Question 1: In neonates and infants, does an IV fluid bolus prior to lumbar puncture (LP) improve success rate?

Admit it—unsuccessful LPs in neonates and infants are really frustrating. While a number of factors play a role in the likelihood of a successful LP, does an IV fluid bolus actually increase the size of the subarachnoid space and possibly improve LP success rate?

Interestingly, we were only able to find a single study addressing this question. It was a prospective, observational study by Rankin et al that sonographically evaluated the subarachnoid space in 40 children (six girls and 34 boys) 0 to 3 months of age before and after an IV fluid bolus.¹ The study was a convenience sample of 40 children who were undergoing sonographic evaluation for pyloric stenosis. According to the authors, eight (20 percent) children were mildly dehydrated, and 32 (80 percent) were moderately dehydrated. It’s important to note that this study did not include performance of LPs but rather assessed changes in the subarachnoid space near the location of an LP that might increase the likelihood of a successful LP. The average age of the patients was 37.1 days, and the subarachnoid space was evaluated before an IV fluid bolus and approximately one hour after the bolus. The mean IV fluid bolus volume was 22 mL/kg, with a range of 20–60 mL/kg.

The authors found that the mean size of the subarachnoid space was not significantly different between the two time periods and was 37.8 mm2 before and 36.9 mm2 one hour after bolus administration (P=0.42). Although there are a number of limitations to this study and we are unable to translate this to LP success, it would suggest that an IV fluid bolus does not change the size of the subarachnoid space at the level that an LP might be performed.

Summary

There is limited data on this topic, and a single study found no significant difference between subarachnoid space size before and after an IV fluid bolus in a small group of children 0 to 3 months of age.

Dr. Jones is assistant professor of pediatric emergency medicine at the University of Kentucky in Lexington.

Dr. Cantor is professor of emergency medicine and pediatrics, director of the pediatric emergency department, and medical director of the Central New York Regional Poison Control Center at Upstate Medical University in Syracuse, New York.

Reference

1. Rankin J, Wang VJ, Goodarzian F, et al. Intravenous fluid bolus prior to neonatal and infant lumbar puncture: a sonographic assessment of the subarachnoid space after intravenous fluid administration. JAMA Pediatr. 2016;170(3):e154636.