Lumbar Puncture Equipment
The use of prepacked lumbar puncture kits is common across EDs. Be aware that the needle contained within the kit may not be the preferred needle for the procedure. Always ensure you have your preferred needle available at the bedside prior to commencing the procedure.
A standard kit might contain:
- Sterile gloves
- Chlorhexidine 2%, cotton balls and forceps
- Lignocaine 1%, 23g needle, syringe
- Spinal needle (see below)
- Pressure measuring tube and three way tap (see below)
- 3 or 4 collection tubes
Note: many kits still have a 20 gauge (yellow) cutting needle, these needles carry up to a 20-30% chance of lumbar puncture headache (dural leak).
The Quincke needle is the original needle, with a cutting open bevel.This is thought to transect the longitudinal fibres of the dura mater, a mechanism which has been proposed to explain the increased risk of post-lumbar-puncture headache when Quincke needles are used. Orienting the needle so that the opening faces laterally may make it behave more like an atraumatic needle.
Atraumatic needles (Sprotte or Whitacre) have rounded, non-cutting bevels with solid tips, called “pencil point”. These needles push between the dural fibres and are associated with a lower risk of post-lumbar-puncture headache. An introducer may be supplied with the needle, and helps with passage through the dermis and the interspinous ligament.
Current consensus is that needle gauges of 22-25 are preferred for LP, with smaller needles lessening the risk of headache (dural leak). By convention, 22 gauge needles are marked black.
There is some evidence that higher pressures will distinguish bacterial from viral meningitis. Other requirements for measuring pressure are usually non acute such as diagnosing benign intracranial hypertension.The rate of flow through smaller needles can be quite low, making pressure measurement more difficult. Consider using 22 gauge needles only if pressure measurement is required, and using 23 to 25 gauge needles otherwise (to minimise risk of post-lumbar-puncture headache). Always use atraumatic needles (Whitacre/Sprotte) if possible.