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PubMed1990

Isolated human blood platelets discriminate between anaesthetic and non-anaesthetic gases at high pressures.

We have compared the effects of the anaesthetic gases nitrogen and argon on adenosine diphosphate (ADP)-induced human blood platelet aggregation with the effects of the non-anaesthetic gas helium. All three gases showed dose-dependent inhibition of platelet aggregation. For nitrogen and argon there was a linear relationship between gas pressure and inhibition of aggregation over the range 15-68 atmospheres absolute (atm abs), whereas helium had a threshold for inhibition of approximately 34 atm abs. The inhibition by all gases was reversible after slow decompression. At pressures greater than 55 atm abs, nitrogen produced less inhibition than helium, indicating anaesthetic-pressure antagonism. Whereas pressure alone and the anaesthetic gases inhibited aggregation, the platelet shape change elicited by ADP was resistant to both nitrogen and helium, indicating that ADP binding and the early events in platelet activation were relatively unaffected by these conditions.

Adenosine Diphosphate↗

PubMed1998

Production and elimination of sulfur-containing gases in the rat colon.

Highly toxic sulfur-containing gases have been pathogenetically implicated in ulcerative colitis. Utilizing a rat model, we studied the production and elimination of sulfur-containing gases within the unperturbed colon. The major sulfur-containing gases were hydrogen sulfide (H2S), methanethiol, and dimethyl sulfide with cecal accumulation rates of 2.6, 0.096, and 0.046 microliter/min, respectively. The dependence of H2S production on dietary components was demonstrated via a sixfold reduction with fasting and a fivefold increase with carrageenan (a nonabsorbable, sulfur compound) feeding. Zinc acetate reduced cecal H2S by fivefold, indicating the importance of H2S binding by divalent cations. During passage from the cecum to the rectum, > 90% of the sulfur gases were absorbed or metabolized. An H2 35S turnover of 97%/min was observed in the isolated cecum. Thus mucosal exposure is > 10 times the measured accumulation rate. Cecal mucosal tissue very rapidly metabolized H2S and methanethiol via a nonmethylating reaction.

Animals↗

PubMed1985

Decompression outcome following saturation dives with multiple inert gases in rats.

This investigation examined the question of whether gas mixtures containing multiple inert gases provide a decompression advantage over mixtures containing a single inert gas. Unanesthetized male albino rats, Rattus norvegicus, were subjected to 2-h simulated dives at depths ranging from 145 to 220 fsw. At pressure, the rats breathed various He-N2-Ar-O2 mixtures (79.1% inert gas-20.9% O2); they were then decompressed rapidly (within 10 s) to surface pressures. The probability of decompression sickness (DCS), measured either as severe bends symptoms or death, was related to the experimental variables in a Hill equation model incorporating parameters that account for differences in the potencies of the three gases and the weight of the animal. The relative potencies of the three gases, which affect the total dose of decompression stress, were determined as significantly different in the following ascending order of potency: He less than N2 less than Ar; some of these differences were small in magnitude. With mixtures, the degree of decompression stress diminished as either N2 or Ar was replaced by He. No obvious advantage or disadvantage of mixtures over the least potent pure inert gas (He) was evident, although limits to the expectation of possible advantage or disadvantage of mixtures were defined. Also, model analysis did not support the hypothesis that the outcome of decompression with multiple inert gases in rats under these experimental conditions can be explained totally by the volume of gas accumulated in the body during a dive.

Animals↗

PubMed1986

Diffusion-related differences in elimination of inert gases from the lung.

Partial pressures of intravenously infused acetylene, Freon 22, and isoflurane (gases with similar solubilities in blood but differing molecular weights) were compared in arterial and mixed venous blood and mixed expired gas of 13 anesthetized mongrel dogs to determine whether gas molecular weight influenced gas exchange. Analysis of covariance was used to account for the variables of ventilation-perfusion ratio, partition coefficient, and experimental run before individual gas effects were sought. A gas effect difference was observed such that the arterial fractional retention of isoflurane (mol wt 184.5) would be 12% higher than that of acetylene (mol wt 26) if the two gases had identical partition coefficients. This effect was neither significantly increased by positive end-expiratory pressure nor decreased by high-frequency oscillatory ventilation. To test whether the individual gas effect was greater with gases with disparate erythrocyte and plasma partition coefficients, the exchange of ethyl iodide (erythrocyte-to-plasma solubility ratio 8.1) and diethyl ether (solubility ratio 0.95) was compared in five dogs. A larger difference between the elimination of the two gases was observed than predicted from the differences in molecular weight. The observed individual gas effect appears to be diffusion related, influenced both by the molecular weight of a gas and its erythrocyte-plasma partition coefficient ratio.

Acetylene↗

PubMed2000

Morning breath odor: influence of treatments on sulfur gases.

We assessed the effects of several treatments on the concentrations of oral sulfur-containing gases, compounds thought to be responsible for morning breath. Upon awakening in the morning, healthy volunteers collected oral gas samples before and for eight hours after the following treatments: no treatment, brushing the teeth with toothpaste, brushing the tongue, rinsing with 5 mL of 3% hydrogen peroxide, breakfast ingestion, or swallowing two BreathAsure capsules. The gas samples were analyzed for sulfur-containing volatiles via gas chromatography. Baseline collections usually contained three sulfur gases: hydrogen sulfide, methanethiol, and dimethylsulfide. The effectiveness of a treatment was determined via comparison of the areas under gas concentrations-time curves with and without treatment. Brushing the teeth or ingestion of BreathAsure had no apparent influence on the sulfur gases. Ingestion of breakfast and tongue brushing resulted in strong trends toward decreased sulfur gases. Hydrogen peroxide significantly reduced the sulfur gas concentrations for eight hours.

Adult↗

PubMed2001

[Occupational exposure to gases emitted in mild and stainless steel welding].

The objective of this work was to select optimal methods for determination of toxic gases (NOx, NO2, CO, CO2, O3) and to evaluate occupational exposure of welders to those gases. The survey covered workers employed in shipyards, and other metal product fabrication plants engaged in welding mild and stainless steel by different techniques (manual metal are, metal active gas, tungsten inert gas welding; gas, plasma, laser cutting and resistance welding). Personal and stationary air samples were collected to determine time weighted average (TWA) and short-term concentrations of gases. For determination of nitrogen oxides the following analytical techniques were employed: spectrophotometry with collection on liquid and solid sorbents and ion chromatography with collection on solid sorbents. All the gases were determined also by automatic or direct reading methods: flow or diffusion detector tubes and photometric and electrochemical analyzers. The determined TWA concentrations were below respective Maximum Allowable Concentrations (MAC) but exposure limits for short term exposure were exceeded in some cases. The average NO2 i NOx ratio was 1:4. According to Polish regulations regarding the MAC value for nitrogen oxides the analytical method should enable determination of total NOx by either direct or indirect simultaneous determination of both NO and NO2. The applicability of the spectrophotometric method of analysis of atmospheric NOx to determination of low NOx concentrations at welders working posts has been confirmed.

Air Pollutants, Occupational↗

PubMed1985

[Gas chromatographic-mass spectrometric analysis of gases produced by Trichomonas vaginalis in vitro].

Five strains of Trichomonas vaginalis were independently inoculated into Cysteine-Peptone-Liver infusion-Maltose medium (CPLM medium), and gases in the culture bottle were qualitatively analysed at five days after the inoculation by gas chromatography mass spectrometry (GC-MS). Methane, ethane and carbon dioxide were commonly found in the gases produced during the culture of Trichomonas vaginalis in vitro. Carbon monoxide was also found in the gases from 4 of 5 strains. Small amount of both ethylene and propane was also noted in 3 of 5 strains. These gaseous molecules were supposed to be produced by Trichomonas vaginalis in vitro, presumably by the catabolism of amino acids. It was also suggested that these gases, including methane, ethane, carbon dioxide, carbon monoxide, ethylene and propane, were responsible for the foamy discharge found in the vagina of patients with Trichomonas vaginalis.

Carbon Dioxide↗

PubMed1980

Solubility of inert gases in biological fluids and tissues: a review.

Data have been tabulated from more than 150 references on the solubility of inert gases in fluids and tissues of biological interest. Thirty-two gases have been studied in blood with measured solubility ranging from 0.005 to 16 ml of gas at 37 degrees C per ml of blood per ATA (Ostwald coefficient). For most gases, solubility in other tissues such as muscle or brain is between 60% and 300% of blood solubility. Measured solubilities in biological tissues do not correspond well to solubility in water and oil. Most gases decrease in solubility by 1%-6% for each degree C rise in temperature. The effect of pressure on solubility has not been well studied, and only crude estimates can be obtained by using methods of chemical thermodynamics.

Humans↗

PubMed1981

Pharmacokinetics of inhaled gases and vapors.

Physiological and biochemical factors determine the kinetic patterns of uptake, distribution, metabolism, and elimination of inhaled gases and vapors. For metabolically inert gases, true equilibrium is achieved after appropriately long exposures and the overall shape of the time-course curves of uptake and elimination should be concentration-independent. At equilibrium, achieved internal concentrations will be linearly related to exposure concentration. The rate of approach to equilibrium depends on blood flows for poorly soluble chemicals and on alveolar ventilation for soluble gases and vapors. For metabolized gases and vapors, steady-state is achieved where net pulmonary uptake replaces chemical removed from the circulation by metabolism. The shape of time-course curves for soluble, well-metabolized chemicals will be concentration-dependent, and steady-state blood:gas concentration ratios will be complexly related to inhaled concentrations. Physiological models of inhalation pharmacokinetics allow extrapolation of results in one species to untested species, based on knowledge of changing physiology between animal-to-animal. Two potential applications of interspecies extrapolation are discussed.

Animals↗

PubMed1998

[Magnetic resonance tomography with inhalation of polarized noble gases: new perspectives in functional imaging diagnosis of emphysema].

PURPOSE: Based on a review of the background of MRI using inhaled hyperpolarized noble gases first experiences and perspectives for functional imaging in emphysema patients are presented. MATERIAL AND METHODS: In vonventional MRI, the spin density of protons, which is defined by the Boltzmann equilibrium, is the source of the imaging signal. Since proton density in the lungs is low and multiple air-tissue interfaces exist, MRI of the lung parenchyma is unsatisfactory. The possibility to artificially enrich the spin density (hyperpolarization) in noble gases (H3-3, Xe-129) by optical pumping results in a non-equilibrium polarization five orders of magnitude higher than the Boltzmann equilibrium. Hyperpolarized noble gases can then be applied as "inhaled contrast media" using a dedicated application device. At the MR unit several prerequisites must also be fulfilled: transmit-receive coil, boradband amplifier and fast sequences with low flip angles. These are essential for dynamic scans in breath-hold tecnique of the highly diffusible He-3 or the well soluble Xe-129. RESULTS: He-3 and Xe-129 have been successfully applied for imaging of the ventilated airspaces. Besides the well-known narcotic effects of Xenon no adverse effects were observed. A homogeneous distribution of signal intensity can be regarded as a normal findings in people without lung disease. Obstructive diseases and emphysematous changes lead to generalized or localized signal inhomogeneities. Most likely they are caused by disorders of the distribution of ventilation bases on a different functional vehavior of different alveolar regions. By making use of the paramagenetic properties of oxygen, He-3 can also be used for local measurements of oxygen partial pressure in the lung. Xe-129 exhibits a different chemical shift within alveoli, interstitial space and vessels which can be measured by MRI. CONCLUSIONS: MRI using inhaled hyperpolarized noble gases is a functional imaging modality with high spatial and/or temporal resolution. First studies for early detection of obstructive lung diseases and disorders of distribution of ventilation in emphysema are promising.

Administration, Inhalation↗

PubMed2004

Emerging supramolecular chemistry of gases.

Molecular recognition of gases is an emerging area of chemistry. Supramolecular chemistry helps us to understand how gases interact with biological molecules and offers delicate insights into the mechanisms of their physiological activity. Principles of molecular recognition have been used for gas sensing, and have provided fundamental knowledge about the structure and dynamics of receptor-analyte complexes, and novel materials for gas sensing and storage have been developed. Supramolecular chemistry is also enabling us to learn how to transform gases into synthetically useful reagents. The rational design of novel catalysts for gas conversion and, more recently, encapsulation complexes with gases open novel directions in preparative synthetic chemistry.

Journal Article↗

PubMed1991

Effect of vascular puncture on blood gases in the newborn.

Continuous monitoring methods have shown changes of oxygenation in neonates during various procedures. However, actual changes in blood gases during vascular punctures have not been reported. We studied the effect of vascular puncture on arterial blood gases during routine venipuncture in 17 neonates who had indwelling arterial catheters. Arterial blood gases were analyzed before, during, and following recovery from venipuncture. Ventilator settings were not changed during the study, though oxygen concentration (FiO2) was adjusted as indicated by continuous PO2 or saturation monitors. During venipuncture, there was a significant fall in PaCO2 from 38 +/- 5 to 32 +/- 7 mmHg (P less than 0.0001) and in PaO2 from 75 +/- 21 to 58 +/- 23 mmHg (P less than 0.0001). Following venipuncture, both values returned to baseline. The results of this study imply that blood gases obtained by intermittent arterial sticks may provide data that do not accurately reflect the neonates' respiratory status.

Blood Gas Monitoring, Transcutaneous↗

PubMed2002

Analysis of petrol and diesel vapour and vehicle engine exhaust gases using selected ion flow tube mass spectrometry.

We have used selected ion flow tube mass spectrometry (SIFT-MS) to analyse the vapours emitted by petrol and diesel fuels and the exhaust gases from petrol (spark ignition) and diesel (compression ignition) engine vehicles fitted with catalytic converters. Only those components of these media that have significant vapour pressures at ambient temperatures were analysed and thus particulates were obviously not detected. These media have been analysed using the full scope of SIFT-MS, i.e., with the three available precursor ions H3O+, NO+ and O2+. The combination of the H3O+ and NO+ analyses is seen to be essential to distinguish between different product ions at the same mass-to-charge ratio (m/z) especially in identifying aldehydes in the exhaust gases. The O2+ precursor ions are used to detect and quantify the large amount of nitric oxide present in the exhaust gases from both engine types. The petrol and diesel vapours consist almost exclusively of aliphatic alkanes, alkenes and alkynes (and dienes) and aromatic hydrocarbons. Some of these compounds appear in the exhaust gases together with several aldehydes, viz. formaldehyde, acetaldehyde, pentanal, pentenal (acrolein), butenal, and also methanol and ethanol. Acetone, nitric oxide and ammonia are also present, acetone and nitric oxide being much more abundant in the diesel exhaust gas than in the petrol exhaust gas. These data were obtained from samples collected into pre-evacuated stainless steel vessels. Trapping of the volatile compounds from the gas samples is not required and analysis was completed a few minutes later. All the above compounds are detected simultaneously, which demonstrates the value of SIFT-MS in this area of research.

Environmental Exposure↗

PubMed1977

Hydrocarbon gases produced during in vitro peroxidation of polyunsaturated fatty acids and decomposition of preformed hydroperoxides.

Hydrocarbon gases have been used previously as an index of lipid peroxidation in vivo and in vitro. In vitro experiments are reported on the formation of hydrocarbon gases from peroxidizing omega-3 and omega-6 fatty acids. Hydrocarbon gases were not released during a 20-hr peroxidation phase but were released following the decomposition of hydroperoxides by addition of excess ascorbic acid. The major hydrocarbon gas products in iron, copper, or hematin catalyzed peroxidation systems were ethane or ethylene from linolenic acid, and pentane from linoleic acid and arachidonic acid. Calculations of the ratios of hydrocarbon gases formed were based on fatty acid decrease and/or change in diene conjugation and peroxide values. Depending on the fatty acid, catalyst, and calculation basis used, pentane formation was as high as 1.3 mol %, ethane 4.3 mol %, and ethylene 10.6 mol %.

Chemical Phenomena↗

PubMed1990

Passive warming of airway gases (artificial nose) improves accuracy of esophageal temperature monitoring.

The most efficient site for monitoring heart and lung sounds by esophageal stethoscope is not the warmest segment of the esophagus. This study investigated the ability of passive warming of airway gases to increase the accuracy of temperatures measured at this site (i.e., to decrease their difference from core temperature). In 15 adult patients undergoing general anesthesia and endotracheal intubation, esophageal temperatures were measured before and after use of a heat and moisture exchanger (an artificial nose) that passively warmed inspired gases. The resulting values were compared with nasopharyngeal temperatures, which represented core temperature. Before use of the heat and moisture exchanger, esophageal and nasopharyngeal temperatures differed significantly (mean difference +/- SD, 0.9 +/- 0.4 degrees C; P less than or equal to 0.001). After passive warming of inspired gases, esophageal temperatures increased significantly (mean increase +/- SD, 0.5 +/- 0.2 degrees C; P less than or equal to 0.001) but inconsistently (range, 0.1 to 1.2 degrees C). However, the mean difference between esophageal and nasopharyngeal temperatures was still significant (0.5 +/- 0.3 degrees C; P less than 0.001). Discrepancies between esophageal and core temperatures persist when a currently available esophageal stethoscope with adjacent auscultation chamber and temperature probe is used, despite passive warming of airway gases.

Adult↗

PubMed1993

[The effect of halothane on blood gases and arterial acid-base equilibrium in intact rats and in chemo-denervated rats].

Halothane decreases the ventilatory response to hypoxia and the activity of peripheral arterial chemoreceptors, resulting in "chemical chemodenervation." In order to evaluate the role of this halothane-induced "chemical denervation" in acid-base and arterial blood gas changes, these values were measured in intact and chemodenervated rats, awake and under anaesthesia. Since the depth of anaesthesia could be modified by the anatomical chemodenervation, the ED50 of inspired halothane was determined in six rats before and after anatomical chemodenervation. To prevent haemodynamic changes due to halothane and/or anatomical chemodenervation from interfering with the results, systemic arterial blood pressure and heart rate were measured in six intact rats, awake and then anaesthetized, and in the same rats after chemodenervation, awake and then anaesthetized. In nine intact rats and in 19 chemodenervated rats, arterial pH, arterial bicarbonate concentration, and arterial blood gases (PaO2 and PaCO2) were measured before and after administration of halothane. Anatomical chemodenervation modified neither the inspired ED50 (1.1%), nor the mean arterial blood pressure or heart rate. The haemodynamic effects of halothane were comparable in intact and in chemodenervated rats. Changes in arterial blood gases and acid-base balance due to halothane in intact rats and due to chemodenervation in awake rats were not different, but there was a decrease in PaO2 and pHa, and an increase in PaCO2. In chemodenervated rats, halothane caused a further decrease in PaO2 and a further increase in PaCO2. The fact that halothane and anatomical chemodenervation have similar effects on arterial blood gases and acid-base balance favours a "chemical chemodenervating" action of halothane. However, the additional effects of halothane in the anatomically chemodenervated animal show that the action of halothane on blood gases and acid-base balance is the result of multiple sites of impact on the respiratory system.

Acid-Base Equilibrium↗

PubMed2003

[Calibration of a room air gas monitor with certified reference gases].

Photo-acoustic infrared spectrometry is considered to be the gold standard for on-line measurement of anesthetic waste gas in room air. For maintenance of the precision of the measurements, the manufacturer recommends calibration of the gas monitor monitor every 3-12 months. We investigated whether the use of reference gases with analysis certificate could serve as a feasible alternative to commercial recalibration. We connected a multi-gas monitor type1302 (Bruel & Kjaer, Naerum, Denmark) to compressed air bottles containing reference gases with analysis certificate. Using a T-piece with a flow-meter, we avoided the entry of room air during the calibration phase. Highly purified nitrogen was used for zero calibration. The reference concentrations for desflurane, enflurane, halothane, isoflurane, and sevoflurane ranged from 41.6-51.1 ml/m(3) (ppm) in synthetic air. Since there is an overlap of the infrared absorption spectra of volatile anesthetics with alcohol used in operating rooms, we performed a cross-compensation with iso-propanol (107.0 ppm). A two-point calibration was performed for N(2)O (96.2 and 979.0 ppm), followed by cross-compensation with CO(2). Nafion tubes were used in order to avoid erroneous measurements due to molecular relaxation phenomena. The deviation of the measurement values ranged initially from 0-2.0% and increased to up to 4.9% after 18 months. For N(2)O, the corresponding values were 4.2% and 2.7%, respectively. Thus, our calibration procedure using certified reference gases yielded precise measurements with low deterioration over 18 months. It seems to be advantageous that the precision can be determined whenever deemed necessary. This allows for an individual decision, when the gas monitor needs to be calibrated again. The costs for reference gases and working time as well as logistic aspects such as storage and expiration dates must be individually balanced against the costs for commercial recalibration.

2-Propanol↗

PubMed2005

Cytogenetic tests performed on operating room personnel (the use of anaesthetic gases).

OBJECTIVES: Personnel exposure to anaesthetic gases in the health sector, whether in the operating room, recovery room, or in the context of outpatient clinics, may entail a health risk. The goal of this research was to study the cytogenetic effects of chronic exposure to small doses of pollutants in operating theatres. METHODS: Results of cytogenetic analyses [structural chromosomal aberrations (SCAs), sister chromatid exchange (SCE) and micronucleus (MN) test] of anaesthetists and other personnel handling anaesthetic gases, who only occasionally work in zones of ionizing radiation, were compared with results from radiologists, occupationally exposed to ionizing radiation only, and with the results obtained from a group of Slovene citizens who were never exposed to genotoxic agents. RESULTS: This study involved 153 workers handling anaesthetic gases. The average frequency of SCAs in the group working with anaesthesia was 2.693. The result was statistically significantly higher than in the group of radiologists and Slovene citizens. The frequency of SCE and MN was also statistically significant. A number of authors, who used the same cytogenetic tests, found similar results in the group of anaesthetist. CONCLUSION: The results of our study indicate that exposure to anaesthetic gases induced changes in human chromosomes.

Adult↗