Variations in the hemoglobin-oxygen dissociation curve in 10079 arterial blood samples

Abstract

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 (pO₂) versus oxygen saturation (sO₂) and the concentration of total oxygen (ctO₂).

Very large variations in the actual in vivo hemoglobin-oxygen dissociation curve were found. At pO₂ = 8 ± 0.5 kPa the sO₂ range was 69.7 % to 99.4 %, and at sO₂ = 90 ± 2 % the pO₂ extremes were 3.82 and 18.3 kPa. The actual p₅₀ varied from 2.15 to 6.44 kPa. Arterial pO₂ versus oxygen content i.e. at pO₂ = 8 ± 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 of pO₂ or sO₂ in arterial blood.

Key Words:

• Blood gas
• oxygen content
• oxygen saturation
• oxygen status
• oxygen tension
• pulse oximeter
• p₅₀.