The Effect of Beside Ultrasonographic Skin Marking on Infant Lumbar Puncture Success:  A Randomized Controlled Trial

Neal, et al. 

Question: Can visualization of anatomical landmarks with ultrasonography improve first-attempt lumbar puncture success?

The Bottomline: Performing bedside ultrasonography on 4 patients resulted in 1 additional first attempt successful lumbar puncture (LP).

Problem: Lumbar puncture is an important step in the work-up of a febrile neonate, however, the rate of unsuccessful LPs (no CSF obtained or traumatic puncture) can be as high as 40-50%. This has the potential to lead to unnecessary hospitalizations and prolonged antibiotic use, in addition to increased procedure duration and patient discomfort.

What They Did: a randomized, controlled trial of 128 infants younger than 6 months who required an LP as part of their ED work up. One arm had the LP performed using anatomic landmarks while the other arm had an ultrasonography-assisted LP in which a high-frequency linear  transducer was used to identify anatomic landmarks and mark the insertion site prior to LP.

Primary Endpoint: first-attempt lumbar puncture success, defined as CSF obtained with RBC counts less than 1,000/mm3, was greater for the ultrasonography arm 58% (37 out of 64) than in the anatomical arm 31% (20 out of 64); an absolute risk reduction for failure of 27%. 

Strengths: while prior studies in adults have shown no benefit, this study suggests the improved success for neonates could be due to improved structure visualization due to incomplete ossification; broad range of prior LP experience in providers

Weaknesses: failed to demonstrate a reduction in hospitalization duration and length of antibiotic treatment (both secondary end points); ultrasonography marking performed by only 3 clinicians, who did not perform the LP; unblinded study

If ultrasound for landmarking continues to show promise, could the next step be the use dynamic use of ultrasound guided lumbar punctures?

For more information, see: Sonographically guided lumbar puncture in pediatric patients. Wang PI, et al. J Ultrasound Med.2013;32:2191-2197 

Figure 1; from Neal, et al paper.

Identification of anatomic landmarks with bedside ultrasonography. Longitudinal plane (left) vs transverse plane (right); dura (a), spinous process (b), cauda equina (c), transverse process (d), subarachnoid space (e); example of depth measurement (blue line).

References:

Neal, JT, et al. The Effect of Bedside Ultrasonographic Skin Marking on Infant Lumbar Puncture Success: A Randomized Controlled Trial. Annals of Emergency Medicine. 2017;69(5):610-619.

Marin, JR. Ultrasonography for Infant Lumbar Puncture: Time to Pop the Champagne? Annals of Emergency Medicine.2017;69(5):620-621.

Wang PI, et al. Sonographically Guided Lumbar Puncture in Pediatric Patients. J Ultrasound Med. 2013;32:2191-2197