Syringe dead space (revision 4)
Old revision·07:19, 12 Sep 2025·SubQ_Solveig
| Syringe dead space | |
|---|---|
| Also known as | Residual volume; hold-up volume; wastage volume |
| Location | Needle hub, needle lumen, plunger-tip recess |
| Reported magnitude | 0.002–0.100 mL depending on configuration |
| Dominant contributor | Hub cavity, not the needle lumen |
| Topic infobox · conventions | |
Syringe dead space is the volume of liquid that remains inside a syringe and its needle after the plunger has been fully depressed. It occupies the cavity of the needle hub, the lumen of the needle itself and any recess in the face of the plunger tip, and it is not delivered to the injection site.[1]
The quantity matters for two distinct reasons that are frequently conflated. First, the retained liquid is discarded with the device, so each injection consumes the nominal dose plus the dead-space volume; over the life of a reconstituted vial this reduces the number of doses obtainable. Second, if the dead space is occupied by air rather than liquid at the moment the plunger position is read against the graduations, and that air is subsequently expelled, the volume actually delivered is smaller than the volume indicated. The first effect is a wastage problem and does not alter the delivered dose; the second is a dose error and can be large.[2]
Anatomy and terminology
[edit]A hypodermic syringe delivers liquid by advancing a plunger through a graduated barrel. The graduations relate to the position of the plunger tip, so the volume expelled is the barrel volume swept between the starting and finishing plunger positions. Any volume distal to the plunger tip at full depression is outside that swept volume and is retained.
Three cavities contribute:
- the hub, the conical or cylindrical space between the end of the barrel and the proximal end of the needle cannula, which in a Luer fitting is a substantial void;
- the needle lumen, the bore of the cannula itself;
- the plunger-tip recess, any concavity in the elastomeric or moulded tip that is not filled by the barrel end when fully advanced.
References
- ^ Zule WA, Bobashev G. "High dead-space syringes and the risk of HIV and HCV infection among injecting drug users." Drug and Alcohol Dependence 100(3):204–213 (2009).
- ^ Strauss K, van Zundert A, Frid A, Costigliola V. "Pandemic influenza preparedness: the critical role of the syringe." Vaccine 24(24):4874–4882 (2006).