In Reply:-Datex-Ohmeda agrees with many of the points raised in the authors' discussion, however, additional information may be helpful.

Datex-Ohmeda anesthesia systems that incorporate the Selectatec Vaporizer Mounting System, such as the Modulus II identified in the article, were not designed to accommodate vaporizers from other manufacturers. The labeling, including the respective Operation and Maintenance manuals for both the Datex-Ohmeda vaporizers and the anesthesia systems, advises users to mount only Datex-Ohmeda Tec 4, Tec 5, and Tec 6 vaporizers on the Selectatec manifold. This point was further reinforced through a Medical Device Advisory Notice, dated January 20, 1998, mailed to healthcare facilities in the United States by Datex-Ohmeda, advising clinicians against the use of other manufacturers vaporizers with the Datex-Ohmeda Selectatec Vaporizer Mounting System.

The use of a preoperative checkout procedure is clearly supported by Datex-Ohmeda. In fact, the Operation and Maintenance manual for the Modulus II, similar to other Datex-Ohmeda anesthesia systems, includes specific preoperative checkout procedures. As stated by the authors, these procedures include a leak test that would have detected the alleged leak. However, Datex-Ohmeda believes that, if available, the specific anesthesia system preoperative checkout procedures should be used instead of the generic 1993 FDA Anesthesia Apparatus Checkout Recommendations. [1]This is supported by the FDA, as the introduction of FDA Recommendations states, “This is a guideline in which users are encouraged to modify to accommodate differences in equipment design and variations in local clinical practice. Such local modifications should have appropriate peer review. Users should refer to the operator's manual for the manufacturer's specific procedures and precautions, especially the manufacturer's low pressure leak test (step #5).”[1] 

Datex-Ohmeda does not believe that the design features of the Modulus II anesthesia system contributed to the problem. The Modulus II and its specific preoperative checkout procedures performed as intended. Datex-Ohmeda has no control over the design of these other manufacturers vaporizers that are being marketed as compatible with the Selectatec Vaporizer Mounting System. As previously stated, the Selectatec was designed only to accept Datex-Ohmeda Tec 4, Tec 5, and Tec 6 vaporizers.

Raymond T. Riddle

Director; Regulatory Affairs; Datex-Ohmeda; Madison, Wisconsin

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