Fixed versus detachable needles: the trade-offs posts 61–90
This is a continuation of a long topic, addressed by post number rather than by page. Start at post 1 · go to the accepted answer.
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.
post #62 answers the question as asked. The question underneath it is different.
For anyone arriving from a search: the marked solution above is the direct answer, and the replies underneath it add the caveats that make it safe to use.
Aspirating before injection: for subcutaneous injection, aspirating (pulling back on the plunger to check for blood) is not necessary and is sometimes discouraged because it is associated with more discomfort. Subcutaneous injection without aspiration is standard practice.
Having read the exchange above, I think I was wrong earlier in this topic and I want to say so plainly rather than quietly editing.
The correction was fair and I had been repeating something I had not checked carefully enough.
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 separating two things that post #64 runs together.
Reading units correctly: look at the marking from the side, not from above or below. The bottom of the plunger tip is the reading. Parallax error (wrong angle) is a source of dosing error.
Picking up post #66: that is the part I would want checked first.
For anyone arriving from a search: the marked solution above is the direct answer, and the replies underneath it add the caveats that make it safe to use.
Coming back to post #68, because the follow-up matters more than the original answer.
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.
Insulin syringe graduations: U-100 syringes are marked in units where 100 units = 1 mL. Always confirm your syringe is U-100. Confusion between insulin units and milligrams is the most common syringe error.
post #71 answers the question as asked. The question underneath it is different.
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.
Coming back to post #71, 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.
Worth separating two things that post #71 runs together.
Practical note that does not fit anywhere else. Whatever you conclude from this topic, write down what you did and when. The single most useful thing in your own records is not any individual result; it is that they are dated and consecutive.
post #75 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.
Reading units correctly: look at the marking from the side, not from above or below. The bottom of the plunger tip is the reading. Parallax error (wrong angle) is a source of dosing error.
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.
Thank you for the correction. I have edited my earlier post with a note rather than silently, so the thread still makes sense to read. The error was mine and it was the kind that comes from remembering a figure instead of looking it up.
Aspirating before injection: for subcutaneous injection, aspirating (pulling back on the plunger to check for blood) is not necessary and is sometimes discouraged because it is associated with more discomfort. Subcutaneous injection without aspiration is standard practice.
On post #78 — agreed on the reasoning, with one qualification.
Two things before anyone answers the substance.
First, the context in the first post is clear and specific. Second, the question is framed so that an answer can actually address it. Both are the norm here and both matter more than they sound.
Collapsed as off-topic by two members at trust level 3 or above
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.
post #84 is right about the mechanism and I think understates the practical bit.
Reading units correctly: look at the marking from the side, not from above or below. The bottom of the plunger tip is the reading. Parallax error (wrong angle) is a source of dosing error.
Worth separating two things that post #82 runs together.
Aspirating before injection: for subcutaneous injection, aspirating (pulling back on the plunger to check for blood) is not necessary and is sometimes discouraged because it is associated with more discomfort. Subcutaneous injection without aspiration is standard practice.
Syringe barrel size: common sizes are 0.3 mL, 0.5 mL, and 1.0 mL. Smaller barrels are more legible for small doses. Larger barrels hold larger volumes. Choose based on your dose.
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.