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PubMed2006

Assessment of multiphoton absorption in inert gases for the measurement of gas temperatures.

A spatially resolved optical technique to measure gas temperature was assessed. The technique relies on multiphoton absorption in inert gases. In contrast to laser-induced fluorescence, absorption is insensitive to collisional deactivation, and, in contrast to one-photon absorption, multiphoton absorption only occurs around the focus point of a typical laser beam. Multiphoton absorption features both the merits of being insensitive to quenching and of being a spatially resolved technique. In a case study we assessed two-photon absorption in xenon upon exciting the 5p6 1S0-->5p56p[5/2]2 transition in xenon at a wavelength of 256 nm. The amount of light absorbed by xenon is related to the number density of the gas, and if the gas pressure is known then the gas temperature can be inferred from the number density. Two-photon absorbance was measured as a function of xenon number density and was used to validate a theoretical model of the absorption process. We discuss the circumnavigation of experimental challenges in applying this technique and analyze its precision in terms of the inferred gas temperature.

Absorption↗
PubMed2004

Reference values for arterial blood gases in the elderly.

OBJECTIVES: We present reference values for arterial blood gas measurements for persons > 70 years old. At the same time, we wish to examine how different criteria for exclusion from the reference sample with regard to previous smoking and various comorbidities might influence reference values. METHODS: After first screening a random sample of the general elderly population by postal questionnaire, we selected 146 men and women without respiratory disease, significant dyspnea, symptomatic heart disease or hypertension, or current smoker status. Arterial blood samples were drawn from subjects while in the supine position. RESULTS: The mean (SD; lower limit of normal) PaO(2) and arterial oxygen saturation (SaO(2)) for men was 77.0 mm Hg (9.1; 62.0) and 95.3% (1.4; 93.0), respectively, and for women was 73.5 mm Hg (8.4; 59.6) and 94.8% (1.7; 92.0). Mean (SD; upper limit of normal) PaCO(2) was 39.4 mm Hg (3.3; 44.8) for both sexes. None of the blood gas variables were associated with age, smoking history, or presence of various comorbidities. CONCLUSIONS: The reference values for PaO(2) and SaO(2) in elderly persons are sex specific but age independent. Ex-smokers and persons with nonpulmonary comorbidities who do not have significant respiratory symptoms need not be excluded from the reference sample for arterial blood gases.

Age Factors↗
PubMed1996

[Measuring pulmonary CO2 elimination--studies with the lung model using various mixed gases].

One way of determining pulmonary CO2 elimination during anaesthesia is the breath-by-breath method. With this technique, CO2 analysis is carried out using either the mainstream method (MSM), that is, directly in the expired air flow, or in samples of expired air. A disadvantage of MSM is the lack of sensor signal correction for changes in the composition of the gas mixture and barometric pressure. Sidestream systems (SSM) measure respiratory gas flow and gas concentration with adequate accuracy, and also correct the measured values for gas composition and ambient parameters. Disadvantages of breath-by-breath analysis are the SSM-system-related delay and distortion of the CO2 curves. In the present study, a computer-assisted comparative analysis of CO2 elimination measurement by the sidestream and mainstream methods was carried out using different mixtures of gases in a lung model. Under the selected conditions simulated in the lung model, evaluation of CO2 elimination using SSM and MSM is possible with an error of between 0 and 10% versus reference systems. Measuring accuracy of the MSM system in particular is found to depend directly on the composition of the gas mixture. Using the method described here, the measuring error of an SSM system in terms of delay and response time can be compensated with adequate accuracy.

Carbon Monoxide↗
PubMed1992

Stability of blood gases, electrolytes and haemoglobin in heparinized whole blood samples: influence of the type of syringe.

The alterations of blood gases, pH, electrolytes and haemoglobin during 45 min storage in ice-water were measured in 6 types of syringes (1 glass and 5 plastic syringes, among these 3 "blood gas samplers"). It was confirmed that pO2 generally is not stable in plastic syringes. However, considerable differences among plastic syringes were found in this respect, the smallest increase occurring in an ordinary 2 ml syringe for injections and the greatest in one of the special blood gas samplers. Due to the "buffering effect" of deoxyhaemoglobin, the alterations of pO2 are smaller in the hypoxaemic than in the normoxaemic range. Relevant pO2 alterations in plastic syringes are demonstrable after 20 minutes. It is concluded that blood collected in plastic syringes must be analysed within 15 min after sampling, otherwise glass syringes should be used for blood collection. Deviations of pCO2, pH and electrolytes are described in detail. In general, they are due to sampling rather than to storage, and can be effectively minimized by a small dead space of the syringe and by use of an electrolyte-balanced heparin solution. The danger of erroneous haemoglobin measurements due to unequal resuspension of the red cells after storage is pointed out.

Blood Chemical Analysis↗
PubMed1997

Thermographic demonstration of nonshivering thermogenesis in human newborns after birth: its relation to umbilical gases.

This study was undertaken to measure the extent of nonshivering thermogensis (NST) in brown adipose tissue of human newborns receiving routine thermal care and to examine the influence of oxygen levels at birth on the initiation of NST. Fifteen human neonates were studied in an incubator set at 31-31 degrees C. Thermographic measurements were made every 5 seconds for 5 minutes at 10 and 30 minutes, 1, 3, 6 and 24 hours, and 3 days after birth. The skin temperature and rate of heat dissipation from the interscapular area (location of subcutaneous brown adipose tissue), whole back area, and head area were measured. A heat dissipation ratio (HDR) was calculated as (A-B)/B, where A and B, expressed in Cal/cm2/h, represent rates of heat dissipation from the interscapular area and the whole back area, respectively. Umbilical arterial blood gases were measured immediately after birth. The skin temperature of the interscapular, whole back, and head areas increased significantly during the interval from 10 minutes to 1 hour after birth (p < 0.05). The skin temperature of the interscapular area was highest among the sampled sites during the first hour after birth (p < 0.05). The HDR was highest 10 minutes after birth (p < 0.05). By 1 hour after birth the temperature had reached constant values with low HDR. There was a negative correlation between the HDR and the temperature of the whole back area (p < 0.001). A positive correlation was found between the HDR within 30 minutes after birth and the PO2 of the umbilical arterial blood (p < 0.001). The data support the conclusion that nonshivering thermogenesis is initiated within minutes of birth and contributes to the elevation of body temperature. Furthermore, nonshivering thermogenesis after birth is reduced by low arterial PO2 at the time of birth.

Adult↗
PubMed2006

Fluidization of a dipalmitoyl phosphatidylcholine monolayer by fluorocarbon gases: potential use in lung surfactant therapy.

Fluorocarbon gases (gFCs) were found to inhibit the liquid-expanded (LE)/liquid-condensed (LC) phase transition of dipalmitoyl phosphatidylcholine (DPPC) Langmuir monolayers. The formation of domains of an LC phase, which typically occurs in the LE/LC coexistence region upon compression of DPPC, is prevented when the atmosphere above the DPPC monolayer is saturated with a gFC. When contacted with gFC, the DPPC monolayer remains in the LE phase for surface pressures lower than 38 mN m(-1), as assessed by compression isotherms and fluorescence microscopy (FM). Moreover, gFCs can induce the dissolution of preexisting LC phase domains and facilitate the respreading of the DPPC molecules on the water surface, as shown by FM and grazing incidence x-ray diffraction. gFCs have thus a highly effective fluidizing effect on the DPPC monolayer. This gFC-induced fluidizing effect was compared with the fluidizing effect brought about by a mixture of unsaturated lipids and proteins, namely the two commercially available lung surfactant substitutes, Curosurf and Survanta, which are derived from porcine and bovine lung extracts, respectively. The candidate FCs were chosen among those already investigated for biomedical applications, and in particular for intravascular oxygen transport, i.e., perfluorooctyl bromide, perfluorooctylethane, bis(perfluorobutyl)ethene, perfluorodecalin, and perfluorooctane. The fluidizing effect is most effective with the linear FCs. This study suggests that FCs, whose biocompatibility is well documented, may be useful in lung surfactant substitute compositions.

1,2-Dipalmitoylphosphatidylcholine↗
PubMed2004

Medroxyprogesterone at high altitude. The effects on blood gases, cerebral regional oxygenation, and acute mountain sickness.

OBJECTIVE: To study the effect of medroxyprogesterone on blood gases and cerebral regional oxygenation at high altitude, alone and in conjunction with acetazolamide, and to assess the effect on acute mountain sickness (AMS). DESIGN: Two placebo-controlled trials during rapid ascent to high altitude. PARTICIPANTS: In the first trial, 20 participants, and in the second trial, 24 participants. SETTING: During rapid ascent to 4680 m and on rapid ascent to 5200 m. INTERVENTION: In the first trial, participants were randomized to receive medroxyprogesterone 30 mg or a placebo twice a day. In the second trial, participants were randomly assigned to one of 4 groups: a placebo twice daily, medroxyprogesterone 30 mg twice daily, acetazolamide 250 mg plus a placebo twice daily, or acetazolamide 250 mg plus medroxyprogesterone 30 mg twice daily. MAIN OUTCOME MEASURES: Blood gas changes and symptom scores of AMS in both trials and cerebral regional oxygen saturations in the first trial only. RESULTS: Medroxyprogesterone improved peripheral oxygen saturations in both trials and improved PaO2 in combination with acetazolamide. Cerebral regional oxygen saturation was not altered by medroxyprogesterone. The reduction in symptom scores and in the extent of AMS was not significant in this limited study. CONCLUSIONS: Medroxyprogesterone acts as a respiratory stimulant, but the clinical benefit regarding the development of AMS was unproven at high altitude. Combined medroxyprogesterone and acetazolamide gave the best PaO2.

Acetazolamide↗
PubMedDate not supplied

Cattle feedlot soil moisture and manure content: I. Impacts on greenhouse gases, odor compounds, nitrogen losses, and dust.

Beef cattle feedlots face serious environmental challenges associated with manure management, including greenhouse gas, odor, NH3, and dust emissions. Conditions affecting emissions are poorly characterized, but likely relate to the variability of feedlot surface moisture and manure contents, which affect microbial processes. Odor compounds, greenhouse gases, nitrogen losses, and dust potential were monitored at six moisture contents (0.11, 0.25, 0.43, 0.67, 1.00, and 1.50 g H2O g(-1) dry matter [DM]) in three artificial feedlot soil mixtures containing 50, 250, and 750 g manure kg(-1) total (manure + soil) DM over a two-week period. Moisture addition produced three microbial metabolisms: inactive, aerobic, and fermentative at low, moderate, and high moisture, respectively. Manure content acted to modulate the effect of moisture and enhanced some microbial processes. Greenhouse gas (CO2, N2O, and CH4) emissions were dynamic at moderate to high moisture. Malodorous volatile fatty acid (VFA) compounds did not accumulate in any treatments, but their persistence and volatility varied depending on pH and aerobic metabolism. Starch was the dominant substrate fueling both aerobic and fermentative metabolism. Nitrogen losses were observed in all metabolically active treatments; however, there was evidence for limited microbial nitrogen uptake. Finally, potential dust production was observed below defined moisture thresholds, which were related to manure content of the soil. Managing feedlot surface moisture within a narrow moisture range (0.2-0.4 g H2O g(-1) DM) and minimizing the accumulation of manure produced the optimum conditions that minimized the environmental impact from cattle feedlot production.

Animal Husbandry↗
PubMed2003

Mechanism of organophosphates (nerve gases and pesticides) and antidotes: electron transfer and oxidative stress.

Evidence indicates that nerve gas toxins operate in ways in addition to inhibition of acetylcholine esterase. Alternative bioactivities are discussed with focus on electron transfer. The main class, including pralidoxime (2-PAM), incorporates conjugated iminium and oxime moieties that are electron affinic. Various physiological properties of iminium and oxime species are reviewed. The organophosphates encompass both nerve gases and insecticides, possessing similar properties, but different activities. Toxic manifestations are apparently due, in part, to oxidative stress. Alkylation of DNA takes place which may lead to generation of reactive oxygen species. Structure-activity relationships are examined, including reduction potentials and the captodative effect.

Animals↗
PubMed2000

Laboratory measurement of hazardous fumes and gases at a point corresponding to breathing zone of welder during a CO2 arc welding.

Concentrations of fumes, ozone (O3), carbon monoxide (CO), nitric oxide (NO), manganese (Mn) and total and hexavalent chromium (Cr) as well as size distribution of fumes were measured at a point corresponding to the welder's breathing zone during CO2-arc welding, using a welding robot and three kinds of wires. Concentrations of fumes, O3, CO, Mn and total-Cr were found to exceed their corresponding occupational exposure limit (OEL) values, while the concentrations of NO and Cr(VI) were below those OEL levels. Airborne concentration of Mn exceeded its OEL value, and the Mn content was 8 times higher in welding fumes than in the wire. Using an additive equation of OEL and exposure concentration of each hazardous component, health risk in welders with combined exposure to welding fumes and gases was assessed as 18.6 to 46.0 times of OEL, which exceeded the unity. This finding suggests that effective protection of welders from the exposure can be attained by use of the supplied-air respirator or combined use of a dust respirator and a local exhaust system.

Air Pollutants, Occupational↗
PubMed1980

Increased plasma noradrenaline concentration in patients with chronic obstructive lung disease: relation to haemodynamics and blood gases.

Nine patients with chronic obstructive lung disease underwent right heart catheterization. Mean pulmonary arterial pressure was elevated, but none of the patients had clinical signs of cardiac failure. Mean arterial oxygen saturation and carbon dioxide tension were 89% and 47 mmHg, respectively. Plasma noradrenaline (NA) concentration averaged 0.51 ng/ml and was inversely correlated to arterial oxygen saturation and mixed venous oxygen saturation, and positively correlated to arterial carbon dioxide tension and mean pulmonary arterial pressure. Oxygen inhalation did not change plasma NA significantly. Eight months later, plasma NA was increased (mean 0.89 ng/ml), as compared to the first determination (P < 0.02), and to a group of normal subjects (mean 0.26 ng/ml, P < 0.005). Inverse correlation to arterial oxygen saturation and direct correlation to arterial carbon dioxide tension were still present. Plasma adrenaline concentration was normal. The results point to enhanced sympathetic nervous activity in patients with chronic obstructive lung disease, probably caused by the deranged blood gases. The pulmonary haemodynamic changes and increased pulse rate may, at least partly, be due to enhanced sympathetic nervous activity.

Aged↗
PubMed1984

Effects of biosolubility on pulmonary uptake and disposition of gases and vapors of lipophilic chemicals.

Since statistical analysis proved the intercorrelation of tissue-gas partition coefficients of chemicals with similar chemical structures, bioavailability is controlled by one parameter dependent on the physicochemical properties of the chemicals and two constants distinguishing the tissues. Oil-gas partition coefficients are suggested to describe the biosolubility of volatile halogenated aliphatic chemicals. Tissue-gas partition coefficients derived from oil-gas partition coefficients were substituted in a pharmacokinetic model in order to study the effect of biosolubility on uptake, distribution, and elimination of inhaled chemicals. The simulation was focused on occupational exposures (8 h/day, 5 days/wk). Desaturation curves for all tissues show three exponential decays. The analysis of the simulation data indicates three patterns in behavior of inhaled vapors and gases in the body. Tissue uptake of poorly soluble chemicals (oil-gas partition coefficient less than 10) is flow limited at the beginning of exposure, but the partial pressures of such chemicals in the body equilibrate very rapidly with ambient air. Increased pulmonary uptake compensates for metabolic clearance. The rapid response of tissue concentrations to changes in exposure concentrations indicates that the toxic effect can easily be induced by short-term increase of exposure concentration, and that emergence from the reversible effect is rapid when exposure ceases. Tissue uptake of chemicals with oil-gas partition coefficients between 10 and 10(4) is flow limited during the entire 8-h exposure. Tissue concentrations increase slowly. Pulmonary uptake, being restricted by alveolar ventilation, compensates at steady state only for the amount of chemical removed by metabolic clearance. Therefore, tissue concentrations at steady state are lower than biosolubility. Accumulation during occupational exposure is obvious. Dumping of inhaled chemicals in adipose tissue protects the target organ from the occasional short-term increases in the exposure concentration. Tissue uptake of highly soluble chemicals (oil-gas partition coefficients greater than 10(4)) is limited by alveolar ventilation and exposure concentration. The rising and declining of tissue concentrations is very slow, half-times being in the magnitude of months and years. Metabolism reduces the half-time significantly. A lagging acute toxic effect can develop as the chemical accumulates in the body; the effect is most likely to persist long after the termination of the exposure.(ABSTRACT TRUNCATED AT 400 WORDS)

Anesthetics↗
PubMed1992

Arterial blood gases and brain oxygen availability following infusion of intratracheal fluorocarbon neat liquids.

Eight adult New Zealand Swiss rabbits (3-5 kg) having previously implanted chronic bilateral platinum electrodes in the visual cerebral cortex and subcutaneous silver reference electrodes were tranquilized and monitored in multiple 2-3 hour sessions using voltammetric techniques. Six of these were given intratracheal neat liquid fluorocarbons ranging in boiling point from 132 degrees C to 215 degrees C at doses of 2 or 4cc/kg. Each animal received only one fluorocarbon liquid. Two additional rabbits were match-studied as controls. Half of the rabbits have survived more than five months. Both controls and two experimental rabbits were sacrificed after more than seven months due to gastric hairballs. The period of daytime monitoring sessions, when cathodic brain oxygen currents (aO2), arterial blood gases and pH were obtained, was between 34 and 263 days. In some animals the arterial pCO2 was increased during the first week but the pO2 and pH remained nearly normal in all eight animals throughout. The two best fluorocarbons for liquid breathing on the basis of this limited but intensive work are F-methyldecalin and F-5,6H-dec-5-ene (F44E).

Animals↗
PubMed2003

Effect of lasalocid on growth, blood gases, and nutrient utilization in dairy goats fed a high forage, low protein diet.

This study investigated the effect of lasalocid on weight gain, blood gases, nutrient digestibility, and nitrogen utilization in growing dairy goats. In a growth experiment, 24 crossbred dairy does were assigned to diets without or with lasalocid (approximately 30 mg per head per day) for 12 wk. Goats were group fed bermudagrass hay for free choice plus concentrate at a fixed level (approximately 0.264 kg DM per head per d). Goats grew faster when fed lasalocid than those fed the control diet. Jugular blood partial pressure of O2 was lower when goats were supplemented with lasalocid. In contrast, goats fed lasalocid tended to have a higher partial pressure of CO2 than control goats. Percent O2 saturation tended to increase, and concentrations of total CO2 tended to decrease in goats fed lasalocid. Serum glucose and urea N did not differ between treatments. In a metabolism experiment, 8 castrated male goats were fed hay and concentrate identical to those of the growth experiment to determine whole tract nutrient digestibility and N utilization. Lasalocid did not affect feed intake or nutrient digestion coefficients. Daily urinary N output was reduced by lasalocid supplementation. In spite of this, N retention was not significantly affected. With use of ionophore, the proportion of urinary N relative to digested N tended to decrease, and the retained N as a proportion of digested N tended to increase.

Animal Nutritional Physiological Phenomena↗
PubMed1976

Effect of intermittently raised intracranial pressure on breathing pattern, ventilatory response to CO2, and blood gases in anesthetized cats.

In anesthetised cats, breathing pattern, blood gases, and ventilatory response to CO2 were recorded before and during intermittent 10-minute episodes of hydrostatically raised intracranial pressure. The first effect on breathing was a stimulation which was followed at higher pressures by irregularity, depression, and periods of apnea; hyperventilation at high intracranial pressure (ICP was rare. Raised ICP did not consistently depress the ventilatory response to CO2 until ventilation during airbreathing was already depressed; therefore, we cannot experimentally justify applying this test clinically to detect incipient ventilatory depression. When hypoxemia developed during raised ICP, it was compatible with the degree of hypoventilation due to central depression of breathing; thus, there was no evidence of a neurally mediated effect on the lungs, causing defective gas exchange.

Animals↗
PubMed1982

Chromosome changes in workers (smokers and nonsmokers) exposed to automobile fuels and exhaust gases.

The incidence of chromosome changes in men occupationally exposed to automobile fuels and exhaust gases was investigated. Blood samples were taken from the following four groups of 12 men: drivers of diesel-engine trucks, drivers of gasoline-engine trucks, automobile inspectors, and a reference group. The men in the groups were matched with respect to age, smoking habits, and length of time in their respective jobs. Chromosome preparations from lymphocytes were made and analyzed by standardized routine methods, and the frequencies of gaps, breaks, and sister chromatid exchanges were recorded. Statistical analysis of the results gave no evidence for a marked occupational effect, though there remains a grave suspicion that working with diesel motors may cause an increased level of chromosome changes. Smokers showed a significant or near significant increase in breaks, total aberrations, and sister chromatid exchanges over the nonsmokers in three of the groups. An analysis of the data revealed a weak positive correlation between the frequencies of chromosome breaks and sister chromatid exchanges in an individual.

Adult↗
PubMed1994

Recommendations on whole blood sampling, transport, and storage for simultaneous determination of pH, blood gases, and electrolytes. International Federation of Clinical Chemistry Scientific Division.

Pre-analytical variables, e.g., specimen collection, transport, and storage, can contribute significantly to inaccurate pH, blood gas, and electrolyte values. The International Federation of Clinical Chemistry (IFCC), through its Committee on pH, Blood Gases and Electrolytes, has developed specific recommendations to minimize the undesirable effects of pre-analytical variables. The Committee has drawn upon the experiences of its own members as well as published data by others. Specifically, the Committee has included pertinent guidelines and suggestions by the IFCC Working Group on Selective Electrodes (WGSE), the National Committee on Clinical Laboratory Standards (NCCLS), and the Electrolyte/Blood Gas Division of the American Association for Clinical Chemistry (AACC). This paper will familiarize the reader with the effect of different types of specimen containers and anticoagulants. It discusses important aspects of specimen collection procedures including patient status and special precautions during specimen collection from indwelling catheters or cannulae. The paper also identifies different requirements in storage and transport of specimens for blood gas and electrolyte analysis.

Anticoagulants↗