Performing LP with a 10 cc syringe and 21G needle

[prolene60]

Do you really need the stylet and spinal needle to perform an LP. Why can't you just use the sterile syringe in the kit and the needle and then just aspirate. I feel like I've almost missed some LP's because I thought I wasn't in the correct space but actually the fluid is just coming out extremely slow. It seems like performing gentle continuous aspiration(Like with a central line) would let you know immediately when you're in the space as well as get the fluid faster. I haven't tried it yet. Any thoughts? Also if this is not recommended do you guys have any hidden tricks to make this a 100% successful procedure?

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[RPedigo]

I would never exert negative pressure in the CSF, just because of the actual or theoretical (not sure anyone's ever tested it, so not sure which of the two it is) risk of herniation. I don't think there is any trick to give you a 100% successful procedure, but position, position, position has been the most helpful for me. Ensuring the patient is not rotated helps with anatomic midline; ensuring that the patient is maximally flexed at the hips/low back helps open the interspaces (cranking their neck down is probably not helpful since it usually doesn't exert significant flexion on the lumbar spine and may increase risk of apnea in kids); if opening pressure is not measured you can have them sit up and lean over a table (and you can also carefully lay them down after getting CSF if you need an opening pressure). Also, if the patient is dehydrated, rehydrate them before you attempt lumbar puncture as the success rate will be higher. Give anxiolysis if needed to ensure the patient can cooperate (e.g., in kids 0.3 mg/kg intranasal midazolam, etc.) and make the procedure easier for both of you. Ensure your needle is of appropriate length for the patient's body habitus.

If the lumbar puncture really, really needs to be done and fluoroscopic lumbar puncture is not readily available, ultrasound is actually helpful. Sterile ultrasound probe cover, transverse and longitudinal images will give you anatomic midline and the interspace, respectively, and then make your markings and go in.

 

[Libertas]

21g dural puncture? So you'll diagnose one headache, and replace it with another?

 

[Birdstrike]

Do you really need the stylet and spinal needle to perform an LP. Why can't you just use the sterile syringe in the kit and the needle and then just aspirate. I feel like I've almost missed some LP's because I thought I wasn't in the correct space but actually the fluid is just coming out extremely slow. It seems like performing gentle continuous aspiration(Like with a central line) would let you know immediately when you're in the space as well as get the fluid faster. I haven't tried it yet. Any thoughts? Also if this is not recommended do you guys have any hidden tricks to make this a 100% successful procedure?

1-First of all, no procedure in Medicine is 100% successful.

2-You absolutely can be intrathecal without any CSF, but more often than not it's because your needle tip is either up against dura, a nerve root or clogged with tissue (dura, scar tissue, whatever). Aspirating is not going to help if you're just sucking nerve root or dura up onto your needle tip. If you are intrathecal, with a reasonably sized needle, there should be enough CSF pressure to see fluid within a reasonable time frame. If you don't don't see fluid, chances are you need to re-insert stylet to clear the needle tip, rotate the needle tip, or redirect your needle tip to a better position, ie, intrathecal. On the other hand, I've never heard of anyone herniating from the aspiration of 0.1 or 0.2 ml of CSF.

3-Learn the paramedian approach for difficult LPs. It allows a much larger target and avoids the spinous processes altogether, which it what you're getting hung up on more often than not, if going midline. This space can be extremely small on a patient with suboptimal positioning or a degenerated spine.

http://www.pitt.edu/~regional/Epidural/epiduralinsertion.jpg

"When difficulties with needle insertion are encountered with the midline approach, one option is to use the paramedian route, which does not require the same level of patient cooperation or reversal of lumbar lordosis for success....The paramedian approach exploits the larger “subarachnoid target” that exists if a needle is inserted slightly lateral to the midline (see Fig. 42–13)"

http://web.squ.edu.om/med-Lib/MED_CD/E_CDs/anesthesia/site/content/v03/030645r00.HTM


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[Tiger26]

I used to struggle with LPs until one day as an intern when I was gloved up, made one attempt as my attending promised to come in to supervise, and then was nowhere to be found, so I had to troubleshoot on my own.

Things that work for me:
-Positioning is key: if possible I have them sit upright, which keeps everything midline. Practice with sitting and lying down, but for difficult ones, just do it sitting up. Always make sure that you're sitting--I still see interns standing and trying to lean over to do these
-Landmarks are key: palpate the entire spine and iliac crests. I always carry a sharpie, so I mark their entire spine and the iliacs, so I have good sense of anatomy and where to go to troubleshoot
-As long as you're midline, if you think you've gone to far but don't have fluid, then you simply haven't gone far enough. Your area of interest is deceptively deep.
-Use more lido than comes in the kit: I routinely use 6-8cc and aspirate/inject all the way: makes patients comfortable and I think it spreads some of the fibers to make the LP easier (pure conjecture)
-Practice with small needles like 22g pencil tip ones: lowers headache risk

 

[WilcoWorld]

I'm no LP expert, but applying the 4 following principles has dramatically improved my success with almost all procedures:

1 - Positioning: Get the patient/bed in the optimal position
2- Positioning: Get yourself/lighting in the optimal position
3- Positioning: Get disruptive family & friends out of the room
4- Adequate anesthesia: See Tiger26's post and use sedation when necessary/safe

 

[Venko]

I think the advice here from bird strike, and Tiger is marvelous.

I would also add, that before you start if you prepare the patient and family for the following possibilities and what you will do when they occur it can lift some of your stress, and make the conversation after unsuccessful attempt easier.
- may not be able to get it, will have two other providers try, if they can't get it will stop and arrange fluoro
- may be bloody, which makes the diagnosis of SAH uncertain regardless of trend unless there is zero in the last tube. May need follow up CTA or MRI
- may try sitting up as well as laying down.

 

[Khaos]

I'm going to agree with Wilcoworld and tiger26. The biggest thing you can do for yourself is prep. Make sure everything is ready, the patient is as comfortable as possible, and anything that could distract you is gone. Always make it easier on you. Position them as best you can, if they aren't helping much, have a nurse help them. Anesthesize the heck out of the area. I have the nurse bring a 10ml bottle of lido with epi and use that instead of what's in the kit and then just douse the area.

I tell every patient that to me the LP is the most humbling procedure of them all. You never know what you are going to get trying to get an LP. I've explained that sometimes when I believe it will be the easiest it turns out to be the hardest and visa versa. I set it up for failure and they love me when everything goes well.

I know it is rare but the idea of a epidermoid cyst after lumbar puncture secondary to using a needle that does not have an insertion in it is what prevents me from doing the 21 ga and 10 ml syringe. However, studies have shown that once you puncture the skin you can remove the insertion without fear. Also, you can use the 22 ga whitacre needle which has been show to reduce the post HA.

 

[Tiger26]

I'm going to agree with Wilcoworld and tiger26. The biggest thing you can do for yourself is prep. Make sure everything is ready, the patient is as comfortable as possible, and anything that could distract you is gone. Always make it easier on you. Position them as best you can, if they aren't helping much, have a nurse help them. Anesthesize the heck out of the area. I have the nurse bring a 10ml bottle of lido with epi and use that instead of what's in the kit and then just douse the area.

I tell every patient that to me the LP is the most humbling procedure of them all. You never know what you are going to get trying to get an LP. I've explained that sometimes when I believe it will be the easiest it turns out to be the hardest and visa versa. I set it up for failure and they love me when everything goes well.

I know it is rare but the idea of a epidermoid cyst after lumbar puncture secondary to using a needle that does not have an insertion in it is what prevents me from doing the 21 ga and 10 ml syringe. However, studies have shown that once you puncture the skin you can remove the insertion without fear. Also, you can use the 22 ga whitacre needle which has been show to reduce the post HA.

Agree with Khaos, though I apply it to a lot of the areas of our job

Satisfaction = Result divided by expectations

 

[EvoDevo]

I'll agree with what everyone else has said.

- It's positioning, positioning, and even more positioning (self, patients, lights, tray/materials).
- Don't be afraid to triple and quadruple check your landmarks.
- Don't let anyone talk you out of procedural sedation (parents, RNs) if in your estimation that is what's going to be required for a clean, 1-2 attempt procedure. Every SINGLE time that I've allowed myself to be talked out of sedation has been a straight up nightmare for everyone involved.

- Always have your backup plan(s) in place:
* I almost always start with LLD (it's where I'm best). Allow myself 2 tries from this position (with optimal pt positioning)
* Move to seated
* paraspinal approach

- Expectation management: I tell the patient/family that we want to maximize success but that there aren't any guarantees.
Remember, if you have thought ahead and explain to pt/family that if X doesn't work then we're moving to Y (and maybe Z) then you come off as confident, experienced, and it definitely lessens everyone's anxiety.

- Liberal lido
- 21g or 22g whitacre needle

*** And this is the key for me: have a CRYSTAL CLEAR mental picture of the anatomy and what you should be seeing if you only had xray/superhero vision. I find that this really helps with first pass success and when you're trying to troubleshoot.

** the dura is always a little deeper than you think it will be.

Good luck!

Edited to add :AFAIK I have yet to have a pt bounce back with a post lp headache, though I realize that they may have gone somewhere else.

 

[Fiddlergirl]

** the dura is always a little deeper than you think it will be.

I used to miss a lot of LPs because I would get nervous about being "too deep." These days, if I know I'm midline I hub the needle looking for CSF. A couple of times I've thought for sure I was off midline and I just needed to go a little farther!

 

[Old_Mil]

Do you really need the stylet and spinal needle to perform an LP. Why can't you just use the sterile syringe in the kit and the needle and then just aspirate.

The stylet is what prevents the needle from being clogged on the way in.

Ultrasound is what has helped me the most. I don't even bother with the sterile aspect of it, just position the patient and have nursing make sure they don't move, then identify and mark the spinous processes in two axes with a skin marking pen, then clean and go between the marks.

 

[bartleby]

The stylet is a crucial part of needle insertion in an LP -- inserting the needle without the stylet in place is thought to drag skin cells deep along the needle track and create the risk of an epidermoid tumor. Note, however, that once your needle tip is in the deeper issue spaces that the stylet does not need to be in place as you puncture the dura. This can be particularly useful in neonatal LPs as you get CSF back when you enter the space without the stylet in place, since going too deep can contribute to a bloody tap.

There is some evidence that reinserting the stylet can reduce the risk of post LP headache by avoiding the potential to drag bits of the arachnoid membrane through the opening, thus promoting ongoing CSF leak.

Agree with others about NOT aspirating while performing an LP.