The Hazards Of Medical Gases

by Food and Drug Administration (FDA)

The popping sounds from the oxygen concentrator roused the elderly man from his sleep as fire engulfed his bed. With the help of his young granddaughter who was caring for him, the invalid managed to escape before two of the six high-pressure oxygen cylinders stored in a nearby closet exploded and burned the house down. The fire marshal investigation revealed that the oxygen concentrator malfunctioned, starting the blaze. Experts from the Food and Drug Administration, however, suspect that smoking also may have been a factor; both the man and his daughter, who lived with him, smoked cigarettes.

"My experience has been that smoking around oxygen may cause fires," says Duane Sylvia, a consumer safety officer in the Food and Drug Administration's Center for Drug Evaluation and Research. "Smoking anywhere near oxygen, even in the same room, can be extremely dangerous." FDA regulates medical gases, such as oxygen, as prescription drugs, and regulates the related delivery hardware, such as concentrators, tubing, and regulators, as medical devices.

Because of increasing reports about similar disasters involving medical gases, including some deaths, FDA is attempting to heighten both consumer and industry awareness about this specialty area of regulated products. Medical gases are the most frequently administered drugs in the United States, according to National Safety Technologies, Inc. The most commonly used include oxygen, nitrous oxide, carbon dioxide, medical air (which is used to provide a drug product to a patient), and nitrogen. These gases have a variety of medical uses, both in the home and in health-care facilities. For example, oxygen is usually administered at home to patients suffering from various respiratory conditions, such as emphysema. And surgeons use carbon dioxide to inflate the abdomen during laparoscopic surgery.

But in the last five years, FDA has received several reports of deaths and "near hits" (events in which the mistake of administering the wrong gas or contaminated gas was found in time to prevent injury), which have been traced to human error. For example, a patient died after receiving argon, a gas with a variety of industrial uses, instead of oxygen. Because maintenance personnel were not properly trained, argon was inadvertently dispensed in the hospital's main oxygen supply.

In addition, FDA has received 16 reports of aluminum regulators (valves that control the flow of a gas) burning or exploding when used with oxygen cylinders. FDA and The National Institute for Occupational Safety and Health believe that the aluminum in oxygen regulators was a major factor in both the ignition and severity of these fires, although experts say there could have been other contributing factors. Brass regulators are believed to be safer than aluminum for use with high-pressure oxygen. And even though oxygen doesn't burn, it supports combustion. A material, such as the metal in oxygen regulators or cylinders, that will not burn in air (which is only 21 percent oxygen) may burn in the presence of pure, high-pressure oxygen.

FDA's Sylvia also says that applying any lubricant, typically Vaseline or anything greasy, to medical gas apparatus in an attempt to make repairs can cause injuries and deaths. Most people don't know this, he says, since there is a natural tendency to apply some sort of oil to appliances or household equipment that are mechanically difficult to operate. But, in fact, where medical gases are concerned, this practice could be deadly. "It's extremely dangerous in the first place for companies to deliver cylinders or equipment without proper instructions and precautions," which would provide these warnings, he says, but there is no specific requirement for health-care companies to do so. "People shouldn't accept the apparatus without instructions, or use medical gases from a company that isn't registered with FDA and licensed by the state."

Christy Foreman, a biomedical engineer in FDA's Center for Devices and Radiological Health, emphasizes the importance of having all at-home medical gas equipment properly installed and regularly maintained by professionals. Pam Schweikert, a compliance officer in FDA's Office of Enforcement, agrees. Some patient manuals indicate that oxygen concentrators should be serviced every 9,000 hours, yet Schweikert says that just last year FDA issued a warning letter citing a firm for waiting as long as 30,000 hours before servicing a unit.

"Part of the problem is that the small operations [firms that provide medical gases], as well as many of the welding supply companies, haven't been brought up to industry standards," Sylvia says, "and we need to educate these companies about the many risks involved."

It's not easy to tell if a company has delivered the right gas, or if the oxygen cylinder is made with the safest material. Most people rely on the experts to assure that equipment delivered to their homes is in good working order. But there are actions consumers can take to protect themselves:

Always check the label on each high-pressure cylinder or cryogenic vessel before using a medical gas. The label should state for high-pressure cylinders, "Oxygen Compressed U.S.P.," or for liquid vessels, "Oxygen Refrigerated Liquid U.S.P." If the labels do not contain these drug names, do not use the product and call your supplier immediately.

Check to see that the high-pressure cylinders are secured in place, in an upright position, and in a well-ventilated area. Do not allow cylinders to be stored on their sides or loosely on the floor.

Always turn or open cylinder valves slowly. Opening a valve quickly can cause the valve seal or "O" ring to ignite and release dangerous gases.

Always place an oxygen concentrator in a well-ventilated area and not in a closet, back room, or garage where it might mix exhaust fumes with the medical gas.

Do not leave the unit turned on when not in use. A cannula (nose tubing) that is left in contact with a synthetic comforter, for example, could spark a fire.

Do not open an oxygen concentrator. If you detect a problem, contact your supplier immediately.

If you are presently using an oxygen regulator that contains any aluminum, replace it with a regulator made of brass. Consult the manufacturer if you don't know what material the regulator is made of.

If non-aluminum oxygen regulators are not available, contact the Center for Devices and Radiological Health, Office of Compliance, at 301-594-4659 for specific precautions when using aluminum regulators.

About the Author

www.fda.gov
FDA is A United States government body that oversees medical devices, including contact lenses, intraocular lenses, excimer lasers and eyedrops. In the US, these products must be approved by the FDA before they can be marketed.