Lumbar Punctures


Indications: Suspected CNS infection, SAH, Guillain-Barre syndrome, MS, SLE
Measure intracranial pressure (pseudotumor cerebri)

Contraindications: Increased intracranial pressure (except to dx pseudotumor cerebri), supratentorial mass lesion, thrombocytopenia, bleeding dyscrasia

Complications: Post-LP headache, brain herniation if mass lesion present or increased intracranial pressure, bloody tap if venous plexus punctured.

1. Obtain informed consent
2. Position patient with back near edge of bed in lateral recumbent position. Have patient flex hips and draw knees up to chest to increase curvature of spine.
3. Palpate iliac crests and identify L3 and L4 interspaces.
4. Open tray, wear sterile gloves, and set up tubes in order, 1-4.
5. Prep and drape skin in sterile fashion
6. Infiltrate skin with 1% lidocaine
7. Use 20-22 gauge spinal needle. Insert at interspace with needle angled slightly toward umbilicus (cephalad). Keep level of needle in line with horizontal plane.
8. A course resistance can be felt as the needle passes through the paraspinous ligaments and a “pop” may be felt when needle passes through the dura.
9. Withdraw stylus fully to check for fluid.
10. Once fluid is obtained, place stopcock and manometer on hub of needle to obtain opening pressure.
11. Fill tubes in order, 2-3cc per tube
12. Once fluid has been collected, replace stylus and withdraw needle.
13. Cover site with sterile dressing and have patient remain lying down in supine position for 2 hours.
14. Observe tubes for occult blood. Decreasing amounts of blood in tubes 1-4 suggests a bloody tap, while increasing or steady amounts suggests an CNS bleed.
15. Send fluid for analysis:
Tube #1: glucose, protein, protein electrophoresis
Tube #2: Gram stain, culture, bacteria, fungal, TB, viral
Tube #3: cell count, differential
Tube #4: VDRL, India ink, cytology

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