Effect of Nitrous Oxide (N2O) on Intraocular Pressure in Healthy Volunteers

September 15, 2014 updated by: Kirk Lalwani, Oregon Health and Science University

Effect of N2O on Intraocular Pressure in Healthy Volunteers

The purpose of this study is to learn if breathing nitrous oxide (also known as "laughing gas") changes the pressure in a person's eyes. Some patients who need regular eye exams to measure their eye pressure often need to be put to sleep with medicine in order to complete the eye exam. Some of these medicines are known to cause changes in a person's eye pressure. Because of this, such medicines are avoided if the eye doctor needs to measure the patient's eye pressure. One medicine that is frequently used to put patients to sleep is nitrous oxide. No one really knows what effect nitrous oxide might have on a persons' eye pressure. The investigators are interested to see if nitrous oxide causes an increase, decrease, or no change in eye pressure. The investigators also want to investigate if there is a difference in the effects of nitrous oxide on eye pressure between males and females. Understanding these effects of nitrous oxide is important because during such eye exams, the eye doctor uses the pressure measurements to make important decisions about treatment and surgery options for the patient.

The investigators hypothesize that the use of inhaled nitrous oxide (N2O) will result in a decrease in IOP in healthy volunteers.

The investigators aim to determine the magnitude and duration of change, if any, in IOP caused by inhalation of N2O, and to assess if the gender of the patient has a role in this effect.

Study Overview

Status

Completed

Conditions

Intervention / Treatment

Detailed Description

An initial pre-anesthetic evaluation and physical examination will be performed by an attending anesthesiologist, and an eye exam will be performed by an attending ophthalmologist to determine suitability for inclusion according to the above criteria. Ideally the eye exam will take place immediately prior to conduction of the study. However, logistical restraints may require that the eye exam take place at a separate time/date prior to conduction of the study. IOPs will be measured by the attending ophthalmologist (B.E.) who will be blinded to the actual readings of the Tonopen by means of a small screen, and a single trained observer (E.F.) will record observations from the Tonopen. The nitrous oxide sedation will be managed by the attending anesthesiologist (K.L.). All patients will be monitored throughout using standardized monitoring (continuous EKG, non-invasive BP, and continuous pulse oximetry).

Study Type

Interventional

Enrollment (Actual)

20

Phase

  • Phase 4

Contacts and Locations

This section provides the contact details for those conducting the study, and information on where this study is being conducted.

Study Locations

  • United States
    • Oregon
      • Portland, Oregon, United States, 97239
        • OHSU

Participation Criteria

Researchers look for people who fit a certain description, called eligibility criteria. Some examples of these criteria are a person's general health condition or prior treatments.

Eligibility Criteria

Ages Eligible for Study

18 years to 40 years (Adult)

Accepts Healthy Volunteers

No

Genders Eligible for Study

All

Description

Inclusion Criteria:

  • Adults aged 18-40
  • American Society of Anesthesiologists Physical Classification System (ASA) Status 1-2
  • Nil per os (NPO) prior to study (2 hrs clear liquids, 4 hrs milk, 6 hrs light food, 8 hrs heavy/greasy food)

Exclusion Criteria:

  • Lack of volunteer consent
  • Pregnancy
  • History of features suggestive of a difficult airway on pre-anesthetic evaluation and physical examination
  • Active gastroesophageal reflux disease
  • Active obstructive sleep apnea
  • History of recent trauma
  • History of pneumothorax or lung cyst
  • History of Vitamin B12 deficiency
  • History of recent middle ear surgery (<3months)
  • Current or recent (<3 weeks) respiratory tract infection
  • Any acute illness or exacerbation of chronic illness such as asthma, chronic lung disease etc.
  • Any history of cardiac ischemia (angina), myocardial infarction, or cardiac dysrhythmia.
  • Myopia greater than -3 spherical equivalents or hyperopia greater than +3 spherical equivalents
  • History of eye surgery of any sort, including refractive surgery, cataracts, and vitrectomy
  • History of any ocular disease or infection

Study Plan

This section provides details of the study plan, including how the study is designed and what the study is measuring.

How is the study designed?

Design Details

  • Primary Purpose: Diagnostic
  • Allocation: N/A
  • Interventional Model: Single Group Assignment
  • Masking: Single

Arms and Interventions

Participant Group / Arm
Intervention / Treatment
Experimental: Nitrous oxide administration
All 20 healthy volunteers had their intraocular pressure (IOP) measured at baseline and then after 3, 6, 9, and 12 minutes of nitrous oxide administration, and then after 5, 10, and 15 minutes of breathing room air. There was therefore only one study arm, with each individual serving as their control for baseline and then intervention values of IOP measurement.
Drug: Nitrous oxide
Nitrous oxide sedation by inhalation
Other Names:
  • N2O

What is the study measuring?

Primary Outcome Measures

Outcome Measure
Time Frame
Change in Intraocular Pressure During Nitrous Oxide Sedation
Time Frame: Before, during and after administration of nitrous oxide (45 minutes total)
Before, during and after administration of nitrous oxide (45 minutes total)

Collaborators and Investigators

This is where you will find people and organizations involved with this study.

Sponsor

Oregon Health and Science University

Collaborators

Research to Prevent Blindness
Robert L. Bacon Medical Foundation

Investigators

  • Principal Investigator: Kirk Lalwani, MD,FRCA,MCR, Oregon Health and Science University

Study record dates

These dates track the progress of study record and summary results submissions to ClinicalTrials.gov. Study records and reported results are reviewed by the National Library of Medicine (NLM) to make sure they meet specific quality control standards before being posted on the public website.

Study Major Dates

Study Start

August 1, 2009

Primary Completion (Actual)

October 1, 2011

Study Completion (Actual)

October 1, 2011

Study Registration Dates

First Submitted

August 27, 2009

First Submitted That Met QC Criteria

August 27, 2009

First Posted (Estimate)

August 28, 2009

Study Record Updates

Last Update Posted (Estimate)

September 23, 2014

Last Update Submitted That Met QC Criteria

September 15, 2014

Last Verified

September 1, 2014

More Information

Terms related to this study

Keywords

Additional Relevant MeSH Terms

Other Study ID Numbers

  • IRB00005402

This information was retrieved directly from the website clinicaltrials.gov without any changes. If you have any requests to change, remove or update your study details, please contact register@clinicaltrials.gov. As soon as a change is implemented on clinicaltrials.gov, this will be updated automatically on our website as well.

Clinical Trials on Glaucoma

Clinical Trials on Nitrous oxide

Search Similar Trials

Sponsors and Collaborators

Medical Conditions

Drug Interventions

CROs by country

CROs in Qatar

Conditions

Rare Diseases

Drug Interventions

Dietary Supplements

Sponsor/Collaborators

Locations

3
Subscribe