Warning on Using Nitrous Oxide After Intraocular Gas Injection
FDA Patient Safety News: Show #4, May 2002

Here's another example of patients being endangered because of an interaction between two devices or treatments, even though each one is working properly. This involves inert gases that are injected into the eye to treat retinal tears and detachments. If patients who have received this treatment later receive nitrous oxide in dental or surgical procedures, severe eye injury, and even blindness, can occur. The two gases are perfluoropropane (PFP) and sulfur hexafluoride. They're distributed by Alcon and Escalon.

These gases are injected directly into the vitreous cavity, where they produce a gas bubble that can help heal retinal tears. The gas bubble gradually diffuses from the eye over a period of about one to eight weeks.

While the gas bubble is still in the eye, patients must be careful to avoid activities that can increase intraocular pressure, such as flying in an airplane or making other significant changes in altitude. It's the increase in pressure that causes the eye injury. The same effect can occur if a patient with one of these intraocular gas bubbles receives nitrous oxide as an anesthetic during a dental or surgical procedure.

So if you use PFP or sulfur hexafluoride, it's important to warn these patients that until the bubble has diffused out of the eye, which could take up to eight weeks, they can not have nitrous oxide. To help do that, you can get special cards to give patients, explaining the situation. There's also a bracelet the patient can wear, warning any health care provider that might treat this patient about not using nitrous oxide.

And remember, if you're at the other end of this process—that is, if you use nitrous oxide in your practice—don't administer it to any patient who has one of these gas bubbles in the eye. And of course that means asking patients about previous retinal procedures.

FDA Patient Safety News is available at www.fda.gov/psn