(Reprinted with permission from the American Society of Anesthesiologists, Inc. ASA Newsletter, September 2004, Volume 68, issue 9.)

The Committee on Equipment and Facilities has developed guidelines for determining if an anesthesia machine is obsolete and therefore not be used.

The following is an abbreviated version of the guidelines. The complete text is available on the ASA Web site at: www.ASAhq.org/publicationsAndServices/machineobsolescense.pdf. Please share these guidelines with your colleagues and government and credentialing organizations, especially those that regulate office surgery.

Guidelines for Determining Anesthesia Machine Obsolescence

The following guidelines have been developed to assist anesthesia providers and other health care personnel, administrators and regulatory bodies in determining when an anesthesia machine is obsolete. Anesthesia equipment can become obsolete if essential components wear out and cannot be replaced. Equipment also may become obsolete as a result of changes in medical practices, changes in the training and experience of anesthesia providers and/or development of new safety features.

An anesthesia machine should not be considered obsolete solely because it has reached an arbitrary age. Furthermore a machine should not be expected to meet all of the performance and safety requirements specified in United States or international equipment standards published after the machine was manufactured. It is the responsibility of the anesthesia provider to determine if a machine’s failure to meet newer standards represents a sufficient threat to patient safety to render the machine obsolete.

The ASA Standards for Basic Anesthetic Monitoring (www.ASAhq.org/publicationsAndServices/standards/02.pdf#2) apply to all anesthesia care. The equipment necessary to accomplish this monitoring may be integral to the anesthesia machine or separate from it. The criteria for defining obsolescence that are described in this document relate only to the gas and vapor delivery portion of the machine. Integral monitors (e.g., electrocardiograph, oxygen monitor, blood pressure monitor, pulse oximeter, carbon dioxide monitor) should be considered separately and are not addressed in these guidelines.

These guidelines apply only to existing machines and are not intended to unduly restrict the design of machines in the future. It is recognized that future machines may incorporate different safety mechanisms than those in use today to accomplish the same goals.

The guidelines are divided into absolute and relative criteria. Only the absolute criteria are presented here. If any of these criteria are present, the machine is by definition obsolete. The relative criteria are related to practice conditions. These relative criteria and the rationale for all the criteria can be found on the ASA Web site links mentioned above. These criteria should be shared with all component societies and other groups interested in anesthesia machine safety.

Absolute Criteria

An anesthesia machine shall be considered to be obsolete if any of the following criteria apply:

I. Lack of essential safety features

A. Minimum oxygen ratio device (O2/N2O proportioning system) on a machine that can deliver nitrous oxide;

B. Oxygen failure safety (“fail-safe”) device;

C. Oxygen supply pressure failure alarm;

D. Vaporizer interlock device;

Note: This does not apply to an anesthesia machine that allows only one vaporizer to be mounted at a time.

Note: It may be possible to add a vaporizer interlock device to a machine.

E. Pin Index Safety System;

F. Noninterchangeable, gas-specific (e.g., Diameter Index Safety System [DISS]) connectors on the gas pipeline inlets.

II. Presence of Unacceptable Features

A. Measured flow (flowmeter-controlled) vaporizers (e.g., Copper Kettle, Verni-trol);

B. More than one flow control knob for a single gas delivered to the common gas outlet of the machine;

Note: This does not include the flow control knob for an auxiliary oxygen flowmeter.

C. Vaporizer with rotary concentration dial such that the anesthetic vapor concentration increases when the dial is turned clockwise;

Note: It may be possible to replace an unacceptable vaporizer without replacing the entire machine.

D. Connection(s) in scavenging system of the same (i.e., 15-mm or 22-mm) diameter as a breathing system connection.

Note: It may be possible to replace an unacceptable scavenging connection without replacing the entire machine.

III. Adequate Maintenance No Longer Possible

The manufacturer or certified service personnel will not or cannot service the machine with acceptable replacement parts so that it performs within the tolerances to which it was originally designed.

Note: Although a manufacturer may declare that its own subsidiaries will no longer service, support or certify a particular machine, the essential core components of the machine may still be serviceable.

Note: Obtaining acceptable replacement parts can be a problem. In some cases, it may be possible to obtain the parts from the party who supplied them to the machine manufacturer. Alternatively such parts may be obtained from machines that have already been taken out of service.

Note: When a manufacturer declares that it will no longer provide support for a machine, responsibility is typically transferred to the user (health care facility) and/or the third party who services the machine.

When it has been determined that a machine is obsolete, it should not be placed somewhere in the facility where it might be used clinically (for example, as an oxygen delivery device). A machine that has been determined to be obsolete should either be destroyed or donated to a worthy party (e.g., zoo, laboratory or developing country). If the latter course is followed, it would be prudent to obtain legal advice about potential liability relating to the donation. Also it is prudent to ensure that the recipient possesses the infrastructure (e.g., electrical power, medical gases), access to drugs and supplies (e.g., volatile anesthetics, circuits, replacement parts), technical expertise and training to safely use the machine.

Jerry A. Dorsch, MD, is Associate Professor Emeritus at the Mayo Clinic in Jacksonville, FL.