Ultrasound capsules
Echo-guided lumbar puncture
***There are several ways to perform an echo-spotted PL, here I present my way...
For what?
- To identify the midline
- To identify spinous processes that are difficult to palpate
- To reduce the total time of the technique (!)
- To reduce the number of needle redirections and the number of spaces attempted .
A little literature
Technique - summary
1) Position the patient to perform the lumbar puncture --> once the marking is done --> Statue!
2) First identify the sacrum in transverse or sagittal orientation
I prefer transverse
3) Identify the midline below L5 and cephalad at L3 (black Sharpie)
4) Identify the spinous process L5, L4 and L3 (black Sharpie)
- Steps 3 and 4 are interchangeable in order
5) Place the ultrasound, disinfect with chlorhexidine and perform your lumbar puncture!
Exemple de résultat
Technique - Step by Step
1) Choice of probe
Linear = Prioritize for patients of small or medium size. (Spinous process less than 4-5cm deep)
PREFERRED! High resolution makes it easier to identify landmarks.
Curvilinear = Prioritize for obese patients with spinous process more than 4-5 cm deep.
Since the technique is not sterile, you can easily change probes during the survey to adjust!
2) Preparation and positioning
Preparation: Before you begin your survey, you must be ready to perform your lumbar puncture and the equipment should be at the bedside +/- have an assistant who has already started to open the tray and prepare the tubes, lido, etc...
For skin marking, you will need to use a Sharpie! ... A pen will be erased by chlorhexidine...
You will also need a towel to wipe the gel off the skin where you will be using your Sharpie.
Positioning: The patient must be positioned exactly in the position in which you will perform the lumbar puncture. Whether sitting or lying down. The back must already be in the "cat position" and optimized. Once the marking is done, THE PATIENT MUST NOT MOVE. Otherwise, the fat pad, the apophyses, and all your work will move and your landmarks will be incorrect.
3) Identify the sacrum
Are you confident you're at the right height? You can skip this section and go directly to the section on identifying spinous processes.
To identify the sacrum, you can do it transversely or sagittally.
My personal preference is to identify it transversely.
The advantage of the sagittal view is the rapid identification of L5 but requires it to be perfectly aligned... which can be more than difficult!
The sacrum will have the classic bone characteristics: a hyperechoic line followed by a shadow cone.
The sacrum is very long and very wide, so it is generally easily identifiable on ultrasound. Its bony structure will be that of a line with multiple small bumps.
Sacrum
Sagittal view
Cross-sectional view
(2 types of images classically identify the sacrum)
1
2
1 -->
2 -->
4) Identify the spinous processes and the midline
Going up from the sacrum the first spinous process will be L5 then L4 then L3 (duh)
The objective is therefore to mark their height precisely.
You can do this sagittally or transversely.
Sagittal :
Advantage: Allows you to see multiple processes at the same time. Simply activate the M-mode line without activating M-mode (creates a median line) and center the desired process to make the marking.
Disadvantage: The spinous processes are very thin. If you slip, you will lose your vision.
L4
L5
L4
L5
*** ici l'espace inter-épineux est centré à l'écran. Je préfère personnellement centrer les apophyses épineuses et marquer celles-ci que de marquer l'espace inter-épineux. Par contre, les deux options sont bonnes.
Transverse:
- Advantage: allows you to easily find the spinous process even if your probe is not entirely centered on the midline. When the spinous process is centered on the screen (M mode line again here) --> you can also immediately indicate the midline.
Disadvantage: Since the spinous processes are very thin, it can be easier to miss the famous bony landmark when deep.
L5
L5
Apophyse transverse
Transverse process
5) Ranger la sonde, désinfecter et effectuer votre PL!
There you go! Now that you've identified your landmarks... you can perform your PL with exactly the same technique you would normally use!
The only difference is that you "see/imagine" your apophyses instead of feeling them.
Congratulations! Your consultants will breathe a sigh of relief at your success.