In Reply:-Penlon vaporizers are truly compatible with the Ohmeda Selectatec (Madison, WI) back bar. If this was not true, the Food and Drug Administration (FDA) would not have licensed the Penlon vaporizer for use in the United States. Ohmeda admits that the use of a non-Ohmeda vaporizer on an Ohmeda Anaesthetic machine does not affect the machines warranty.

Selectatec back bars of Ohmeda and other manufacture from other companies are used around the world with vaporizers of Ohmeda manufacture and with vaporizers of other manufacturers, including Penlon and Draeger. This is an accepted fact and serves customers well in avoiding a monopoly of supply.

With specific reference to the issues raised

1. “Unfamiliarity with the product”: The report states that, “The anesthesia attending had not been adequately trained in use.” Such training would have great value and would be brief, because the filling system works in exactly the same way as that on the widely used Draeger Vapor and Ohmeda Tec 3 and Tec 4 vaporizers.

2. “Vaporizers design”: The overfill port would have leaked at a very obvious rate had the vaporizer been effectively leak checked. It is true that, in common with other manufacturers vaporizers, the leak would have been discovered only if the vaporizer was turned on.

3. “Anesthesia machine design”: The inclusion of a check valve in the machine originates in the requirements for such features to prevent reverse flow through “Boyles bottle”-type vaporizers. This is, in my opinion, a redundant feature that contributes to the difficulties mentioned in leak checking the Ohmeda Anaesthetic machine.

4. “Use of non-Ohmeda product on an Ohmeda machine”: It is a commercial imperative that Ohmeda, through such devices as a “Medical Device Advisory Notice,” discourages the use of non-Ohmeda vaporizers on Ohmeda machines. It is true that Ohmeda vaporizers are designed to be used on Ohmeda Anaesthetic machine back bars, but they are also sold by Ohmeda for use on other machine manufacturers' Selectatec back bars. It is also true that Penlon, Draeger, and many other manufacturers supply vaporizers that can be specified as Selectatec Back Bar compatible. The dimensions of the Selectatec system are in the public domain, therefore this is not a valid point for consideration.

The issue relating to the statement, “defeat safety features intended by the manufacturer,” is one I have heard directly from Ohmeda before. Contrary to the opinion expressed, the agent is isolated from the back bar when the Penlon vaporizer is not in use. The vaporizer uses a different method than the Ohmeda unit but is equally effective. Indeed, the Penlon method of interfacing the vaporizer to the back bar allows all the interfaces to be checked during the system leak check. The Tec 5 requires the clinician to turn on each individual vaporizer one by one.

5. “Limitations of the 1993 FDA Anesthesia Apparatus Checkout Recommendations [1]”: The limitations of the checklist are highlighted by the Ohmeda machine design. However, as acknowledged, the check recommendations instructed in the machine and the vaporizer user manuals were not applied. The results speak for themselves.

Penlon has 50 years of experience manufacturing anesthesia systems and vaporizers, and we sell our products in every major country, including the United States. Penlon's reputation is for excellence of design, superior quality, and outstanding reliability. With the current Penlon vaporizer, the Sigma Elite, Penlon succeeds in delivering state-of-the-art performance.

The problems illustrated by the report are the product of lack of training and lack of the use of recommended procedures clearly contained within product user manuals.

Craig Thompson

Marketing Manager-Anaesthesia; Penlon Ltd.; Abingdon, OX14 3PH England

United States Food and Drug Administration: Anesthesia Apparatus Checkout Recommendations. Rockville, MD, Food and Drug Administration, 1993