Oxygen Content Calculator
You can read more about the variables and the formula used in the text below the form.
The oxygen content calculator uses the haemoglobin levels in g/dL, the percentage of oxygen saturation and O2 arterial pressure in mmHg, to determine the arteria oxygen content.
Arterial Oxygen Content = Hemoglobin x 1.36 x SaO2 /100 + 0.0031 x PaO2
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Variables and formula
Arterial blood oxygen is the measure of the oxygen in 100 ml of blood both bound or unbound by hemoglobin.
It offers information about the uncombined part of oxygen which can become of interest at high values of PaO2 or in patients diagnosed or suspected of anemia.
The three variables used are described in the table below:
|Hemoglobin||13.8 - 17.2 g/dL for men
12.1 - 15.1 g/dL for women
|Complex protein on the RBCs, involved in oxygen transport|
|SaO2||Between 95 and 100%.||Arterial blood-oxygen saturation, determined during pulse oximetry|
|PaO2||75 and 100 mmHg||Arterial pressure of oxygen|
The following formula is employed:
Arterial Oxygen Content = Hemoglobin x 1.36 x SaO2 / 100 + 0.0031 x PaO2
This can be explained as: CaO2 is the amount of oxygen bound to hemoglobin (1.36 x Hb x SaO2) plus the oxygen dissolved in plasma (0.0031 x PaO2).
The 1.36 constant represents the amount of oxygen (ml at 1 atmosphere) bound per gram of hemoglobin.
In some cases, the 1.36 constant is reduced to 1.34 because of abnormal forms of hemoglobin such as carboxyhemoglobin and methemoglobin.
The dissolved oxygen constant (0.0031) becomes of relevance at very high PaO2 (as in a hyperbaric chamber) or in severe anemia.
1. Anthea M, Hopkins J, McLaughlin CW, Johnson S, Warner MQ, LaHart D, Wright JD. Human Biology and Health. Englewood Cliffs NJ: Prentice Hall, 1993.
2. Stoelting RK, Pharmacology & Physiology in Anesthetic Practice, Lippincott Williams & Wilkins, 1999.
3. Hsia CC. Respiratory function of hemoglobin. N Engl J Med. 1998; 338(4):239-47.
No. Of Variables: 3
Published On: June 7, 2017 · 09:01 AM
Last Checked: June 7, 2017
Next Review: June 7, 2023