This is a clinical trial to determine the extent to which ultrasound-assisted lumbar puncture using a standardized procedure, including use of ultrasound to ascertain the presence of cerebrospinal fluid (CSF) at L3 - L5 and the optimal needle insertion distance, increases the acquisition rate of CSF that is interpretable for patient management.

Lumbar puncture (LP) is a frequently performed procedure in pediatric emergency departments, most often to evaluate meningitis in hyperthermic, hypothermic, or ill-appearing neonates, infants and children. Older children often present with headaches, meningismus, and/or altered mental status.

The risks of LP include introduction of pathogens, pain, the need for multiple attempts, and failure to obtain interpretable CSF. The latter frequently leads to a spine ultrasound study the following day and, if this does not demonstrate an epidural blood clot, repeat lumbar puncture using fluoroscopic guidance by interventional radiologists.

In evaluating the management of infant sepsis, one study found that the success of the initial LP plays a significant role: infants with unsuccessful initial LPs have longer hospital stays and require more resources. Therefore, ensuring successful LPs on the first attempt is critical for minimizing healthcare utilization, optimizing patient care, and decreasing the emotional burden of this procedure on parents and patients.

Unfortunately, epidural hematoma (EDH) is not uncommon after LP, with U/S diagnosed EDH identified among 40% of patients < 6 months with a traumatic LP and among 31% of unsuccessful but nontraumatic LP's, with complete effacement of the thecal sac in 17%. The spinal canal is wide enough to accommodate EDH with only rare sequelae. However, intramedullary hemorrhage of the conus medullaris resulting in paraplegia in a neonate has been reported.

Since the introduction of the revised febrile neonate guidelines in 2021,4 the number of lumbar punctures performed in young infants has decreased substantially. A consequence of performing fewer lumbar punctures is that clinicians-particularly trainees and early-career practitioners-have fewer opportunities to maintain procedural competence. As procedural skill and confidence decline, the risk of obtaining non-interpretable or traumatic samples increases.

Clearly, improvement of the traditional approach to LP in neonates and infants and young children is needed to prevent these complications. Ultrasound is an imaging modality that is frequently used in the emergency department and does not involve ionizing radiation. Ultrasound can be used prior to lumbar punctures to identify critical anatomical landmarks and needle-insertion distances to avoid the posterior epidural venous plexus and to increase the proportion of LP's with non-traumatic, interpretable CSF. However, an ultrasound technique that is easily learned and that can be applied accurately and efficiently in the emergency department is lacking. Incorporating ultrasound (U/S) into LP training or performance may help clinicians who perform the procedure infrequently to improve success rates and obtain interpretable cerebrospinal fluid samples through identifying optimal intervertebral spaces, visualizing spinal anatomy, and guiding needle placement.

This study employs a standardized, ultrasound-assisted LP approach that integrates pre-procedural identification of spinal anatomy and measurement of the optimal needle insertion distance along the angled trajectory to potentially minimize traumatic taps. Unlike traditional LP methods, this approach provides objective, reproducible guidance that can be given and applied by clinicians. The study is novel in its prospective assessment of ultrasound-guided LP outcomes. By evaluating interpretable CSF yield, this research advances pediatric procedural methodology and has the potential to establish a new standard of care for LP in young infants.

The overarching aim of this research is to determine whether U/S-assisted LP increases the rate of interpretable CSF from the current, approximately 65% to at least 80%.

Primary Aim: To determine the extent to which ultrasound-assisted lumbar puncture using a standardized procedure, including use of ultrasound to ascertain the presence of cerebrospinal fluid (CSF) at L3 - L5 and the optimal needle insertion distance, increases the acquisition rate of CSF that is interpretable for patient management.

Hypothesis: The standardized, ultrasound-assisted procedure for lumbar puncture in neonates and infants is associated with yield of interpretable CSF of at least 85%.

A Sufficient U/S study includes visualization of the following with each reported by the proceduralist on the data report form:

1. Lower lumbar and S1 spinous processes visualized
2. S1 drop-off
3. L4-5 and/or L3-5 interspaces visualized
4. Presence of CSF sufficient for LP
5. Cauda Equina

Inclusion of lumbar punctures for which U/S was not performed:

We will review and record the results of studies performed without U/S guidance, the technique used by clinicians not participating in this study provide a prospectively acquired control group with which to compare outcomes after U/S measurement. This data will be used in the multivariable regression models described below.

Use of Previously Obtained Ultrasound Images:

As part of this study, investigators may utilize ultrasound images that were obtained as part of routine clinical care prior to the performance of lumbar puncture. These ultrasound images will have been acquired independently of, and prior to, study enrollment and will not require any additional imaging procedures for research purposes. When used for research analysis, ultrasound images will be limited to those relevant to the study objectives. Images will be accessed only by authorized study personnel and will be de-identified prior to analysis whenever feasible. No additional risk to participants is anticipated as a result of using these previously obtained clinical images.

Inclusion Criteria:

• - Neonates and infants (< 12 months)
• Hemodynamically stable
• Undergoing a lumbar puncture for diagnostic testing

Exclusion Criteria:

• - Infants > 12 months and 1 day
• Signs of clinical instability
• Known spinal anomalies (e.g., spina bifida, meningomyelocele) or previous spinal surgery

Will consider requests for data sharing individually and with a Data Use Agreement executed and approved by Vanderbilt University Medical Center.