Lumbar Puncture

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Lumbar Puncture

Intranasal or Oral midazolam 20 min prior to procedure

Midazolam 10mg/mL intranasal solution
Midazolam suspension

Blood clots obstructing flow?

Try corrective maneuvers

Inclusion Criteria
  • Clinical need for lumbar puncture
Exclusion Criteria
  • Clinically unstable patient
  • Patients at risk of decreased venous return to heart from LP positioning
  • Soft tissue infection over puncture site
  • Anatomical issues (obesity, orthopedic issues, etc.) making LP very difficult

CSF flowing?

Insert stylet, remove needle and attempt at different site

Consider delaying LP or consulting interventional radiology for fluoroscopic guidance

Patient positioning

Lateral recumbent

  • Opening pressure needs to be measured


  • May improve CSF flow in patients < 2 weeks
  • May be better for patients at risk of respiratory compromise from neck flexion
  • Patients in respiratory distress

Risk of increased intracranial pressure?

Potential thrombocytopenia or coagulation factor deficiency?

Able to correct obvious cause?

Consult hematologist

< 3 months?

Contraindications to topical anesthetics?

Place topical anesthetic

Need to measure opening pressure?

Patient to require sedation?

Patient to require anxiolysis?

Contraindications to nitrous oxide?

Contraindications to midazolam?

Puncture the skin and remove the stylet

Attach manometer via 3-way stopcock and read opening pressure (normal 50 -200 mmH20 in relaxed patient, 100 to 280 mm H2O with the neck and legs flexed)

Diet NPO

Oral sucrose

Sterilize working field and puncture site with providone-iodine or chlorhexidine. Place sterile drapes around field

Bony resistance?

Withdraw needle to subcutaneous tissues, check rotation and puncture site, position patient for optimal flexion, redirect to a more cephalad angle and reintroduce into the interspinous space

Contraindications to midazolam

  • History of adverse event
  • Current disease process causing myocardial depression
  • Patients at risk for hypoventilation

Corrective measures

  • Advance slowly until you meet resistance
  • Rotate needle (90 - 180 degrees)
  • Pull back and redirect needle
  • Remove needle and attempt with a new needle at a different site
  • Remove needle and attempt a different positioning

Nitrous Oxide Inhalation Analgesic

Contraindications to topical anesthetics?

  • Urgent need for IV access
  • Allergy or hypersensitivity
  • Wound or lack of intact skin over anatomic site
  • Medication specific contraindications
  • EMLA: risk for methemoglobinemia

Determine optimal patient positioning

Obtain head imaging (CT or MRI) to ensure safety to continue LP

MRI Brain WO Contrast
CT Head WO Contrast

Topical anesthetics & peak effect

  • EMLA
    • 60 min
  • Liposomal lidocaine (ELA-max)
    • 30 min
  • Self heating patch (Synera)
    • 20 min

Needle size

  • Infant 1.5 inch (3.8 cm)
  • Child 2.5 inch (6.3 cm)
  • Adult 3.5 inch (8.9 cm)

Determine optimal puncture site (L3/4 or L4/5), consider using ultrasound guidance

Anesthetize skin over puncture site with 1% lidocaine

Needle angle

  • Less than 12 months old: 45 degrees from perpendicular
  • Greater than 12 months old: 30 degrees from perpendicular

Ensure that the spinal needle (highest gauge possible) has a stylet firmly in place. Align the spinal needle midline in the back and turn the bevel parallel to the fibers of the ligamentum flavum (upwards in the lateral decubitus - sideways for sitting)

Aim the needle cephalad toward the umbilicus and advance through spinous ligaments and dura

Collect CSF in sterile tubes (1 ml per tube) or infuse desired medication, return stylet prior to removal of needle

Contraindications to nitrous oxide

  • History of adverse event
  • Vomiting
  • Pregnancy
  • Gas within body cavities (SBO, Pneumothorax, Otitis Media, etc)

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