This is a continuation of a long topic, addressed by post number rather than by page. Start at post 1.
Coming back to post #59, because the follow-up matters more than the original answer.
Adding a reference point for 0.3 ml versus 0.5 ml. Mine is a single case, collected without controls, and I am posting the method alongside it so it can be discounted appropriately.
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.
If anyone can point at the primary source I would be grateful.
This is the first time the answer has come with its own limits attached. Appreciated.
This follows post #61 rather than contradicting it.
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.
The honest answer is that it depends, and here is what it depends on.
I had written a reply contradicting post #64 and deleted it. Here is what survived.
The version of 0.3 ml versus 0.5 ml that circulates here is a simplification of a simplification. It is not wrong, but it has lost the conditions under which it holds, and those conditions are where the interesting cases live.
Confirming post #64 from a second method, which matters more than confirming it from a second person.
Two people in this thread mean different things by 0.3 ml versus 0.5 ml and are disagreeing about the definition while believing they are disagreeing about the facts. Worth pausing to define it.
A detachable luer needle plus hub can retain enough volume to matter. Whether it matters to you depends on your dose, and the arithmetic is worth doing once.
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.
Counterpoint on 0.3 ml versus 0.5 ml, offered without confidence: the same observation is consistent with a much duller explanation, and nobody has ruled the dull one out.
A definition problem is doing most of the work in this 0.3 ml versus 0.5 ml discussion. Once the term is pinned down I suspect the disagreement mostly goes away and what is left is small.
Where I part company with post #68, and it is a narrow parting.
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 has been true for the cases I have seen and I have not seen many.
What I would check first on 0.3 ml versus 0.5 ml is whether the thing being measured moved or whether the way of measuring it moved. Those look identical in a graph.
Filing a mild objection to the consensus on 0.3 ml versus 0.5 ml. Mild because I might be wrong; an objection because nobody has addressed the case that does not fit.
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.
My understanding of 0.3 ml versus 0.5 ml is a few years old and may have been superseded. If it has been, I would genuinely like to know rather than keep repeating it.
Same experience here, different supplier, so it is at least not unique to one of them.
Post #77 is right about the mechanism and I think understates the practical bit.
Sharps containers are a legal requirement for disposal in several jurisdictions and a sensible precaution everywhere. A rigid sealed container is the minimum.
Practical note on 0.3 ml versus 0.5 ml: write down what you expect before you look. The number of times I have found what I went looking for is higher than chance would allow.
Post #81 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.
That is a description of practice, not a recommendation of it.
Sharps containers are a legal requirement for disposal in several jurisdictions and a sensible precaution everywhere. A rigid sealed container is the minimum.
A modest claim, modestly supported.
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.
Reading back through, this was answered upthread and I missed it. My fault.
Picking up post #85: that is the part I would want checked first.
Two things can be true about 0.3 ml versus 0.5 ml at once: the mechanism is plausible and the evidence for the size of the effect is thin. Most of the argument here is people defending the first against attacks on the second.
Post #85 put the caveat in the right place and I want to underline it.
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.
Somebody will have a better source than mine, and I hope they post it.
Building on post #88 rather than restating it.
Sharps containers are a legal requirement for disposal in several jurisdictions and a sensible precaution everywhere. A rigid sealed container is the minimum.
It is a small point and it changes the answer, which is an awkward combination.