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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↗
PubMed1977

Simultaneous determination of hemoglobin derivatives, oxygen content, oxygen capacity, and oxygen saturation in 10 microliters of whole blood.

We describe a new method for simultaneous determination of four hemoglobin derivatives (deoxyhemoglobin, Hb; oxyhemoglobin, HbO2; methemoglobin, Hb+; and carbon monoxide hemoglobin, HbCO) and total oxygen content in 10 microliters of whole blood. Percentage HbO2, HbCO, Hb+, total hemoglobin (Hbt), and oxygen capacity can also be obtained from the experimental data by simple calculations. Total analysis time is 1 min. Blood is diluted 100-fold with a buffer contained in a quasi-anaerobic cuvette, where simultaneous measurements of oxygen pressure (by a po2 electrode) and adsorbance (at 497, 565, and 620 nm) are made. The decrease of oxygen pressure, as recorded by the oxygen electrode, is proportional to the amount of deoxyhemoglobin. The concentrations of HbO2, HbCO, and Hb+ can be obtained from absorbance measurements at the specified wavelengths. The new method eliminates the use of short-path optical cells and, due to the low sample volume requirement, makes possible the automated measurement of hemoglobin derivatives and oxygen saturation in arterialized capillary blood.

Carboxyhemoglobin↗
PubMed1992

[Home oxygen therapy using liquid oxygen system].

Home oxygen therapy (HOT) for patients with chronic respiratory failure has been believed to increase the quality of life and to improve the prognosis of such patients. In Japan, HOT for chronic respiratory failure has been supported by health insurance since March 1985. Since then, patients with HOT have increased progressively, and it has been reported that there are now over 20,000 patients with HOT. The oxygen concentrator which extracts oxygen from atmospheric air has been commonly used as the oxygen delivery system. Recently the liquid oxygen system has provided an attractive, convenient source of oxygen. Since April 1990, HOT using liquid oxygen system has been supported by health insurance, and its use will become widespread in Japan. A major characteristic of this system is that oxygen condensed into a liquid form allows storage of a larger supply. This system consists of two parts: stationary type which stores the liquid oxygen, and a portable type which can easily be refilled with oxygen a larger source. In the present study, we examined the efficacy of portable liquid oxygen in 50 patients with chronic pulmonary diseases including patients with chronic respiratory failure who had PaO2 < 55 mmHg during air breathing. We measured changes of ten minutes walking distance (10 MD) and blood gas analysis with and without portable liquid oxygen. We also performed on estimation of efficacy of liquid oxygen by questionnaires in patients receiving liquid oxygen for HOT. We did not find a significant improvement of 10 MD with portable liquid oxygen, but found a significant improvement of arterial oxygen tension at the end of walking.(ABSTRACT TRUNCATED AT 250 WORDS)

Carbon Dioxide↗
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↗
PubMed1977

Elevated coronary venous oxygen content during oxygen breathing in the ischemic myocardium under pacing-induced stress in dogs.

The purpose of the present study was to investigate the effect of oxygen inhalation on the stressed (pacing-induced) ischemic myocardium. In 13 open-chest dogs, the left anterior descending coronary artery was partially occluded, the coronary vein accompanying the artery was cannulated for coronary venous blood sampling and a myocardial strain gauge arch was sutured on the myocardium perfused with the partially occluded coronary artery in order to measure the myocardial contractile force. The heart rate was increased by left atrial pacing to increase myocardial oxygen consumption. Respiration was instituted either with oxygen or with room air. Increase of the heart rate caused an increase of blood flow through the partially occluded coronary artery, an increase of the local myocardial oxygen consumption and no consistent change of the local myocardial contractile force both during air breathing and oxygen breathing, provided that the heart rate was less than 200. These values decreased if the heart rate was increased more than 200 both during air and oxygen breathings. Coronary venous oxygen content from the local coronary vein accompanying the partially occluded coronary artery was 2.7 ml per 100 ml on the average during air breathing, while it was elevated to 3.8 ml per 100 ml during oxygen breathing. Although, pacing caused a similar change on coronary blood flow or myocardial contractile force both during air and oxygen breathings, elevated coronary venous oxygen content during oxygen breathing might indicate that ischemic myocardium becomes more aerobic during oxygen breathing. This may be one of the reasons why patient with coronary artery disease can perform more work without complaining chest pain during oxygen breathing.

Animals↗
PubMed1992

Effect of maternal oxygen administration on fetal oxygenation during graded reduction of umbilical or uterine blood flow in fetal sheep.

OBJECTIVE: Effects of maternal oxygen administration on fetal blood gases and on oxygen delivery and consumption during reduced uterine and reduced umbilical blood flows were examined. STUDY DESIGN: In eight pregnant sheep (gestational age 133 +/- 4 days) flow transducers were applied to a uterine and the common umbilical artery. Graded reductions in uterine and umbilical blood flows were achieved by a hypogastric artery snare and a balloon cuff encircling the umbilical cord. Fetal femoral arterial and umbilical venous oxygen contents and flows were measured at varying flow reductions with the ewe breathing air or oxygen. RESULTS: During 75% reduction in umbilical blood flow maternal oxygen administration significantly increased fetal oxygen delivery (6.4 +/- 2.5 to 7.7 +/- 2.3 ml/min/kg) and oxygen consumption (4.3 +/- 1.2 to 5.0 +/- 0.8 ml/min/kg). With similar reduction of uterine flow oxygen administration increased oxygen delivery from 8.3 +/- 2.4 to 12.3 +/- 3.6 and oxygen consumption from 3.3 +/- 0.8 to 4.7 +/- 1.6 ml/min/kg. CONCLUSION: Maternal oxygen inhalation improves fetal oxygenation during umbilical but especially during uterine blood flow reduction.

Animals↗
PubMed1992

[The quality of oxygen therapy delivery systems using oxygen-saving valves. A multicenter study. The ANTADIR Medico-Technical Commission].

The saturation of oxygen (SaO2) using oxygen therapy with an oxygen saving system, Optimox (CFPO) or COS 5 (Puritan, Bennett) has been compared to the SaO2 using continuous oxygen therapy. The oxygen output using the oxygen saving system was regulated in such a way as to be equivalent to the oxygen flow without the economiser. Three situations were studied: the day, the night and during effort. Ninety four patients (84 men and 10 women), aged 65.3 +/- 9.7), who were hypoxaemic (SaO2: 84.5 +/- 6.4%) coming from twelve pneumology units were included in the study. The percentage of time spent above SaO2 (T greater than 90) was used to judge the criteria of the efficacy of the oxygen therapy. T greater than 90 without (SSECO) and with the oxygen saving system (AVECO) were compared in each subject. T greater than 90 AVECO was below T greater than 90 SSECO in 52% of patients and was greater in 23% of subjects. The nasal, auditory and respiratory comfort was good whatever the period of examination for more than half of the subjects. In conclusion for an equivalent oxygen flow the addition of an oxygen saving device significantly alters the quality of diurnal and nocturnal oxygen therapy in one patient out of two.

Aged↗
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↗
PubMed1976

Oxygen transport during extracorporeal oxygenation for the treatment of adult respiratory distress syndrome.

An inventory of hemodynamic and respiratory measurements was obtained in two patients with acute respiratory failure syndrome prior to and during venoarterial extracorporeal membrane oxygenation for study of oxygen transport. As the inspired oxygen concentration fraction was reduced from 1.0 to 0.5 and paO2 was increased from less than 50 to physiologic ranges during extracorporeal membrane oxygenation, tachycardia and pulmonary hypertension were reversed. Total oxygen transport was reduced rather than increased. Oxygen consumption and oxygen extraction were not altered during extracorporeal membrane oxygenation. However, a striking reduction was observed in cardiac output. After reversal of anoxemia, the total of the cardiac output of the patient and the extracorporeal membrane oxygenation flow were less than the cardiac output of the patient prior to extracorporeal membrane oxygenation. These observations provide evidence that the beneficial effects of extracorporeal membrane oxygenation stem, at least in part, from a reduction of the work load on the heart. Since high cardiac output failure is observed during progression of adult respiratory distress syndrome, mechanical support of circulation during extracorporeal membrane oxygenation may be of primary therapeutic benefit.

Adult↗
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↗
PubMed1977

Efficient oxygen mask for patients undergoing hyperbaric oxygen therapy.

Hyperbaric oxygen (HBO) is established therapy for various disorders, but its effectiveness depends on the efficiency of the oxygen delivery system. A mask oxygen delivery system, consisting of the standard USAF aviator's A-14 regulator and the MBU-5/P oxygen mask, is installed in all USAF hyperbaric chambers. The efficiency of the mask oxygen delivery system at the USAF Hyperbaric Center, Brooks AFB, Tx, was evaluated breath-by-breath at sea level and 2.4 ATA via two different measuring techniques. Three groups of subjects were evaluated. Four subjects in Group I and seven subjects in Group II were randomly selected to use a single instrumented mask which was improperly fitted. The result was variable inspired oxygen levels from 64% to 100%. Six subjects in Group III wore properly fitted masks and achieved end-inspired oxygen levels ranging from 96% to 99%, for a mean of 97.8 +/- 0.5 (S.E.)%. A mean end-inspired oxygen level of 88,5 +/- 3,5 (S.E.)% was achieved within 5 min of mask donning. Inspiratory gas analyses indicate that the USAF aviator MBU-5/P mask and the A-14 regulator as used at the USAF Hyperbaric Center constitute a highly efficient oxygen delivery system for HBO therapy. This view has been refleced in arterial blood gas measurements and in preliminary data from tissue oxygen measurements in a gas gangrene patient. Future improvements in patient therapy masks are recommended.

Air↗
PubMed1975

Oxygen delivery, anoxic metabolism and hemoglobin-oxygen affinity (P50) in patients with acute myocardial infarction and shock.

Changes in systemic oxygen delivery after acute myocardial infarction were investigated in 21 patients. In seven patients with shock, circulatory failure was characterized by a significant reduction in cardiac index, a decrease in oxygen transport and oxygen consumption and an increase in concentration of blood lactate; a decrease in the affinity of hemoglobin for oxygen (increased P50) was also noted. The P50 averaged 28.8 plus or minus 0.87 (standard error of the mean) torr in patients with shock and 26.0 plus or minus 0.45 torr (P less than 0.05) in patients without circulatory failure. However, there was no significant difference in oxygen extraction from arterial blood between the two groups. The time course of the changes in P50, cardiac index and oxygen consumption was separately examined in 12 patients. In six patients with shock, P50 increased by an average of 4.6 plus or minus 2.05 torr (P less than 0.05) and this augmentation accounted for an estimated 18 percent increase in oxygen release. Maximal P50 values were observed after 24 hours of circulatory failure. In the absence of shock, no consistent changes in P50, cardiac index or oxygen consumption were observed. These data indicate that a reduction in oxygen delivery after acute myocardial infarction is followed by a compensatory increase in P50. This change in P50 accounts for increases in oxygen availability independently of changes in cardiac output.

Aged↗
PubMed1975

Magnitude of subunit inequivalence for oxygen release from hemoglobin: reinvestigation of the oxygen-pulse experiment.

Two hypotheses have been presented to explain the grossly biphasic oxygen release kinetics observed when hemoglobins are studied with the oxygen pulse technique [Gibson (1973) Proc. Nat. Acad. Sci. USA 70, 1-4]. Hypothesis I suggests that the two phases result from cooperativity, with the fast phase being oxygen release from the low affinity (T) state and the slow phase being oxygen release from molecules that have switched to the high affinity (R) state. Hypothesis II suggests that the biphasic curves are due to a large (factor of 20-30) difference in oxygen release from the two types of subunits within deoxyhemoglobin. In order to experimentally discriminate between these two hypotheses, we reinvestigated the oxygen pulse reaction for hemoglobin Kansas (alpha2 beta2 102 Asn leads to Thr) in the absence and presence of inositol hexaphosphate, since recent high resolution nuclear magnetic resonance studies have shown that this allosteric cofactor stabilizes hemoglobin Kansas in T even when fully liganded [Ogawa, Mayer, and Shulman (1972) Biochem. Biophys. Res. Commun. 49, 1485-1491]. The results of these studies clearly favor hypothesis I over hypothesis II as being the correct interpretation for the oxygen pulse results. However, we have found evidence that suggests that oxygen release and binding in T are surprisingly faster than previously observed. Furthermore, within T, there is some spectral and kinetic heterogeneity for oxygen release from adult hemoglobin and hemoglobin Kansas. The magnitude of this kinetic heterogeneity in T appears to be about the same as that seen in the high affinity, R, state. The exchange of hypothesis II for hypothesis I more strongly favors views of cooperative oxygen binding involving both types of subunits, as required if the allosteric model of Monod, Wyman, and Changeux [(1965) J. Mol. Biol. 12, 88-118] is considered operative.

Adult↗
PubMed1975

[Application of the theory of oxygen transfer: determination of the Michaelis constant of glucose oxidase with respect to oxygen].

The oxidation of beta-D-glucose with glucose oxidase generally requires oxygen, which, under normal conditions is present at low concentrations in the reaction medium. Experiments show that glucose oxidase is no longer saturated by oxygen at enzyme concentrations greater than 0.4 mg.ml1. This is due to the decrease in the oxygen concentration of the solution. The value of the oxygen mass transfer coefficients and dissolved oxygen concentrations are determined. These dissolved oxygen concentrations are found to correlate with direct measurements with an oxygen electrode. From this, the Michaelis constant of glucose oxidase for oxygen is calculated. These experiments also show that oxygen is a limiting factor for this reaction.

Aspergillus niger↗
PubMed1976

Arterial oxygen tension and response to oxygen breathing in differential diagnosis of congenital heart disease in infancy.

Arterial oxygen tension was measured from radial artery samples in 276 infants referred for cardiological investigation. Values obtained during air breathing in infants with congenital heart disease showed considerable overlap between 'cyanotic' and 'acyanotic' groups, and are of limited diagnostic use. By contrast, values obtained while breathing oxygen in concentrations of over 80%, measured in 182 infants, allowed clear differentiation between these groups. All infants with acyanotic, but only 2 of 109 with cyanotic lesions, achieved an arterial oxygen tension of more than 150 mmHg. In the cyanotic group the response to oxygen breathing was significantly greater in common mixing situations and in the hypoplastic left heart syndrome than with either pulmonary outflow tract obstruction or transposition of the great arteries. Infants with transposition had a significantly lower mean arterial oxygen tension in air than infants with other forms of cyanotic congenital heart disease. Of 23 infants whose final diagnosis was primary lung disease but in whom cyanotic congenital heart disease had been suspected, 7 achieved arterial oxygen tensions of more than 150 mmHg during oxygen breathing, and on this basis cardiac catheterization was not performed. We therefore conclude that measurement of the arterial oxygen tension while breathing high concentrations of oxygen should be routinely performed in the initial assessment of sick infants with suspected congenital heart disease.

Cyanosis↗