Lumbar Puncture in Emergency Under Nitrous OXide

Study Overview
=================
Brief Summary
-----------------
Lumbar puncture (LP) is a frequent exam that can cause pain and anxiety. In a scheduled setting, it has been shown that nitrous oxide use during the procedure was able to reduce both pain and anxiety. The goal of this trial is to confirm these results in a more heterogeneous group of patients having a LP, in an emergency setting.

Detailed Description
-----------------
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 scheduled setting.Thus, this study is designed to evaluate the analgesic effect of N2O on the pain induced during lumbar puncture. Patients with urgent 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. 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.

Official Title
-----------------
Impact of 50% Nitrous Oxide Inhalation on Pain Induced by Lumbar Puncture in Emergency: a Double-blind Randomized Controlled Trial.

Conditions
-----------------
Pain, Anxiety

Intervention / Treatment
-----------------
* Drug: Fixed 50:50 mixture of nitrous oxide and oxygen
* Other: Placebo


Participation Criteria
=================
Eligibility Criteria
-----------------
Inclusion Criteria: Adult patients coming in emergency service who need a lumbar puncture in emergency for a diagnostic purpose at least 18 affiliated to the French state healthcare insurance system able to give consent to participation Exclusion Criteria: Previous use of nitrous oxide (medical or recreational) Contra-indication to nitrous oxide use Face mask phobia Stage II obesity (BMI > 35) Hemodynamic instability and/or any case when coagulation results cannot be waited Cognitive condition defined by a previous Mini Mental State Examination < 24/30 Confusion or any consciousness disorder that might interfere with judgment or consent Patient unable to communicate verbally Patient placed under a legal protection measure (tutorship, curatorship or a mandate) Any medical condition that might contra-indicate medical research, in physician's opinion

Ages Eligible for Study
-----------------
Minimum Age: 18 Years

Sexes Eligible for Study
-----------------
All

Accepts Healthy Volunteers
-----------------
No

Study Plan
=================
How is the study designed?
-----------------

Design Details

Primary Purpose: Treatment
Allocation: Randomized
Intervention Model: Parallel Assignment
Interventional Model Description: 1:1 randomization to receive experimental treatment (50% N2O - 50% O2) or placebo (Medical Air: 22% O2 - 78% N2).
Masking: Triple


Arms and Interventions

| Participant Group/Arm | Intervention/Treatment |
| --- | --- |
| Experimental: Nitrous oxyde<br>will inhale experimental treatment throughout the entire procedure (50% N2O - 50% 02) | Drug: Fixed 50:50 mixture of nitrous oxide and oxygen<br>* Gaz inhalation will start 5 minutes before the puncture and will be continued until the end of the procedure.<br>|
| Placebo Comparator: Placebo<br>will inhale medical air throughout the entire procedure (22% O2 + N2 Q.S.) | Other: Placebo<br>* inhale medical air (22% O2 - 78% N2)<br>|

What is the study measuring?
-----------------
Primary Outcome Measures

| Outcome Measure | Measure Description | Time Frame |
| --- | --- | --- |
| Maximal pain perceived during the lumbar puncture evaluated using a simple numeric 0-10 pain scale | Maximal level of pain during lumbar puncture. The patient will be asked to circle the digit that best describes the maximal level of pain felt during the procedure. If the patient is too painful and/or is incapacitated, the collection notebook will be fulfilled by the care provider after asking the following question: On a scale of 0 to 10, 0 being the absence of pain and 10 the maximal pain you can imagine, what is the digit best describing the maximal pain you felt during the procedure? | 2-3 minutes after the end of gas inhalation | 

Secondary Outcome Measures

| Outcome Measure | Measure Description | Time Frame |
| --- | --- | --- |
| Maximal anxiety perceived during lumbar puncture evaluated using a simple numeric 0-10 scale | Proportion of patients with significant anxiety | 2-3 minutes after the end of gas inhalation | 
| Side effects | Every side effect reported by the patients attributable to gas inhalation during the procedure up to emergency service discharge. Presence, intensity and reversibility will be recorded | From the beginning of gas inhalation to a minimum of 2 hours later | 
| Spinal puncture duration | Comparison of LP duration between both groups measured in minutes (from the beginning of gas inhalation to needle removal). | 2-3 minutes after the end of lumbar puncture | 
| Number of attempts before successful LP | Comparison of number of attempts needed to get spinal fluid, defined as number of needle removals for a single exam. | 2-3 minutes after the end of lumbar puncture | 
| Patient Satisfaction | overall satisfaction based on a 0-10 score and proportion of patients that would accept another lumbar puncture in the same conditions | 2-3 minutes after the end of gas inhalation | 
| Blinding quality | Assessment of blinding in clinical trials (according to Bang et al. 2004) | 2-3 minutes after the end of gas inhalation | 
| Induced cost | supplementary cost induced by the use of nitrous oxide inhalation for a total of 88 patients throughout the study (gas and consumables such as masks and pipes) | through study completion, an average 4 months | 

 Terms related to the study
=================
Keywords Provided by Centre Hospitalier Valida
-----------------
Spinal puncture, Nitrous oxide, Pain, Anxiety, Emergency