/L (P = .004) and 42.18 ± 27.82 mcg/L (P < .001). CONCLUSIONS: PACU personnel were environmentally and biologically exposed to SEVO, but exposure levels were minimal according to current recommendations.

Genetic damage of operating and recovery room personnel occupationally exposed to waste anaesthetic gases.

Occupational exposure to the waste anaesthetic gases (WAGs) is a crucial problem for healthcare personnel. Cancer is among the potential long-term adverse effects of WAGs. The present occupational molecular epidemiology study was conducted in healthcare personnel (anaesthetists, nurses and technicians; n = 46), working in operating rooms (ORs; n = 34) and recovery units (RUs; n = 12) of the same hospital, to assess the genotoxicity risk of WAGs exposure. Twenty-one healthy available hospital staff allocated to other wards, without the history of working in ORs and RUs were the control group. A micronucleus test was carried out for peripheral blood lymphocytes (PBLs) and buccal epithelial cells (BECs). Exposure to the anaesthetics was assessed with sevoflurane concentrations and inorganic fluoride levels in post-shift urine samples of the healthcare staff. As an exposure marker, sevoflurane concentrations in ORs and RUs were measured using passive samplers. The micronuclei frequencies were increased in both PBLs (approximately two times) and BECs (approximately three times) of the healthcare personnel. Urinary sevoflurane concentrations exceeded the biological equivalent level in 23 personnel. Air sevoflurane levels in the breathing zone in three ORs and one RU did not exceed the established occupational exposure limits. Both in surrogate tissue (PBLs) and in target tissue (BECs) of the personnel of RUs and ORs of the same hospital, the genotoxicity risk was evident and similar. Originality of this study, in addition to the WAGs exposure confirmation of the healthcare personnel, was the involvement of the RU personnel for the genotoxicity assessment, which was the first time in the scientific literature.

Low anaesthetic waste gas concentrations in postanaesthesia care unit: A prospective observational study.

BACKGROUND: Volatile anaesthetics are a potential hazard during occupational exposure, pregnancy or in individuals with existing disposition to malignant hyperthermia. Anaesthetic waste gas concentration in postanaesthesia care units (PACU) has rarely been investigated. OBJECTIVE(S): The current study aims to assess concentrations of volatile anaesthetics in relation to room size, number of patients and ventilator settings in different PACUs. DESIGN: A prospective observational study. SETTING: Two different PACUs of the Hannover Medical School (Hannover, Germany) were evaluated in this study. The rooms differed in dimensions, patient numbers and room ventilation settings. PATIENTS: During the observation period, sevoflurane anaesthesia was performed in 65 of 140 patients monitored in postanaesthesia unit one and in 42 of 70 patients monitored in postanaesthesia unit two. MAIN OUTCOME MEASURES: Absolute trace gas room concentrations of sevoflurane measured with a compact, closed gas loop high-resolution ion mobility spectrometer. RESULTS: Traces of sevoflurane could be detected in 805 out of 970 samples. Maximum concentrations were 0.96 ±â€Š0.20 ppm in postanaesthesia unit one, 0.82 ±â€Š0.07 ppm in postanaesthesia unit two. Median concentration was 0.12 (0.34) ppm in postanaesthesia unit one and 0.11 (0.28) ppm in postanaesthesia unit two. CONCLUSION: Low trace amounts of sevoflurane were detected in both PACUs equipped with controlled air exchange systems. Occupational exposure limits were not exceeded.

High volatile anaesthetic conservation with a digital in-line vaporizer and a reflector.

BACKGROUND: A volatile anaesthetic (VA) reflector can reduce VA consumption (VAC) at the cost of fine control of its delivery and CO2 accumulation. A digital in-line vaporizer and a second CO2 absorber circumvent both of these limitations. We hypothesized that the combination of a VA reflector with an in-line vaporizer would yield substantial VA conservation, independent of fresh gas flow (FGF) in a circle circuit, and provide fine control of inspired VA concentrations. METHOD: Prospective observational study on six Yorkshire pigs. A secondary anaesthetic circuit consisting of a Y-piece with 2 one-way valves, an in-line vaporizer and a CO2 absorber in the inspiratory limb was connected to the patient's side of the VA reflector. The other side was connected to the Y-piece of a circle anaesthetic circuit. In six pigs, an inspired concentration of sevoflurane of 2.5% was maintained by the in-line vaporizer. We measured VAC at FGF of 1, 4 and 10 l/min. RESULTS: With the secondary circuit, VAC was 55% less than with the circle system alone at FGF 1 l/min, and independent of FGF over the range of 1-10 l/min. Insertion of a CO2 absorber in the secondary circuit reduced Pet CO2 by 1.3-2.0 kpa (10-15 mmHg). CONCLUSION: A secondary circuit with reflector and in-line vaporizer provides highly efficient anaesthetic delivery, independent of FGF. A second CO2 absorber was necessary to scavenge the CO2 reflected by the anaesthetic reflector. This secondary circuit may turn any open circuit ventilator into an anaesthetic delivery unit.

Comparison of waste anesthetic gases in operating rooms with or without an scavenging system in a Brazilian University Hospital / Comparação de resíduos de gases anestésicos em salas de operação com ou sem sistema de exaustão em hospital universitário brasileiro

Abstract Background and objectives Occupational exposure to waste anesthetic gases in operating room without active scavenging system has been associated with adverse health effects. Thus, this study aimed to compare the trace concentrations of the inhalational anesthetics isoflurane and sevoflurane in operating room 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 120 min after the start of surgery) in both operating room types. Results All isoflurane and sevoflurane concentrations in unscavenged operating room were higher than the US recommended limit (2 parts per million), regardless of the location and time evaluated. In scavenged operating room, 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 operating room. In scavenged operating room, the concentrations of sevoflurane, and to a lesser extent those of isoflurane, exceeded the recommended limit value. Thus, the operating room scavenging system analyzed in the present study decreased the anesthetic concentrations, although not to the internationally recommended values.

Resumo Justificativa e objetivos A exposição ocupacional aos resíduos de gases anestésicos em salas de operação (SO) sem sistema ativo de exaustão tem sido associada a efeitos adversos à saúde. Assim, o objetivo do estudo foi comparar os resíduos dos anestésicos inalatórios isoflurano e sevoflurano em SO com e sem sistema de exaustão. Método Concentrações residuais de isoflurano e sevoflurano foram mensuradas por analisador infravermelho em diferentes locais (próximo à área respiratória do auxiliar de enfermagem e do anestesiologista e próximo à estação de anestesia) e em dois momentos (30 e 120 min após o início da cirurgia) em ambos os tipos de SO. Resultados Todas as concentrações de isoflurano e sevoflurano nas SO sem sistema de exaustão foram mais elevadas em relação ao valor limite recomendado pelos EUA (2 partes por milhão), independentemente do local e momento avaliados. Nas SO com sistema de exaustão, as concentrações médias de isoflurano ficaram dentro do limite de exposição, exceto para as mensurações próximas à estação de anestesia, independentemente dos momentos avaliados. Para o sevoflurano, as concentrações excederam o valor limite em todos locais de medição e nos dois momentos. Conclusões A exposição a ambos os anestésicos excedeu o limite internacional nas SO sem sistema de exaustão. Nas SO com sistema de exaustão, as concentrações de sevoflurano, e em menor extensão, as de isoflurano excederam o valor limite recomendado. Dessa forma, o sistema de exaustão das SO analisado no presente estudo diminuiu as concentrações dos anestésicos, embora não tenha reduzido a valores internacionalmente recomendados.

[Comparison of waste anesthetic gases in operating rooms with or without an scavenging system in a Brazilian University Hospital]. / Comparação de resíduos de gases anestésicos em salas de operação com ou sem sistema de exaustão em hospital universitário brasileiro.

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.

Noninvasive Strategy Based on Real-Time in Vivo Cataluminescence Monitoring for Clinical Breath Analysis.

The development of noninvasive methods for real-time in vivo analysis is of great significant, which provides powerful tools for medical research and clinical diagnosis. In the present work, we described a new strategy based on cataluminescence (CTL) for real-time in vivo clinical breath analysis. To illustrate such strategy, a homemade real-time CTL monitoring system characterized by coupling an online sampling device with a CTL sensor for sevoflurane (SVF) was designed, and a real-time in vivo method for the monitoring of SVF in exhaled breath was proposed. The accuracy of the method was evaluated by analyzing the real exhaled breath samples, and the results were compared with those obtained by GC/MS. The measured data obtained by the two methods were in good agreement. Subsequently, the method was applied to real-time monitoring of SVF in exhaled breath from rat models of the control group to investigate elimination pharmacokinetics. In order to further probe the potential of the method for clinical application, the elimination pharmacokinetics of SVF from rat models of control group, liver fibrosis group alcohol liver group, and nonalcoholic fatty liver group were monitored by the method. The raw data of pharmacokinetics of different groups were normalized and subsequently subjected to linear discriminant analysis (LDA). These data were transformed to canonical scores which were visualized as well-clustered with the classification accuracy of 100%, and the overall accuracy of leave-one-out cross-validation procedure is 88%, thereby indicating the utility of the potential of the method for liver disease diagnosis. Our strategy undoubtedly opens up a new door for real-time clinical analysis in a pain-free and noninvasive way and also guides a promising development direction for CTL.