Lumbar Puncture Patient Position

Patient Positioning

  • The spinal cord ends at L1/L2 level in adults.
  • Place one hand on each ASIS and move medially to the midline, locating the spine. This is L4 and LP may be performed through the 2 spaces above (L3/L4 or L2/L3) or one space below (L4/L5).
  • LP can be performed with the patient either lying down or sitting up. Choose the position that you and the patient are most comfortable with.
  • Optimise patient position to increase the interspinous distance as much as possible: flex the spine and hips.
  • Perform LP on infants and unconscious patients, with the patient lying down, and an assistant maintaining spinal flexion.

Sitting

  • This position generally makes it easier to identify anatomical landmarks and planes.
  • Sit the patient on a firm surface.
  • Patient should lean forward, and can hug a pillow on a table at the right height to flex (not extend) the back.
  • Lift the patient’s legs by putting their feet on a stool or chair and flex the hips to above 90 degrees.
  • If pressure measuring is required, lie the patient on their side (after successful needle insertion) with assistance and then open the tap to measure the pressure.

Lying down

  • Patient should be lying in the lateral decubitus position.
  • Ensure the vertical plane of the patients back is perpendicular to the bed.
  • Flex knees and hips so that knees are close to the chest.
  • While flexion of the neck is often taught as important, evidence suggests that this has no effect of the size of the interspinous opening and may be uncomfortable for the patient.

  • Postioning correctly is all about increasing the interspinous distance as much as possible.

Preparation

  • Using ultrasound to identify landmarks increases the chance of success and reduces the number of passes required, particularly in obese patients.
  • Wear a face mask.
  • Wash hands and use sterile gloves.
  • Prepare the skin with povidone-iodine or chlorhexidine.
  • Apply sterile drape(s).
  • Uncap specimen tubes.
  • Infiltrate skin with local anaesthetic.
  • Use introducer needle on syringe with LA, insert in the plane for the LP
  • Aim in between spinous processes, towards the umbilicus (ie slightly cephalad).
  • Inject LA as you go, remove syringe and leave introducer needle in situ.

Puncture

  • Use the spinal needle (with stylet in) to pierce the skin ( or where you have used an introducer needle insert) over the selected interspinous space in the midline.
  • Aim in between spinous processes, towards the umbilicus (ie slightly cephalad).
  • As the needle passes through the interspinous ligament, there is likely to be increased resistance.
  • Advance the needle through the ligament until there is a decrease in resistance. The needle tip is now likely to be near or within the subarachnoid space.
  • In a 70 kg male the ligamentum flavum sits at around 4.5 cm, use this distance or a measured distance from ultrasound.
  • Remove the stylet to check for CSF.If there is no flow of CSF, replace the stylet and advance the needle slightly before checking again for CSF.
  • Alternatively, remove the stylet once the needle is in the interspinous ligament and advance the open needle slowly, watching for flow of CSF.
  • If the needle meets hard (bony) resistance, withdraw the open needle slowly, watching for flow of CSF. If there is no flow once the needle tip has backed into the ligament, try advancing in a different direction using either technique.
  • When there is reliable flow of CSF, attach a 3-way-tap if measuring pressures, or collect a sample directly into the specimen containers.
  • Collect 10 to 20 drops (5 to 10 for children) in each container, keeping track of the order in which containers are filled (they may already be numbered).
  • After collection, replace the stylet and remove the needle and stylet together.
  • Apply a sterile dressing to the puncture site.

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