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

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.