Volume 8, No. 1 • Spring 1993

Danger Seen Possible from Contaminated Medical Gases

Ervin Moss, M.D.; Fred Evans; Pete Winboume


Scattered reports describing particulate matter in gas pipelines and potential bacterial contamination of medical air prompted the Anesthesia Patient Safety Foundation during its October, 1992 annual meeting to request its Committee on Technology to prepare a white paper concerning maintenance of anesthesia equipment. A subcommittee has been appointed consisting of Patrick A. Foster, M.D., Hershey Medical Center, Michael Good, M.D., University of Florida, Gainesville, and Ervin Moss, M.D., New Jersey State Society of Anesthesiologists. Their task will be the investigation, evaluation as to risk, and documentation of particulate matter in and contamination of gas lines, storage cylinders, valves, medical air dryers, and compressors. Prevention and correction of these problems would be included in any document about maintenance of anesthesia equipment.

While in recent years anesthesiologists have become aware of the mechanics of their anesthesia machines, the interfacing of monitors, and the machine to patient interface, medical gas lines (once they disappear through OR, ICU, nursery, hospital room, and emergency room walls) seem to enter a .no man’s land’ for which accountability is left to the hospital engineering department. Even the FDA, when approached with the early suspicion of potential problems, responded that their responsibility applied to the equipment or medical devices contained in the walls of the various locations to which the medical gases flowed.

APSF Involved

It is the intent of the APSF committee to make sure the anesthesia community is aware that particulate matter entering ventilators and anesthesia equipment can affect the functioning of such equipment. It is also the intent of the committee to open up the ‘no man’s land’ beyond the walls so that anesthesiologists will extend their knowledge to include the anatomy of the medical gas line system starting from the machine, through the wall, through the valves, and to the source of the gas supply. Included will be the understanding of how medical air and oxygen reach all locations throughout the hospital.

Recent reports which caused the APSF to decide to explore the issue included an incident involving the malfunction of an infant ventilator due to particulate matter contamination. After the massive fire in Kuwait, almost all the medical air systems of that country were contaminated by oil. Even medical gas lines were contaminated due to cracks in pipelines caused by explosions. Another example was the removal of 30 pounds of particulate matter from the pipelines of a 700 bed hospital in the United States. Also of interest was the report from a manufacturer of medical equipment in which 20 workers on the assembly fine were sickened by noxious fumes in the compressed air used to air clean parts before assembly. The fumes were the result of oil entering the compressor during servicing. If that compressor had supplied medical air to a nursery, the toxic fumes released could have caused serious complications.

A future edition of the APSF Newsletter will feature a report on another danger of gas within the OR: particulate matter, bacteria, and fungi pumped into the abdominal cavity in contaminated C02 during laparoscopic surgery. Dr. Douglas Ott, a gynecologist from Macon, GA, will discuss the results of his research on contamination of CO2 cylinders and the physiologic changes caused by cold and dry C02.

The APSF is the only forum within anesthesiology where industry representatives and clinicians share their expertise, and a great resource of information has become available through the cooperation of members of industry who are active in the APSF. In addition, the FDA and the JCAHO are represented on the board. As projects develop, these bodies can be most helpful in implementing any suggestions that might result.

The first material relevant to this topic is presented below:

The Health of Our Piped Medical Gas Distribution Center

by Mssrs. Fred Evans and Pete Winboume

In recent years there has been a growing awareness of and concern about the relationship between medical gas pipelines and related medical equipment malfunction. This view has been shared by various experts within related fields. A recent exchange of information has led us to the conclusion that the problem warrants further study.

It is interesting to note that medical gases constitute, by volume, the most common and the most voluminous prescription drugs administered in the hospital. However, not enough attention is paid to the packaging and the delivery network.

Medical gas systems are not difficult to design or install. Difficulties arise from the fact that designers and installers have scant knowledge of how or why these systems are utilized within the hospital.

For a number of years, certain NFPA (National Fire Protection Association) recommendations were felt to address the correct design and installation of medical gas systems. While these recommendations were a start, they did not clearly address the intent of the code, especially in the area of installation procedures.

Installation is complicated to some degree by assuming the manufacturer has supplied the correct pipe, the designer was code knowledgeable, and the interpretation of the NFPA is not confused. However, in recent years, systems that were installed prior to NFPA 99, 1990 began to present new problems. Some of these compromise patient safety and care.

Prior to NFPA 99, 1990 recommendations, the pipe brazing process did not call for a procedure using an inert gas to prevent carbon oxidation within the pipe. The carbon scale deposits from the old process loosen over time and migrate toward the areas of greatest gas flow. Such particulate contamination probably constitutes the largest single source of problems within medical gas systems.

New NFPA recommendations address this issue. It then becomes a matter of proper inspection during construction. This should be an essential part of a ‘Pipeline Certification Procedure.’ Proper certification of a system is NOT performed at the end of installation. Many end users rely on a final pipeline certification report without reading the fine print disclaiming design, labeling, solid particulate contamination, brazing, and other major abnormalities. Prevention of problems, rather than corrections, should be the cornerstone. It then follows that proper design criteria are paramount for any medical gas system.

It is not the intent of this article to address all possible design and installation flaws. Some, however, must be mentioned. The design, ” and configuration of medical air compressors create probably the second most prevalent type of problem. Moisture within the air system will result in particulate contamination and very often in growth of gram negative bacteria within the compressed air system.

When an air system has been contaminated with water, it is not a simple matter to drain and clean it; zone valve drops and other piping configurations make this extremely difficult. These areas usually act as reservoirs and support and harbor potentially infectious bacteria. For that matter, gram negative bacteria have been cultured from piped oxygen systems. How they were introduced is conjecture at this point.

If a medical air system contains any ‘abnormal odor,’ a proper inspection should be performed, and steps taken to correct the problem. Although no conclusive data exist, it cannot be of any benefit to administer ‘contaminated air’ to any patient, especially one who may be on ventilator support. These potential problems are not restricted to any particular type or make of air compressor.

New NFPA 99 recommendations will go far in correcting existing problems and if adhered to, greatly reduce patient risk. It would be well to remember also that NFPA 99 recommendations are minimum recommendations and must not be compromised. Under these new guidelines, every health care facility must institute procedures that address correction of existing pipeline problems.

Odors, particulate contaminate, copper or brass shavings, copper carbonate, iron oxide, calcium carbonate, oil, gram negative bacteria, sodium chloride, flux and other debris are all recognized contamination hazards within medical gas piping systems. Except for bacteria, it seems highly improbable that these elements could be introduced into a patient’s lungs. However, they do have a demonstrated detrimental effect on equipment to which the patient is attached:

Actual Cases

1. There have been recorded instances of trichloroethane administered to a patient, which resulted from an improperly cleaned zone valve, and an improper pipeline certification.

2. One facility experienced eight adult ventilator failures due to heavy amounts of solid particulates from the gas pipeline.

3. Numerous reports of oxygen blender failures due to solid particulates.

4. An oxygen outlet in an emergency room had a reduced flow due to solid particulate obstruction.

5. An anesthesia machine malfunctioned due to heavy amounts of contaminating solids at the inlet filter.

The contamination problem is not hopeless. The systems affected do not have to be replaced, but can be properly cleaned, decontaminated, and certified by companies which perform these functions. We believe it would be prudent to begin an update program to conform to NFPA 99 and JCAHO requirements. Patients deserve no less than an uncompromised medical gas delivery system.

Dr. Moss of the New Jersey State Society of Anesthesiologists is a Director of the APSF. Mr. Fred Evans is president of Medical Gas Management, Inc., of Bethany, OK, and Mr. Pete Winbourne is director of risk management for anesthesia programs for Health Care Insurance Services of Houston, TX.