Emergency Procedure: Lumbar Puncture
There’s only on place to start for our regular procedures post.
This core skill is worth knowing inside out. You need the confidence to put the patient at ease and perform it well.
Detailed written instructions and explanation are available in our Free App (iOS and Android). This video is hot off the press and we want your help improving it. Drop us a line with any suggestions
So, without further ado…here is the video
Why do you prefer performing an LP in the seated position?
We prefer the seated position as it improves success rate. Rotation of the back is minimised, as is sideways curvature of the spine from the patient sinking into the mattress.
If the patient has a reduced GCS or is not well enough to sit up safely, the lying position is required.
But I won’t be able to measure opening pressure with the patient seated, is that ok?
Yes, we suggest measuring opening pressure is not routinely required in ED.
The emergency indications for LP are suspected sub arachnoid haemorrhage or meningoencephalitis. These conditions raise ICP, but the diagnosis is not based on this variable and a raised CSF pressure (20cm water) does not affect our treatment.
Measuring opening pressure requires a lying position and a larger (22G) needle which are associated with higher failure rates and complications.
We prefer to elect the higher success and reduced complications of recommending the sitting position with a smaller (25G) needle.
In unusual circumstances where yourself or an admitting team require an opening pressure (e.g., assessing for benign intracranial hypertension) you should use the lying position and a 22G needle.
Why do you recommend a pencil point needle + a larger cutting needle introducer?
Pencil point needles have lower complication rates and allow the sensation of a pop or give as we pass ligamentum flavum and the dura, giving us tactile feedback. They are however not sharp enough to easily piece the skin hence a sharp introducer is used to pass skin and set needle angle.
Do I need to reinsert the stylet for minor adjustments of the LP needle?
Traditionally the stylet was reinserted to reduce the rare risk of seeding epithelial cells into deep tissues with risk of epidermoid tumours. This could occur with the bigger cutting needles with no stylet used in the past.
Having used an introducer needle to pass through the skin and soft tissue as well as using smaller pencil point needle, we do not have to worry about this complication. Insert your LP needle with stylet into the introducer needle and have one pass, if on removing the stylet no CSF is seen, you can adjust the LP needle until CSF is seen without reinserting the stylet.
How should I consent someone for a lumbar puncture?
For patient with capacity, the clinician needs to provide information to allow the patient to make an informed decision.
The clinician should explain the benefits, possible adverse effects, complications, alternatives, and the likely result if the procedure is not performed. Ideally the patient should be provided with written information and given time to reflect and ask questions.
An LP has potentially serious complications (e.g. Epidural Haematoma). Although consent is a process rather than a signature, documenting written consent for procedures with significant risk can be useful to record that the process has been completed.
What PPE to I need to perform a lumbar puncture?
The standard of care for all procedures in the hospital is aseptic non-touch technique. This means sterile equipment should not be touched and should be inserted through disinfected skin.
For a lumbar puncture sterile gloves and a large sterile field are required as we manipulate multiple sterile pieces of equipment (needles, manometer, tubes) without our hands and need space to work.
We are standing close to our sterile field and a sterile gown is recommended to protect the equipment from a touching the body.
Respiratory droplets from the clinician are a common cause of needle contamination and so a mask is additionally required.
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Dr James Miers BSc BMBS (Hons) FACEM, Staff Specialist Emergency Medicine, Prince of Wales Hospital. Lead author of Lead author of Emergency Procedures App | Twitter |
Dr John Mackenzie MBChB FACEM Dip MSM. Staff Specialist Emergency Prince of Wales Hospital; Consultant Hyperbaric Therapy POW HBU. Lead author of Emergency Procedures App | Twitter | Linkedin |
MBBS FACEM Staff Specialist, Prince of Wales Hospital. Medical education enthusiast.