That is the distinction I keep failing to hold on to. Written down now.
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Devices · Syringes & needles · continued
0.3 mL versus 0.5 mL versus 1 mL barrels: resolution matters posts 91–115
This is a continuation of a long topic, addressed by post number rather than by page. Start at post 1.
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 short version is the first sentence; the rest is why.
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v.rautio, post #3: Where I part company with the opening post, and it is a narrow parting. 0.3 ml versus 0.5 ml 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. Go to post
Answering the question post #90 raises rather than the one it answers.
On 0.3 ml versus 0.5 ml I would separate what is worth knowing from what is worth acting on. The first list is long and the second is short, and conflating them is how threads get heated.
cohort_watch, post #33: Checked the 0.3 ml versus 0.5 ml claim against the primary source this morning. It survives, with a narrower scope than the version quoted here. Posting the narrower scope. Go to post
Genuine question rather than a rhetorical one: has anyone here actually observed 0.3 ml versus 0.5 ml, as opposed to read about it? The thread is long and I cannot tell.
I have no financial interest in anything named in this thread and I want to say so before I comment on 0.3 ml versus 0.5 ml, because it is the sort of subject where it matters.
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r.jhannsdttir, post #13: Since 0.3 ml versus 0.5 ml keeps coming up, it should probably be a maintained page rather than a recurring thread. I am happy to draft it if someone with more direct experience will review it. Go to post
Post #94 describes the usual case. This is about the unusual one.
Dead volume: residual liquid in the hub and needle after withdrawal. Typical residual is 0.01 to 0.02 mL for an insulin syringe with a fixed needle. Accounting for it matters if precision matters.
Adding this to the thread rather than to the wiki, because I am not confident enough for the wiki.
peak_purity, post #45: Sharps containers are a legal requirement for disposal in several jurisdictions and a sensible precaution everywhere. A rigid sealed container is the minimum. That is all I can say without guessing. Go to post
This follows post #96 rather than contradicting it.
Reporting rather than recommending, on 0.3 ml versus 0.5 ml. What happened is above. Whether it should have is a different question and not one I am qualified to answer.
Post #98 is the version of this I will quote in future. One addition.
0.3 ml versus 0.5 ml has a well-known answer and a correct answer, and the interesting work is establishing that they are the same. Nobody has done that here yet.
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r.coelho, post #9: Two sentences on 0.3 ml versus 0.5 ml and then I will stop, because the rest is speculation and the thread is better without mine. What is documented is narrow. What is inferred from it is broad. The gap between them is where every argument here lives. Go to post
Reframing 0.3 ml versus 0.5 ml slightly, because I think the disagreement is about the question rather than the answer. If the question is "does it happen", yes. If it is "how often", nobody here knows.
a.coelho, post #32: Coming back to post #28, because the follow-up matters more than the original answer. 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. Reporting the observation and leaving the explanation open… Go to post
Post #101 describes the usual case. This is about the unusual one.
Fixed versus detachable needles: insulin syringes usually have fixed needles (no dead volume loss to the hub). Luer-lock syringes use detachable needles (more dead volume). Fixed needles are preferred for small doses.
I would treat that as a working assumption and revisit it.
That is a cleaner way of putting what I was circling around.
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ak.kravchenko, post #20: 0.3 ml versus 0.5 ml is a question about a distribution, not about a value, and treating it as a value is what produces the confident wrong answers. Go to post
Picking up post #106: that is the part I would want checked first.
Barrel size determines resolution and nothing else. A 0.3 mL barrel and a 1 mL barrel deliver the same volume equally well; the smaller one lets you see what you are delivering.
Noting that the question and the thing people usually mean by it are different.
Coming back to post #108, because the follow-up matters more than the original answer.
Dead volume: residual liquid in the hub and needle after withdrawal. Typical residual is 0.01 to 0.02 mL for an insulin syringe with a fixed needle. Accounting for it matters if precision matters.
That is what I would do. It may not be what is correct.
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batchlog, post #103: Reframing 0.3 ml versus 0.5 ml slightly, because I think the disagreement is about the question rather than the answer. If the question is "does it happen", yes. If it is "how often", nobody here knows. Go to post
Post #111 is right about the mechanism and I think understates the practical bit.
Practical answer on 0.3 ml versus 0.5 ml, since the theoretical one is upthread: do the simplest check first, write down the result, and only then decide whether the complicated explanation is needed. It usually is not.
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.
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I read post #111 twice before replying, because I had assumed the opposite.
Reading the barrel at eye level matters more than any equipment choice. Parallax at a shallow angle is enough to shift a reading by a graduation.
One more caveat and then I will stop qualifying: the sample selected itself.
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- About the Syringes & needles categoryDevices › Syringes & needles · 4 replies
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