Intravenous Fluid Bolus Prior to Neonatal and Infant Lumbar Puncture: A Sonographic Assessment of the Subarachnoid Space After Intravenous Fluid Administration.

IMPORTANCE: Neonatal and infant lumbar puncture is a commonly performed procedure in emergency departments, yet traumatic and unsuccessful lumbar punctures occur 30% to 50% of the time. Dehydration may be a risk factor for unsuccessful lumbar punctures, but to our knowledge, no studies have investigated the use of intravenous (IV) fluid bolus prior to lumbar puncture.

OBJECTIVE: To investigate the association of IV fluid bolus administration with the sonographic measure of the neonatal and infant lumbar subarachnoid space. We hypothesized that IV fluids would increase subarachnoid space size.

DESIGN, SETTING, AND PARTICIPANTS: Prospective observational study conducted from August 2012 to April 2015.The study took place at the emergency department of the Children's Hospital Los Angeles, an urban pediatric emergency department with an annual census of 76,000 visits.A convenience sample of patients aged 0 to 3 months were enrolled if they had a clinical presentation consistent with pyloric stenosis. This population was used as a proxy because they are similar in age to patients undergoing lumbar puncture for evaluation of neonatal fever and are routinely given IV fluids for dehydration.

EXPOSURES: Patients with a sonographic diagnosis of pyloric stenosis underwent additional ultrasonography evaluation to determine the size of the subarachnoid space before and after IV fluids.

MAIN OUTCOMES AND MEASURES: Primary outcomes included the difference in the size of the subarachnoid space in millimeters squared before and 1 hour after administration of an IV fluid bolus in the emergency department. Interobserver consistency for the subarachnoid space measurement between attending radiologists was measured using intraclass correlation coefficient. The Wilcoxon signed-rank test was used to examine changes in subarachnoid space measurements (millimeters squared).

RESULTS: The study sample consisted of 40 patients with a mean (SD) age of 37 (11.3) days (range, 15-71 days). The mean (SD) size of the subarachnoid space before and 1 hour after IV fluid bolus was 37.8 (11.1) mm(2) and 36.9 (11.2) mm(2) respectively (P = .42). The intraclass correlation coefficient ranged from 0.96 to 0.99 (95% CI, 0.90-0.99).

CONCLUSIONS AND RELEVANCE: Intravenous fluid boluses were not associated with a significant increase in the sonographic measure of the neonatal and infant subarachnoid space.