Handling and measurement
Dead Space
Last updated
The liquid that stays inside the needle and its hub when the plunger has been pushed all the way down. It was drawn out of the vial but is never delivered, and no amount of pressure gets it out. A standard syringe with a screw-on needle typically holds somewhere around 0.05 to 0.1 mL there. An insulin syringe with a permanently attached needle holds a small fraction of that, often under 0.01 mL, because there is no hub cavity for liquid to sit in.
Why it matters here
Dead space is why the fixed-needle design wastes so much less, and it is a fixed loss each time rather than a percentage, so it counts for proportionally more the less there is in the barrel. It also settles what happens if you change needles between drawing and injecting: everything sitting in the first needle leaves with it.
What it is not
Dead space is not an air bubble and is not a mistake you can correct. A bubble is air in the barrel that you can push back into the vial. Dead space is liquid in a place the plunger cannot reach, present in every syringe by design, and pushing harder only produces a stray squirt from the tip.
Also called
- dead space
- deadspace
- dead volume
- residual volume
- hub space
- low dead space
- lds
- waste volume
Hub space, residual volume and waste volume all name the same thing. Manufacturers sell low dead space or LDS syringes, which is a claim about the geometry of the tip and not a different measuring scale.
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.