Revisiting: Filter needles: when they help and what they cost you — setting out what I have, and where I think it stops being reliable.
Trying to work out what would count as evidence on Filter needles, before collecting any. This is the part I usually skip and it is the part that makes the rest useful.
If two explanations predict the same observation, observing it does not help. So: what observation would separate them?
What I would want before treating Filter needles as settled: the method, the sample, and whether anyone tried to find the opposite result. Two of the three are usually missing.
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.
A single observation, in a thread that deserves better than single observations.
Building on post #3 rather than restating it.
Safety-engineered needles are worth using if you have children or anyone else in the house, and the retraction mechanism occupies dead volume that ordinary syringes do not.
I would be glad to be shown a cleaner way of putting this.
Answering the question post #3 raises rather than the one it answers.
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.
I checked the source rather than the summary, and they differ.
Sharps containers are a legal requirement for disposal in several jurisdictions and a sensible precaution everywhere. A rigid sealed container is the minimum.
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.
That is what the documentation says. What happens in practice is usually close.
Post #8 is right about the mechanism and I think understates the practical bit.
Needle gauge: smaller numbers (30G) are finer and less painful. Larger numbers (25G) are courser. For subcutaneous injection, 27-30G is typical. Finer needles take longer to draw up but hurt less.
Where I would look next, rather than where I would stop.
Gauge is the outside diameter and higher numbers are thinner. Thinner needles hurt less and draw more slowly, which is the entire trade.
Everything in post #10 holds. The case it does not cover is the one I have.
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.
Building on post #12 rather than restating it.
An update on my earlier Filter needles post: the pattern held for another six weeks and then stopped, which I did not predict and cannot explain.
This is the sort of exchange that makes the archive worth searching.
Answering the question post #14 raises rather than the one it answers.
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 put this at better than even and not much better.
An honest declaration on Filter needles: I have a prior here and it is strong enough that you should weight what I say downward. Stating it rather than hiding it.
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.
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.
The confident version of this sentence would be wrong, so here is the hedged 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.
Worth reading the earlier posts in this thread before acting on mine.
Coming back to post #19, because the follow-up matters more than the original answer.
Answering the Filter needles 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.
On Filter needles: the maintained page in the documentation commons covers the general case with citations and a review date, which is more reliable than any reply here including this one.
Sharps containers are a legal requirement for disposal in several jurisdictions and a sensible precaution everywhere. A rigid sealed container is the minimum.
The mechanism is plausible, which is not the same as established.
This follows post #23 rather than contradicting it.
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.
I am not the right person to answer the follow-up to this.
Fair, and the limits you put on it are the part I will remember.
Post #26 and I disagree about the size of the effect, not about the direction.
Agreed on Filter needles, 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.
Taking post #29 at face value and following it one step further.
If someone has run Filter needles properly I would rather read that than my own reconstruction of it. Posting mine only because the thread has gone quiet.