I think the 0.3 ml versus 0.5 ml question is answerable and has not been answered, which is a more optimistic position than most of this thread.
On the subject in the title: 0.3 mL versus 0.5 mL versus 1 mL barrels: resolution matters Working notes rather than a conclusion.
A follow-up question about 0.3 ml versus 0.5 ml that I did not know to ask the first time.
The earlier thread answered what I asked. What I should have asked is below, and I think it is the one that matters.
Everything in the opening post holds. The case it does not cover is the one I have.
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.
Small point, but it is the one that usually catches people.
Adding thanks rather than a view. I do not have a view worth the space.
The arithmetic in post #2 is right; the assumption feeding it is the part to check.
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.
Written from notes rather than memory, which is why the numbers are specific.
I think the 0.3 ml versus 0.5 ml question is answerable and has not been answered, which is a more optimistic position than most of this thread.
Where the 0.3 ml versus 0.5 ml reasoning breaks down for me is the step from the group result to the individual case. That step is almost never argued for.
Where I part company with post #4, and it is a narrow parting.
Sharps containers are a legal requirement for disposal in several jurisdictions and a sensible precaution everywhere. A rigid sealed container is the minimum.
On reflection I would soften that slightly.
0.3 ml versus 0.5 ml has been discussed here with more heat than it deserves, mostly because two definitions have been in play the whole time.
Clear enough that I do not think I have a follow-up, which is unusual.
What I would want before treating 0.3 ml versus 0.5 ml as settled: the method, the sample, and whether anyone tried to find the opposite result. Two of the three are usually missing.
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.
I would call that likely rather than established.
Post #11 and I disagree about the size of the effect, not about the direction.
Sharps containers are a legal requirement for disposal in several jurisdictions and a sensible precaution everywhere. A rigid sealed container is the minimum.
The claim is narrower than it sounds, and deliberately so.
Taking post #11 at face value and following it one step further.
Answering the 0.3 ml versus 0.5 ml question as asked, then the question I think is meant. As asked: yes, with the qualification below. As meant: it depends on how the first measurement was taken.
Taking 0.3 ml versus 0.5 ml seriously for a moment rather than deflecting: the honest position is that the community has observations and no controlled comparison, and those two things support very different sentences.
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.
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.
None of the above is medical advice and I am not qualified to give any.
Building on post #15 rather than restating it.
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.
If anyone can point at the primary source I would be grateful.
Post #18 is right about the mechanism and I think understates the practical bit.
Agreed on 0.3 ml versus 0.5 ml, with one qualification that I think matters. The reasoning holds for the case as described. Change the starting assumption and it does not, and the starting assumption is the part nobody states.
What I would tell a new member reading about 0.3 ml versus 0.5 ml for the first time: the confident posts are not the reliable ones, and the reliable ones are longer.
Graduation spacing is worth checking before you buy rather than after. Some 1 mL barrels are marked every two units and some every one, and that changes what doses you can read.
Second-hand, so weight it accordingly.
Adding the measurement that post #20 says would settle it.
The strongest argument against my own position on 0.3 ml versus 0.5 ml, stated as well as I can state it, since nobody else has yet.
Adding a null result on 0.3 ml versus 0.5 ml. I looked, carefully, and found nothing, and null results deserve posting precisely because they never are.
Sharps containers are a legal requirement for disposal in several jurisdictions and a sensible precaution everywhere. A rigid sealed container is the minimum.
I have left out the parts I could not verify.
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.
It is worth checking rather than assuming, which costs nothing.
Building on post #27 rather than restating it.
I would rather this thread reach "we do not know" about 0.3 ml versus 0.5 ml than reach a confident answer that nobody can support when asked.
Post #26 put the caveat in the right place and I want to underline it.
On 0.3 ml versus 0.5 ml, the part that usually goes wrong is that the question is asked as though it has one answer. It has a range, and the width of the range is the interesting bit.
If you can post the two or three numbers you are working from, several people here will check the arithmetic rather than argue about the conclusion.