Blood sampling through a peripheral venous infusion line

The usefulness of a blood sampling technique for the measurement of blood glucose concentration through a peripheral venous infusion line was investigated with patients under general anesthesia. An infusion line was connected through a T-connector to a venous catheter indwelled in a forearm vein, and lactated Ringer's solution was infused at a flow rate of 100 ml/hour. At an arbitrary time, 0.5 ml of blood sample was obtained through the T-connector after discarding 1.5 ml of blood, while a vein in another arm was punctured to obtain 0.5 ml of blood. As a result, the glucose concentration in the samples from the venous infusion line was strongly correlated with that obtained by direct puncture, and the regression line passed through the origin. This suggests that blood sample from a peripheral venous line can be used in place of samples obtained by direct puncture.