Lidocaine for lumbar punctures. A help not a hindrance

To determine whether premedication for lumbar puncture (LP) with lidocaine hinders collection of cerebrospinal fluid (CSF) through either increased number of attempts or increased incidence of traumatic punctures.

A randomized controlled trial.

The pediatric emergency department of an innercity teaching hospital.

A convenience sample of 100 children, younger than 3 years, who required an LP as part of their diagnostic workup.

Patients were randomized to receive either lidocaine or no local anesthetic before undergoing an LP.

Comparison of the number of attempts needed to obtain CSF and the number of traumatic LPs between the lidocaine-treated and no local anesthetic groups.

The 51 patients randomized to receive lidocaine did not differ markedly in age from the 49 patients randomized to receive no local anesthetic. Ease of obtaining CSF, as measured by number of attempts, did not differ with 59% of the patients in each group requiring 1 attempt. Defining a traumatic LP as more than 1000 x 10(6)/L red blood cells in the CSF showed notably more traumatic LPs in the lidocaine-treated group. Defining a traumatic LP as one with more than 10,000 x 10(6)/L red blood cells in the CSF showed no significant difference in the number of traumatic LPs whether or not the patient was premedicated with lidocaine. The level of experience of the physician performing the LP did not affect the outcome.

Premedication with lidocaine for an LP does not binder the ease of obtaining CSF. The clinical relevance of a greater number of traumatic LPs in the lidocaine-treated group is questionable because this finding is negated when traumatic is defined as more than 10,000 x 10(6)/L CSF red blood cells. Based on these results, we advocate premedication with a local anesthetic when an LP is performed in the pediatric emergency department.