Lumbar Punctures in Neonates: Improving Success Rates and Minimizing Pain

The purpose of this study is to compare two medications used to numb an infant's back when performing a lumbar puncture. A lumbar puncture (LP) is often needed in newborns to obtain cerebrospinal fluid (CSF). This is achieved by inserting a small needle between the infant's vertebrae. In the past, doctors did not know if newborns could feel the pain from a procedure like this in the same way that adults do. Investigators now know that the newborns do experience pain during this procedure, but we do not know the best way to control this pain. Investigators also think that when the newborns have pain, they move during the test. The movement can increase the chance of having blood mix with this normally clear fluid leading to limitations in our clinical application of these results. This study will compare the injected and topical forms of Lidocaine to see which gives us better pain control and more clear results. The investigators hypothesize that subcutaneous 1% Lidocaine, due to its deeper penetration, will be 25% superior to topical liposomal Lidocaine (LMX-4) in both the rate of clinically useful results and pain scores. The investigators hypothesize that both forms of Lidocaine will be 25% superior to our historical control cohort in the rate of clinically useful results.

When the decision is made that an infant needs a lumbar puncture for clinical indications, parental consent will be obtained for the actual procedure and a separate consent for participation in this study will be attached. Randomization for this study will be via permuted block randomization. The expected 122 patients will be pre-randomized, with the arm for each patient number 1 through 122 sealed in an envelope. After consent is obtained the patient will be assigned the next numerical study identification number and the corresponding envelope will be opened. If the infant has been randomized to the topical liposomal lidocaine group, 1 gram of LMX-4 will be placed over the L3-L4 space immediately, covered with a cotton ball and occlusive tegaderm, for minimum 30 minutes prior to the needle insertion during the lumbar puncture (LP). While the LMX-4 is in place, other procedures that are part of a routine septic work-up may be performed. Thus, the application of this medication should not cause an unnecessary delay in the ultimate procedure or antibiotic administration.

If the infant has been randomized to the subcutaneous lidocaine group, after using sterile procedure to prepare the area, 0.1ml/kg of 1% Lidocaine will be injected using a 25 gauge tuberculin needle over the L3-L4 region. The injection point will be below the actual level desired with the needle going in at a 5-10 degree angle and moving toward the head after insertion. A subcutaneous wheal will form over the desired L3-L4 space when the Lidocaine is injected. The provider will wait at minimum 2 minutes after the injection of the Lidocaine prior to the insertion of the LP needle. Once the required time for local anesthesia in either arm has elapsed, the procedure will be performed with routine technique.

With consent for the video portion of the study, a video camera will be set up to tape the infants face only during the procedure with notation of the LP needle insertion(s). During the procedure, an assistant will record heart rate and oxygen saturation values. The information from the video and documented vital signs will be used to assign a PIPP score by a blinded investigator. Once the procedure is complete the following information will be obtained for study purposes, in addition to the above video tape and vital signs: infant gestational age, infant birth weight, gender, day of life of procedure, level of provider(s) performing the procedure, attempts required to obtain cerebrospinal fluid (CSF) specimen, color of fluid (clear, pink, xanthochromic, or grossly bloody), presence of CSF culture, and Red Blood Cell count of CSF specimen. Infants in our institution will already be monitored continuously and will continue to be so for at minimum 6 hours after the procedure. Any adverse reaction that could be attributed to the procedure or medications used for the procedure will be recorded, with the most expected reaction to be a skin rash. Additional changes in the infant, such as apnea, sustained arrhythmia, oxygen desaturation 10% below baseline, or seizure will also be noted whether or not it is thought to be associated with the procedure.

Eligibility Criteria:
Inclusion Criteria:

* neonate requiring lumbar puncture
* gestational age at birth equal to or greater than 34 weeks

Exclusion Criteria:

* on mechanical ventilation
* receiving sedation (opioids or benzodiazepines)
* suspected congenital spinal anomaly
* infants older than 1 week of life