Lidocaine for Lumbar Punctures
ABSTRACT & COMMENTARY
Synopsis: Premedication with lidocaine before lumbar puncture does not make lumbar puncture more difficult or less successful for the operator.
Source: Carraccio C, et al. Lidocaine for lumbar punctures. Arch Pediatr Adolesc Med 1996;150:1044-1046.
In an effort to study the effects of premedication with lidocaine on the performance of lumbar puncture (LP), Carraccio et al recently conducted a randomized controlled trial using a convenience sample of 100 children under 3 years of age. Children were randomized to receive either premedication with subcutaneous lidocaine or no premedication. Given that one hypothesis being tested was that infiltration with anesthetic obscures landmarks and makes the performance of an LP more difficult, no placebo was administered.
Of the 100 patients enrolled in the study, 51 received lidocaine, and 49 received no anesthetic. The mean ages of the children in the two groups were similar. In both groups, only one attempt was required for 59% of the patients, suggesting that the prior infiltration with lidocaine did not interfere with successful performance of the LP. Also compared were the number of traumatic LPs observed. When a traumatic LP was defined as CSF with 1000 ´ 106 or more RBCs/L in the CSF, the percentage of patients in the lidocaine group with a traumatic tap was significantly greater than in the control group (33% vs 12%; P = 0.02). With a less conservative definition of a traumatic LP (310,000 ´ 106 RBCs/L), no difference in the percentage of traumatic procedures was noted between the lidocaine and control groups (14% vs 6%). Analysis of the rate of traumatic LP relative to the level of physician training was also made, with the only significant difference occurring at the post-graduate year 2 level. Sufficient spinal fluid for meaningful analysis was obtained from all but three patients, two of whom were in the lidocaine-treated group.
COMMENT BY DAVID T. BACHMAN, MD, FAAP
Carraccio et al should be applauded for their efforts to debunk a long standing myth about LPin children, namely that infiltration with lidocaine makes the procedure technically more difficult. Certainly, their study can be criticized for the lack of blinding and for a failure to limit the number of physicians performing the procedures (LP is perhaps the most operator-dependent bedside procedure in pediatrics). On the other hand, they did demonstrate that administration of lidocaine does not compromise the ability of even relatively inexperienced practitioners to perform LP successfully in children. It should be pointed out the Carraccio was one of the authors of an earlier study that examined the overall rate of administration of lidocaine to children undergoing LPin the same emergency department.1 Only nine of 198 children under age 18 years received anesthetic. Eight of the nine children who did receive premedication were 4 years or older; only one of the 186 children under that age received lidocaine. Explanations offered for not using lidocaine included a desire to avoid a second needle stick, a belief that the lidocaine would obscure landmarks, and a concern about the pain of the lidocaine injection itself.
I do not believe it is necessary to prolong the debate regarding the pros and cons of lidocaine administration for LP. There is no question as to whether or not children perceive pain. It is quite clear that LP performed without the benefit of local anesthetic, even in the most skilled hands, can be a painful procedure. And, it can no longer be argued that the prior administration of lidocaine compromises successful performance of the procedure. I would maintain (as studies in neonates have suggested) that use of lidocaine diminishes the inevitable wiggling and struggling that occur when the spinal needle is insertedthereby simplifying the LP for all concerned. Should time permit, it can also be argued that use of EMLA cream (eutectic mixture of lidocaine 2.5% and prilocaine 2.5%) should be considered as well, although it should not be used in children under 1 month or with older infants receiving methemoglobin-inducing agent).
Children do feel pain. We as physicians should do all we can to guarantee that their discomfort is minimized.
Reference
1. Quinn M, et al. Pain, punctures, and pediatricians. Pediatr Emerg Care 1996;9:12-14.
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