The accuracy and variability of bolus injections with different sized syringes

The accuracy of bolus injections using different sized syringes was studied. A 1 ml bolus was delivered from a 1 ml, 5 ml, 10 ml, and a 20 ml syringe (n = 205). The 1 ml syringe was the most accurate (P less than 0.001) and the bolus delivered was the least variable (P less than 0.001). Variability increased as syringe size increased. A 3 ml bolus was delivered from a 3 ml, 5 ml, 10 ml, and a 20 ml syringe (n = 164). The 5 ml syringe was the most accurate (P less than 0.05) and the 3 ml and 5 ml syringes delivered a bolus with the least variability (P less than 0.001). A 5 ml bolus was delivered from a 5 ml, 10 ml, and a 20 ml syringe (n = 123); in this case there was no significant difference in the accuracy or variability of bolus among the three syringes. We conclude that for accuracy of small volume boluses (less than 5 ml), small-sized syringes should be used.