Evaluation of the Analgesy With Emla and/or Nitrous Oxide in Pediatric Patients for Lumbar Puncture

Inclusion Criteria: * Age between four and 14 years; * Not present cognitive disabilities; * Necessity to perform the clinical procedure; * Accordance in participating in the study. Exclusion Criteria: * Continuity skin lesion in the procedure site; * Metahemoglobinemia; * Neuromuscular disability; * Presence of pneumothorax, emphysema, intra-abdominal infection, cranioencephalic traumatism, otitis media, sinusitis and intracranial hypertension; * Vitamin B12 known deficits; * Urgency for the procedure; * Disagreement in participating of the project; * Patients in use of Dapsone.