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

Completed · Phase 4

Conditions studied: Glaucoma, Sedation

In brief

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.

Key facts

Study ID

NCT00967694

Run by

Oregon Health and Science University

People needed

20

Starts

2009-08-01

Expected to finish

2011-10-01

Last updated by the study team

2014-09-23

Who can join

Age: 18 and older, up to 40. Sex: any. Healthy volunteers: accepted.

You may qualify if…

• 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)

You may not qualify if…

• 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

Where it is running

• OHSU — Portland, Oregon, United States

Full record on ClinicalTrials.gov

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