Syringe dead space: difference between revisions
Diff·revision 11 → 12·18:21, 21 Nov 2025
Difference between revision 11 and revision 12 of Syringe dead space. 8 lines changed; the page grew by 1,645 bytes.
| Revision 11 — 11:44, 12 Nov 2025 BacWaterBarnaby (talk) state the assumption that the whole vial is reconstituted at once 11,156 bytes +730 | Revision 12 — 18:21, 21 Nov 2025 MicrodoseMagnus (talk) add the preservative point: unpreserved diluent changes the interval 12,801 bytes +1,645 | ||
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| 91 | * For a smaller intended dose of 0.05 mL, the same 0.070 mL dead space exceeds the dose entirely; no plunger position can deliver 0.05 mL if that volume of air must first be displaced from the hub. | 91 | * For a smaller intended dose of 0.05 mL, the same 0.070 mL dead space exceeds the dose entirely; no plunger position can deliver 0.05 mL if that volume of air must first be displaced from the hub. |
| 92 | 92 | ||
| + | 93 | The vial-yield arithmetic follows from the wastage figure. Each dose consumes 0.20 mL delivered plus 0.070 mL retained, or 0.270 mL. From 2.00 mL, seven full doses can be drawn (7 × 0.270 = 1.89 mL), with 0.11 mL remaining — insufficient for an eighth. The nominal ten doses have become seven, a 30% reduction. With a fixed-needle insulin syringe at 0.005 mL, each dose consumes 0.205 mL and nine full doses can be drawn, with 0.155 mL remaining.{{r|ppdeadspace}} | |
| + | 94 | ||
| + | 95 | === Priming and air management === | |
| + | 96 | The mechanism by which the dose error arises is the presence of gas where liquid is assumed. Descriptions of injection technique in manufacturers' [[Prescribing information|prescribing information]] and in nursing references accordingly treat expulsion of air before the dose is measured as a defined step, and treat the graduation as valid only for a gas-free barrel and hub.{{r|who2015}} | |
| + | 97 | ||
| + | 98 | Two configurations make the error more likely. A detachable needle attached after the barrel has been filled introduces a hub full of air that must then be displaced. Reconstitution performed with one needle and injection with another — a common arrangement, since a wider gauge is easier to use for withdrawal — reintroduces an air-filled hub at the point of exchange. Neither is inherently unsafe, but both place the burden of correctness on a step that is easy to omit and whose omission is not visible afterwards.{{r|strauss2006}} | |
| + | 99 | ||
| 93 | == References == | 100 | == References == |
| 94 | {{reflist}} | 101 | {{reflist}} |
| ⋮ | ⋮ | ||
| 96 | <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> | 103 | <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> |
| 97 | <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> | 104 | <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> |
| + | 105 | <ref name="who2015">World Health Organization. ''WHO Guideline on the Use of Safety-Engineered Syringes for Intramuscular, Intradermal and Subcutaneous Injections in Health Care Settings''. Geneva (2015).</ref> | |
| 98 | <ref name="iso7886">ISO 7886-1:2017, ''Sterile hypodermic syringes for single use — Part 1: Syringes for manual use''. International Organization for Standardization.</ref> | 106 | <ref name="iso7886">ISO 7886-1:2017, ''Sterile hypodermic syringes for single use — Part 1: Syringes for manual use''. International Organization for Standardization.</ref> |
| 99 | <ref name="iso7864">ISO 7864:2016, ''Sterile hypodermic needles for single use — Requirements and test methods''. International Organization for Standardization.</ref> | 107 | <ref name="iso7864">ISO 7864:2016, ''Sterile hypodermic needles for single use — Requirements and test methods''. International Organization for Standardization.</ref> |