Compressed gas cylinders.

Healthcare facilities use a variety of compressed gases that are packaged in many forms. Often, medical gases are piped to the point of use—the patient’s bedside in the intensive care unit (ICU) or a laminar flow hood in the lab. This is fine for common gases (oxygen, nitrous oxide, nitrogen, and carbon dioxide, for example) where there is a fixed or single point of recurrent use. However, sometimes a special gas mixture or, more often, a portable gas source (like oxygen for ambulatory patients) is required. The most portable package is the compressed gas cylinder. This cylinder provides a number of advantages as well as some potentially lethal disadvantages. By understanding the disadvantages, we can mitigate the risks in using compressed gas cylinders. Compressed gas cylinders are of two basic styles—refillable cylinders and single-use lecture bottles (see sidebar, next page). Refillable cylinders are the most common type found in healthcare facilities. Most of the time, the company supplying the gas owns the cylinders containing the gas that it “loans” to the healthcare facility. A cylinder is considered “empty” when the usable gas supply has been exhausted; that is, once the contents have reached a minimum pressure the cylinder is considered empty although a small volume of positively pressurized gas remains. The gas supplier exchanges the empty cylinder for a refilled one. This exchange occurs either on a regular or on an as-needed basis, depending upon the terms of the contract between the gas supplier and the facility. Occasionally, the biomed will use a lecture bottle to repressurize gas in a certain component of a medical device, such as adding sulfur hexafluoride to a tube head. Both styles come to us from outside vendors and must be disposed of differently. No matter which style one is dealing with, cylinders of compressed gas expose all those around them to a number of hazards.