THE EFFECT OF THE PARTIAL-PRESSURE OF OXYGEN ON BLOOD-GLUCOSE CONCENTRATION EXAMINED USING GLUCOSE-OXIDASE WITH FERRICYAN ION

Glucose oxidase with ferricyan ion (GOD-F) is widely applied in clinic al settings as a glucose sensor. However, blood oxygen concentration a ffects this blood glucose value because oxygen, at increased concentra tions, consumes blood glucose, which cannot then be measured by this s ensor. We investigated the effect of Po-2 on blood glucose concentrati on in 48 patients who were breathing high concentrations of oxygen. Ar terial and pulmonary arterial blood glucose values were analyzed using the GOD-F method and, as a control, the hexokinase method. The respec tive Po-2 values were also measured. The blood glucose concentrations measured by the GOD-F method show a significant linear relation with t hat measured by the hexokinase method in both arterial (y = -24.4 + 1. 01x, r = 0.99) and pulmonary arterial blood (y = -3.4 + 1.01x, r = 0.9 6). The difference of intercepts is statistically significant, but bec ause of the relatively large limits of agreement indicating any hidden extraneous variabilities, the error of the GOD-F method could not be assessed just by the difference. The equation defining the effect of P o-2 on the percent change between blood glucose measured by the GOD-F method and that measured by the hexokinase method is -19.8/(1 + 203900 /Po-2(2.68)) (r = 0.62). This formula generally follows our measured m aterials and introduces the relationship among blood glucose value, Po -2, and the error of the GOD-F method. We hesitate to suggest that the arterial blood glucose concentration when measured by the GOD-F metho d could be underestimated by as much as 20% in patients with high arte rial oxygen pressure. The underestimation is not a clinical problem wh en blood glucose is high, but anesthesiologists should pay attention t o easy evaluation of hypoglycemia by the GOD-F method when blood Po-2 is high.