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NCT Number: NCT07618676

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.

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Key information

Conditions

Acute Pain Anxiety Anxiety Disorders Central Venous Catheter Mental Disorders Neurologic Manifestations Pain Pathological Conditions, Signs and Symptoms Signs and Symptoms

Age range

18 year–65 year

Sex eligibility

All sexes

Study type

Interventional

Phase

Not applicable

Primary location

Who can participate

Healthy volunteers accepted: Yes

Only the study team can determine whether someone qualifies for participation.

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.
  • 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)

Treatment and study plan

Nitrous Oxide-Oxygen

Drug

After placing the patient in the appropriate supination + Trendelenburg position, the operative field (neck and subclavian region) is prepared using antiseptic measures.Five minutes before needle insertion, a mask connected to a 50:50 Nitrous Oxide/Oxygen cylinder with a flow rate of 6 liters per minute is placed on the patient's face and held by the patient. The mask has a valve that opens only when the patient creates negative pressure during inhalation.The patient is instructed to breathe spontaneously; the mask is removed once the catheter is inserted into the target vein or after cessation of painful stimulation.

Other names: Experimental Treatment

Lidocaine 2% Injectable Solution

Drug

After placing the patient in the appropriate supination + Trendelenburg position, the operative field (neck and subclavian region) is prepared using antiseptic measures. Then, under ultrasound control, the most favorable central vein for puncture is determined (v. jugularis interna or v. subclavia) and a 25-gauge needle is used to infiltrate the skin and subcutaneous tissue above the selected vein with local anesthetic. Five minutes after infiltration, puncture of the selected vein is performed using the Seldinger technique. Continuous communication with the patient is maintained throughout the procedure.

Other names: Control

Primary outcomes

  1. Pain Intensity During Needle Insertion

    Time frame: At the time of needle insertion

    Assessed using a standard Numeric Rating Scale (NRS) ranging from 0 (no pain) to 10 (worst imaginable pain). Higher scores indicate greater pain intensity.

  2. Pain Intensity During Catheter Placement

    Time frame: During catheter placement

    Assessed using a standard Numeric Rating Scale (NRS) ranging from 0 (no pain) to 10 (worst imaginable pain). Higher scores indicate greater pain intensity.

  3. Pain Intensity Post-Intervention

    Time frame: 2 minutes after gas inhalation (Treatment 1) or 2 minutes post-intervention (Treatment 2)

    Assessed using a standard Numeric Rating Scale (NRS) ranging from 0 (no pain) to 10 (worst imaginable pain). Higher scores indicate greater pain intensity.

Secondary outcomes

  1. Patient Anxiety Score

    Time frame: Post-intervention (at the conclusion of the central venous catheterization procedure)

    Assessed using a standard Numeric Rating Scale (NRS) ranging from 0 (no anxiety) to 10 (worst imaginable anxiety). Higher scores indicate greater anxiety levels.

  2. Patient Satisfaction Score

    Time frame: Post-intervention (at the conclusion of the central venous catheterization procedure)

    Assessed using a Numeric Rating Scale (NRS) where patients rate their overall satisfaction with the anesthetic method. The scale ranges from 0 (completely unsatisfied) to 4 (completely satisfied). Higher scores indicate greater satisfaction.

  3. Incidence of Treatment-Related Adverse Events

    Time frame: From the start of the intervention through 30 minutes post-procedure

    Percentage of participants experiencing specific adverse events, including nausea/vomiting, unpleasant dreams, paresthesias, dizziness, and euphoria, as recorded by subjective patient reports.

Study contacts

Contact information is provided by the study sponsor or research team.

Ana Cvetkovic, MD,PhD

CONTACT

[email protected]

+381 11 2067 100

Sponsors and collaborators

Lead sponsor

Institute for Oncology and Radiology of Serbia

Other

Registry information

Official study title

The 50:50 Nitrous Oxide Challenge: A Prospective Randomised Trial - Needle, Meet Your Match

Important dates

Study start
2025
Primary completion
2026
Study completion
2026
First posted
Jun 1, 2026
Registry last updated
Jun 1, 2026

OpenTrials presents study information sourced from ClinicalTrials.gov. The official registry record should be consulted for the latest information.

View the official ClinicalTrials.gov record (opens in a new tab)

This listing is for discovery and informational purposes only. It is not medical advice, does not guarantee that a study is recruiting, and does not determine eligibility. Contact the study team and a qualified healthcare professional when considering participation.

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