# Lumbar Puncture- Adult

# Overview

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

# Indications

# Contraindications

# 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

assistant

assistant

Insist on an assistant as this procedure has many potential risks if performed alone.

. Prepare a trolley with equipment.

### Documentation

### Equipment

# Site & Positioning

Position the patient sitting upright or

lying on their side

lying on their side

On their left side if you are right-handed, or on their right side if you are left-handed.

, 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.

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.

# 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.

The CSF is blood-stained.

This is a “bloody tap”.

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

new needle

new needle

Call an assistant to open the needle onto the sterile field for you.

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

# References