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This is… Lumbar Puncture

Case: Jane is a 2 week-old, previously healthy, ex- full term girl who presents to the ED from her PCPs office after being found to have a temperature of 102.5 rectally. On exam, she is fussy but consolable and has an otherwise normal exam.  In addition to blood and urine studies, you plan to perform a lumbar puncture. What would be other indications and even contraindications for an LP? What are the various techniques? Should you use local anesthesia?  

 

Lumbar Puncture: The basics

Indications

  • The most common indication for lumbar puncture is to diagnose meningitis (Bonadio, 2014)
    • Other indications include diagnosing: demyelinating diseases, subarachnoid hemorrhage, or idiopathic intracranial hypertension (formerly pseudotumor cerebri)

Contraindications

  • Suspected intracranial pressure elevation
  • Clinical/Physiological Instability (hypotension, respiratory distress, status epilepticus)
  • Coagulopathy
  • Infection of overlying skin

 

Basics of setup

After discussing the case with the team, you decide that Jane has no contraindications and that it is important to rule out meningitis.  What do you need, and how do you set up?

1.  Equipment

  • Most (if not all) of your equipment will be included in a commercially available tray (Figure 1 as an example).
    • In general, you will need the following
      • Spinal needle (1.5″ or 3″ depending on the patient)
      • sterile gloves and drapes
      • Povidone-Iodine scrub
      • Monometer tune (to measure CSF pressure)
      • Sterile tubes for CSF collection

 

Figure 1: LP Tray (Picture from Bonadio, 2014)

   

2. Position 

  • In the younger child, and in those you need to measure CSF pressures, the child should be placed in the lateral decubitus position
  • In older children, the seated position can also be used (Figure 2)
  • Remember, the spinal cord ends around L2. Therefore, the needle should enter the L3/4 or L4/5 disc space
    • The L3/4 disc space will be transected by the line that connects the iliac crests (as seen in Figure 2).

 

Figure 2: LP Landmarks (Picture from Bonadio, 2014)

 

Maximizing Success

As you are gathering your materials, you begin wondering what can be done to maximize the success of your procedure.

1.)  Anesthesia

  • Topical (“EMLA”) vs local (1% lidocaine infiltration)
    • Use of local anesthetic associated with an increased odds ratio (OR = 2.2) for success (Baxter, 2006)
    • Other RCTs (Pinheiro et al, 1993; Nigrovic, 2007) found that local infiltration did not increase success, but statistically decreased the amount of struggling in infants.
      • Note: Despite not finding any differences in success rates between the two methods, it is important to note that local infiltration did not lead to decreased success (concern for a loss of landmarks, etc).

2.) Early stylet removal (“Cincinnati” Method)

  • In this method, the stylet is removed after puncturing the epidermis
    • Baxter et al found a trend towards increased success in residents employing this method, but this was not statistically significant (Baxter, 2006)
    • Nigrovic et al did find an association between leaving the stylet in and with the composite outcome of traumatic or unsuccessful lumbar puncture (Nigrovic, 2007)

Conclusion: Use an anesthetic (topical or local infiltrate) and consider removing the stylet early

 

Now that we know what we need, where we need to go, and what helps maximize success, how do we do the procedure?

 

NEJM Tutorial

https://www.youtube.com/watch?v=weoY_9tOcJQ

Another Example from EM:RAP

Video: https://www.emrap.org/

Faculty Reviewer: Jeff Riese, MD

References

  • Baxter AL et al. “Local Anesthetic and Stylet Styles: Factors Associated with Resident Lumbar Puncture Success.” Pediatrics. 2006;117(3)876-881
  • Bonadio W. “Pediatric Lumbar Puncture and Cerebrospinal Fluid Analysis.” The Journal of Emergency Medicine. 2014;46(1)141-150.
  • Nigrovic et al. “Risk Factors for Traumatic or Unsuccessful Lumbar Punctures in Children.” Annals of Emergency Medicine. 2007;49(6)762-771
  • Pinheiro JM et al. “Role of Local Anesthesia During Lumbar Puncture in Neonates” Pediatrics. 1993;91(2)379-82

 

1 Comment

  1. Some truly excellent info, Glad I noticed this.

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