Handling and measurement
Air Bubble
Last updated
Air drawn into the barrel along with the liquid. It shows up as one large bubble or as a scatter of small ones clinging to the walls. Air takes up space in the barrel, so a reading taken with air still in it counts that air as liquid. The usual way to clear it is to hold the syringe needle upwards, tap the barrel until the bubbles rise to the tip, push them back into the vial, and then read the mark again.
Why it matters here
A bubble does not change what you drew, it changes what you think you drew, and the error always runs the same way: there is less liquid in there than the mark says. Small bubbles stuck along the wall are easy to overlook and they add up, and drawing quickly through a fine needle is what produces them in the first place.
What it is not
It gets confused with air embolism, the scenario from films, which involves a large volume of air going directly into a vein and is a different route and a different scale entirely. In a syringe the practical problem a bubble creates is a wrong reading. It is also not dead space: a bubble is air in the barrel that you can push out, while dead space is liquid in the needle that no amount of pushing reaches.
Also called
- air bubble
- air bubbles
- bubble
- bubbles
- air in syringe
- burping
- priming
- tapping out bubbles
Burping the syringe is the informal name for clearing the air. Priming is borrowed from pens and pumps, where it means pushing liquid through until it appears at the tip so the air in the line is expelled, and the word carries over loosely to syringes.
Compounds carrying this term
None on file yet. This term is in the controlled vocabulary but no compound record currently uses it — which is a statement about our coverage, not about the term.