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

This study has been completed.
Sponsor:
Collaborators:
Robert L. Bacon Medical Foundation
Research to Prevent Blindness
Information provided by (Responsible Party):
Kirk Lalwani, Oregon Health and Science University
ClinicalTrials.gov Identifier:
NCT00967694
First received: August 27, 2009
Last updated: May 3, 2012
Last verified: May 2012

August 27, 2009
May 3, 2012
August 2009
October 2011   (final data collection date for primary outcome measure)
Change in intraocular pressure during nitrous oxide sedation [ Time Frame: Before, during and after administration of nitrous oxide (45 minutes total) ] [ Designated as safety issue: No ]
Same as current
Complete list of historical versions of study NCT00967694 on ClinicalTrials.gov Archive Site
Not Provided
Not Provided
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Effect of Nitrous Oxide (N2O) on Intraocular Pressure in Healthy Volunteers
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.

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).

Interventional
Phase 4
Endpoint Classification: Efficacy Study
Intervention Model: Single Group Assignment
Masking: Single Blind (Investigator)
Primary Purpose: Diagnostic
  • Glaucoma
  • Sedation
Drug: Nitrous oxide
Nitrous oxide sedation by inhalation
Not Provided
Not Provided

*   Includes publications given by the data provider as well as publications identified by ClinicalTrials.gov Identifier (NCT Number) in Medline.
 
Completed
20
October 2011
October 2011   (final data collection date for primary outcome measure)

Inclusion Criteria:

  • Adults aged 18-40
  • ASA 1-2
  • 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
Both
18 Years to 40 Years
Yes
Contact information is only displayed when the study is recruiting subjects
United States
 
NCT00967694
IRB00005402
No
Kirk Lalwani, Oregon Health and Science University
Oregon Health and Science University
  • Robert L. Bacon Medical Foundation
  • Research to Prevent Blindness
Principal Investigator: Kirk Lalwani, MD,FRCA,MCR Oregon Health and Science University
Oregon Health and Science University
May 2012

ICMJE     Data element required by the International Committee of Medical Journal Editors and the World Health Organization ICTRP