Scandinavian Journal of Clinical and Laboratory Investigation
ISSN: 0036-5513 (Print) 1502-7686 (Online) Journal homepage: http://www.tandfonline.com/loi/iclb20
Variations in the hemoglobin-oxygen dissociation curve in 10079 arterial blood samples I. H. Gøthgen, O. Siggaard-andersen & G. Kokholm To cite this article: I. H. Gøthgen, O. Siggaard-andersen & G. Kokholm (1990) Variations in the hemoglobin-oxygen dissociation curve in 10079 arterial blood samples, Scandinavian Journal of Clinical and Laboratory Investigation, 50:sup203, 87-90, DOI: 10.3109/00365519009087495 To link to this article: http://dx.doi.org/10.3109/00365519009087495
Published online: 08 Jul 2009.
Submit your article to this journal
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Citing articles: 1 View citing articles
Full Terms & Conditions of access and use can be found at http://www.tandfonline.com/action/journalInformation?journalCode=iclb20 Download by: [McMaster University]
Date: 07 May 2016, At: 13:49
Scand J Clin Lab Invest 1990; 50, Suppl. 203: 87-90
Variations in the hemoglobin-oxygen dissociation curve in 10079arterial blood samples
Downloaded by [McMaster University] at 13:49 07 May 2016
I. H. GBTHGEN’, 0. SIGGAARD-ANDERSEN’& G. KOKHOLM)
’ Department of Anaesthesia, Gentofte Hospital, DK-2900 Hellerup, Department of Clinical Chemistry, Herlev Hospital, DK-2730 Herlev, Radiometer A/S, DK-2400 Copenhagen NV, Denmark. G~thgenIH, Siggaard-Andersen 0, Kokholm G. Variations in the hemoglobinoxygen dissociation curve in 10079 arterial blood samples. Scand J Clin Lab Invest 1990; 50, Suppl. 203: 87-90. A multicenter study including 10079 arterial blood gas measurements were used to describe the clinical variation in the hemoglobin-oxygen dissociation curve i.e. the relationship between measured values of oxygen tension (PO,) versus oxygen saturation (so,) and the concentration of total oxygen (ctO,). Very large variations in the actual in vivo hemoglobin-oxygendissociation curve were found. At PO, = 8 + 0.5 kPa the SO,range was 69.7 % to 99.4 %, and at SO, = 90 f 2 % thepO, extremes were 3.82 and 18.3 Wa. The actualp, vaned from 2.15 to 6.44 kPa. Arterial PO, versus oxygen content i.e. at PO, = 8 f. 0.5 kPa the total oxygen concentration ranged from 2.04 to 10.76 mmol/L. The results indicate that it is essential to know the actual position of the hemoglobin-oxygen dissociation curve, as well as the hemoglobin concentration in the individual patient, for correct interpretation ofpO, or SO,in arterial blood.
Key words: Blood gas; oxygen content; oxygen saturation; oxygen status; oxygen tension; pulse oximeter,pw Reprints: I. H. G~thgen,Department of Intensive Care, Gentofte Hospital, DK2900 Hellerup, Denmark.
1”T’RODUCTION The hemoglobin-oxygendissociation curve is non-linear. Various factors displace the dissociation curve: e.g. temperature, pH, p C 0 , and 2.3-DPG. A convenient approach to quantify a shift of the dissociation curve is to indicate the PO, required for 50 %
saturation. This is known as the p9 and the standard value is 3.6 Wa [1,2]. For the individual patient, treated with oxygen and ventilatory assistance, the hemoglobin-oxygendissociation curve may deviate significantly from the standard curve [3,4,5] and therefore monitoring only one oxygen parameter, PO, or $0,(e.g. pulse oximeter),
88 I. H. G@thgen,0. Siggaard-Andersen & G. Kokholm
Downloaded by [McMaster University] at 13:49 07 May 2016
may introduce potential error in the therapy. The multicenter study [6] where accuracy and precision of modern blood gas measurements are documented is used to evaluate the potential clinical variations in the hemoglobin-oxygen dissociation curve. This paper describes and evaluates the relationship between measured values of oxygen tension @O,)versus oxygen saturation (SO,) and the concentration of total oxygen (ct0,) in the arterial blood samples. MATERIAL. AND RESULTS The multicenter study is described in detail by Kokholm [6]. The arterial data from the multicenter study are unique with respect to the number of measurements (n= 10079) as well as the documentation of the quality control procedures. No blood samples were obtained specifically for the study. Only blood gas analyses requested for routine patient care were used. Measurements were performed simultaneously on the Radiometer ABL @O,, p C 0 , and pH) and OSM analyzers (SO,, concentration of total hemoglobin and fractions of carboxy- and methemoglobin). All PO, and SO, values were measured and reported at 37 "C. The actualp, was calculated by the simplified oxygen status algorithm [3], using 37 "C and actual values of pH, p C 0 , and dyshemoglobins. Statistical analysis includes median value (50 % fractile) and range as well as 95 %, 75 %, 25 % and 5 % percentiles.
PO,versus SO,: Oxygen tension versus saturation for all arterial samples is shown in Fig. 1. A large variation in the in vivo ranges of the hemoglobin-oxygen dissociation curve is demonstrated. The actual p, median value is 3.44 P a (range 2.15 - 6.44) and the 90 % interval 2.97 - 4.30 kPa (Table I). More illustrative in the clinical situation may be the variation at arbitrarily chosen low values of PO, and SO, (Table I): at PO,
= 8k0.5 kPa the measured SO, values range from 69.7 % to 99.4 %, and the 90 % interval 87.1 % - 94.2 %. At SO,= 90*2 % the PO,extremes are 3.82 and 18.3 Wa, and the 90 % interval 6.80 - 9.35 kPa.
PO,versus ctO,: Oxygen tension versus total oxygen- concentration for all arterial samples is shown in Fig. 2. The figure demonstrates that the blood oxygen content is almost independent of the arterial PO,. At a low PO, value of 8k0.5 P a the total oxygen concentration may range from 2.04 to 10.76 mmol/L (Table I).
DISCUSSION The multicenter study confirms the statement made by J.F. NUM in 1966: "Arterial blood is a discrete entity which may be sampled and its oxygen level may be measured by techniques which permit calibration and whose accuracy may be defined' [7]. The evaluation of the variations in the hemoglobin-oxygen dissociation curve can, due to the design of study, only be descriptive. A special characteristic of the present multicenter study is the well designed quality control program. The random selection of the 10079 arterial samples is quite unique, and describes the overall distribution of the values in a Scandinavian population of patients. The extremes of the potential variations are very large e.g. the variation in PO, for a given SO, value, but many other factors (e.g. the general condition of the patient) may reduce the possible error in interpretation of a measured variable. The information that may be obtained from the data,'is that the observed variation in the hemoglobin-oxygen dissociation curve strongly advise that the measurement and interpretation of the arterial oxygen status should include several parameters. Arterial PO, alone may be sufficient for the evaluation of the degree of respiratory insuf-
Variations in the hemoglobin-oxygen dissociation curve in 10079 arterial blood samples
89
TABLEI. Non-parametricanalysis of the relationship between oxygen tension and oxygen saturation/oxygen content in 10079 arterial blood samples.
PO,= 8.0f0.5 Wa
Downloaded by [McMaster University] at 13:49 07 May 2016
.........................
SO, = 9Oi-2 %
___________________
SO, = 50 %
_______________-
so,
PO2
Pa
%
cto, mmol/L
kPa
Ma
n
978
975
1074
5479
Minimum MaximW
69.7 99.4
2.04 10.76
3.82 18.30
2.15 6.44
Median
90.1
5.97
7.45
3.44
95 % percentil 75 % percentil 25 % percentil 5 % percentil
94.2 92.7 90.0 87.1
8.90 7.85 5.96 4.80
9.35 8.09 7.35 6.80
4.30 3.70 3.24 2.97
ctOJmmol L 1
.. ,.
I
.
0.1
"0
XI
M
30
40
60
80
70
80 p0,lWa
XI
20
30
40
50
Bd
70
80 pO,/Wa
Measured oxygen tension versus measured oxygen saturation in 10079 arterial blood samples.
nG.2. Measured oxygen tension versus total oxygen concentration (oxygen content) in 10079 arterial blood samples.
ficiency, but using arterial SO, alone may introduce potential errors. A detailed description of the oxygen status of the blood comprises the following three parts [8]: - PO, as a measure of the activity of oxygen or the concentration of free 0, in the blood.
-
FIG. 1.
-
concentration of total oxygen, implicitly given in the form of the oxygen saturation and the hemoglobin concentration.
relationship betweenp0, and concentration of total 0, (or oxygen saturation), i.e. the hemoglobin-oxygen dissociation curve.
The data also indicates that there is no simple answer to the question : "What is the safe lower limit of arterial oxygenation?". The new oxygen parameters [3,4,5], e.g. the arterial oxygen extraction tension, may be a useful answer.
90 I. H. Gothgen, 0.Sigaard-Andersen & G. Kokholm
CONCLUSION The results indicate that it is essential to know the actual position of the hemoglobinoxygen dissociation curve, as well as the hemoglobin concentration in the individual patient, for correct interpretation of PO, or SO,in arterial blood.
REFERENCES
Downloaded by [McMaster University] at 13:49 07 May 2016
1.
2.
Siggaard-Andersen 0, Wimberley PD, FoghAndersen N, G~thgenIH, Siggaard-Andersen M. A mathematical model of the hemoglobin-oxygen dissociation curve of human blood and of the oxygen partial pressure as a function of temperature. Clin Chem 1984; 30: 1646-51. Siggaard-Andersen 0, Wimberley PD, FoghAndersen N, Gethgen IH. Measured and derived quantities with modern pH and blood gas equipment: calculation algorithms with 54 equations. Scand J Clin Lab Invest 1988, 48, Suppl. 189 7-15.
3.
4.
Siggaard-Andersen 0, Wimberley PD, FoghAndersen N, G~thgenIH. Blood oxygen parameters: "uncompensated venous oxygen tension" and "cardiac compensation factor". Ugeskr Laeger 1988; 150: 2899-901. Willis N, Clapham MCC, Mapleson WW. Additional blood gas variables for the rational control of oxygen therapy. Br J Anaesth 1987; 59: 1160-70.
5.
Siggaard-Andersen 0, G~thgenIH, Wimberley PD, Fogh-Andersen N. The oxygen status of the arterial blood revised relevant oxygen parameters for monitoring the arterial oxygen availability. Scand J Clin Lab Invest 1990,50, Suppl. 203 17-28.
6.
Kokholm G. Simultaneous measurements of blood pH, p C 0 , p 0 , and concentrations of hemoglobin and its derivates - A multicenter study. S a n d J Clin Lab Invest 1990; 50, Suppl. 203: 75-86.
7.
8.
Nunn JF. Oxygen Measurement and its significance in anaesthesia. Proc R SOCMed 1966, 5 9 905-10. Siggaard-Andersen 0. Hydrogen ions and blood gases. In: Brown SS, Mitchell FL, Young DS. Chemical diagnosis of disease. Amsterdam: Elsevier, 1979: 181-245.
ISSN: 0036-5513 (Print) 1502-7686 (Online) Journal homepage: http://www.tandfonline.com/loi/iclb20
Variations in the hemoglobin-oxygen dissociation curve in 10079 arterial blood samples I. H. Gøthgen, O. Siggaard-andersen & G. Kokholm To cite this article: I. H. Gøthgen, O. Siggaard-andersen & G. Kokholm (1990) Variations in the hemoglobin-oxygen dissociation curve in 10079 arterial blood samples, Scandinavian Journal of Clinical and Laboratory Investigation, 50:sup203, 87-90, DOI: 10.3109/00365519009087495 To link to this article: http://dx.doi.org/10.3109/00365519009087495
Published online: 08 Jul 2009.
Submit your article to this journal
Article views: 13
View related articles
Citing articles: 1 View citing articles
Full Terms & Conditions of access and use can be found at http://www.tandfonline.com/action/journalInformation?journalCode=iclb20 Download by: [McMaster University]
Date: 07 May 2016, At: 13:49
Scand J Clin Lab Invest 1990; 50, Suppl. 203: 87-90
Variations in the hemoglobin-oxygen dissociation curve in 10079arterial blood samples
Downloaded by [McMaster University] at 13:49 07 May 2016
I. H. GBTHGEN’, 0. SIGGAARD-ANDERSEN’& G. KOKHOLM)
’ Department of Anaesthesia, Gentofte Hospital, DK-2900 Hellerup, Department of Clinical Chemistry, Herlev Hospital, DK-2730 Herlev, Radiometer A/S, DK-2400 Copenhagen NV, Denmark. G~thgenIH, Siggaard-Andersen 0, Kokholm G. Variations in the hemoglobinoxygen dissociation curve in 10079 arterial blood samples. Scand J Clin Lab Invest 1990; 50, Suppl. 203: 87-90. A multicenter study including 10079 arterial blood gas measurements were used to describe the clinical variation in the hemoglobin-oxygen dissociation curve i.e. the relationship between measured values of oxygen tension (PO,) versus oxygen saturation (so,) and the concentration of total oxygen (ctO,). Very large variations in the actual in vivo hemoglobin-oxygendissociation curve were found. At PO, = 8 + 0.5 kPa the SO,range was 69.7 % to 99.4 %, and at SO, = 90 f 2 % thepO, extremes were 3.82 and 18.3 Wa. The actualp, vaned from 2.15 to 6.44 kPa. Arterial PO, versus oxygen content i.e. at PO, = 8 f. 0.5 kPa the total oxygen concentration ranged from 2.04 to 10.76 mmol/L. The results indicate that it is essential to know the actual position of the hemoglobin-oxygen dissociation curve, as well as the hemoglobin concentration in the individual patient, for correct interpretation ofpO, or SO,in arterial blood.
Key words: Blood gas; oxygen content; oxygen saturation; oxygen status; oxygen tension; pulse oximeter,pw Reprints: I. H. G~thgen,Department of Intensive Care, Gentofte Hospital, DK2900 Hellerup, Denmark.
1”T’RODUCTION The hemoglobin-oxygendissociation curve is non-linear. Various factors displace the dissociation curve: e.g. temperature, pH, p C 0 , and 2.3-DPG. A convenient approach to quantify a shift of the dissociation curve is to indicate the PO, required for 50 %
saturation. This is known as the p9 and the standard value is 3.6 Wa [1,2]. For the individual patient, treated with oxygen and ventilatory assistance, the hemoglobin-oxygendissociation curve may deviate significantly from the standard curve [3,4,5] and therefore monitoring only one oxygen parameter, PO, or $0,(e.g. pulse oximeter),
88 I. H. G@thgen,0. Siggaard-Andersen & G. Kokholm
Downloaded by [McMaster University] at 13:49 07 May 2016
may introduce potential error in the therapy. The multicenter study [6] where accuracy and precision of modern blood gas measurements are documented is used to evaluate the potential clinical variations in the hemoglobin-oxygen dissociation curve. This paper describes and evaluates the relationship between measured values of oxygen tension @O,)versus oxygen saturation (SO,) and the concentration of total oxygen (ct0,) in the arterial blood samples. MATERIAL. AND RESULTS The multicenter study is described in detail by Kokholm [6]. The arterial data from the multicenter study are unique with respect to the number of measurements (n= 10079) as well as the documentation of the quality control procedures. No blood samples were obtained specifically for the study. Only blood gas analyses requested for routine patient care were used. Measurements were performed simultaneously on the Radiometer ABL @O,, p C 0 , and pH) and OSM analyzers (SO,, concentration of total hemoglobin and fractions of carboxy- and methemoglobin). All PO, and SO, values were measured and reported at 37 "C. The actualp, was calculated by the simplified oxygen status algorithm [3], using 37 "C and actual values of pH, p C 0 , and dyshemoglobins. Statistical analysis includes median value (50 % fractile) and range as well as 95 %, 75 %, 25 % and 5 % percentiles.
PO,versus SO,: Oxygen tension versus saturation for all arterial samples is shown in Fig. 1. A large variation in the in vivo ranges of the hemoglobin-oxygen dissociation curve is demonstrated. The actual p, median value is 3.44 P a (range 2.15 - 6.44) and the 90 % interval 2.97 - 4.30 kPa (Table I). More illustrative in the clinical situation may be the variation at arbitrarily chosen low values of PO, and SO, (Table I): at PO,
= 8k0.5 kPa the measured SO, values range from 69.7 % to 99.4 %, and the 90 % interval 87.1 % - 94.2 %. At SO,= 90*2 % the PO,extremes are 3.82 and 18.3 Wa, and the 90 % interval 6.80 - 9.35 kPa.
PO,versus ctO,: Oxygen tension versus total oxygen- concentration for all arterial samples is shown in Fig. 2. The figure demonstrates that the blood oxygen content is almost independent of the arterial PO,. At a low PO, value of 8k0.5 P a the total oxygen concentration may range from 2.04 to 10.76 mmol/L (Table I).
DISCUSSION The multicenter study confirms the statement made by J.F. NUM in 1966: "Arterial blood is a discrete entity which may be sampled and its oxygen level may be measured by techniques which permit calibration and whose accuracy may be defined' [7]. The evaluation of the variations in the hemoglobin-oxygen dissociation curve can, due to the design of study, only be descriptive. A special characteristic of the present multicenter study is the well designed quality control program. The random selection of the 10079 arterial samples is quite unique, and describes the overall distribution of the values in a Scandinavian population of patients. The extremes of the potential variations are very large e.g. the variation in PO, for a given SO, value, but many other factors (e.g. the general condition of the patient) may reduce the possible error in interpretation of a measured variable. The information that may be obtained from the data,'is that the observed variation in the hemoglobin-oxygen dissociation curve strongly advise that the measurement and interpretation of the arterial oxygen status should include several parameters. Arterial PO, alone may be sufficient for the evaluation of the degree of respiratory insuf-
Variations in the hemoglobin-oxygen dissociation curve in 10079 arterial blood samples
89
TABLEI. Non-parametricanalysis of the relationship between oxygen tension and oxygen saturation/oxygen content in 10079 arterial blood samples.
PO,= 8.0f0.5 Wa
Downloaded by [McMaster University] at 13:49 07 May 2016
.........................
SO, = 9Oi-2 %
___________________
SO, = 50 %
_______________-
so,
PO2
Pa
%
cto, mmol/L
kPa
Ma
n
978
975
1074
5479
Minimum MaximW
69.7 99.4
2.04 10.76
3.82 18.30
2.15 6.44
Median
90.1
5.97
7.45
3.44
95 % percentil 75 % percentil 25 % percentil 5 % percentil
94.2 92.7 90.0 87.1
8.90 7.85 5.96 4.80
9.35 8.09 7.35 6.80
4.30 3.70 3.24 2.97
ctOJmmol L 1
.. ,.
I
.
0.1
"0
XI
M
30
40
60
80
70
80 p0,lWa
XI
20
30
40
50
Bd
70
80 pO,/Wa
Measured oxygen tension versus measured oxygen saturation in 10079 arterial blood samples.
nG.2. Measured oxygen tension versus total oxygen concentration (oxygen content) in 10079 arterial blood samples.
ficiency, but using arterial SO, alone may introduce potential errors. A detailed description of the oxygen status of the blood comprises the following three parts [8]: - PO, as a measure of the activity of oxygen or the concentration of free 0, in the blood.
-
FIG. 1.
-
concentration of total oxygen, implicitly given in the form of the oxygen saturation and the hemoglobin concentration.
relationship betweenp0, and concentration of total 0, (or oxygen saturation), i.e. the hemoglobin-oxygen dissociation curve.
The data also indicates that there is no simple answer to the question : "What is the safe lower limit of arterial oxygenation?". The new oxygen parameters [3,4,5], e.g. the arterial oxygen extraction tension, may be a useful answer.
90 I. H. Gothgen, 0.Sigaard-Andersen & G. Kokholm
CONCLUSION The results indicate that it is essential to know the actual position of the hemoglobinoxygen dissociation curve, as well as the hemoglobin concentration in the individual patient, for correct interpretation of PO, or SO,in arterial blood.
REFERENCES
Downloaded by [McMaster University] at 13:49 07 May 2016
1.
2.
Siggaard-Andersen 0, Wimberley PD, FoghAndersen N, G~thgenIH, Siggaard-Andersen M. A mathematical model of the hemoglobin-oxygen dissociation curve of human blood and of the oxygen partial pressure as a function of temperature. Clin Chem 1984; 30: 1646-51. Siggaard-Andersen 0, Wimberley PD, FoghAndersen N, Gethgen IH. Measured and derived quantities with modern pH and blood gas equipment: calculation algorithms with 54 equations. Scand J Clin Lab Invest 1988, 48, Suppl. 189 7-15.
3.
4.
Siggaard-Andersen 0, Wimberley PD, FoghAndersen N, G~thgenIH. Blood oxygen parameters: "uncompensated venous oxygen tension" and "cardiac compensation factor". Ugeskr Laeger 1988; 150: 2899-901. Willis N, Clapham MCC, Mapleson WW. Additional blood gas variables for the rational control of oxygen therapy. Br J Anaesth 1987; 59: 1160-70.
5.
Siggaard-Andersen 0, G~thgenIH, Wimberley PD, Fogh-Andersen N. The oxygen status of the arterial blood revised relevant oxygen parameters for monitoring the arterial oxygen availability. Scand J Clin Lab Invest 1990,50, Suppl. 203 17-28.
6.
Kokholm G. Simultaneous measurements of blood pH, p C 0 , p 0 , and concentrations of hemoglobin and its derivates - A multicenter study. S a n d J Clin Lab Invest 1990; 50, Suppl. 203: 75-86.
7.
8.
Nunn JF. Oxygen Measurement and its significance in anaesthesia. Proc R SOCMed 1966, 5 9 905-10. Siggaard-Andersen 0. Hydrogen ions and blood gases. In: Brown SS, Mitchell FL, Young DS. Chemical diagnosis of disease. Amsterdam: Elsevier, 1979: 181-245.
