Nitrous Oxide for Lumbar Puncture (NO for LP)

Impact of 50% Nitrous Oxide Inhalation on Pain and Anxiety Induced by Lumbar Puncture: a Multicenter Double-blind Randomized Controlled Trial

University Hospital, Bordeaux, Hospices Civils de Lyon, Inserm U1107, NeuroDol, Université d'Auvergne

Lumbar puncture (LP) is a frequent exam that can cause pain and anxiety. In a pilot single-center study, it has been shown that nitrous oxide use during the procedure was able to reduce both pain and anxiety (Moisset et al., Eur J Neurol 2017). The goal of this multi-center trial is to confirm these results in a larger and more heterogeneous group of patients having a LP.

Nitrous oxide (N2O) has analgesic and anxiolytic properties that are known for more than a century. Nonetheless, it's use during lumbar puncture in adults has only been investigated in a single-centre study. Thus, this study is designed to evaluate the analgesic effect of N2O on the pain induced during lumbar puncture. Patients with scheduled lumbar puncture realized for diagnosis purposes will be randomized in 2 groups. One group will inhale N2O for the 5 minutes before the puncture and during the rest of the procedure. The second group will inhale compressed air during the same period of time. Neither the investigator realizing the lumbar puncture, nor the patient will know which type of gaz they are inhaling (double-blinding). The maximal pain level that occurred during the procedure will be evaluated on a Numerical Rating Scale (NRS). NRS will also be used to evaluate the maximal anxiety induced by the procedure.

1:1 randomization to receive experimental treatment (50% N2O - 50% O2) or placebo (Medical Air: 22% O2 - 78% N2)

double blinding. Gaz bottles are in undistinguishable boxes. Neither the patients nor the person doing the LP and the evaluation of pain and anxiety will know the treatment used

Gaz inhalation will start 5 minutes before the puncture and will be continued until the end of the procedure.

maximal pain and anxiety perceived during the lumbar puncture evaluated using a simple numeric 0-10 scale

maximal pain and anxiety perceived during the lumbar puncture evaluated using a simple numeric 0-10 scale

every side effects reported by the patients during the procedure up to 24 hours after the lumbar puncture, including post-puncture puncture headache

supplementary cost induced by the use of nitrous oxide inhalation for a total of 81 patients throughout the study

Inclusion Criteria: Patients coming in the neurology department for a lumbar puncture at least 18 no previous use of nitrous oxide Exclusion Criteria: contra-indication to nitrous oxide use Body Mass Index>35 Mini Mental State Examination <24/30 Temperature >38°C Confusion Patient unable to communicate verbaly