The design of a conventional syringe includes a dead space between the needle and barrel of the syringe called the hub. This space collects liquid that once drawn up, cannot be plunged out. As a result, the substance remaining in the hub is inevitably wasted and difficult to account for. Little information is known about the true amount of hub loss that is expected from a given vial of controlled substances. We calculated and measured the hub volume using a variety of different syringes and vial volumes to determine the anticipated substance loss. Additionally, we tested the effects of interpersonal variability, number of syringes used per vial, volume drawn up in each syringe, and other real world conditions. Prior to finding the hub loss per vial, we calculated the hub volume of three different syringe and needle types. The two conventional 1ml syringe types used had means of 0.068ml and 0.066ml of hub loss. The hubless tuberculin syringe had a mean of 0ml of hub loss. After calculating the hub volume of each syringe, we tested expected hub loss from 10ml and 20ml vials. The trend of these tests showed an increase in hub loss as the number of syringes used increased. When 50 syringes were used to draw out half of a 10ml vial, there was a mean of 3.3ml of hub loss. When 10 syringes were used to draw out half of a 10ml vial, there was a mean of 0.5ml of hub loss. Of the recorded hub loss, the range of all datasets ranged from 0.1 to 2.9. These wide ranges display inconsistent amounts of hub loss per vial. The inconsistency may have been due to real world variables such as imprecise starting vial volumes, interpersonal variability, air bubbles, and unstable pressure within vials. The aim of this study was to establish a reasonable range of hub loss to monitor the usage of controlled substances. Based on our data, a reasonable range of hub loss depends on the number of syringes used to draw from a single vial, with the volume per draw not significantly affecting hub loss. As an example, a reasonable amount of hub loss from a vial when 10 syringes are used is 0.1ml-1.07ml. When 50 syringes are used, 1.99ml-4.53ml. The study may also be used to improve laboratory protocols so hub loss can be minimized.
Measuring and Predicting Syringe Hub Loss
Mouse Biology Project
Dr. Kristin Grimsrud