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Microbiology - Lumbar puncture

Indications

CNS infection suspected (meningitis, encephalitis)

Or

Subarachnoid haemorrhage suspected (12 hours post headache onset and after normal CT brain)

Contraindications (absolute in bold)

Coagulopathy (inherited or platelets <50, INR >1.5, heparin, warfarin, NOAC use)

Suspected elevated ICP (reduced level of consciousness, papilloedema)

Haemodynamic instability

Trauma to lumbar vertebrae

Overlying skin infection

Alternatives

Defer lumbar puncture (without delay in clinical treatment)

CT angiogram in suspected subarachnoid haemorrhage (identify aneurysms)

Informed consent

Medical emergency

Consent is not required if the patient lacks capacity or is unable to consent

Brief verbal discussion is recommended if the situation allows

or

Written consent

More complex non-emergency procedure with higher risk of complications

Potential complications

Failure to obtain CSF

Back pain and radicular pain (20%)

Headache (20% with 22g needle)

Bleeding (epidural or soft tissue haematoma)

Infection (meningitis, epidural abscess, discitis, osteomyelitis)

Nerve damage

Epidermoid tumours

Cerebral herniation

Procedural hygiene

Standard precautions

Aseptic non-touch technique

PPE: sterile gloves, sterile gown, surgical mask

Area

Monitored bed space

Staff

Procedural clinician and assistant

Equipment

Atraumatic spinal needle 90mm (Sprotte or Whitacre), 22g if measuring opening pressure, 23-25g otherwise)

Longer spinal needle (BMI 25-35 likely to require 120mm needle, BMI >35 likely to require 150mm needle)

Lumbar puncture set (manometer, three-way stopcock Luer lock, 3-4 collecting tubes)

Consider ultrasound (to measure depth of ligamentum flavum and guide needle)

Positioning sitting

Patient leans forward, hugging a pillow over a table adjusted to flex the back

Lift the patient’s legs by putting their feet on a stool or chair and flex the hips to above 90 degrees

Opening pressure cannot be measured in the sitting position.

Positioning lying down

Position patient lying on their side with their back at the edge of the bed

Ensure the vertical plane of the patient’s back is perpendicular to the bed

Flex knees and hips so that knees are close to the chest (neck flexion not important)

If patient unconscious an assistant is required to maintain spinal flexion

Medication

Lignocaine 1% 5mls

Consider midazolam 1-2mg IV titrated to anxiolysis

Consider ketamine 10-20mg IV (pain relief adjusted to co-morbid status)

Sequence (lumbar puncture)

Confirm any lower limb neurological findings in history

Identify insertion point: midline at level of iliac crests (L4-5) or space above (L3-4) and mark with needle cap

Infiltrate area with local anaesthetic (introducer needle can be used and left in situ)

Aim in between spinous processes, towards the umbilicus (slightly cephalad)

Insert spinal needle (with stylet in) through skin (or via introducer needle)

Advance until first loss of resistance, (passed interspinous ligament) removed stylet and check for CSF return

If no CSF return, continued to advance 1mm then re-check (with or without stylet in situ)

If bony resistance, withdraw the open needle slowly, if no flow advance in a different direction

Collected 10-20 drops (2ml) of CSF in three numbered collection tubes (20 drops last tube for xanthochromia)

Replaced stylet and remove needle, then place sterile dressing over insertion site

Sequence (measuring opening pressure, lying position only)

After reliable flow of CSF is achieved attach a three-way stop cock Luer lock and manometer

Allow CSF to rise and create a vertical fluid column in the manometer

Straighten the patient’s legs during measurement (avoids falsely elevated pressure)

Record the height of the vertical column when it stops rising, then drain into collecting tubes using three-way stopcock

Post-procedure care

CSF sent for:

Xanthochromia (bilirubin by spectrophotometry, protect from light in transport)

CSF microscopy, culture, cell count, protein, glucose

+/-PCR for Neisseria meningitides, herpes simplex, varicella zoster, enterovirus

Inform the patient they may mobilise immediately if they wish (no benefit to bedrest)

Document (completion, attempts and complications)

Tips

NSAIDs do not appear to increase the risk of epidural haematoma with lumbar puncture

Lumbar puncture with other coagulopathies carries a 2% chance of epidural haematoma with risk of paralysis

We recommend introducers to aid passage through the dermis and the interspinous ligament

Pencil point needles (Whitacre, Sprotte) cause less post-LP headache than bevelled (Quincke) needles

If only bevelled needles are available, orient the bevel laterally to split longitudinal fibres and minimise trauma

23-25g needles are generally preferred (to minimise risk of post-lumbar-puncture headache)

22g needles are useful if measuring pressure (rate of flow slower with smaller needles)

Advancing an inserted needle without the stylet improves success without increasing risk of epidermoid tumour

Moving patient from lying to sitting with the needle in situ (to measure opening pressure) is not recommended

Simple analgesia is the initial treatment for a post-LP headache

Bed rest and patient position do not affect the incidence of post-LP headache

Discussion

Lumbar puncture of a patient with raised ICP has approximately a 10% chance of cerebral herniation (5% immediate, 5% delayed).

Most cases of suspected intracranial infection do not require brain imaging. CT scanning is required only in cases of suspected raised intracranial pressure to reduce the risk of cerebral herniation post-LP. Although a CT is not a direct measure of intracranial pressure, mass lesions causing elevated ICP are usually easily identified and the scan can be scrutinised for more subtle signs, including diffuse brain swelling (loss of grey and white differentiation), ventricular enlargement, effacement of sulci and effacement of basal cisterns.

Prospective studies have shown with suspected raised ICP, a lumbar puncture is safe after a normal CT scan. We would recommend using the 25g needle (smaller) needle in this group to minimise CSF leak.

The following groups should undergo a CT brain prior to LP:

Age >60 yrs

Immunocompromised state

Focal neurological findings

Reduced level of consciousness

History of CNS lesions

Seizure activity within preceding seven days

CT scanning should never delay the immediate administration of antibiotics if indicated.

Peer review

This guideline has been reviewed and approved by the following expert groups:

Emergency Care Institute

Please direct feedback for this procedure to ACI-ECIs@health.nsw.gov.au.

References

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Sydney Children’s Hospital Network. Lumbar puncture practice guideline. Sydney: SCHN; 2019. 12pp. Guideline 2014-9039 v5. Available from: https://www.schn.health.nsw.gov.au/_policies/pdf/2014-9039.pdf

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Arevalo-Rodriguez I, Ciapponi A, Roqué i Figuls M, Muñoz L, Bonfill Cosp X. Posture and fluids for preventing post-dural puncture headache. Cochrane Database Syst Rev. 2016;3(3):CD009199. Published 2016 Mar 7. doi:10.1002/14651858.CD009199.pub3

Arevalo-Rodriguez I, Muñoz L, Godoy-Casasbuenas N, et al. Needle gauge and tip designs for preventing post-dural puncture headache (PDPH). Cochrane Database Syst Rev. 2017;4(4):CD010807. Published 2017 Apr 7. doi:10.1002/14651858.CD010807.pub2

Baxter AL, Fisher RG, Burke BL, Goldblatt SS, Isaacman DJ, Lawson ML. Local anesthetic and stylet styles: factors associated with resident lumbar puncture success [published correction appears in Pediatrics. 2006 May;117(5):1870]. Pediatrics. 2006;117(3):876-881. doi:10.1542/peds.2005-0519

Nath S, Koziarz A, Badhiwala JH, et al. Atraumatic versus conventional lumbar puncture needles: a systematic review and meta-analysis. Lancet. 2018;391(10126):1197-1204. doi:10.1016/S0140-6736(17)32451-0

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