Lumbar Puncture- Adult

Lumbar Puncture Opener.jpeg

Overview

This module describes how to collect a sample of cerebrospinal fluid (CSF) from the subarachnoid space.


Indications

  1. Diagnostic:

    1. Suspected CNS infection such as meningitis
    2. Suspected subarachnoid haemorrhage
    3. Suspected CNS disease such as multiple sclerosis
  2. Therapeutic: relieving raised intracranial pressure due to

    1. ​​Cryptococcal meningitis
    2. TB meningitis
    3. Benign intracranial hypertension
  3. Therapeutic: injecting medication

    1. Spinal anaesthesia
    2. Certain chemotherapy agents
    3. Certain antibiotics


Contraindications

  1. with risk of cerebral herniation

  2. Uncorrected coagulopathy such as haemophilia; INR > 1.5; DIC; platelet count < 50

  3. Local infection, anatomical distortion or previous surgery at the puncture site


Patient Information & Consent

Always verify your patient’s identity and obtain informed consent before proceeding.

How do I explain this procedure?

“I need to put a thin needle into your back to collect fluid from around your spine for testing. The needle will not go into the nerves or spinal cord itself.”

What can my patient expect?

“You will be awake, but I will inject the area to make it numb. When the feeling returns later on, it may feel tender. You may have a headache or backache for a day or two afterwards. This is usually not serious. The test results can sometimes take several days.”

What is my patient’s role?

“Let me know if you have any allergies, have had back surgery, have a bleeding tendency, or use blood thinners. Fearing blood or needles is normal, but tell me if you have fainted from it. Help me by bending over forwards, and by staying still. If you feel strange sensations or pain during or some time after the procedure, let us know.”


Preparation

Ask for an

. Prepare a trolley with equipment.

Lumbar Puncture Prep.png

Documentation

  1. Laboratory request forms

  2. Patient notes

  3. Patient labels

Equipment

  1. Sterile gloves

  2. Sterile pack

  3. Lignocaine for anaesthesia

  4. Alcohol swab

  5. 3-5 ml syringe

  6. One aspiration needle (ideally blunt fill) and one injection needle

  1. CSF

    numbered in order

  2. Dry gauze and a transparent film dressing (Tegaderm or Opsite)

  3. Specimen bag

  4. If measuring

    :

    1. Manometer and 2 three-way taps


Site & Positioning

Position the patient sitting upright or

, as close to your edge of the bed as possible. The patient should arch their back as much as possible, and may hold a pillow to assist with positioning. For measuring opening pressure, the patient must be in the lateral position.

Lumbar Puncture Anatomy 1.jpeg

The puncture site is in the midline of the spine, between the L4 and L5 vertebrae. This site is best identified with the patient sitting upright. Expose the patient’s back. Palpate with the fingers of both hands the highest points of the iliac crests, and use your thumbs in a straight line from these points to palpate the L4/L5 space. You may use a thumbnail to mark this space on the skin. If the L4/L5 space does not yield CSF, the L3/L4 space (one vertebra higher) may be used. This is why an area covering both spaces should be anaesthetised.


Procedure

Follow medical asepsis with sterile gloves.

  1. Perform hand hygiene.

  2. Open the sterile pack and create a sterile field.

  3. Open and drop onto the field: needles, syringe, manometer & taps, dressing, and any sterile collection tubes. Fill the well or bowl with skin disinfectant.

  4. Place beside the field: sterile gloves, lignocaine, alcohol swab, any non-sterile collection tubes, and specimen bag.

  5. Don sterile gloves.

  6. Attach the three-way tap to the manometer, loosen the tap, and set it back on the field.

  7. the site.

  8. Drape the area with sterile sheets.

  9. Draw up 2-3 ml lignocaine. An

    should clean the top of the lignocaine with an alcohol swab and hold it for you to draw it up.

  10. the area.

  11. Uncap the spinal needle and

    it into the L4/5 space. Advance until you feel a “pop” sensation (this may be very subtle), or until 50-75% of the needle is buried.

  12. Remove the stylet and wait for CSF to appear in the hub of the needle. Note the

    of the CSF.

  13. if required.

  14. . Your assistant may open, hand over, and close tubes for you. After touching an unsterile tube, that hand becomes unsterile.

  15. If therapeutic tap: drain CSF and measure closing pressure as for opening pressure, ensuring it is now normal.

  16. Disconnect the manometer and three-way tap. Replace the stylet and remove the spinal needle in a swift motion. Discard needle in sharps bin.

  17. Dress the puncture site with gauze and

    .

  18. Dispose of medical waste safely.

  19. Place specimens with laboratory request form in specimen bag and send to the lab. Document the procedure in patient notes. Prescribe simple analgesia as required.


Troubleshooting

There is no assistant available.

Before opening the sterile pack and donning sterile gloves, don non-sterile gloves, draw up the lignocaine, clean the puncture site with an alcohol swab, and anaesthetise it as a non-sterile procedure. Discard the medical waste safely. You may now open the pack, create a sterile field and continue with the procedure. Alternatively, tape the lignocaine bottle upside-down to an IV pole and clean the cap before getting sterile. That way you can draw up while sterile without compromising sterility.

I’ve hit something hard while advancing the needle.

It’s not uncommon to hit a vertebra. Withdraw the needle to the skin surface and advance it again, using a different angle. Never move the needle without the stylet in place. Try angling more towards the head.

I felt a pop but there is no CSF draining.

This is a “dry tap”. Either the patient is very dehydrated, or you’re not in the right space.

  1. Rotate the bevel and look for CSF in the hub.

  2. Replace the stylet. Advance 1-2 mm. Repeat until CSF observed.

  3. If still no CSF, check that you are in the midline, with the needle aimed towards the umbilicus. If still no CSF, try again using a

    , and the L3/4 space.

The CSF is blood-stained.

This is a “bloody tap”.

  1. Rotate the bevel 45° and wait to see if the fluid clears.

  2. If not, reinsert the stylet and wait a few minutes. Remove the stylet and check again.

  3. If still bloody, remove the needle and try again using a

    and the L3/4 space.

Patient is complaining of pain or paraesthesia.

You are most likely aiming laterally. Ask the patient which leg hurts. Retract to the skin with the stylet in place and reinsert the needle, angled slightly away from the painful leg. If this does not resolve the pain, remove the needle completely and try again using a

and the L3/4 space.

The patient is obese.

Use a longer spinal needle if available. If morbidly obese, an experienced clinician may perform the lumbar puncture using ultrasound guidance.

I don’t have a manometer.

Open an IV line onto the sterile field and attach to the 3 way tap instead of the manometer using the same technique. An assistant may measure CSF height (keeping the IV line upright) with a measuring tape. This method consistently underestimates the pressure. The upper limit of normal, 25 cm using a manometer, measures as 19 cm using the giving set method.

The CSF is coming out very slowly.

Don’t ever aspirate the CSF with a syringe. Ask the patient to cough or strain. Turn the needle 45°, or simply wait.


Risks

  1. Bleeding, bruising, and pain at the site

  2. Infection: cellulitis, meningitis, or epidural empyemas

  3. Spinal nerve damage

  4. with spinal cord compromise


References

  1. Schneider VF. In: Dehn R, Asprey D, eds. Essential Clinical Procedures. 3rd ed. Philadelphia: Elsevier; 2013.

  2. Doherty CM & Forbes RB. Diagnostic Lumbar Puncture. The Ulster Medical Journal. 2014;83(2):93–102.

  3. Naidoo C, Ross A. How to perform a lumbar puncture in an adult. In: Mash B, Blitz-Lindeque J, eds. South African Family Practice Manual. 2nd ed. Pretoria: Van Schaik Publishers; 2010: 331-332.

  4. Henning P.Lumbar Puncture. In Neonatology: A guide for doctors. Department of Paediatrics and Child Health and Stellenbosch University. Tygerberg Hospital South Africa. 2012. p. 160-161

  5. Joolay Y, Horn A, et al.Lumbar Puncture. In: Neonatal Guidelines and Drug Dosages. Division of Neonatal Medicine Groote Schuur Hospital. 2012. p. 135