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PubMed1997

Relationship between exercise hyperpnea, hemodynamics, and blood gases before and during glyceryl trinitrate infusion in patients with exercise-induced elevation of pulmonary artery wedge pressure.

BACKGROUND: The mechanisms underlying the excessive ventilatory response to exercise in patients with cardiac failure are still not fully understood. HYPOTHESIS: This study was undertaken to investigate the mechanisms behind exercise hyperpnea in patients with exercise-induced left ventricular dysfunction. METHODS: In 18 patients, aged 57-82 years, all with atherosclerotic lumbar aorta aneurysm and pulmonary artery wedge pressure (PAWP) > 25 mmHg during supine exercise, ventilation (V), central hemodynamics, and arterial and venous blood gases were examined during supine rest and exercise, before and during infusion of glyceryl trinitrate (GTN). RESULTS: Before GTN, exercise PAWP was 32.2 +/- 6.1 mmHg and V/V O2 was 33.8 +/- 7.7 l/l (130% of predicted). With GTN, exercise PAWP was markedly reduced to 15.3 +/- 3.8 mmHg (p < 0.001), whereas V/V O2 was only marginally reduced to 32.3 +/- 3.0 l/l (124% of predicted) (p < 0.05). Exercise physiologic dead space (VD/VT) declined from 0.31 +/- 0.16 to 0.26 +/- 0.17 (p < 0.05), while PaCO2 was reduced from 5.20 +/- 0.31 to 5.10 +/- 0.24 kPa (p < 0.05). PvO2 and cardiac output (CO), however, were unchanged below normal. CONCLUSION: The data show that exercise-induced hyperpnea was not substantially reduced by rapid normalization of PAWP and could not be related to preservation of normal PaCO2 in the presence of high VD/VT. The persistence of exercise hyperpnea and reduced PvO2 after GTN is consistent with augmented ventilatory stimuli from hypoxia-induced metabolic abnormalities in the skeletal muscles, or/and persistently reduced CO, due to changes in the integrated superior command of ventilation and circulation.

Aged↗

PubMedDate not supplied

Diazepam and meperidine on arterial blood gases in patients with chronic obstructive pulmonary disease.

Arterial blood gases were not significantly altered by 0.15 mg/kg intravenous dose of diazepam in patients with chronic obstructive lung disease. The PalphaO-2 was significantly reduced and the P-alphaCO-2 increased after administration of 1.5 mg/kg meperidine intravenously and the combination of 1.5 mg/kg meperidine with 0.15 mg/kg diazepam. Diazepam did not, however, significantly increase the ventilatory depression induced by meperidine. Therefore, 0.15 mg/kg diazepam intravenously causes no ventilatory depression by meperidine in patients with chronic obstructive lung diseases.

Adult↗

PubMed1988

The effect of methotrimeprazine on arterial blood gases in human volunteers.

Since methotrimeprazine proved to be both an effective tranquilizer and analgesic, its effect in a tranquilizing dose of 0.15 mg/kg on the arterial blood gases was determined in human volunteers. Because of the known potentiating effect of some phenothiazines on the narcotic-analgesic induced respiratory depression and analgesia, the effect of methotrimeprazine on the meperidine-induced respiratory depression was also studied. Before, and at five minute intervals after the administration of the test drugs, PaO2, PaCO2 and pH were determined by a Radiometer Copenhagen Blood Gas Analyzer (Radiometer Copenhagen, 72 Endruvej, Denmark) through a Riley-needle. Continuous ECG lead II tracings were taken during the experiment. No significant decrease in PaO2 or increase in PaCO2 (P less than 0.01) was observed in 6 healthy volunteers (mean age = 25 yrs) after 0.15 mg/kg i.v. methotrimeprazine. In 19 volunteers (mean age = 32 yrs), the intravenous infusion of 1.5 mg/kg meperidine caused significant decrease in PaO2 and increase in PaCO2 five minutes after its administration. The combined administration of both drugs to 6 volunteers (mean age = 23 yr) caused initially the same decrease in PaO2 as after meperidine alone with subsequent increase in PaO2 over normal levels, however, the PaCO2 significantly increased both as compared to baseline values and as compared with meperidine alone. The pH reductions after the combination of both drugs were greater than after meperidine alone, which in combination with the PaCO2 values confirms the potentiation of meperidine-induced respiratory depression by methotrimeprazine. The results indicate the methotrimeprazine alone causes no significant respiratory depression, but it potentiates the respiratory depression caused by meperidine.

Adult↗

PubMed1989

Effect of hydroxyzine and meperidine on arterial blood gases in healthy human volunteers.

Because hydroxyzine hydrochloride is frequently used to tranquilize patients, who are receiving narcotic analgesics for pain relief, its effect alone and in combination with meperidine on arterial blood gases and ventilation in patients at rest was evaluated in 65 healthy volunteers, who gave informed consent. Hydroxyzine hydrochloride, 1.5 mg/kg IV given over 30 seconds, caused no decrease but rather a significant (P less than .001) increase in PaO2 and no increase in PaCO2 and/or pH at 5, 10, 20, 30, and 60 minutes (N = 29; mean age = 47.0 years). Meperidine, 1.5 mg/kg IV given over 30 seconds, caused a significant (P less than .01) reduction in PaO2 at 5 minutes indicating ventilatory depression but no increase in PaCO2 and/or pH (N = 19; mean age = 32.4 years). The combination of the same doses of hydroxyzine with meperidine IV caused a significantly greater decrease in PaO2 only at 10 minutes but a greater increase in PaCO2 and pH at all times for 60 minutes than did meperidine alone (N = 17; mean age = 39.5 years), which indicates greater ventilatory depression with the combination than with hydroxyzine alone. However, PaO2, PaCO2 and pH remained within the awake normal ranges for PaO2, PaCO2, and pH for the age group of volunteers even at 10 minutes after IV injection of the drug combination when most of the volunteers were asleep. In conclusion, hydroxyzine even when given IV in excess of the maximum IM therapeutic doses caused no changes in PaO2, PaCO2 or pH, which would indicate clinically important ventilatory depression.(ABSTRACT TRUNCATED AT 250 WORDS)

Adolescent↗

PubMed2006

Proton affinities of maingroup-element hydrides and noble gases: trends across the periodic table, structural effects, and DFT validation.

We have carried out an extensive exploration of the gas-phase basicity of archetypal neutral bases across the periodic system using the generalized gradient approximation (GGA) of the density functional theory (DFT) at BP86/QZ4P//BP86/TZ2P. First, we validate DFT as a reliable tool for computing proton affinities and related thermochemical quantities: BP86/QZ4P//BP86/TZ2P is shown to yield a mean absolute deviation of 2.0 kcal/mol for the proton affinity at 298 K with respect to experiment, and 1.2 kcal/mol with high-level ab initio benchmark data. The main purpose of this work is to provide the proton affinities (and corresponding entropies) at 298 K of the neutral bases constituted by all maingroup-element hydrides of groups 15-17 and the noble gases, that is, group 18, and periods 1-6. We have also studied the effect of step-wise methylation of the protophilic center of the second- and third-period bases.

Journal Article↗

PubMed2003

High accuracy method for the application of isotope dilution to gas chromatography/mass spectrometric analysis of gases.

A new isotope dilution mass spectrometry (IDMS) method for high-accuracy quantitative analysis of gases has been developed and validated by the analysis of standard mixtures of carbon dioxide in nitrogen. The method does not require certified isotopic reference materials and does not require direct measurements of the highly enriched spike. The relative uncertainty of the method is shown to be 0.2%. Reproduced with the permission of Her Majesty's Stationery Office.

Journal Article↗

PubMed2000

Synthetic spectra of simulated terrestrial atmospheres containing possible biomarker gases.

NASA's proposed Terrestrial Planet Finder, a space-based interferometer, will eventually allow spectroscopic analyses of the atmospheres of extrasolar planets. Such analyses would provide information about the existence of life on these planets. One strategy in the search for life is to look for evidence of O3 (and hence O2) in a planet's atmosphere; another is to look for gases that might be present in an atmosphere analogous to that of the inhabited early Earth. In order to investigate these possibilities, we have calculated synthetic spectra for several hypothetical terrestrial-type atmospheres. The model atmospheres represent four different scenarios. The first two, representing inhabited terrestrial planets, are an Earth-like atmosphere containing variable amounts of oxygen and an early Earth-type atmosphere containing methane. In addition, two cases representing Mars-like and early Venus-like atmospheres were evaluated, to provide possible "false positive" spectra. The calculated spectra suggest that ozone could be detected by an instrument like Terrestrial Planet Finder if the O2 concentration in the planet's atmosphere is > or = 200 ppm, or 10(-3) times the present atmospheric level. Methane should be observable on an early-Earth type planet if it is present in concentrations of 100 ppm or more. Methane has both biogenic and abiogenic sources, but concentrations exceeding 1000 ppm, or 0.1% by volume, would be difficult to produce from abiogenic sources alone. High methane concentrations in a planet's atmosphere are therefore another potential indicator for extraterrestrial life.

Astronomy↗

PubMed1997

The Coagulation Rate of Charged Aerosols in Ionized Gases

We obtain analytical expressions for the coagulation rate of aerosols in ionized gases taking into account the statistical distribution of the aerosol charge due to the random nature the charging process. Depending on the asymmetry of the ionic environment, the charge distribution may be bipolar (symmetric charging) or unipolar (highly asymmetric charging). In symmetric charging the attraction between opposite charges is almost exactly counterbalanced by repulsion between like charges and the net effect is a slight increase in the overall coagulation rate. In asymmetric charging all particles carry charges of the same polarity, interparticle interactions are repulsive, and the rate of coagulation decreases. However, the effect of the charge distribution in these systems is to increase the rate of coagulation above the rate that would be obtained if all particles carried the mean charge. This increase is substantial for larger particles in highly asymmetric ionic environments.

Journal Article↗

PubMed1997

Solubilization of Gases by Polyethoxylated Octyl Phenols

Measurements have been made to determine the solubilities of a number of gases in aqueous solutions of commercially available polyethoxylated octyl phenols at temperatures ranging from 25°C to 45°C (298-318 K). The solubilities determined for each gas increase linearly with surfactant concentration. The intramicellar gas solubilities derived from these data are found to be relatively insensitive to temperature and sodium chloride in the external aqueous phase. When analyzed in terms of surfactant composition, the intramicellar gas solubilities are found to depend solely on the octyl phenol content of each surfactant. This suggests that the ethylene oxide chains of the micellized surfactant molecules do not contribute directly to the solubilization process, even under conditions near the cloud point. Copyright 1997 Academic Press. Copyright 1997Academic Press

Journal Article↗

PubMed1998

IR Spectroscopic Study of Adsorption of Binary Gases over Ion-Exchanged ZSM-5 Zeolites.

Adsorption of binary gases (CH4/CO, CO/NO, and CO/CO2) on alkali metal (Li, Na, K, Rb, and Cs) ion-exchanged ZSM-5 zeolites were studied using IR spectroscopy. IR absorption bands of preadsorbed CH4, particularly that of nu1 (induced band), decreased with the increase in the partial pressure of CO, indicating the preferential adsorption of CO on the cation site of zeolite. In addition, IR band profiles of adsorbed CO changed in a different manner when CH4, NO, or CO2 was added to the system, suggesting that the selectivity of adsorption was governed not only by the polarity of adsorbates but also by the nature of sites present in the ZSM-5 pore bearing different electric field strengths. Copyright 1998 Academic Press.

Journal Article↗

PubMed1998

Sorption Isotherms of Gases by Polymer Membranes in the Glassy State: An Explanation Based on the Nonequilibrium Thermodynamics.

Sorption isotherms of glassy polymers are concave to the pressure axis, and the absolute sorption levels are almost an order of magnitude higher than that of rubbery polymers on the relatively low-pressure side. There are several models to interpret this behavior, and the dual sorption model is the most widely accepted one among them. In the present work, sorption isotherms were first derived from permeation data with several gases for four polymer membranes which might be representative of the dual sorption model: two of them were in a glassy state (cellulose acetate and polyamide), the third one was a block copolymer which was composed of a glassy polymer and a rubbery polymer at the measuring temperature, and the fourth one was a Nafion membrane which was taken as a model membrane because of its channel structure with adsorption sites of charged groups supported by a rubbery polymer. These results did not necessarily support the dual sorption model. Subsequently, the validity of the underlying assumptions of two other sorption models for glassy polymers, that is, the matrix model and the deformation model, were examined and a new equation for the sorption isotherm with an ordering parameter was derived, which implied that the glassy polymer was in a nonequilibrium state and changed from the glassy to the rubbery state by absorbing the gas. Copyright 1998 Academic Press.

Journal Article↗

PubMed1999

Study of the Effect of Solubilized Gases on the Properties of Microemulsion Droplets.

The effect of dissolved gas (nitrogen, argon) on the properties of the droplets in water-in-oil and oil-in-water microemulsions (surfactant aggregation number, microviscosity, and micropolarity) has been investigated by means of time-resolved fluorescence quenching and spectrofluorometry. This study extends a similar one on aqueous micellar solutions (R. G. Alargova et al., Langmuir 14, 1575, 1998). The selected microemulsions were characterized by droplets of fairly large size and high volume fraction, in order to minimize the effect of the curvature of the surfactant layer and maximize the amount of gas that can be solubilized in the system. Within the experimental error, the investigated properties (surfactant aggregation number, intradroplet quenching rate constant which is related to the droplet microviscosity, and fluorescent probe lifetime and micropolarity) were found to be independent on whether the system was degassed, nitrogen-saturated, or argon-saturated, in the temperature range between 10 and 35 degrees C. The results confirm the conclusion reached in the above study; i.e., the effect of solubilized gases on the hydrophobic interaction which controls the formation of surfactant assemblies is extremely small and well below the sensitivity of the fluorescence probing techniques used in this investigation. Copyright 1999 Academic Press.

Journal Article↗

PubMed1989

Effect of phosphate on oxygen-hemoglobin affinity, diphosphoglycerate and blood gases during recovery from diabetic ketoacidosis.

The effects of intravenous phosphate administration on the hemoglobin-oxygen affinity, the 2,3 diphosphoglycerate level and blood gases were investigated in twenty severe diabetic patients with ketoacidosis in the intensive care unit. Ten received phosphate (mean total amount for each patient = 300 mEq) and the others did not. The only significant difference noted in all indices measured during the recovery period of eight days was seen to occur after 48 h; the P50 in vivo (Torr) was slightly higher in the group who received phosphate (22.5 +/- 1.6 vs 20.5 +/- 2.2) and for the Hill coefficient (2.4 +/- 0.2 vs 2.2 +/- 0.1). This drop in the oxygen affinity of hemoglobin may be useful in subjects at risk of hypoxia, for example those with cardiac or respiratory failure and justifies the use of phosphate in the first 48 h of treatment of patients with diabetic ketoacidosis.

Adult↗

PubMed1990

A comparison of blood gases and acid-base measurements in arterial, arterialized venous, and venous blood during short-term maximal exercise.

The purpose of this study was to determine the relationship between blood gases and acid-base measurements in arterial, arterialized venous, and venous blood measured simultaneously during short-term maximal exercise. Ten well-trained male cyclists performed a graded maximal exercise test on a cycle ergometer to determine the power output corresponding to their peak oxygen consumption (test I), and a short-term maximal test on a cycle ergometer at peak power output (test II). During test II arterial, arterialized venous and venous blood were sampled simultaneously for determination of partial pressures of oxygen and carbon dioxide, pH, bicarbonate (HCO3-), base excess (BE), and lactate (La). Samples were taken at rest, the end of 1 min of exercise (1 ME), at the end of exercise (EE), and at 2 min of recovery (REC). During test II, subjects maintained a peak power output of 370.6 (62.1) W [mean (SD)] for 4.5, SD 1.6 min. Except at rest venous and arterialized venous measurements tended to be the same at all sampling intervals, but differed significantly from measurements in arterial blood (P less than 0.05). BE was the only variable that rendered consistently significant correlations between arterial and arterialized venous blood at each sampling interval. The pooled correlation coefficient between arterial and arterialized venous BE was r = 0.83 [regression equation: BEa = (0.84 BEav)-0.51]. Arterial La was significantly higher than venous La at 1 ME (2.8, 0.7 vs 0.8, 0.3 mmol.l-1) and higher than both venous and arterialized venous La at EE.(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗

PubMed1983

Results of hepatic and hemopoietic controls in hospital personnel exposed to waste anesthetic gases.

The authors report on pollution measures in some operating theatres and consider biological data for the hepatic and hemopoietic functions in operating room personnel and in control groups. Waste gas concentrations range from 17.3 to 22.6 ppm for enfluorane and from 500 to 1275 for N2O in theatres not equipped with antipollution systems. Pollution is 3-8 times lower when a scavenging system is present, while with horizontal laminar air flow exhaust in function, the gas concentration in the air is insignificant. Tests for the hepatic and hematological functions, done on 61 operating room personnel, 87 ward nurses, and 69 technicians and physicians of radiology services, do not show any significant difference between those exposed to anesthetic gases and controls.

Adult↗

PubMed1992

Methods to produce calibration mixtures for anesthetic gas monitors and how to perform volumetric calculations on anesthetic gases.

A simple procedure for making calibration mixtures of oxygen and the anesthetic gases isoflurane, enflurane, and halothane is described. One to ten grams of the anesthetic substance is evaporated in a closed, 11,361-cc glass bottle filled with oxygen gas at atmospheric pressure. The carefully mixed gas is used to calibrate anesthetic gas monitors. By comparison of calculated and measured volumetric results it is shown that at atmospheric conditions the volumetric behavior of anesthetic gas mixtures can be described with reasonable accuracy using the ideal gas law. A procedure is described for calculating the deviation from ideal gas behavior in cases in which this is needed.

Anesthesia, Inhalation↗

PubMed1994

Continuous monitoring of blood gases during hypercapnia in a patient with severe acute lung failure.

We report about our first experiences with a new device for continuous intra-arterial monitoring of blood gases in a patient with severe acute respiratory failure. This device facilitated continuous monitoring of PaO2, PaCO2 and pH while weaning the patient from extracorporeal membrane oxygenation (ECMO). Although sufficient oxygenation at FIO2 0.45 could be achieved after disconnection from ECMO, carbon dioxide elimination remained inadequate and resulted in severe respiratory acidosis. Within six hours, PaCO2 increased to 95 mmHg. Continuous monitoring of pH and PaCO2 helped to monitor CO2 retention and assisted the decision making process for reinstitution of ECMO.

Acute Disease↗

PubMed1981

Effects of 4-dimethylaminophenol on blood flow and blood gases in the brain.

The effects of i.v. injected 4-dimethylaminophenol HCl, a ferri-hemoglobin-forming substance, on cerebral blood flow, brain temperature, blood gases, and lactate concentration in the sinus sagittalis blood were measured on male beagle dogs anesthetized with chloralose. An increase in cerebral blood flow became measurable when 5% or more of the hemoglobin was oxidized to ferrihemoglobin. The local cerebral blood flow of the cingulum region and the flow in the sinus sagittalis increased, while the sinus pO2 decreased. An increase in the ferrihemoglobin content of some 20% of the total hemoglobin at a constant arterial pO2 and pCO2 was attended with a decrease in the sinus pO2 of about 10 mm Hg when less than 40% of the heme iron was oxidized. The sinus pO2 approached a threshold value of some 8 mm Hg when the ferrihemoglobin content was increased above 40%. The lactate concentration began to rise very rapidly when 40-50% of the hemoglobin was oxidized. At the same time pCO2 increased and pH decreased in the sinus blood. The brain temperature remained unchanged. The behavior of conscious dogs with a ferrihemoglobin content of 40% of the total hemoglobin showed no abnormalities.

Aminophenols↗