The 50:50 Nitrous Oxide vs 2% Lidocaine Challenge

The main goal of the project is to assess pain levels and patient comfort during the administration of a 50:50 Nitrous Oxide/Oxygen gas mixture, in comparison to the same parameters under the standard method used at our institution, which includes injecting a local anaesthetic at the site of planned puncture for central venous catheterisation.

Inclusion Criteria: * Subjects who have not previously received Nitrous Oxide. * Subjects of both sexes, aged between 18 and 65 inclusive. * Subjects who have signed informed consent with full disclosure; no study-related procedure may begin until the subject signs the consent form. Exclusion Criteria: * Infection at the planned puncture site. * Pregnancy. * Intracranial hypertension. * Vitamin B12 deficiency. * Hemodynamic instability. * BMI over 35. * Glasgow Coma Scale (GCS) score less than 15. * Presence of chronic pain. * Neurological disorders. * Hematologic disorders. * Systemic or intrathecal methotrexate therapy * More than two attempts at venous puncture (Subject Withdrawal Criterion). * Subject experienced an adverse event requiring early discontinuation (Subject Withdrawal Criterion). * Withdrawal of consent by the subject (Subject Withdrawal Criterion)