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Study on Reducing Suicidal Thoughts in Emergency Patients Using Nitrous Oxide and Oxygen Therapy

Registered drugNo placebo
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What is this trial about?

A plain-language summary of the goals, design and what participants do

This clinical trial is focused on the treatment of suicidal ideation, which refers to having thoughts about or an unusual preoccupation with suicide. The study will use a treatment involving a mixture of two gases: nitrous oxide and oxygen, known as KALINOX 50%/50%. This mixture is a type of medicinal gas that is inhaled. Another medicinal gas, Medical Air, which contains nitrogen and oxygen, will also be used in the study.

The purpose of the study is to evaluate whether inhaling the nitrous oxide and oxygen mixture can reduce suicidal thoughts. Participants will inhale the gas mixture for one hour while they are in the emergency department. The study will monitor the intensity of suicidal thoughts four hours after the inhalation. The study will also assess the participants' symptoms over a period of time, including at 24 hours, 48 hours, one week, and one month after the initial treatment.

Throughout the study, various assessments will be conducted to measure changes in suicidal thoughts, depressive symptoms, and anxiety levels. These assessments will help determine the overall improvement in the participants' condition. The study aims to provide insights into the potential benefits of using this gas mixture as a treatment for individuals experiencing suicidal thoughts.

The research process

The trial runs in 6 steps – from screening to follow-up. Each step says what happens and what the team monitors.

  1. Step 1

    Initial assessment

    Upon arrival at the emergency department, a psychiatric evaluation is conducted to assess the presence of active suicidal thoughts.

    The Beck Suicidal Ideation Scale (SSI) is used to measure the severity of suicidal thoughts. A score of 8 or higher is required for participation.

  2. Step 2

    Informed consent

    The patient is provided with detailed information about the study and must sign an informed consent form to participate.

  3. Step 3

    Treatment administration

    The patient receives an inhalation treatment consisting of a 50% nitrous oxide and 50% oxygen mixture, known as KALINOX, for a duration of one hour.

    This treatment is administered in the emergency department.

  4. Step 4

    Initial evaluation post-treatment

    Four hours after the inhalation treatment, the intensity and severity of suicidal thoughts are reassessed using the SSI scale.

    Additional assessments include the Columbia Suicide Severity Rating Scale (C-SSRS) and the Montgomery-Asberg Depression Rating Scale (MADRS).

  5. Step 5

    Follow-up evaluations

    Further evaluations are conducted at 24 hours, 48 hours, 7 days, and 30 days post-treatment.

    These evaluations include the SSI, C-SSRS, MADRS, Patient Health Questionnaire (PHQ-9), and the State and Trait Anxiety Inventory (STAI).

    The Clinical Global Impression - Improvement (CGI) scale is used to measure overall improvement.

  6. Step 6

    Monitoring and final assessment

    The patient is monitored for any suicidal actions within the month following inclusion in the study.

    The use of any anxiety or sedative medications is recorded between the initial treatment and four hours post-treatment.

Who can join the trial?

8 criteria

  • Be between 18 and 50 years old. This age limit is set to reduce the chance of other health issues and minor memory problems that are more common in older people.
  • Have active thoughts of suicide during a mental health evaluation in the emergency room.
  • Have a score of 8 or higher on the Beck Suicidal Ideation Scale, which is a tool used to measure how strong someone's thoughts of suicide are.
  • Speak French.
  • Be admitted to the psychiatric emergency department at the CHRU of Tours.
  • Be able to wear a face mask.
  • Have signed the informed consent form, which means you agree to participate in the study after being told all the details.
  • Be affiliated with social security, which means you are part of a system that provides health coverage.
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Investigated drugs

Protoxyde d'Azote: This medication, also known as nitrous oxide, is used in this trial to help reduce suicidal thoughts. It is inhaled as a gas mixture with oxygen for one hour. The goal is to see if it can quickly decrease suicidal thoughts in patients who are in emergency situations.

What is already known about the treatment

Nitrous Oxide – This medication is administered through inhalation, typically in a hospital emergency setting. It is currently being studied for its potential to reduce suicidal thoughts, with research focusing on its effects a few hours after administration. The main therapeutic indication is the treatment of suicidal ideation. At the molecular level, nitrous oxide acts by modulating neurotransmitter systems in the brain, which may help alleviate acute mental distress. It is classified pharmacologically as an anesthetic and analgesic gas.

Investigated diseases

Suicidal Ideation – Suicidal ideation refers to having thoughts about or an unusual preoccupation with suicide. It can range from fleeting thoughts to detailed planning. The condition often occurs in the context of mental health disorders such as depression, anxiety, or substance abuse. Individuals experiencing suicidal ideation may feel overwhelmed by feelings of hopelessness and despair. The intensity and frequency of these thoughts can vary, and they may be accompanied by other symptoms like mood swings or withdrawal from social interactions. It is important to recognize that suicidal ideation is a serious condition that requires attention and support.
Trial detailsLast updated 14 Oct 2026
Age18+ yearsPhasePhase IITrial ID2023-506329-12-00Estimated enrolment30 patientsSponsorCentre Hospitalier Regional Universitaire De Tours

sourced from the EU Clinical Trials Register and site verification

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