Lumbar Puncture - 2
Important Good patient positioning and an experienced assistant are the most important factors for success.
Preparation
- assemble equipment.
- explain procedure to patient and parents and obtain verbal consent.
- give parents the option of remaining with the child or leaving the room whilst the procedure is performed. An LP can be distressing, especially if it does not go to plan.
- explain the procedure to the patient (age appropriate for children)
- warn about the risk of headache (20%), and infection
Technique
- Use universal precautions and aseptic technique.
- In children, topical anaesthesia may be used, but this requires one hour to work well.
DO NOT delay an urgent procedure in order to wait for topical anaestheseia. In any case, if you strongly suspect meningitis, give antibiotics BEFORE attempting a lumbar puncture. [Yes you might kill some bacteria in the CSF, but the aim is to save the patient's life, not collect the perfect CSF sample].
Lateral recumbent position
The patient lies on side in a foetal position. Their spine should be flexed. This is very important as it opens up the interspinous spaces.
Sitting position
Place the patient in a seated position on the edge of the examination table. Place the thighs against the abdomen and flex the trunk. The assistant will stabilize the patient by grasping the patient.
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Which position should I use ?
Lateral Recumbent Position:
best for measurement of CSF pressure.
Sitting Position:
best for obese patients and patients with respiratory disease.
In young infants, avoid hyperflexion of the neck that can precipitate respiratory obstruction.
Identifying landmarks
Palpate the iliac crests - a line between these crosses the spine at the level of the L3-L4 interspace.
Palpate this space in the midline.
Use this space as the starting point for the lumbar puncture. Remember that the spinal cord should terminate at L1/2 in an adult.
