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PubMedDate not supplied

[Temperature variations of respiratory gases during episodes of anesthetic circuit disconnection in controlled ventilation].

Temperature variations of respiratory gases during episodes of disconnexion of the anesthetic circuit in controlled ventilation were measured with a temperature sensor located in the anesthetic circuit close to the endotracheal tube which was connected to a temperature monitor with alarm limits of 0.5 degrees C. We compared the activation times of the ventilator pressure alarm with those of the temperature. The activation time of the respirator alarm (8.9 +/- 1.6 sec) was significantly shorter (p less than 0.001) than that of the temperature monitor. This difference was more apparent when the anesthetic circuit was disconnected distantly from the sensor (10.5 +/- 1.8 sec for disconnexion between the tracheal tube and the sensor, and 36.8 +/- 12.2 sec when the disconnexion occurred at the entrance of the respiratory branch of the ventilator tubes). The maximal individual value for the activation time of the temperature alarm was 67 seconds. In all instances hemoglobin saturation (SpO2) during anesthetic circuit disconnexion was higher than 95%. In each group there was a positive and significant correlation between the temperature alarm time and the adjustment of the predetermined alarm level with respect to the basal temperature of the respiratory gases. Temperature monitorization of the respiratory gases did not offer additional advantages to the conventional monitorization of the respiratory circuit disconnexion.

Adult↗
PubMed1990

The climatisation of anesthetic gases under conditions of high flow to low flow.

The aim of climatisation of anesthetic gases in prolonged anesthesia is to maintain tracheobronchial climate comparable to that of spontaneous nasal breathing. The humidity and temperature of inspired gases attained in the circle system at a fresh gas flow of 6.0, 3.0 and 1.5 l/min are inadequate for prolonged anesthesia. According to the results of our study with the scanning electron microscope, the minimal flow technique (0.5 l/min) leads to major improvement of heat (28 to 32 degrees C) and moisture (20 to 27 mg H2O/l) conditions of anesthetic gases in anesthesia systems.

Anesthesia, Closed-Circuit↗
PubMedDate not supplied

[Mathematical model of the dynamics of transport of inert gases in the microcirculatory system].

A mathematical model imitating transport of inert gases in the system of microcirculation under increased pressures was constructed. It has been shown that saturation of microareas nucleus of the brain cortex of average dimensions proceeds in about 90 sec. Effect of the blood flow velocity, gases tension in arterial blood and density of the capillary net on the dynamics of mass transfer of gases in a tissue was investigated.

Biological Transport↗
PubMed1980

[Effects of toxic gases and phagocytic defense of the respiratory system. "In vitro" approach].

A new technique of cell culture in gas phase may be used for the "in vitro" study of the effects of toxic gases on the alveolar macrophages responsible for phagocytic defence of the respiratory system. Macrophage cells deposited on a porous membrane applied to the surface of a reservoir filled with nutrient fluid, survive in direct contact with the atmosphere, retaining normal metabolic and functional activities for several days. It is then possible to analyse the effects exerted on these cells by various types of gaseous aerocontaminants. This "in vitro" technique is highly sensitive. Nitrogen dioxide and ozone have cytotoxic effects after 30 minutes exposure at concentrations at less than 1 p.p.m. Acrolein has a harmful effect only at concentrations of 8 to 35 p.p.m. A mixture of oxygen (95 p. cent) and of CO2 (5 p. cent) causes much slower cell destruction, in a period varying from 2 to 6 days. Information provided by this method must be interpreted taking two concepts into account: 1--"in vitro" cytotoxicity explores only one aspect of the harmfulness of a gas, since the latter may have pathological effects by other mechanisms: irritant action on the respiratory mucosa resulting in hypersecretion and bronchospasm, ciliary paralysis or destruction, changes in the alveolar wall also capable of disturbing the phagocytic intervention of alveolar macrophages; 2--"in vitro", certain gaseous aerocontaminants are fixed or neutralised in part in the upper airway or by secretions lining the respiratory mucosa. In addition, the constant supply of new cells from the interstitium or pulmonary capillaries, limits the consequence of any possible destruction of phagocytic cells exposed to toxic gases. However, these reservations are compensated by the new possibilities offered by the "in vitro" study of the cytotoxicity of gases in the following areas: establishment of a hierarchy of gaseous pollutants, evaluation of their mechanism of action and determination of methods of protection against their harmful effects.

Acrolein↗
PubMed1977

Gases released from tissue and analyzed by infrared and gas chromatography/mass spectroscopy techniques.

Two techniques for analyzing contaminants released as gases from postmortem tissues were described and compared. One technique used gas chromatography/mass spectrometry (GC/MS); the other, infrared spectroscopy (IR). Brain, lung, liver, blood and urine specimens were obtained from suspected drug-overdose victims whose deaths were contributed to or caused by inhalation of unknown gases or vapors during the period immediately preceding death. Gases from the postmortem tissues and liquid samples were separately admitted into an evacuated IR gas cell, the IR spectra recorded, and gas samples then removed for GC/MS analysis. Nitrous oxide, glue, and paint solvent constituents were identified and measured. Only the brain and lung tissues contained measurable amounts of inhalants. Both IR and GC/MS methods were adequate for normal confirmatory analyses; the GC/MS system was judged superior for fast routine efforts normally hampered by incomplete sample history.

Brain Chemistry↗
PubMed1981

[Variations of the sum of the arterial partial pressure of inert gases during changes in the composition of inhaled gas without a variation of the ambient pressure, in a hyperbaric atmosphere].

In hyperbaric environments, when inhaled inert gas composition is abruptly modified, the sum of the arterial inert gases partial pressures is different to the sum of these same gases in the inhaled mixture. While switching from a helium-oxygen to a nitrogen-oxygen mixture of same P1O2 and total pressure, the sum of the arterial inert gas partial pressure was transiently less than the one in the inspired gases: there was an arterial under-saturation: PaHe + PaN2 = 0.68 (P1He + P1N2). During the opposite switch (from nitrogen to helium), a reversed time course, namely a transient over saturation, was observed: PaHe + PaN2 = 1.31 (P1He + P1N2). Amongst the different possible explanatory hypotheses, the most probable is that inert gas partial pressure equilibrium through the alveolo-capillary membrane is not achieved when the blood leaves the pulmonary capillary.

Animals↗
PubMed1995

AANA journal course: update for nurse anesthetists--medical gases, hospital pipelines, and medical gas cylinders: how safe are they?

Medical gases which hospital personnel are familiar with include oxygen, nitrous oxide, medical air, carbon dioxide, and nitrogen. Their composition and packaging is defined by the Code of Federal Regulations and the United States Pharmacopeia/National Formulary. Unfortunately, numerous safety issues and even cases of death occur each year that relate to the use of these gases in medical settings. This review documents incidents of near hits and deaths of patients from pipeline and gas cylinder use and describes the key role that anesthesia and healthcare personnel play in verifying the integrity of gases used and the systems which deliver them.

Anesthesia, Inhalation↗
PubMed1993

[Solubility of 6 gases in blood and various liquid media].

Sulfur hexafluoride, ethane, cyclopropane, enflurane, diethyl ether and acetone are six gases commonly used in the measurement of the distribution of ventilation-perfusion ratios. In order to obtain reference data, their liquid/gas partition coefficients (K) have been determined in water at three different temperatures and in several inorganic, organic and biologic media at 37 degrees C, by a headspace-gas chromatographic method. As expected, an increase in temperature and concentration of solutes in the liquid matrix reduces the solubility of the gases. All gases, except acetone, are more soluble in olive oil than in water. The solubility of SF6, ethane, cyclopropane and enflurane in human and rat blood is greater than in water, the solubility of ether remains practically unchanged, and that of acetone is lower in blood than in water.

Acetone↗
PubMed2004

Developmental evaluation of children born to mothers occupationally exposed to waste anesthetic gases.

BACKGROUND: The etiology of developmental delay in children is frequently unknown. Increasing evidence supports the possibility that environmental and occupational factors might be part of the basis for such delays. This study focuses on the development of children born to mothers who were exposed during their pregnancy to waste anesthetic gases. METHODS: The study population included 40 children aged 5-13 years born to female anesthesiologists and nurses working in operating rooms (OpRs) exposed to waste anesthetic gases, and 40 unexposed children born to female nurses and physicians who worked in hospitals during their pregnancy but did not work in OpRs. The unexposed group was matched for children's age and gender and maternal occupation (nurses vs. doctors). By means of standardized developmental tests, the present study population was evaluated for their medical and neurodevelopmental state. Questionnaires were given for the detection of attention and activity levels as perceived by the parents. Additional questionnaires dealt with information concerning developmental milestones, maternal and fetal morbidity, and gynecological history. RESULTS: No differences were noted between the groups as newborns or in developmental milestones at the age of 5-13 years; however, the mean score of gross motor ability was significantly lower in the exposed versus the unexposed group. Additionally, the mean score of the DSM-III-R Parent-Teacher Questionnaire (PTQ) (i.e., measure of inattention/hyperactivity) was higher in the exposed group. The level of exposure, as measured by the number of weekly hours in the OpRs, was significantly and negatively correlated with fine motor ability and the score of IQ performance. CONCLUSIONS: Our study supports the hypothesis that occupational exposure to anesthetic gases might be a risk factor for minor neurological deficits of children born to mothers who work in OpRs and therefore indicates the need for more studies in this area and perhaps more caution among OpR pregnant women and employers.

Adolescent↗
PubMed2004

Enhancement of the solubilization capacity of water in Triton X-100/cyclohexane/water system by compressed gases.

The effect of compressed CO2 and ethylene on the properties of Triton X-100/cyclohexane/water systems was studied at different temperatures and pressures. Surprisingly, it was discovered that the compressed gases had the functions of co-surfactants. At suitable pressures, the water-to-surfactant molar ratio (W0) was enhanced significantly by the dissolution of the gas in the solution. The microenvironment in the reverse micelles was investigated by UV-visible spectroscopy by using methyl orange (MO) as a probe. The influence of n-hexane, Na2CO3, NaHCO3, H2C2O4, and CaCl2 at various concentrations on the solubilization of water in the absence of compressed gases was also investigated in order to obtain some information about the mechanism of the interesting phenomenon. This new route to stabilize reverse micelles may have potential applications to other similar systems. Moreover, the results of this work provide some useful information to get insight into the mechanism of co-surfactants, because a conventional co-surfactant usually contains both polar group and hydrocarbon chain, and it is very difficult to clarify the functions these two groups, while the gases used in this work are small nonpolar molecules, which solely have the function of the hydrocarbon chain in a co-surfactant.

Journal Article↗
PubMed2003

Fast measurement of relaxation times by steady-state free precession of 129Xe in carrier agents for hyperpolarized noble gases.

Hyperpolarized gases ((129)Xe and (3)He) are being used increasingly in both MRI and NMR spectroscopy studies. However, it has been shown that carrier agents are required to preserve the long relaxation times of gases in biological fluids. Optimized gas transport can be achieved through controlled T(1) and T(2) measurements of (129)Xe gas at equilibrium, using the steady-state free precession method (SSFP). The accuracy of the method was proven with the use of CuSO(4)-doped water samples and xenon dissolved in chloroform. The following T(1) and T(2) values were measured for xenon dissolved in a 30% intralipid emulsion: T(1) = 29 +/- 3 s; T(2) = 1.0 +/- 0.1 s. The values obtained in the intralipid emulsion contrast significantly with those obtained in conventional gas NMR experiments, in which it is commonly assumed that T(1) = T(2). This highlights the importance of obtaining accurate relaxation time measurements for medical applications of hyperpolarized gases.

Drug Carriers↗
PubMed2004

On-line analysis of diesel engine exhaust gases by selected ion flow tube mass spectrometry.

Selected ion flow tube mass spectrometry (SIFT-MS) has been used to analyse on-line and in real time the exhaust gas emissions from a Caterpillar 3304 diesel engine under different conditions of load (idle and 50% of rated load) and speed (910, 1500 and 2200 rpm) using three types of fuel: an ultra-low-sulphur diesel, a rapeseed methyl ester and gas oil. SIFT-MS analyses of the alkanes, alkenes and aromatic hydrocarbons in the headspace of these fuels were also performed, but the headspace of the rapeseed methyl ester consists mainly of methanol and a compound with the molecular formula C4H8O. The exhaust gases were analysed for NO and NO2 using O2+* reagent ions and for HNO2 using H3O+ reagent ions. The following aldehydes and ketones in the exhaust gases were quantified by using the combination of H3O+ and NO+ reagent ions: formaldehyde, acetaldehyde, propenal, propanal, acetone, butanal, pentanal, butanone and pentanone. Formaldehyde, acetaldehyde and pentenal, all known respiratory irritants associated with sensitisation to asthma of workers exposed to diesel exhaust, are variously present within the range 100-2000 ppb. Hydrocarbons in the exhaust gases accessible to SIFT-MS analyses were also quantified as total concentrations of the various isomers of C3H4, C3H6, C4H6, C5H8, C5H10, C6H8, C6H10, C7H14, C6H6, C7H8, C8H10 and C9H12.

Air Pollutants, Occupational↗
PubMed2002

Selected ion flow tube studies of the reactions of H3O+, NO+ and O2+ with the anaesthetic gases halothane, isoflurane and sevoflurane.

We have carried out a study of the reactions of H(3)O(+), NO(+) and O(2) (+), the commonly used precursor ions for selected ion flow tube mass spectrometry (SIFT-MS), with three anaesthetic gases, halothane, isoflurane and sevoflurane. The motivation for this study was to provide the necessary kinetic data that would allow the quantification of these anaesthetic gases in operating theatre air and in the breath of theatre staff and post-operative patients. A clear negative result from these experiments is that NO(+), although undergoing the simplest chemistry, is unsuitable for this SIFT-MS application. However, although the ion chemistry of H(3)O(+) and O(2) (+) with these compounds is very complex, there being several product ions in each reaction, many of which react rapidly with water molecules, monitor ions have been identified for all three anaesthetic gases when using H(3)O(+) and O(2) (+) as precursor ions. The detailed ion chemistry is discussed and the specific monitor ions are indicated. Hence, the feasibility of on-line breath monitoring is demonstrated by simple examples. These studies have opened the way to measurements in the clinical environment.

Anesthetics, Inhalation↗
PubMed1992

Variability of blood gases, pulse oximeter saturation, and end-tidal carbon dioxide pressure in stable, mechanically ventilated trauma patients.

We evaluated the short-term variability of PaO2, PaCO2, pulse oximeter saturation (SpO2), and end-tidal PCO2 (PETCO2) in mechanically ventilated trauma patients. All patients were stable and undisturbed during the evaluation periods. Blood gases were obtained from an arterial catheter 4 times at 20-minute intervals. SpO2 and PETCO2 were recorded when the blood gases were obtained. Fifty evaluations were made in 26 patients; 24 patients were evaluated twice, with greater than or equal to 24 hours between evaluation periods. Variability was expressed as coefficient of variation (%CV) for each evaluation period. The median %CVs were 3.6% for PaO2 (95th percentile = 9.8%), 0.5% for SpO2 (95th percentile = 1.4%), 2.8% for PaCO2 (95th percentile = 7.4%), and 2.4% for PETCO2 (95th percentile = 7.1%). The overall correlation between PaCO2 and PETCO2 was r = 0.80, and the mean difference between PaCO2 and PETCO2 was 0.9 +/- 3.6 mm Hg. The variability of PETCO2 was similar to the variability of PaCO2. However, the variability of PaO2 was considerably greater than that of SpO2, which was probably related to the shape of the oxyhemoglobin dissociation curve and the relatively high saturations of the patients in this study. Variability of blood gases, SpO2, and PETCO2 should be considered when these values are clinically interpreted.

Adult↗
PubMed1986

Dedicated monitoring of anesthetic and respiratory gases by Raman scattering.

The monitoring of respiratory and anesthetic gases in the operating room is important for patient safety. This study measured the accuracy and response time of a multiple-gas monitoring instrument that uses Raman light scattering. Measurements of oxygen, carbon dioxide, nitrogen, nitrous oxide, halothane, enflurane, and isoflurane concentrations were compared with a gas mixer standard and with measurements made with an infrared anesthetic agent analyzer. Correlation coefficients were all greater than 0.999, and probable errors were less than 0.43 vol% for the gases and less than 0.03 vol% for the volatile anesthetics. Response time was 67 ms with a sample flow rate of 150 ml/min. There was some signal overlap between nitrogen and nitrous oxide and between the volatile anesthetic agents. Such overlap can be compensated for by linear matrix analysis. The Raman instrument promises a monitoring capability equivalent to the mass spectrometer and should prove attractive for the monitoring of respiratory and anesthetic gases in the operating room.

Air↗
PubMed1999

Influence of different gases and intraperitoneal instillation of antiadherent or cytotoxic agents on peritoneal tumor cell growth and implantation with laparoscopic surgery in a rat model.

BACKGROUND: A generally accepted approach to prevent tumor implantation with laparoscopic surgery does not exist. Alternative gases in combination with intraperitoneal instillation of different antiadherent or cytotoxic agents have not been evaluated. METHODS: The effect of taurolidine, heparin, and povidone-iodine on the growth of colon adenocarcinoma DHD/K12/TRb was measured in rats undergoing laparoscopy with carbon dioxide (n = 40), helium (n = 40), or xenon (n = 40). In the procedure, 10(4) tumor cells were administered intraperitoneally, and pneumoperitoneum was established over 30 min at 8 mmHg with the different gases. The rats additionally received intraperitoneal instillation with one of the following: 1 ml of Ringer's solution, 1 ml of 0.5% taurolidine, 1 ml 0.5% taurolidine with heparin (10 U/ml), or 1 ml 0.25% of povidone-iodine. Tumor growth was measured after 4 weeks. RESULTS: Median intraperitoneal tumor weight was lower in rats receiving taurolidine (CO(2): 10 mg; helium: 50 mg; xenon: 39.5 mg) or taurolidine with heparin (CO(2): 4 mg; helium: 4.5 mg; xenon: 46.5 mg) in all gas groups than in the control groups (CO(2): 427 mg; helium: 268 mg; xenon: 345 mg) (p < 0.001). Whereas povidone-iodine caused significantly lower tumor growth in the CO(2) group (56.5 mg) (p < 0.01), the combination of helium (145 mg) and xenon (457 mg) with povidone-iodine produced no reduction of tumor growth as compared with the control groups (helium: 268 mg; xenon: 345 mg). CONCLUSIONS: Taurolidine and taurolidine with heparin significantly inhibit intraperitoneal tumor growth, with different gases used for pneumoperitoneum. Only povidone-iodine caused significant decrease of tumor growth in combination with CO(2). The combination of xenon and povidone-iodine should not be used in patients with cancer because of increased tumor growth.

Adenocarcinoma↗
PubMed1995

Fetal venous, intracardiac, and arterial blood flow measurements in intrauterine growth retardation: relationship with fetal blood gases.

OBJECTIVE: Our purpose was to investigate arterial, venous, and intracardiac blood flow in growth-retarded fetuses and to relate the Doppler results to blood gases in umbilical venous blood obtained by cordocentesis. STUDY DESIGN: A cross-sectional, pulsed-wave color Doppler ultrasonographic study of 23 severely growth-retarded fetuses undergoing cordocentesis and measurement of blood gases was performed. Blood velocity waveforms were recorded from the descending thoracic aorta, middle cerebral artery, inferior vena cava, ductus venosus, and atrioventricular valves. RESULTS: The Doppler studies demonstrated evidence of redistribution in the arterial system with increased impedance to flow in the aorta and decreased impedance in the cerebral circulation. The velocity of flow in the venous system and across the atrioventricular valves was decreased, whereas pulsatility of waveforms in the inferior vena cava and ductus venosus was increased. The mean umbilical venous blood PO2 and pH were decreased, and there were significant associations between blood gases and Doppler parameters in the thoracic aorta, middle cerebral artery, and ductus venosus. CONCLUSION: In severe intrauterine growth retardation the degree of fetal acidemia can be estimated from Doppler measurements of pulsatility in both the arterial system and the ductus venosus.

Aorta, Thoracic↗
PubMed1983

Gas exchange, blood gases and acid-base status in the chick before, during and after hatching.

To study the transition from chorioallantoic to pulmonary gas exchange in birds, blood gases and acid--base variables were measured in chicks of domestic fowl before, during and after hatching. Measurements were made in samples of 'venous' blood (from allantoic arteries or the right ventricle, respectively) entering the gas exchanger (chorioallantois or lungs, respectively) and arterialized blood (from allantoic veins or the left ventricle, respectively) leaving the gas exchanger. Also, O2 uptake was measured and blood flow of the gas exchanger was determined according to the Fick principle. During the last days of incubation PO2 decreased PCO2 increased in both arterialized and 'venous' blood, but the changes of pH were small due to a concomitant increase in bicarbonate concentration, in accordance with the results of previous studies. After external pipping and hatching pronounced hypocapnia developed, but the respiratory alkalosis was partiallY compensated by a transitory non-respiratory reduction of bicarbonate. In spite of arterial hypoxia at the end of incubation and some loss of blood during hatching, blood O2 transport was not seriously impaired during pipping and hatching as revealed by 'venous' blood gases. The blood gases and pH of 17-day-old chicks were close to those of adult chickens.

Acid-Base Equilibrium↗