Fixed versus detachable needles: the trade-offs posts 91–120

Everything in post #101 holds. The case it does not cover is the one I have.

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.

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.

Whatever the answer on fixed versus detachable needles turns out to be, the method for getting there is the same: state the assumption, do the arithmetic in public, invite the correction.

Taking post #105 at face value and following it one step further.

On fixed versus detachable 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.

Understood. Thank you for being specific about the limits of it.

Post #108 answers the question as asked. The question underneath it is different.

Sharps containers are a legal requirement for disposal in several jurisdictions and a sensible precaution everywhere. A rigid sealed container is the minimum.

It took me longer than it should have to see that.

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.

On fixed versus detachable needles, 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.

Taking post #112 at face value and following it one step further.

Two claims get bundled together under fixed versus detachable 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.

Thank you for the correction. I would rather find out here than later.

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.

Where I would look next, rather than where I would stop.

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.

That much is documented. The rest is how I have interpreted it.

This follows post #116 rather than contradicting it.

Fixed versus detachable needles has been discussed here with more heat than it deserves, mostly because two definitions have been in play the whole time.

Worth separating two things that post #115 runs together.

The most useful thing anyone has posted about fixed versus detachable needles in this category was a table of what had been measured and by whom. That is what I would want again.

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.

The confident version of this sentence would be wrong, so here is the hedged one.