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Devices · Syringes & needles · continued

Follow-up: Dead volume across syringe and needle combinations 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.

CI
citation_indexTL2Member6 Nov 2024#61

Coming back to post #59, because the follow-up matters more than the original answer.

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.

0 likes 21mo
PF
p.fontaineTL2 Moderator8 Nov 2024#62

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.

18 likes 21mo
B
BirkelandTL3Regular10 Nov 2024#63
aliquot_line, post #16: 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. Go to post

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.

4 likes in reply to #16 21mo
VR
v.rautioTL2 Moderator12 Nov 2024#64
n.ekstrom, post #2: 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. Go to post

post #63 answers the question as asked. The question underneath it is different.

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.

0 likes in reply to #2 20mo
K
KStephanopoulosTL3Regular14 Nov 2024#65

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.

0 likes 20mo
AK
ar.kravchenkoTL2 Moderator16 Nov 2024#66

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.

25 likes 20mo
FE
footnote_entryTL3Regular17 Nov 2024 · edited#67

Worth separating two things that post #63 runs together.

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.

7 likes 20mo
MO
m.oyelaranTL2 Moderator19 Nov 2024#68
e.roos, post #9: I read post #7 twice before replying, because I had assumed the opposite. 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. Go to post

post #67 is right about the mechanism and I think understates the practical bit.

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.

1 like in reply to #9 20mo
BP
bench_peakTL3Regular21 Nov 2024#69

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.

0 likes 20mo
RC
r.coelhoTL2 Moderator23 Nov 2024#70

Picking up post #67: that is the part I would want checked first.

I disagree with the reply above, and I think the disagreement is substantive rather than terminological.

The distinction being drawn does not survive when you look at the published data for this specific question. I would be glad to be shown wrong on this, because the version I am arguing against is more convenient.

0 likes 20mo
SS
system_suitabilityTL3Analytical chemist25 Nov 2024#71
n.rowntree, post #58: Worth separating two things that post #54 runs together. 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. Go to post

post #70 is right about the mechanism and I think understates the practical bit.

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.

0 likes in reply to #58 20mo
NI
n.ibarraTL2 Moderator27 Nov 2024#72

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.

2 likes 20mo
KO
k.otieno_statsTL3Statistician28 Nov 2024#73

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.

13 likes 20mo
ES
e.steinerTL2 Moderator30 Nov 2024#74

I read post #72 twice before replying, because I had assumed the opposite.

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.

27 likes 20mo
QZ
q.zhao_qaTL3Quality assurance2 Dec 2024#75
bench_peak, post #69: 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. Go to post

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.

0 likes in reply to #69 20mo
IL
i.lehtinenTL2 Moderator4 Dec 2024#76

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.

0 likes 20mo
UC
unit_conversionTL3Regular6 Dec 2024#77

Picking up post #74: that is the part I would want checked first.

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.

8 likes 20mo
MB
m.balogunTL2 Moderator7 Dec 2024#78

Coming back to post #76, because the follow-up matters more than the original answer.

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.

20 likes 20mo
PN
p.novotnyTL2Regular9 Dec 2024#79

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.

2 likes 20mo
FH
f.haddadTL2 Moderator11 Dec 2024 · edited#80

Worth separating two things that post #76 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.

8 likes 20mo
PF
p.fontaineTL2 Moderator13 Dec 2024#81

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.

0 likes 19mo
B
BirkelandTL315 Dec 2024#82
MO
m.oyelaranTL2 Moderator16 Dec 2024#83
k.marchand, post #17: post #16 answers the question as asked. The question underneath it is different. 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. Go to post

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.

20 likes in reply to #17 19mo
NR
n.rowntreeTL3Regular18 Dec 2024#84

This follows post #81 rather than contradicting it.

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.

9 likes 19mo
GA
g.amankwahTL2 Moderator20 Dec 2024#85

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.

2 likes 19mo
OF
outline_firstTL3Wiki editor22 Dec 2024 · edited#86
k.kuusela, post #55: 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. Go to post

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.

0 likes in reply to #55 19mo
DB
da.bakkerTL2 Moderator23 Dec 2024#87

Coming back to post #85, 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.

28 likes 19mo
CT
cannula_traceTL3Regular25 Dec 2024#88

Picking up post #85: that is the part I would want checked first.

I disagree with the reply above, and I think the disagreement is substantive rather than terminological.

The distinction being drawn does not survive when you look at the published data for this specific question. I would be glad to be shown wrong on this, because the version I am arguing against is more convenient.

13 likes 19mo
IB
i.boatengTL2 Moderator27 Dec 2024#89

Worth separating two things that post #85 runs together.

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.

0 likes 19mo
SS
steady_stateTL3Regular29 Dec 2024#90
footnote_entry, post #67: Worth separating two things that post #63 runs together. 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. Go to post

post #89 is right about the mechanism and I think understates the practical bit.

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.

21 likes in reply to #67 19mo