scholarly journals Relating oxygen partial pressure, saturation and content: the haemoglobin–oxygen dissociation curve

Breathe ◽  
2015 ◽  
Vol 11 (3) ◽  
pp. 194-201 ◽  
Author(s):  
Julie-Ann Collins ◽  
Aram Rudenski ◽  
John Gibson ◽  
Luke Howard ◽  
Ronan O’Driscoll
Keyword(s):  
Oxygen Saturation ◽  
Partial Pressure ◽  
Pulse Oximetry ◽  
Blood Gas Analysis ◽  
Gas Analysis ◽  
Oxygen Dissociation Curve ◽  
Blood Gas ◽  
Dissociation Curve ◽  
Oxygen Dissociation ◽  
The Relationship

Key PointsIn clinical practice, the level of arterial oxygenation can be measured either directly by blood gas sampling to measure partial pressure (PaO2) and percentage saturation (SaO2) or indirectly by pulse oximetry (SpO2).This review addresses the strengths and weaknesses of each of these tests and gives advice on their clinical use.The haemoglobin–oxygen dissociation curve describing the relationship between oxygen partial pressure and saturation can be modelled mathematically and routinely obtained clinical data support the accuracy of a historical equation used to describe this relationship.Educational AimsTo understand how oxygen is delivered to the tissues.To understand the relationships between oxygen saturation, partial pressure, content and tissue delivery.The clinical relevance of the haemoglobin–oxygen dissociation curve will be reviewed and we will show how a mathematical model of the curve, derived in the 1960s from limited laboratory data, accurately describes the relationship between oxygen saturation and partial pressure in a large number of routinely obtained clinical samples.To understand the role of pulse oximetry in clinical practice.To understand the differences between arterial, capillary and venous blood gas samples and the role of their measurement in clinical practice.The delivery of oxygen by arterial blood to the tissues of the body has a number of critical determinants including blood oxygen concentration (content), saturation (SO2) and partial pressure, haemoglobin concentration and cardiac output, including its distribution. The haemoglobin–oxygen dissociation curve, a graphical representation of the relationship between oxygen satur­ation and oxygen partial pressure helps us to understand some of the principles underpinning this process. Historically this curve was derived from very limited data based on blood samples from small numbers of healthy subjects which were manipulated in vitro and ultimately determined by equations such as those described by Severinghaus in 1979. In a study of 3524 clinical specimens, we found that this equation estimated the SO2 in blood from patients with normal pH and SO2 >70% with remarkable accuracy and, to our knowledge, this is the first large-scale validation of this equation using clinical samples. Oxygen saturation by pulse oximetry (SpO2) is nowadays the standard clinical method for assessing arterial oxygen saturation, providing a convenient, pain-free means of continuously assessing oxygenation, provided the interpreting clinician is aware of important limitations. The use of pulse oximetry reduces the need for arterial blood gas analysis (SaO2) as many patients who are not at risk of hypercapnic respiratory failure or metabolic acidosis and have acceptable SpO2 do not necessarily require blood gas analysis. While arterial sampling remains the gold-standard method of assessing ventilation and oxygenation, in those patients in whom blood gas analysis is indicated, arterialised capillary samples also have a valuable role in patient care. The clinical role of venous blood gases however remains less well defined.

The Invention and Development of Blood Gas Analysis Apparatus

2002 ◽  
Vol 97 (1) ◽  
pp. 253-256 ◽  
Author(s):  
John W. Severinghaus
Keyword(s):  
Carbon Dioxide ◽  
Partial Pressure ◽  
Clinical Medicine ◽  
Blood Gas Analysis ◽  
Oxygen Electrode ◽  
Gas Analysis ◽  
Oxygen Dissociation Curve ◽  
Blood Gas ◽  
Dissociation Curve ◽  
Oxygen Dissociation

In 1953, the doctor draft interrupted Dr. Severinghaus' anesthesia and physiology training and sent him to the National Institutes of Health as director of anesthesia research at the newly opened Clinical Center. He developed precise laboratory partial pressure of carbon dioxide (PCO(2)) and pH analysis to investigate lung blood gas exchange during hypothermia. Constants for carbon dioxide solubility and pK' were more accurately determined. In August 1954, he heard Richard Stow describe invention of a carbon dioxide electrode and immediately built one, improved its stability, and tested its response characteristics. In April 1956, he also heard Leland Clark reveal his invention of an oxygen electrode. Dr. Severinghaus obtained one and constructed a stirred cuvette in which blood partial pressure of oxygen (PO(2)) could be accurately measured. Technician Bradley and Dr. Severinghaus combined these, making the first blood gas analysis system in 1957 and 1958, and shortly thereafter, they added a pH electrode. Blood gas analyzers rapidly developed commercially. Dr. Severinghaus collaborated with Astrup and other Danes on the Haldane and Bohr effects and their concepts of base excess during two sabbaticals in Copenhagen. Work with both Astrup and Roughton on the oxygen dissociation curve led Dr. Severinghaus to devise a modified Hill equation that closely fit their new, better human oxygen dissociation curve and a blood gas slide rule that solved oxygen dissociation curve, PCO(2), pH, and acid-base questions. Blood gas analysis revolutionized both clinical medicine and cardiorespiratory and metabolic physiology.

scholarly journals Comparison of oxygen saturation measured by pulse oximetry and arterial blood gas analysis in neonates

2016 ◽  
Vol 43 (6) ◽  
pp. 211
Author(s):  
Srie Yanda ◽  
Munar Lubis ◽  
Yoyoh Yusroh
Keyword(s):  
Oxygen Saturation ◽  
Pulse Oximetry ◽  
Heart Defects ◽  
Blood Gas Analysis ◽  
Gas Analysis ◽  
Blood Oxygenation ◽  
Blood Gas ◽  
Cross Sectional ◽  
Arterial Blood Gas ◽  
Arterial Blood

Background Arterial blood gas is usually beneficial to discern thenature of gas exchange disturbances, the effectiveness of com-pensation, and is required for adequate management. AlthoughPaO 2 is the standard measurement of blood oxygenation, oxygensaturation measured by pulse oximetry (SapO 2 ) is now a custom-ary noninvasive assessment of blood oxygenation in newborn in-fants.Objective To compare oxygen saturation measured by pulse oxi-metry (SapO 2 ) and arterial blood gas (SaO 2 ), its correlation withother variables, and to predict arterial partial pressure of oxygen(PaO 2 ) based on SapO 2 values.Methods A cross sectional study was conducted on all neonatesadmitted to Pediatric Intensive Care Unit (PICU) during February2001 to May 2002. Neonates were excluded if they had impairedperipheral perfusion and/or congenital heart defects. Paired t-testwas used to compare SapO 2 with SaO 2 . Correlation between twoquantitative data was performed using Pearson’s correlation. Re-gression analysis was used to predict PaO 2 based on SapO 2 val-ues.Results Thirty neonates were included in this study. The differ-ence between SaO 2 and SapO 2 was significant . There were sig-nificant positive correlations between heart rate /pulse rate andTCO 2 , HCO 3 ; respiratory rate and TCO 2 , HCO 3 , base excess (BE);core temperature and HCO 3 , BE; surface temperature and pH,TCO 2, HCO 3, BE; SapO 2 and pH, PaO 2 ; and significant negativecorrelation between SapO 2 and PaCO 2 ; the correlations were weak.The linear regression equation to predict PaO 2 based on SapO 2values was PaO 2 = -79.828 + 1.912 SapO 2 .Conclusion Pulse oximetry could not be used in place of arterialblood gas analysis available for clinical purpose

The oxygen dissociation curve of haemoglobin in dilute solution

1936 ◽  
Vol 120 (819) ◽  
pp. 484-495 ◽  
Keyword(s):  
Spectroscopic Method ◽  
Marked Change ◽  
Maternal Blood ◽  
Gas Analysis ◽  
Dilute Solution ◽  
Dissociation Curve ◽  
Foetal Haemoglobin ◽  
Oxygen Dissociation ◽  
Dissociation Curves ◽  
The Relationship

The spectroscopic determination of the oxygen dissociation curves of haemoglobin has an advantage over the tonometer and gas analysis method, in that much smaller quantities of haemoglobin can be made use of. The spectroscopic method was used to determine the relationship between the foetal and maternal haemoglobins in the sheep during a study of foetal respiration made by Barcroft (1935). The conditions for the comparison of the haemoglobins were a dilute solution of the haemoglobin at p H 9·2 (borate buffer) and at 20° C. These conditions were chosen because of the very accurate determinations of the dissociation curves of dilute haemoglobin of the sheep by Forbes and Roughton (1931) and because these authors recommend p H 9·2 at room temperature as most suitable for a study of the oxygen equilibrium of haemoglobin, all the haemoglobin being in the form of the alkali salt. McCarthy (1933) and Hall (1934) had found previously that the haemoglobins of the foetal and maternal goat were different, the foetal haemoglobin (in the blood and as purified haemoglobin) having a higher affinity for oxygen. The same relationship was found to exist in the sheep haemoglobins in dilute solution at 20° C and p H 9·2. When samples of human foetal and maternal blood (sent by Professor Fleming from the Obstetrical Department of the Royal Free Hospital) were compared in dilute solution it was found that the foetal haemoglobin had a lower affinity for oxygen than the maternal. This was also found by Haurowitz (1935) for dilute solutions of the haemoglobins of mother and new born infant. Haurowitz, however, pointed out that in the corpuscles the affinity for oxygen is less in the infant’s haemoglobin than in that of the mother, but the method used by him did not allow of measurements on suspensions of corpuscles. In the present work the dissociation curves of dilute suspensions of corpuscles have been compared with similar solutions of the haemoglobin. It was found that the relationship of the dissociation curves for human foetal and maternal corpuscles is the same as that found by Barcroft in the goat and in the sheep. It has now been found that by a dilution of human adult haemoglobin the dissociation curve is altered by 200% to a position of higher affinity for oxygen, without any marked change in shape. The haemoglobin of the human foetus, on the other hand, is much less affected by dilution, thus explaining the anomaly of the reversed relationship when solutions of the haemoglobins are used instead of suspensions of corpuscles. It was shown by the work of Bock, Field, and Adair (1924), and by Adair (1925), that a solution of haemoglobin free from stromata and of a similar concentration to blood gives a dissociation curve like whole blood. This makes it clear that in the comparison of dilute haemoglobin solutions with suspensions of corpuscles we are concerned, not simply with a change in the haemoglobin due to haemolysis, but a change due to a dilution of the contents of the corpuscle.

scholarly journals Hemoglobin Non-equilibrium Oxygen Dissociation Curve

2020 ◽  
Author(s):  
Rosella Scrima ◽  
Sabino Fugetto ◽  
Nazzareno Capitanio ◽  
Domenico L. Gatti
Keyword(s):  
Partial Pressure ◽  
Correct Diagnosis ◽  
Oxygen Affinity ◽  
Oxygen Dissociation Curve ◽  
Dissociation Curve ◽  
High Affinity ◽  
Oxygen Dissociation ◽  
Sequential Binding ◽  
Non Equilibrium

AbstractAbnormal hemoglobins can have major consequences for tissue delivery of oxygen. Correct diagnosis of hemoglobinopathies with altered oxygen affinity requires a determination of hemoglobin oxygen dissociation curve (ODC), which relates the hemoglobin oxygen saturation to the partial pressure of oxygen in the blood. Determination of the ODC of human hemoglobin is typically carried out under conditions in which hemoglobin is in equilibrium with O2 at each partial pressure. However, in the human body due to the fast transit of RBCs through tissues hemoglobin oxygen exchanges occur under non-equilibrium conditions. We describe the determination of non-equilibrium ODC, and show that under these conditions Hb cooperativity has two apparent components in the Adair, Perutz, and MWC models of Hb. The first component, which we call sequential cooperativity, accounts for ∼70% of Hb cooperativity, and emerges from the constraint of sequential binding that is shared by the three models. The second component, which we call conformational cooperativity, accounts for ∼30% of Hb cooperativity, and is due either to a conformational equilibrium between low affinity and high affinity tetramers (as in the MWC model), or to a conformational change from low to high affinity once two of the tetramer sites are occupied (Perutz model).

An electrolytic method for determining oxygen dissociation curves using small blood samples: the effect of temperature on trout and human blood

1976 ◽  
Vol 65 (1) ◽  
pp. 21-38
Author(s):  
G. M. Hughes ◽  
J. G. O'Neill ◽  
W.J. van Aardt
Keyword(s):  
Human Blood ◽  
Marked Effect ◽  
Effect Of Temperature ◽  
Oxygen Dissociation Curve ◽  
Dissociation Curve ◽  
Oxygen Dissociation ◽  
Fish Blood ◽  
Bohr Factor ◽  
Dissociation Curves ◽  
The Relationship

1. A detailed account is given of an electrolytic method for determining the oxygen dissociation curve of fish blood using a single sample of 50–100 mul for the whole curve. The accuracy and some of the problems arising from its uses are discussed. 2. Oxygen dissociation curves have been determined for trout blood and human blood at temperatures of 15 and 37 degrees C. The relationship between P50 and temperature is similar to that obtained using other methods. Absolute values of P50 are generally lower than those obtained by other methods, especially in the case of fish blood. 3. The effect of PCO2 and pH on the oxygen dissociation curve of trout blood is tested and it is shown that PCO2 has a more marked effect than pH when the other factor is maintained at a constant level. The Bohr factor (delta log P50/delta pH) appears to be approximately the same and independent of the PCO2. 4.The P50 of ray blood determined from fish during and after an operation showed an increased Bohr factor.

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