Filter needles: when they help and what they cost you posts 31–51
This is a continuation of a long topic, addressed by post number rather than by page. Start at post 1.
The arithmetic in post #29 is right; the assumption feeding it is the part to check.
U-100 means the barrel is graduated for a solution containing one hundred units of insulin per millilitre. For anything that is not insulin, the units are simply hundredths of a millilitre.
The most useful thing anyone has posted about filter needles in this category was a table of what had been measured and by whom. That is what I would want again.
Gauge is the outside diameter and higher numbers are thinner. Thinner needles hurt less and draw more slowly, which is the entire trade.
Flagging that the sources on this are thinner than the confidence in the thread suggests.
Post #33 describes the usual case. This is about the unusual one.
U-100 means the barrel is graduated for a solution containing one hundred units of insulin per millilitre. For anything that is not insulin, the units are simply hundredths of a millilitre.
Adding the measurement that post #33 says would settle it.
Coring the stopper is a real phenomenon with repeated entries at the same point and blunt needles. Varying the entry point slightly and using a fresh needle prevents it.
Filing this under things that are true until someone shows me otherwise.
Two claims get bundled together under filter needles and they need separating. The descriptive one — this is what was observed — is usually well supported. The causal one — this is why — usually is not.
Almost every disagreement in threads like this one dissolves once you say which of the two you are making.
Sharps disposal: needles and syringes should be disposed in a sharps container (a rigid, puncture-resistant container). Do not put them in regular trash. Many pharmacies accept filled sharps containers.
Two people can read the same figure differently here and both be reasonable.
Adding a data point of agreement rather than a data point.
Post #38 is right about the mechanism and I think understates the practical bit.
Filter needles was covered in the wiki last year and the page has a review date on it, which is a better starting point than my memory of a thread.
Needle length for subcutaneous delivery is a question about tissue depth and injection angle together. Short needles at ninety degrees and longer ones at an angle reach comparable depths.
Worth checking against a second source before it gets quoted onward.
On filter needles, I would rather understate and be corrected upward than overstate and be quoted. That is a house style here and it is a good one.
Agreed on all of that, and I have nothing to add to it.
I had written a reply contradicting post #44 and deleted it. Here is what survived.
Needle length: typical lengths for subcutaneous injection are 4-6 mm (short), 8 mm (standard), or 10-12 mm (longer). Longer needles are needed for deeper tissue or if you have abdominal adiposity.
That is all the detail I have. Someone else will have more.
Filing a mild objection to the consensus on filter needles. Mild because I might be wrong; an objection because nobody has addressed the case that does not fit.
The quoted dead-volume figures for common configurations vary between manufacturers and the ordering is stable: fixed needle least, luer with hub more, luer with filter needle most.
Where I part company with post #48, and it is a narrow parting.
Adding a small correction to the filter needles summary above rather than a disagreement with it. The substance holds; one of the figures is out by a factor that matters.
U-100 means the barrel is graduated for a solution containing one hundred units of insulin per millilitre. For anything that is not insulin, the units are simply hundredths of a millilitre.
That distinction has done more work for me than anything else in this category.
This topic was referenced in
- 0.3 mL versus 0.5 mL versus 1 mL barrels: resolution mattersDevices › Syringes & needles · 114 replies
- Reading a syringe in poor light, and how to avoid needing toDevices › Syringes & needles · 2 replies
- Follow-up: Dead volume across syringe and needle combinationsDevices › Syringes & needles · 98 replies
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