Syringe dead space: difference between revisions
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| 11 | 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.{{r|strauss2006}} | 11 | 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.{{r|strauss2006}} |
| 12 | 12 | ||
| + | 13 | Magnitudes vary across almost two orders of magnitude between device types. A 1 mL insulin syringe with a permanently attached fine needle has a dead space of a few microlitres, because the plunger tip enters the needle hub and displaces almost all of it. A general-purpose syringe with a detachable needle on a Luer fitting retains of the order of 70–100 µL, most of it in the hub rather than in the needle.{{r|zule2009,zule2013}} | |
| + | 14 | ||
| 13 | == Anatomy and terminology == | 15 | == Anatomy and terminology == |
| 14 | 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. | 16 | 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. |
| ⋮ | ⋮ | ||
| 20 | * the '''plunger-tip recess''', any concavity in the elastomeric or moulded tip that is not filled by the barrel end when fully advanced. | 22 | * the '''plunger-tip recess''', any concavity in the elastomeric or moulded tip that is not filled by the barrel end when fully advanced. |
| 21 | 23 | ||
| + | 24 | Terminology in the literature is inconsistent. ''Dead space'', ''dead volume'', ''residual volume'' and ''hold-up volume'' are all used for the same quantity, and ''residual volume'' is also used in a different sense for liquid left in the source container after withdrawal. The two are separate: the liquid left in a [[vial]] because the needle cannot reach it, or because the vial geometry traps it, is a container property and is discussed at [[Underfilling|underfilling]] and at [[Vial|vial]]. This article uses ''dead space'' for the syringe-and-needle quantity only.{{r|iso7886}} | |
| + | 25 | ||
| 22 | == References == | 26 | == References == |
| 23 | {{reflist}} | 27 | {{reflist}} |
| 24 | <ref name="zule2009">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).</ref> | 28 | <ref name="zule2009">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).</ref> |
| + | 29 | <ref name="zule2013">Zule WA, Cross HE, Stover J, Pretorius C. "Are major reductions in new HIV infections possible with people who inject drugs? The case for low dead-space syringes in highly affected countries." ''International Journal of Drug Policy'' 24(1):1–7 (2013).</ref> | |
| 25 | <ref name="strauss2006">Strauss K, van Zundert A, Frid A, Costigliola V. "Pandemic influenza preparedness: the critical role of the syringe." ''Vaccine'' 24(24):4874–4882 (2006).</ref> | 30 | <ref name="strauss2006">Strauss K, van Zundert A, Frid A, Costigliola V. "Pandemic influenza preparedness: the critical role of the syringe." ''Vaccine'' 24(24):4874–4882 (2006).</ref> |
| + | 31 | <ref name="iso7886">ISO 7886-1:2017, ''Sterile hypodermic syringes for single use — Part 1: Syringes for manual use''. International Organization for Standardization.</ref> | |
| 26 | 32 | ||
| 27 | {{DEFAULTSORT:Syringe dead space}} | 33 | {{DEFAULTSORT:Syringe dead space}} |
| 28 | [[Category:Injection technique]] | 34 | [[Category:Injection technique]] |
| 29 | [[Category:Dosing and titration]] | 35 | [[Category:Dosing and titration]] |
| + | 36 | [[Category:Preparation and handling]] | |
| 30 | 37 |