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At least 19 recordsLinked to original sources
PubMed1978

The relationships among arterial oxygen flow rate, oxygen binding by hemoglobin, and oxygen utilization in chronic cardiac decompensation.

We have examined the interrelationships among CaO2, blood flow, oxygen binding by hemoglobin, and VO2 in cardiac patients with and without chronic cardiac decompensation. We have quantified the role that decreased oxygen-binding to hemoglobin may play in maintaining VO2 in the presence of low systemic blood flow rates. The volume rate of oxygen delivery to tissues was expressed as the OFIa, the product of CO2 and blood flow. OFIa varied from 738 to 262 ml/min/m2, whereas VO2 varied from 170 to 117 ml/min/m2. Thus, in the patients with lowest OFIa (63% below the highest OFIa), VO2 was only down 19%. VO2 was maintained because the extraction of oxygen rose from about 20% to 50% in close association with the decrease in OFIa. Oxygen binding to hemoglobin was lower in patients with the lowest OFIa--and therefore, at in vivo conditions of pH, PCO2, and temperature, P50 in vivo was higher. The resulting facilitation of oxygen release at the PO2 of tissue capillaries could explain about one third of the observed increment in oxygen extraction in patients with low OFIa. An alternative interpretation is that a high P50 in vivo minimizes the reduction in PVO2 needed to maintain VO2 when increased proportional extraction of O2 compensates for decreased OFIa.

Aged↗
PubMedDate not supplied

Is oxygen consumption of surviving tissues determined by the oxygen tension of the suspension medium?

Oxygen tension in the suspension medium and oxygen uptake of the isolated diaphragm of the mouse have been determined simultaneously with systematic variation of shaking frequency and oxygen concentration of the gas phase. Oxygen tension in the suspension medium reaches its final value during the usual equilibration period of 10 minutes and remains constant for the whole measuring period. Each combination of shaking frequency and oxygen concentration of the gas phase results in a reproducible value of oxygen tension in the medium. Equal oxygen tension in the fluid phase can be attained by different combinations of shaking frequency and oxygen concentration of the gas phase. Oxygen uptake at the same oxygen tension of the suspension medium can be very different; it is the higher the higher the shaking rate in the combination. On the other hand the same oxygen consumption of the tissue samples can be observed with highly different oxygen tensions in the medium. It must be concluded from the data in this paper, that the influence of shaking rate per se on the oxygen uptake of isolated tissue can be of the same order as the influence of oxygen tension.

Animals↗
PubMed1978

The use of arterial--central venous oxygen differences to calculate cardiac output and oxygen consumption in critically ill surgical patients.

Simultaneous determinations of cardiac output (using the cardiogreen indicator dilution technique) and arterial--central venous oxygen differences [C(a-cv)O2] were obtained in 200 critically ill surgical patients. The average initial values +/- SD included arterial--central venous oxygen differences of 3.6 +/- 1.6 vol%, cardiac index of 3.4 "/- 1.2 liter/min/sq m, and oxygen consumption of 100 ml/min/sqm. As might be expected, low arterial--central venous oxygen differences, especially if less than 2.0 vol%, were associated with high cardiac indices, but the oxygen consumptions were much lower than normal and the mortality rates were increased. The cardiac indices calculated from the C(a-cv)O2 averaged 4.1 liter/min/sq m and correlated rather well with the measured cardiac indices, particularly if the patients with a C(a-cv)O2 of less than 2.0 vol% were excluded. Arterial pH values did not correlate well with the calculated oxygen consumption. Arterial oxygen contents of more than 16.2 vol% equivalent to a hemoglobin of 12.5 gm/dl or higher with an oxygen saturation of 95%, provided better arteriovenous oxygen differences, oxygen consumptions, and survival rates than those found with lower hemoglobin values. Arterial--central venous oxygen differences and calculated oxygen consumptions can be practical clinical and prognostic value.

Arteries↗
PubMed1979

Influence of seed moisture content and post-irradiation hydration temperature on the kinetics of reactivity towards oxygen or decay of oxygen-sensitive sites.

The rate of development of post-irradiation oxygen-dependent damage when oxygen is available, and its rate of elimination when seeds are first post-hydrated in oxygen-free water prior to their transfer to oxygenated water, was studied in barley seeds of approximately 3 per cent, approximately 8 per cent and approximately 9 per cent moisture contents at 3 degrees C, 25 degrees C and 37 degrees C. The magnitude of oxic damage at a given dose (35 krad) decreases as the initial seed moisture content increases from approximately 3 per cent to approximately 9 per cent. Significant (P = 0.01) oxic damage is observed in seeds of all the three moisture contents at 3 degrees C and 25 degrees C; however, at 37 degrees C significant (P = 0.01) oxic damage is observed only in seeds of approximately 3 per cent and approximately 8 per cent moisture contents. The magnitude of oxic damage in seeds of a given moisture content remains unaltered following oxygenated post-hydration of seeds at 3 degrees C and 25 degrees C, but it registers a significant (P = 0.01) decrease if post-hydration in oxygenated water is carried out at 37 degrees C. The radiation-induced oxygen-sensitive (An) sites react with oxygen approximately 6 to 8 times faster as compared to their rate of decay in the absence of oxygen at both 3 degrees C and 25 degrees C; however, at 37 degrees C they react only approximately 3 to 4 times faster, in seeds of all the three moisture contents. Moreover, the initiation of the decay of An sites becomes evident much earlier in very dry (approximately 3 per cent moist) seeds than in relatively moist (approximately 8 per cent and approximately 9 per cent) seeds. It is also observed that this fraction of An sites which is capable of a very rapid rate of decay in the absence of oxygen is capable also of an even more rapid rate of reactivity towards oxygen.

Kinetics↗
PubMed1976

Comparative evaluation of a new disposable rotating membrane oxygenator with bubble oxygenator.

The comparative in vivo performance of adult-size bubble and rotating membrane oxygenators was evaluated during closed-chest cardiopulmonary bypass for six hours in two groups of dogs. The results show that the rotating membrane oxygenator is efficient in oxygen and carbon dioxide transfer with minimal trauma to blood, while platelet destruction and hemolysis were marked with the bubble oxygenator. Cerebral, cardiac, and respiratory complications were frequent with the bubble oxygenator and absent with the membrane oxygenator.

Animals↗
PubMed1979

Extrapulmonary factors influencing the ratio of arterial oxygen tension to inspired oxygen concentration in burn patients.

The ratio of arterial oxygen tension to inspired oxygen concentration (PaO2/FIO2) as an index of respiratory function was evaluated in 22 patients with body surface area burns of 15--80%. These results indicate that this ratio is limited in its applicability because extrapulmonary factors, such as cardiac output, oxygen consumption, and arterial oxygen content, can affect this index by alterations in the amount of venous desaturation. Useful estimates of intrapulmonary right to left shunt (Qs/Qt) from PaO2/FIO2 were obtained only when arteriovenous oxygen content differences (avDO2) were between 3--5 ml/dl. There were avDO2 values above and below 3--5 ml/dl in at least 35% of the observations. Under these circumstances, PaO2/FIO2 did not correctly reflect changes in Qs/Qt. Blood gases from central venous catheters did not mirror changes in true mixed venous blood and, thus, can lead to erroneous estimations of Qs/Qt. Rational therapy of reduced arterial oxygen saturation requires measurement of both extra- and intrapulmonary factors contributing to arterial desaturation. Measurement of PaO2/FIO2 alone will not estimate these factors.

Adolescent↗
PubMed1979

Oxygen concentration from room air. A new source for oxygen therapy in the home.

Most oxygen concentrators use molecular sieves that selectively adsorb molecules according to their size and polarity. Their present rental cost is about half that of the traditional oxygen tanks or liquid-oxygen systems. Two concentrators have been tested. They are able to produce both high oxygen concentrations (95% oxygen at 2 L/min) and high flow rates (10 L/min with 40% oxygen), which remained stable for one week. After 24 hours of continuous use, neither machine concentrated toxic gases from room air in a city. Both were suitable for use with 24% and 28% Venturi masks.

Chronic Disease↗
PubMed1979

Oxygen as a factor in eukaryote evolution: some effects of low levels of oxygen on Saccharomyces cerevisiae.

A comparative study of the effects of varying levels of oxygen on some of the metabolic functions of the primitive eukaryote, Saccharomyces cerevisiae, has shown that these cells are responsive to very low levels of oxygen: the level of palmitoyl-Co A desaturase was greatly enhanced by only 0.03% (v/v) oxygen. Similarly, an acetyl-CoA synthetase associated predominantly with anaerobic growth, was stimulated by as little as 0.1% oxygen, while an isoenzyme correlated with aerobic growth, was maximally active at much higher oxygen levels (greater than 1%). Closely following this latter pattern were three mitochondrial enzymes that attained maximal activity only under atmospheric levels of oxygen.

Acetate-CoA Ligase↗
PubMedDate not supplied

Superoxide, hydrogen peroxide, and oxygen tolerance of oxygen-sensitive mutants of Escherichia coli.

Oxygen-intolerant mutants of Escherichia coli K12 were selected by a replica plating technique after treatment with the mutagen, N-methyl-N'-nitro-N-nitrosoguanidine, to a lethality of 99.5%. One group of mutants had lost the ability to induce both peroxidase and catalase when exposed to oxygen but retained the ability to induce the manganese-superoxide dismutase. The second group of mutants had lost the ability to induce the activity of all these enzymes. Failure to induce peroxidase and catalase was associated with enhanced susceptibility of the bacteria to the lethal effect of oxygen. When a member of the first group of mutants was prevented from producing the manganese-superoxide dismutase by the presence of puromycin, its susceptibility to the lethal effects of oxygen was greatly increased. Two types of revertants were seen. In one group the ability to induce enzyme activity was recovered and was accompanied by the return of oxygen tolerance. Members of the other group lost the ability to respire and, therefore, no longer produced O2- AND H2O2. These results indicated that enzymic scavenging of both H2O2 and O2- provides an important defense against oxygen toxicity. The parallel loss of peroxidase and catalase, which was seen in all mutants, suggests that these enzymes constitute a precursor-product pair in E. coli. The parallel loss in two of these mutants of peroxidase, catalase, and the manganese-superoxide dismutase suggests a control linkage for these enzymes, the basis of which remains to be explored.

Escherichia coli↗
PubMed1979

[Non-invasive determination of oxygen saturation with the oxygenmet pulse wave oximeter on fingers, metacarpus and wrist of infants. Comparison with the oxygen saturation calculated from the pH and pO2 of the blood gas analysis (author's transl)].

Oxygen saturation was determined non-invasively with the oxygenmet pulse wave oximeter 1471 and mathematically from the pH and pO2 of the blood gas analysis. The determination of the oxygen saturation by the aid of the oximetric method was carried out on fingers, metacarpus and wrist of 80 infants (male = 44, female = 36 - ages: 1 day - 1 year and 8 months). Blood gas analysis was done just behind the oximetric analysis and oxygen saturation was calculated from the pH and pO2. The comparison of the oxygen saturations determined non-invasively on fingers, metacarpus and wrist among themselves, showed no statistical significant differences. Also no statistical significant differences were observed between the results obtained with the pulse wave oximeter and the results calculated from the blood gas analysis. The comparison of the oxygen saturations determined with the oxygenmet oximeter (mean of fingers, metacarpus, wrist) with the oxygen saturations calculated from the blood gas analysis showed a very close correlation. The correlation coefficient was 0.930.

Blood Gas Analysis↗
PubMed1979

Effect of increased blood-oxygen affinity on oxygen transport in hemorrhagic shock.

Effect of increased blood-oxygen affinity on tolerance of hemorrhagic shock was studied in pentobarbital-anesthetized rats. Rats were first exchanged transfused with blood whose P50 had been reduced by various methods by 4-21 Torr. Hypotension (BP = 30 Torr) was induced and maintained at this level by controlled hemorrhage; it was terminated when reinfusion of shed blood became necessary to sustain this blood pressure. Initial rate of bleeding during shock was inversely proportional to P50, varying from 0.52 ml.min-1.kg-1 in controls to 1.5 ml.min-1.kg-1 in the group with the lowest P50, a reaction probably indicating increased sympathetic output in the latter group. Duration of shock tolerance varied from 50 +/- 16 min in controls to 28 +/- 11 min (SD, P less than 0.001) in the group with the lowest P50. Central venous SO2 (SCVO2) and PO2 (PCVO2) were significantly higher and lower, respectively, in low-P50 animals than in controls, probably because of limited oxygen extraction due to increased blood oxygen affinity. VO2 and cardiac output were significantly lower, and mortality was significantly greater, in low-P50 animals. The data suggest that a left shift of the oxygen dissociation curve limits oxygen delivery during hemorrhagic shock.

Animals↗
PubMed1977

Gas flow in relation to blood flow in oxygenators. An evaluation of the new Shiley bubble oxygenator.

A new bubble oxygenator, designed by the Shiley Laboratories, which utilizes a low gas flow for oxygenation, was first tested in dogs and then in 100 clinical cases. For perfusion in adult patients, a gas flow as low as 0.6 litre oxygen per 1 litre blood has given adequate oxygenation and removal of carbon dioxide with no untoward effect on the blood, as compared with other oxygenators, including the membrane type.

Adult↗
PubMed1979

[Oxygen therapy by means of an oxygen concentrator (author's transl)].

Oxygen for therapy of chronically hypoxemic patients can be supplied by an oxygen concentrator (De Vilbiss, DeVO2). By these means longterm oxygen therapy can be carried out on a round-the-clock-basis without risk of hypercapnia and without the need of handling the refill of oxygen containers. 9 patients in severe respiratory failure were treated with 2 to 4 l/min from the concentrator through 4 hour 4 days. Serial bloodgas analyses showed marked improvement of hypoxemia in all patients and prevention of exercise-induced failure in one patient. The oxygen concentrator therefore is suitable for the home treatment of patients with severe hypoxemia.

Adult↗
PubMed1979

Use of phosphorus-31 nuclear magnetic resonance to distinguish bridge and nonbridge oxygens of oxygen-17-enriched nucleoside triphosphates. Stereochemistry of acetate activation by acetyl coenzyme A synthetase.

Adenosine 5'-(thiophosphate) AMPS) contains a prochiral phosphorus center. Differentiation of the two diastereotopic oxygens would allow elucidation of the stereochemical course of biological adenylyl transfer reactions. A general method was developed to distinguish between the "pro-R" and "pro-S" oxygens. When we converted the AMPS to the isomer A of adenosine 5'-(1-thiotriphosphate) (ATPalphaS), which is known to have S configuration at Palpha, the pro-R oxygen is incorporated into the bridge position, whereas the pro-S oxygen is located at the nonbridge position. The 31P NMR spectra of the 17O-enriched compounds were used to distinguish between the bridge and nonbridge oxygens based on the decrease in the peak intensity of 31P NMR signals caused by the directly bound 17O isotope. The method was used to elucidate the stereochemical course of acetate activation catalyzed by yeast acetyl coenzyme A (CoA) synthetase. The results indicate that yeast acetyl-CoA synthetase is specific for the isomer B of ATPalphaS and that the nucleophilic displacement proceeds with net inversion of configuration at Palpha of ATPalphaS (B), supporting the "in-line" mechanism.

Acetate-CoA Ligase↗
PubMed1975

Variable-column bubble oxygenator. A new system for bubble oxygenation.

A new bubble oxygenator has been developed. Its main advantage is that the dimensions of the oxygenating chamber can be varied. Thus, the capacity for oxygenation may be adapted to different patients. It was used in 2,700 open-heart operations performed at the Institut do Coracão, Faculdade de Medicina, Universidade de São Paulo, between January, 1971, and December, 1973. A group of 50 patients were subjected to more detailed studies. We found that the average hemolysis was 38.67 mg. per cent with a mean perfusion duration of 69 minutes, 38 seconds. Fibrinogen and platelet concentrations decreased by 14 and 25 per cent, respectively. The pH, PcO2, PO2, and base excess before and after cardiopulmonary bypass ranged within normal levels, and oxygenation (PO2) was always satisfactory.

Adolescent↗
PubMedDate not supplied

Oxygen transport and oxygen consumption in shock.

A review of data from patients in shock, or with very low cardiac output, shows that oxygen consumption is maintained above 90 ml . min-1 . m-2, even at the lowest values of arterial oxygen transport. CAIN [3] has found a limiting value of oxygen delivery in anesthetized, hypoxic dogs of about 10 ml . kg-1 . min-1, below which oxygen consumption falls dramatically. No comparable value has been established for man in shock.

Aged↗
PubMed1979

Application of an automatic oxygenation technique to analysis of oxygen equilibrium curves for hemoglobinopathic red cells and functional screening of clinically important hemoglobinopathies.

The automatic oxygenation technique of Imai et al (Biochimica Biophysica Acta, 200:189--196, 1970) was slightly modified and applied to the study of oxygen equilibrium curves of dilute, red-cell suspensions from normal subjects and individuals with hemoglobinopathies, enzymopathies, and other hematologic disorders. The p50 values of non-smoking, normal adults were 25.9 +/- 0.6 mm Hg at pH 7.4 and 37 degrees C, and corresponded to the values for whole blood reported in the literature. The oxygen equilibrium curves of suspensions from subjects with enzymopathies revealed shifts in position which are thought to be due to alterations in the concentration of 2,3-DPG of the red cells. Abnormalities in shape of the equilibrium curves were observed only for the hemoglobinopathic red cells, and could best be illustrated by the abnormally low Hill's exponent (n*). Analyses of the n* values of 34 patients with various red-cell disorders of unknown causes led to the identification of ten cases showing low values. In five of the ten patients, the presence of an abnormal hemoglobin was confirmed using column chromatography on Amberlite CG--50. These results point to the usefulness of the Hill Plot analysis of red-cell oxygen dissociation curves in functional screening for clinically important hemoglobinopathies.

Erythrocytes↗