Colonoscopy Using Nitrous Oxide- A Pilot Study in the USA


Colon cancer is the second most common cancer in men and the third most common cancer in women worldwide. The clinical objectives of administering sedation for GI endoscopy are to relieve patient anxiety and discomfort and to improve the outcome of the examination. Use of N2O could potentially provide an alternate safe and cheap option for patients who do not prefer IV sedation for colonoscopy

Study Type

  • Study Type: Interventional
  • Study Design
    • Allocation: Randomized
    • Intervention Model: Crossover Assignment
    • Primary Purpose: Treatment
    • Masking: Single (Outcomes Assessor)
  • Study Primary Completion Date: December 2020

Detailed Description

Patients who are considered low risk for anesthesia administration (ASA class <IV) receive moderate sedation with a combination of intravenous benzodiazepine and opioid medication. an alternative method of providing analgesia with "on-demand" inhalation of nitrous oxide (hereafter referred to as N2O) combined with oxygen has been postulated. Nitrous Oxide has been used for analgesia in various procedures including childbirth, general anesthesia, pediatric dentistry, bone marrow aspiration, fracture reductions, and minor surgical procedures (surgical dressings, pulmonary endoscopy, an abscess . It could potentially reduce overall costs for the procedure, in addition to providing a quicker recovery, turn over


  • Drug: Nitrous Oxide
    • Patient receiving nitrous oxide are evaluated for success of the procedure

Arms, Groups and Cohorts

  • Experimental: Nitrous Oxide
    • Patient receiving Nitrous Oxide are evaluated for success of the procedure
  • Active Comparator: IV Sedation group
    • In this group a combination of Midazolam and Fentanyl is used per endoscopic discretion

Clinical Trial Outcome Measures

Primary Measures

  • Cecal intubation rates and time of the procedure – total time and recovery
    • Time Frame: 1 to 30 minutes
    • Time required to complete the procedure and reach end of the colon

Participating in This Clinical Trial

Inclusion Criteria

Men and women, more than 18 years old Scheduled for a colonoscopy at the Endoscopy unit

Exclusion Criteria

  • High ASA risk (IV/ >)
  • History of chronic pain
  • Allergy to N2O or opioid or BDZ
  • Non-English-speaking patients
  • No consent
  • Recent head injury with impairment of consciousness or Intracranial / Middle Ear surgery within the previous 6 months with or without residual deficits.
  • Pneumothorax, air embolism
  • Decompression sickness or within 48 hours of an underwater dive
  • Severe emphysema with bullae
  • Gross abdominal distension with suspicion for bowel obstruction
  • Intoxication
  • Maxillofacial injuries (where patient unable to administer the drug using a mouthpiece/mask, or there is the risk of causing further damage to facial wounds and there may also be a significant risk of blood inhalation)
  • Patients with chronic pulmonary disease for whom an inspired oxygen concentration of more than 28% oxygen might be dangerous
  • Patients on Methotrexate
  • Where patients need assistance to hold the mask or mouthpiece.
  • Retinal surgery within the last three months
  • Any patient who does not otherwise clinically qualify for standard sedation methods (i.e., those who require general anesthesia)

Gender Eligibility: All

Minimum Age: 18 Years

Maximum Age: N/A

Are Healthy Volunteers Accepted: Accepts Healthy Volunteers

Investigator Details

  • Lead Sponsor
    • University of Arkansas
  • Provider of Information About this Clinical Study
    • Sponsor
  • Overall Official(s)
    • Benjamin Tharian, MD, MRCP, FACP, FRACP, Principal Investigator, University of Arkansas
  • Overall Contact(s)
    • Benjamin Tharian, MD, MRCP, FACP, FRACP, 501-686-7847,

Clinical trials entries are delivered from the US National Institutes of Health and are not reviewed separately by this site. Please see the identifier information above for retrieving further details from the government database.

At, we keep tabs on over 200,000 clinical trials in the US and abroad, using medical data supplied directly by the US National Institutes of Health. Please see the About and Contact page for details.